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1

High sensitivity charge amplifier for ion beam uniformity monitor  

DOEpatents

An ion beam uniformity monitor for very low beam currents using a high-sensitivity charge amplifier with bias compensation. The ion beam monitor is used to assess the uniformity of a raster-scanned ion beam, such as used in an ion implanter, and utilizes four Faraday cups placed in the geometric corners of the target area. Current from each cup is integrated with respect to time, thus measuring accumulated dose, or charge, in Coulombs. By comparing the dose at each corner, a qualitative assessment of ion beam uniformity is made possible. With knowledge of the relative area of the Faraday cups, the ion flux and areal dose can also be obtained.

Johnson, Gary W. (Livermore, CA)

2001-01-01

2

Current feedback operational amplifiers as fast charge sensitive preamplifiers for photomultiplier read out  

Microsoft Academic Search

Fast charge sensitive preamplifiers were built using commercial current feedback operational amplifiers for fast read out of charge pulses from a photomultiplier tube. Current feedback opamps prove to be particularly well suited for this application where the charge from the detector is large, of the order of one million electrons, and high timing resolution is required. A proper circuit arrangement

A. Giachero; C. Gotti; M. Maino; G. Pessina

2011-01-01

3

Charge-sensitive poly-silicon TFT amplifiers for a-Si:H pixel particle detectors  

SciTech Connect

Prototype charge-sensitive poly-Si TFT amplifiers have been made for the amplification of signals (from an a-Si:H pixel diode used as an ionizing particle detector). They consist of a charge-sensitive gain stage, a voltage gain stage and a source follower output stage. The gain-bandwidth product of the amplifier is {approximately} 300 MHz. When the amplifier is connected to a pixel detector of 0.2 pF, it gives a charge-to-voltage gain of {approximately} 0.02 mV/electrons with a pulse rise time less than 100 nsec. An equivalent noise charge of the front-end TFT is {approximately} 1000 electrons for a shaping time of 1 {mu}sec.

Cho, G.; Perez-Mendez, V. [Lawrence Berkeley Lab., CA (United States); Hack, M.; Lewis, A. [Xerox Palo Alto Research Center, CA (United States)

1992-04-01

4

Current feedback operational amplifiers as fast charge sensitive preamplifiers for photomultiplier read out  

NASA Astrophysics Data System (ADS)

Fast charge sensitive preamplifiers were built using commercial current feedback operational amplifiers for fast read out of charge pulses from a photomultiplier tube. Current feedback opamps prove to be particularly well suited for this application where the charge from the detector is large, of the order of one million electrons, and high timing resolution is required. A proper circuit arrangement allows very fast signals, with rise times down to one nanosecond, while keeping the amplifier stable. After a review of current feedback circuit topology and stability constraints, we provide a "recipe" to build stable and very fast charge sensitive preamplifiers from any current feedback opamp by adding just a few external components. The noise performance of the circuit topology has been evaluated and is reported in terms of equivalent noise charge.

Giachero, A.; Gotti, C.; Maino, M.; Pessina, G.

2011-05-01

5

Charge-sensitive amplifier front-end with an nJFET and a forward-biased reset diode  

SciTech Connect

A new configuration of a resistorless charge sensitive preamplifier with an nJFET as an input device was tested. The dc level of the input of the amplifier was kept constant by a slightly forward-biased np junction connected between the input of the amplifier and ground. A noise level of 22 root mean square (r.m.s.) electrons is measured at 295 K and 15 r.m.s. electrons at 253 K. The dynamic behavior of the amplifier is investigated with different leakage current conditions. The technological benefits and the suitability of the front-end connection for room temperature detectors, particularly multianode drift chambers, are highlighted.

Fazzi, A. [Politecnico di Milano (Italy)] [Politecnico di Milano (Italy); Jalas, P. [Univ. of Helsinki, Espoo (Finland)] [Univ. of Helsinki, Espoo (Finland); Rehak, P. [Brookhaven National Lab., Upton, NY (United States)] [Brookhaven National Lab., Upton, NY (United States); Holl, P. [Max Planck Inst., Garching (Germany)] [Max Planck Inst., Garching (Germany)

1996-12-01

6

Longitudinal space charge amplifier  

NASA Astrophysics Data System (ADS)

Longitudinal space charge (LSC) driven microbunching instability in electron beam formation systems of X-ray FELs is a recently discovered effect hampering beam instrumentation and FEL operation. The instability was observed in different facilities in infrared and visible wavelength ranges. In this paper we propose to use such an instability for generation of vacuum ultraviolet (VUV) and X-ray radiation. A typical longitudinal space charge amplifier (LSCA) consists of few amplification cascades (drift space plus chicane) with a short undulator behind the last cascade. If the amplifier starts up from the shot noise, the amplified density modulation has a wide band, on the order of unity. The bandwidth of the radiation within the central cone is given by inverse number of undulator periods. A wavelength compression could be an attractive option for LSCA since the process is broadband, and a high compression stability is not required. LSCA can be used as a cheap addition to the existing or planned short-wavelength FELs. In particular, it can produce the second color for a pump-probe experiment. It is also possible to generate attosecond pulses in the VUV and X-ray regimes. Some user experiments can profit from a relatively large bandwidth of the radiation, and this is easy to obtain in LSCA scheme. Finally, since the amplification mechanism is broadband and robust, LSCA can be an interesting alternative to self-amplified spontaneous emission free electron laser (SASE FEL) in the case of using laser-plasma accelerators as drivers of light sources.

Schneidmiller, E. A.; Yurkov, M. V.

2013-05-01

7

Charge amplifier with bias compensation  

DOEpatents

An ion beam uniformity monitor for very low beam currents using a high-sensitivity charge amplifier with bias compensation. The ion beam monitor is used to assess the uniformity of a raster-scanned ion beam, such as used in an ion implanter, and utilizes four Faraday cups placed in the geometric corners of the target area. Current from each cup is integrated with respect to time, thus measuring accumulated dose, or charge, in Coulombs. By comparing the dose at each corner, a qualitative assessment of ion beam uniformity is made possible. With knowledge of the relative area of the Faraday cups, the ion flux and areal dose can also be obtained.

Johnson, Gary W. (Livermore, CA)

2002-01-01

8

Operational Transconductance Amplifier Based Two-Stage Differential Charge Amplifiers  

Microsoft Academic Search

\\u000a A novel approach to the design of high-performance operational-amplifier-based differential charge amplifiers is proposed.\\u000a It is based on a two-stage topology: The first stage performs a differential measurement to single ended signal conversion,\\u000a providing a common mode rejection that only depends on the matching between two resistors; the second stage filters the signal.\\u000a These novel topologies that are based on

Dinesh. B. Bhoyar; Bharati Y. Masram

2010-01-01

9

Preamplifiers and Amplifiers of Silicon Surface-Barrier Detector Pulses for Charged Particle Studies.  

National Technical Information Service (NTIS)

A small-sized charge-sensitive preamplifier, fast preamplifier and fast amplifier for energy charged-particle spectra studies by the method of fast-slow coincidences are described. To pick up a fast signal the current amplifier with the input wide-band tr...

N. N. Tkach

1976-01-01

10

Noise beating in hybrid phase-sensitive amplifier systems.  

PubMed

We investigate the effect of noise loading in a hybrid phase-sensitive amplifier system, analyzing the effect of noise beating between the signal and idler waves coupled in a parametric amplifier. Through analyzing input and output optical signal to noise ratios, we find that system performance of a phase-sensitive amplifier is 3 to 6 dB improved over a phase-insensitive amplifier, depending on the ratio of loaded noise power to that of vacuum fluctuations. PMID:24663914

Corcoran, B; Malik, R; Olsson, S L I; Lundström, C; Karlsson, M; Andrekson, P A

2014-03-10

11

New Charge Sensitive Preamplifier with a Fast Timing Signal Output.  

National Technical Information Service (NTIS)

A charge sensitive preamplifier with a fast timing output has been developed. Different from the Sherman's method which uses a low gain fast amplifier and a high gain slow amplifier in parallel as the second stage, the timing output of this preamplifier i...

S. Watanabe

1977-01-01

12

A Low Noise High Gain Bandwidth Charge Sensitive Preamplifier  

Microsoft Academic Search

The concept of the charge sensitive amplifier is discussed and a novel method for obtaining a high gain amplifier stage through the use of a positive current feedback dynamic plate load is described. It is shown that under certain conditions this type of feedback can provide increased bandwidth as well as increased low frequency gain. The schematic of a preamplifier

Jack Hahn; Ralph Mayer

1962-01-01

13

Monolithic integrated circuit charge amplifier and comparator for MAMA readout  

NASA Technical Reports Server (NTRS)

Prototype ICs for the Solar Heliospheric Observatory's Multi-Anode Microchannel Array (MAMA) have been developed; these ICs' charge-amplifier and comparator components were then tested with a view to pulse response and noise performance. All model performance predictions have been exceeded. Electrostatic discharge protection has been included on all IC connections; device operation over temperature has been consistent with model predictions.

Cole, Edward H.; Smeins, Larry G.

1991-01-01

14

Simulations of Charge Gain and Collection Efficiency from Diamond Amplifiers  

Microsoft Academic Search

A promising new concept of a diamond amplified photocathode for generation of high-current, high-brightness, and low thermal emittance electron beams was recently proposed and is currently under active development. To better understand the different effects involved, we have been developing models, within the VORPAL computational framework, to simulate secondary electron generation and charge transport in diamond. The implemented models include

D. A. Dimitrov; J. Smedley; R. Busby; J. R. Cary; I. Ben-Zvi; X. Chang; T. Rao; J. Keister; E. Muller; A. Burrill

2010-01-01

15

Low noise charge sensitive preamplifier using drain current feedback  

Microsoft Academic Search

A method of charge-sensitive amplifier feedback is described, in which the input FET drain current is controlled by the preamplifier output voltage producing stable operation. The circuit design has the benefit of eliminating the feedback resistor, thereby eliminating its parallel white and 1\\/f noise components. The circuit is simple, requiring no specialized FET designs. The FETs may remain in their

F. Olschner; J. C. Lund

1992-01-01

16

Integrated Circuit Charge Sensitive Preamplifier  

Microsoft Academic Search

An integrated circuit charge-sensitive preamplifier has been designed for use with gas filled proportional counters and\\/or silicon nuclear particle detectors. The circuit uses positive current feedback to achieve open loop voltage gains over 2000. The preamplifier noise with zero input capacitance is 1750 ion pairs (rms) which is equivalent to 14.3 kev (FWHM, silicon detector). The rms noise versus capacitance

Keith V. Warble; Norman J. Gri

1966-01-01

17

A fast low noise CMOS charge sensitive preamplifier for column parallel CCD readout  

Microsoft Academic Search

A fast, low noise charge sensitive preamplifier for column parallel CCD readout application is presented. This prototype has been implemented on a commercial CMOS 65nm process. This preamplifier consists of a two stage transconductance amplifier with capacitive feedback to accommodate two gain ranges and a second transconductance amplifier to reset the circuit. An equivalent noise charge of 37 electrons for

J. P. Walder; Peter Denes; Carl Grace; Henrik von der Lippe; Bob Zheng

2011-01-01

18

Simulations of Charge Gain and Collection Efficiency from Diamond Amplifiers  

SciTech Connect

A promising new concept of a diamond amplified photocathode for generation of high-current, high-brightness, and low thermal emittance electron beams was recently proposed and is currently under active development. To better understand the different effects involved, we have been developing models, within the VORPAL computational framework, to simulate secondary electron generation and charge transport in diamond. The implemented models include inelastic scattering of electrons and holes for generation of electron-hole pairs, elastic, phonon, and charge impurity scattering. We will discuss these models and present results from 3D VORPAL simulations on charge gain and collection efficiency as a function of primary electron energy and applied electric field. The implemented modeling capabilities already allow us to investigate specific effects and compare simulation results with experimental data.

Dimitrov, D.A.; Smedley, J.; Busby, R.; Cary, J.R.; Ben-Zvi, I.; Chang, X.; Rao, T.; Keister, J.; Muller, E.; Burrill, A.

2010-03-15

19

Implementation and analysis of an innovative digital charge amplifier for hysteresis reduction in piezoelectric stack actuators  

NASA Astrophysics Data System (ADS)

Smart actuators are the key components in a variety of nanopositioning applications, such as scanning probe microscopes and atomic force microscopes. Piezoelectric actuators are the most common smart actuators due to their high resolution, low power consumption, and wide operating frequency but they suffer hysteresis which affects linearity. In this paper, an innovative digital charge amplifier is presented to reduce hysteresis in piezoelectric stack actuators. Compared to traditional analog charge drives, experimental results show that the piezoelectric stack actuator driven by the digital charge amplifier has less hysteresis. It is also shown that the voltage drop of the digital charge amplifier is significantly less than the voltage drop of conventional analog charge amplifiers.

Bazghaleh, Mohsen; Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu; Oskouei, Reza

2014-04-01

20

Mode structure of a noiseless phase-sensitive image amplifier  

NASA Astrophysics Data System (ADS)

Optical parametric amplifiers (OPAs) configured as phase-sensitive amplifiers (PSAs) can be used for noiseless optical image amplification, generation of non-classical states of light, and, in particular, for multimode squeezed light generation. For all these applications and for effective use of the quantum properties of the multimode PSA, we need to know its independently squeezed (or amplified) eigenmodes. First we present the quantum theory of a spatially multimode traveling-wave PSA pumped by a high-power pump beam with arbitrary spatial profile. To quantitatively identify the Green's function of the PSA, we have developed a semi-analytical coupled-mode-theory of the PSA using 2D Hermite-Gaussian mode expansions of the signal- and pump-beam spatial distributions. By using Green's functions of the classical OPA, we calculate the normally ordered quadrature correlators at its output, which provide complete quantum description of the phase-sensitive OPA and enable determination of its independently squeezed eigenmodes. We find the number of the supported eigenmodes and their shapes for a spatially broadband frequency-degenerate optical parametric amplifier with elliptical Gaussian pump. We conclude by discussing our recent extensions of the coupled-mode-theory to study higher-order pump modes, compact representation of the PSA eigenmodes (especially convenient for experiments), and effect of non-zero phase mismatch on the PSA eigenmodes. We expect that the results from our model can be used for optimum mode matching in phase-sensitive image amplification and multimode squeezing generation.

Annamalai, Muthiah

21

Localization of the Cochlear Amplifier in Living Sensitive Ears  

PubMed Central

Background To detect soft sounds, the mammalian cochlea increases its sensitivity by amplifying incoming sounds up to one thousand times. Although the cochlear amplifier is thought to be a local cellular process at an area basal to the response peak on the spiral basilar membrane, its location has not been demonstrated experimentally. Methodology and Principal Findings Using a sensitive laser interferometer to measure sub-nanometer vibrations at two locations along the basilar membrane in sensitive gerbil cochleae, here we show that the cochlea can boost soft sound-induced vibrations as much as 50 dB/mm at an area proximal to the response peak on the basilar membrane. The observed amplification works maximally at low sound levels and at frequencies immediately below the peak-response frequency of the measured apical location. The amplification decreases more than 65 dB/mm as sound levels increases. Conclusions and Significance We conclude that the cochlea amplifier resides at a small longitudinal region basal to the response peak in the sensitive cochlea. These data provides critical information for advancing our knowledge on cochlear mechanisms responsible for the remarkable hearing sensitivity, frequency selectivity and dynamic range.

Ren, Tianying; He, Wenxuan; Porsov, Edward

2011-01-01

22

Source follower or charge amplifier? An experimental comparison using a detector with integrated electronics  

SciTech Connect

In spectroscopy systems where the front-end amplifier is an external circuit, charge sensitive preamplifiers have been shown to be superior in performance with respect to voltage amplifiers as the first stage of amplification. The paper studies how these two circuit configurations behave when they are integrated in high resolution semiconductor detectors of very small capacitance. This paper for the first time compares, in this new condition, the stability of amplification of the source follower with the optimum behavior of the charge preamplifier, reporting its dependence on the detector bias, on the input transistor bias, and on the operating temperature. This paper then discusses the consequent loss in linearity and resolution that a system with an integrated source follower may undergo depending on the type of reset mechanism. The point of how the instabilities of the integrated feedback capacitance limit the performance of an integrated charge amplifier is also addressed. The analysis is based on experimental results obtained with the same detector with integrated electronics used in the two different configurations.

Sampietro, M.; Fasoli, L.; Bertuccio, G. [Politecnico di Milano (Italy). Dept. di Elettronica e Informazione] [Politecnico di Milano (Italy). Dept. di Elettronica e Informazione

1996-08-01

23

Feedback stability of charge amplifiers with continuous reset through forward-biased diode junctions  

SciTech Connect

A low noise charge sensitive amplifier that does not require a feedback resistor nor an additional reset device has recently been proposed and successfully tested in several spectroscopy systems. The discharge of the leakage and signal current from the detector is performed continuously through the forward-biased gate to channel junction of the input JFET or, in general, through a diode shunting the preamplifier input. Up to now this forward-biased FET charge amplifier (FBFA) has been used only with detectors having currents limited to a few tens of pA. Recent applications of the FBFA for larger area detectors operating at room temperature with leakage current up to few nA reveals that the original feedback configuration of the FBFA is no longer stable and can show low frequency oscillations. In this work the double feedback loop of the FBFA and its stability is analyzed in detail, and a solution to the mentioned problem is found. The acceptable limit of the input current value in the original configuration of the amplifier is analytically determined, and a new configuration of the singularities of the loop gain, which guarantees stability of the FBFA response at higher input current, is proposed. Experimental tests are presented that show the critical condition of the original FBFA configuration and verify the feasibly of the new proposed solution.

Fasoli, L.; Fiorini, C.; Bertuccio, G. [Politecnico di Milano (Italy). Dipt. di Elettronica e Informazione] [Politecnico di Milano (Italy). Dipt. di Elettronica e Informazione

1996-08-01

24

In-line phase sensitive amplifier based on PPLN waveguides.  

PubMed

We demonstrate a ?(2)-based in-line PSA with a carrier-recovery and phase-locking system for a phase shift keying (PSK) signal. By doubling the signal phase using a wavelength conversion technique, the carrier was recovered from a PSK signal. The carrier phase was synchronized to a local oscillator using optical injection locking. Phase sensitive amplification with a wide phase sensitive dynamic range of 20 dB was achieved using degenerate parametric amplification in a periodically poled LiNbO(3) (PPLN) waveguide. The phase regeneration effect was examined for a degraded signal by means of constellation analyses and bit-error rate measurements. The in-line PSA also operated successfully as a repeater amplifier in a 160 km fiber link without a power penalty. Finally, we demonstrate the regeneration of non-linear impairments induced by fiber non-linearity. PMID:23736428

Umeki, Takeshi; Asobe, Masaki; Takenouchi, Hirokazu

2013-05-20

25

Implementation and analysis of an innovative digital charge amplifier for hysteresis reduction in piezoelectric stack actuators.  

PubMed

Smart actuators are the key components in a variety of nanopositioning applications, such as scanning probe microscopes and atomic force microscopes. Piezoelectric actuators are the most common smart actuators due to their high resolution, low power consumption, and wide operating frequency but they suffer hysteresis which affects linearity. In this paper, an innovative digital charge amplifier is presented to reduce hysteresis in piezoelectric stack actuators. Compared to traditional analog charge drives, experimental results show that the piezoelectric stack actuator driven by the digital charge amplifier has less hysteresis. It is also shown that the voltage drop of the digital charge amplifier is significantly less than the voltage drop of conventional analog charge amplifiers. PMID:24784651

Bazghaleh, Mohsen; Grainger, Steven; Cazzolato, Ben; Lu, Tien-Fu; Oskouei, Reza

2014-04-01

26

Miniature, Low Power Charge Sensitive Preamplifier.  

National Technical Information Service (NTIS)

The results of the tests of a new miniature micro-power charge sensitive preamplifier for processing the pulses from silicon surface barrier detectors are presented. This inexpensive preamplifier is compared with two other types which are not suitable for...

S. Watnick N. Latner

1982-01-01

27

A Low-Noise Charge Sensitive Preamplifier for Semiconductor Detectors Using Paralleled Field-Effect-Transistors  

Microsoft Academic Search

The use of a 2N3823 or a 2N3819 (the Silex equivalent of the 2N3823) field-effect transistor (FET) has led to the design of an improved charge sensitive preamplifier. The amplifier has provisions for paralleling FET's in the input stage which gives considerable improvement in the resolution vs capacitance slope over single FET's. Measured resolution of the amplifier temperature was 0.53

K. F. Smith; J. E. Cline

1966-01-01

28

Design of a charge sensitive preamplifier on high resistivity silicon  

SciTech Connect

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the feedback loop. The output stage of the preamplifier can drive a load up to 20pF. The power dissipation of the preamplifier is 13mW. The amplifying elements are ''Single Sided Gate JFETs'' developed especially for this application. Preamplifiers connected to a low capacitance anode of a drift type detector should achieve a rise time of 20ns and have an equivalent noise charge (ENC), after a suitable shaping, of less than 50 electrons. This performance translates to a position resolution better than 3..mu..m for silicon drift detectors. 6 refs., 9 figs.

Radeka, V.; Rehak, P.; Rescia, S.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Strueder, L.; Kemmer, J.

1987-01-01

29

Design of a charge sensitive preamplifier on high resistivity silicon  

SciTech Connect

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the feedback loop. The output stage of the preamplifier can drive a load up to 20rhoF. The power dissipation of the preamplifier is 13mW. The amplifying elements are ''Single Sided Gate JFETs'' developed especially for this application. Preamplifiers connected to a low capacitance anode of a drift type detector should achieve a rise time of 20ns and have an equivalent noise charge (ENC), after a suitable shaping, of less than 50 electrons. This performance translates to a position resolution better than 3..mu..m for silicon drift detectors.

Radeka, V.; Rehak, P.; Rescia, S.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Struder, L.; Kemmer, J.

1988-02-01

30

Miniature, low power charge sensitive preamplifier  

Microsoft Academic Search

The results of the tests of a new miniature micro-power charge sensitive preamplifier for processing the pulses from silicon surface barrier detectors are presented. This inexpensive preamplifier is compared with two other types which are not suitable for our laboratory requirements for portable instrumentation.

S. Watnick; N. Latner

1982-01-01

31

Miniature, low power charge sensitive preamplifier  

SciTech Connect

The results of the tests of a new miniature micro-power charge sensitive preamplifier for processing the pulses from silicon surface barrier detectors are presented. This inexpensive preamplifier is compared with two other types which are not suitable for our Laboratory requirements for portable instrumentation.

Watnick, S.; Latner, N.

1982-09-01

32

HYBRID DC ACCURATE CHARGE AMPLIFIER FOR LINEAR PIEZOELECTRIC POSITIONING  

Microsoft Academic Search

Abstract: Piezoelectric transducers are known,to exhibit l ess hysterisis when,driven with current or charge rather than voltage. Despite this advanta ge, such methods have found little practical application due to the poor low frequency response of present current and charge driver designs. This paper introduces a new circuit topology free from low-frequency drift and DC load offsets. The hybrid load

Andrew J. Fleming; S. O. Reza Moheimani

33

A simple charge sensitive preamplifiers for experiments with a small number of detector channels  

Microsoft Academic Search

We present a Charge Sensitive Preamplifiers, CSP, based on a very simple design. The CSP consists of an input transistor and a Differential Amplifier, DA, in the second stage. The circuit does not make use of a cascode connection to load the input transistor, to minimize the supply voltage, with a consequent reduction of power dissipation. In addition, only two

Claudio Arnaboldi; Gianluigi Pessina

2007-01-01

34

Investigation of Charge Gain in Diamond Electron Beam Amplifiers Via 3D Simulations  

Microsoft Academic Search

A promising new concept of a diamond amplified photocathode for generation of high-current, high-brightness, and low thermal emittance electron beams was recently proposed and is currently under active development. To better understand the different effects involved in the generation ofelectron beams from diamond, we have been developing models (within the VORPAL computational framework) to simulate secondary electron generation and charge

R. Busby; T. Rao; D. A. Dimitrov; J. R. Cary; I. Ben-Zvi; X. Chang; J. Keister; E. Muller; J. Smedley; Q. Wu

2009-01-01

35

Charge sensitive preamplifier and pulse shaper using CMOS process for germanium spectroscopy  

Microsoft Academic Search

The authors have developed a low noise, low power charge sensitive amplifier and pulse shaping circuit. The application is for a double-sided germanium strip detector, nominally providing 50 independent spectroscopy channels. An array of these detectors would provide significant improvements in imaging, spectroscopy and sensitivity for space-based gamma-ray astronomy. The key features of these electronics are low noise, very low

R. A. Kroeger; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; M. D. Allen; G. T. Alley; C. L. Britton; L. C. Clonts; M. N. Ericson; M. L. Simpson

1995-01-01

36

Charge sensitive preamplifier and pulse shaper using CMOS process for germanium spectroscopy  

Microsoft Academic Search

We have developed a low noise, low power charge sensitive amplifier and pulse shaping circuit. Our application is for a double-sided germanium strip detector, nominally providing 50 independent spectroscopy channels. An array of these detectors would provide significant improvements in imaging, spectroscopy, and sensitivity for space-based gamma-ray astronomy. The key features of these electronics are low noise, very low power,

R. A. Kroeger; W. N. Johnson; R. L. Kinzer; J. D. Kurfess; S. Inderhees

1994-01-01

37

Position Sensitive Detection System for Charged Particles  

SciTech Connect

The position sensitive detection system presented in this work employs the Anger logic algorithm to determine the position of the light spark produced by the passage of charged particles on a 170 x 170 x 10 mm3 scintillator material (PILOT-U). The detection system consists of a matrix of nine photomultipliers, covering a fraction of the back area of the scintillators. Tests made with a non-collimated alpha particle source together with a Monte Carlo simulation that reproduces the data, suggest an intrinsic position resolution of up to 6 mm is achieved.

Coello, E. A. [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Favela, F. [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Curiel, Q. [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Chavez, E [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Huerta, A. [Instituto de Fisica, Univ. Nacional Autonoma de Mexico; Varela, A. [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Mexico; Shapira, Dan [ORNL

2012-01-01

38

Phase-Sensitive Detection and the Back-Action Evasion of Amplifier Force Noise  

NASA Astrophysics Data System (ADS)

Limitations on the sensitivity for detecting a weak classical force acting on a harmonic oscillator are imposed by the quantum mechanical properties associated with a "standard" amplitude-and-phase measurement and, classically, by the back reaction noise associated with the finite noise temperature of the amplifier used to process the measurement. These are known as the "standard quantum limit" and the "standard amplifier limit", respectively. We present the theoretical motivation behind the quest to circumvent these limits, and examine a single -transducer back-action evading measurement scheme designed to perform a phase-sensitive coupling to the oscillator, with the concomitant circumvention of the standard amplifier limit via the "squeezing" of amplifier back reaction noise. The applicability of squeezing in the detection of gravitational radiation is explored via the dependence of detection sensitivity on the physical temperature and quality factor of the resonant -bar gravitational radiation antenna, on the noise temperature of the amplifier, and on the squeezing factor of the back -action evading measurement; the success of back-action evasion in improving upon the optimum amplitude-and-phase detection sensitivities depends critically upon these parameters. Using the LSU superconducting dual-cavity accelerometer as a test platform, we present direct evidence for the establishment of a phase-sensitive coupling to an oscillator, along with a variety of indirect corroborating evidence. This data indicates that our phase-sensitive measurement scheme is indeed more sensitive to one component of the oscillator than to the other component. We also present the first evidence for the existence of back-action evasion of amplifier back reaction noise. We show theoretical expectations and experimental results for the dependence of squeezing on: input signal phases, amplitudes, and frequencies; amplifier back reaction levels; background noise; mechanical oscillator frequency; and coherent carrier contribution at the cavity resonance frequency. Squeezing factors of up to fifteen were achieved by our back-action evading measurement scheme.

Spetz, Gary W.

39

Generation of coherent broadband photon pulses with a cascaded longitudinal space-charge amplifier.  

PubMed

The longitudinal space-charge amplifier has been recently proposed by Schneidmiller and Yurkov as an alternative to the free-electron laser instability for the generation of intense broadband radiation pulses [Phys. Rev. ST Accel. Beams 13, 110701 (2010)]. In this Letter, we report on the experimental demonstration of a cascaded longitudinal space-charge amplifier at optical wavelengths. Although seeded by electron beam shot noise, the strong compression of the electron beam along the three amplification stages leads to emission of coherent undulator radiation pulses exhibiting a single spectral spike and a single transverse mode. The on-axis gain is estimated to exceed 4 orders of magnitude with respect to spontaneous emission. PMID:23848882

Marinelli, A; Hemsing, E; Dunning, M; Xiang, D; Weathersby, S; O'Shea, F; Gadjev, I; Hast, C; Rosenzweig, J B

2013-06-28

40

Noise Minimization of MOSFET Input Charge Amplifiers Based on and Models  

Microsoft Academic Search

The optimization of the noise performance of integrated complementary metal-oxide semiconductor (CMOS) charge amplifiers is studied in detail considering accurate 1\\/f noise modeling for the input metal-oxide semiconductor field-effect transistor (MOSFET) biased in a strong inversion-saturation region. This paper aims to generalize and correct previously published analyses which have been based on two limiting and sometimes not applicable assumptions: a

Giuseppe Bertuccio; Stefano Caccia

2009-01-01

41

A Charge Integrating Amplifier Operated at Low Temperature for Near-Infrared Low-Level Light  

NASA Astrophysics Data System (ADS)

A convenient InGaAs charge integrating amplifier was fabricated working at the temperature of -60°C without using liquid nitrogen. The temperature of -60°C was easily achieved using a commercial cooler. The minimum detectable power of 10-13W (NEP 2×10-13W/Hz1/2) was accomplished. The spectrum of singlet oxygen from Rose-Bengal was measured successfully.

Mizumoto, Iwao; Suzuki, Nobutaka

42

Neutron cross section sensitivity for minor actinide transmutation in energy amplifier systems  

Microsoft Academic Search

The nuclear data sensitivity in 3D Monte Carlo burnup calculations of minor actinide transmutation in Energy Amplifier Systems is assessed. Ansaldo Nucleare’s 80MWth Energy Amplifier Demonstration Facility (EADF) design serves as a technical and geometrical platform for the analysis. The accelerator-driven EADF is a fast, subcritical system based on classical MOX-fuel technology and on molten lead–bismuth eutectic cooling. For Monte

Marcus Dahlfors; Yacine Kadi; Adonai Herrera-Martķnez

2007-01-01

43

Cyclodextrin carriers of positively charged porphyrin sensitizers.  

PubMed

The cationic sensitizer 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP) forms supramolecular complexes with native, per-methylated, sulfonated and dimethyl-sulfonated cyclodextrins (CDs). Binding interactions were proved by NMR, mass spectra, capillary zone electrophoresis, UV-Vis and fluorescence spectroscopy. The 2D-NMR experiments on native CDs indicate that the interaction of TMPyP with the external CD surface is the dominant binding mode. The high binding affinity of TMPyP towards sulfonated CDs is due to electrostatic interactions. Binding is accompanied by an increase of the TMPyP basicity. Whereas betaCD does not affect the lifetime of the TMPyP triplet states, binding with sulfonated CDs causes the protonation of the TMPyP triplet states even in neutral solution. The diprotonated anionic sensitizer 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPSH(2)(2+)) forms host-guest complexes with native betaCD and gammaCD, similarly as in its non-protonated state. The positive charge of pyrrole nitrogen atoms does not significantly influence the mode of the interaction. In contrast to TMPyP, the lifetimes of the triplet states of bound TPPSH(2)(2+) to native CDs increase. PMID:19707685

Mosinger, Jirķ; Slavetķnskį, Lenka; Lang, Kamil; Coufal, Pavel; Kubįt, Pavel

2009-09-21

44

DNA Biosensor with High Sensitivity Amplified by Gold Nanoparticles  

Microsoft Academic Search

A biosensor based on quartz crystal microbalance (QCM) using 50 nm gold nanoparticles as the amplification probe for DNA detection was reported in this paper. It had been found that a DNA detection sensitivity of 10-14 M could be obtained, which was higher than what has been ever reported using the same method. In the curve of weight increase (?m)

H. Q. Zhao; L. Lin; J. R. Li; J. A. Tang; M. X. Duan; L. Jiang

2001-01-01

45

Photophysical, amplified spontaneous emission and charge transport properties of oligofluorene derivatives in thin films.  

PubMed

We investigate the photophysical and amplified spontaneous emission properties of a series of monodisperse solution-processable oligofluorenes functionalized with hexyl chains at the C9 position of each fluorene unit. Thin films of these oligofluorenes are then used in organic field-effect transistors and their charge transport properties are examined. We have particularly focused our attention on the influence of oligofluorene length on the absorption and steady-state fluorescence spectra, on the HOMO/LUMO energy levels, on the photoluminescence lifetime and quantum yield as well as on the amplified spontaneous emission properties and the charge carrier mobilities. Differential scanning calorimetry and X-ray diffraction measurements demonstrate that, among all oligofluorene derivatives used in this study, only the structure and morphology of the pentafluorene film is significantly modified by a thermal treatment above the glass transition temperature, resulting in a 9 nm blue-shift of the fluorescence spectrum without significant changes in the photoluminescence quantum yield and in the amplified spontaneous emission threshold. In parallel, hole field-effect mobility is significantly increased from 8.6 × 10(-7) to 3.8 × 10(-5) cm(2) V(-1) s(-1) upon thermal treatment, due to an increase of crystallinity. This study provides useful insights into the morphological control of oligofluorene thin films and how it affects their photophysical and charge transport properties. Moreover, we provide evidence that, because of the low threshold, the tunability of the amplified spontaneous emission and the photostability of the films, these oligofluorenes are promising candidates for organic solid-state laser applications. PMID:25005146

Choi, E Y; Mazur, L; Mager, L; Gwon, M; Pitrat, D; Mulatier, J C; Monnereau, C; Fort, A; Attias, A J; Dorkenoo, K; Kwon, J E; Xiao, Y; Matczyszyn, K; Samoc, M; Kim, D-W; Nakao, A; Heinrich, B; Hashizume, D; Uchiyama, M; Park, S Y; Mathevet, F; Aoyama, T; Andraud, C; Wu, J W; Barsella, A; Ribierre, J C

2014-07-23

46

Phase-sensitive detection and the back-action evasion of amplifier force noise  

NASA Astrophysics Data System (ADS)

Limitations on the sensitivity for detecting a weak classical force acting on a harmonic oscillator are imposed by the quantum mechanical properties associated with a standard amplitude-and-phase measurement and, classically, by the back reaction noise associated with the finite noise temperature of the amplifier used to process the measurement. These are known as the standard quantum limit and the standard amplifier limit, respectively. The theoretical motivation behind the quest to circumvent these limits is presented, and a single-transducer back-action evading measurement scheme designed to perform a phase-sensitive coupling to the oscillator is examined, with the concomitant circumvention of the standard amplifier limit via the squeezing of amplifier back reaction noise. The applicability of squeezing in the detection of gravitational radiation is explored via the dependence of detection sensitivity on the physical temperature and quality factor of the resonant-bar gravitational radiation antenna, on the noise temperature of the amplifier, and on the squeezing factor of the back-action evading measurement; the success of back-action evasion in improving upon the optimum amplitude-and-phase detection sensitivities depends critically upon these parameters.

Spetz, G. W.

1985-12-01

47

Design Criteria for the Optimization of Hybrid Charge-Sensitive Preamplifiers for High Resolution ?-Ray Spectroscopy  

Microsoft Academic Search

Design criteria for the optimization of hybrid charge-sensitive preamplifiers for germanium high resolution ?-ray detectors are presented. In particular we studied the optimization of the Transimpedance Amplifier (T.A.) following the input JFET and realized with Bipolar Junction Transistors. Our aim was to highlight and adjust the key parameters of the T.A. in order to maximize the loop gain of the

F. Zocca; A. Pullia

2006-01-01

48

A simple method for rise-time discrimination of slow pulses from charge-sensitive preamplifiers  

Microsoft Academic Search

Performance of a simple method of particle identification via pulse rise-time discrimination is demonstrated for slow pulses from charge-sensitive preamplifiers with rise times ranging from 10 to 500ns. The method is based on a comparison of the amplitudes of two pulses, derived from each raw preamplifier pulse with two amplifiers with largely differing shaping times, using a fast peak-sensing ADC.

Jan Tõke; Michael J. Quinlan; Wojtek Gawlikowicz; W. Udo Schröder

2008-01-01

49

A simple method for rise-time discrimination of slow pulses from charge-sensitive preamplifiers  

Microsoft Academic Search

Performance of a simple method of particle identification via pulse rise-time discrimination is demonstrated for slow pulses from charge-sensitive preamplifiers with rise times ranging from 10 to 500 ns. The method is based on a comparison of the amplitudes of two pulses, derived from each raw preamplifier pulse with two amplifiers with largely differing shaping times, using a fast peak-sensing

Jan Tõke; Michael J. Quinlan; Wojtek Gawlikowicz; W. Udo Schröder

2008-01-01

50

Improvement in the sensitivity of microfluidic ELISA through field amplified stacking of the enzyme reaction product.  

PubMed

In this article, we demonstrate a novel approach to enhancing the sensitivity of enzyme-linked immunosorbent assays (ELISA) through pre-concentration of the enzyme reaction product (resorufin/4-methylumbelliferone) in free solution. The reported pre-concentration was accomplished by transporting the resorufin/4-methylumbelliferone molecules produced in the ELISA process towards a high ionic-strength buffer stream in a microfluidic channel while applying a voltage drop across this merging region. A sharp change in the electric field around the junction of the two liquid streams was observed to abruptly slow down the negatively charged resorufin/4-methylumbelliferone species leading to the reported pre-concentration effect based on the field amplified stacking (FAS) technique. It has been shown that the resulting enhancement in the detectability of the enzyme reaction product significantly improves the signal-to-noise ratio in the system thereby reducing the smallest detectable analyte concentration in the ELISA method. Applying the above-described approach, we were able to detect mouse anti-BSA and human TNF-? at concentrations nearly 60-fold smaller than that possible on commercial microwell plates. For the human TNF-? sample, this improvement in assay sensitivity corresponded to a limit of detection (LOD) of 0.102pg mL(-1) using the FAS based microfluidic ELISA method as compared to 7.03pg mL(-1) obtained with the traditional microwell plate based approach. Moreover, because our ELISAs were performed in micrometer sized channels, they required sample volumes about two orders of magnitude smaller than that consumed in the latter case (1?L versus 100?L). PMID:24439502

Giri, Basant; Dutta, Debashis

2014-01-31

51

Wide-Band Low-Noise Charge Sensitive Preamplifier  

Microsoft Academic Search

This paper presents the design considerations and experimental characteristics of a transistorized charge-sensitive preamplifier that has a noise line-width significantly lower than that of the best vacuum-tube preamplifiers, and a high gain-bandwidth product which allows stabilization of the charge gain against detector capacitance fluctuations over a wide range of pulse-shaping time-constants. The open-loop gain of both the input charge-sensitive section

T. V. Blalock

1966-01-01

52

Luminescence of charge transfer sensitizers anchored to metal oxide nanoparticles  

Microsoft Academic Search

The photoluminescence (PL) properties of inorganic charge transfer sensitizers anchored to nanometer sized metal oxide particles are presented. The charge transfer sensitizers are inorganic coordination compounds such as ruthenium tribipyridine, Ru(bpy)2+3, which have long lived metal-to-ligand charge transfer (MLCT) excited states. The metal oxides are insulators or semiconductor materials in the form of powders, colloidal solutions, and porous nanocrystalline films.

Todd A. Heimer; Gerald J. Meyer

1996-01-01

53

Highly sensitive immunoassay of carcinoembryonic antigen by capillary electrophoresis with gold nanoparticles amplified chemiluminescence detection.  

PubMed

A noncompetitive immunoassay based on gold nanoparticles (AuNPs) amplified capillary electrophoresis (CE) chemiluminescence (CL) detection was developed for the determination of carcinoembryonic antigen (CEA). In this method, citrate-modified AuNPs were conjugated with horseradish peroxidase (HRP) labeled CEA antibody (Ab*), and incubated with limited amount of CEA antigen. CEA-Ab*-AuNPs complex and excess of Ab*-AuNPs were then separated and quantified by CE with CL detection. Highly sensitive CL detection was achieved by means of p-iodophenol (PIP) enhanced luminol-H2O2-HPR CL reaction and AuNPs amplified. Under the optimal conditions, the CE assay was accomplished within 5min. The linear range for CEA detection was 0.05-20ng/mL with a detection limit of 0.034ng/mL (signal/noise=3), which is three orders magnitude lower than that of without AuNPs amplified. The current method was successfully applied for the quantification of CEA in human serum samples. It was demonstrated that the current CE-CL AuNPs amplified noncompetitive immunoassay was sensitive and highly selective. It may serve as a tool for clinical analysis of CEA to assist in the diagnosis of cancer. PMID:23422894

Jiang, Jing; Zhao, Shulin; Huang, Yong; Qin, Guoxin; Ye, Fanggui

2013-03-22

54

Water-developable negative-tone single-molecule resists: high-sensitivity nonchemically amplified resists  

NASA Astrophysics Data System (ADS)

A water developable, non-chemically amplified, negative tone single molecule resist (tris(4-hydroxy-3,5-dimethylphenyl)sulfonium tosylate, otherwise referred to as TAS-tBoc-Ts) was synthesized, characterized, and imaged using high resolution electron beam lithography. The solubility switching in the negative tone imaging mode in this material, which occurs for no or low temperature post-exposure bakes, occurs through photolytic conversion of some fraction of the ionic PAG molecules into non-ionic photoproducts which act as strong dissolution inhibitors to the remaining unreacted molecules in the film. It was also shown that this resist system can dmonstrate positive tone chemically amplified imaging behavior under different processing conditions, i.e. when using higher temperature post-exposure bakes above 100 °C . Pure water was found to be the preferential developer as compared to conventional aqueous alkaline TMAH developers in this particular system for negative tone imaging. Under 100 keV e-beam imaging and water development, a sensitivity of 66 ?C/cm2 and contrast of 7.9 was obtained. TAS-tBoc-Ts obtained 40 nm 1:2 line-space resolutions with a low LER of 5.3 nm using electron beam imaging with no apparent swelling or residue problems. This new material and its negative tone imaging process provide a possible path forward for designing non-chemically amplified resists that may obtain higher resolutions than current chemically amplified resists at competitive sensitivities.

Lawson, Richard A.; Lee, Cheng-Tsung; Yueh, Wang; Tolbert, Laren; Henderson, Clifford L.

2008-04-01

55

DPSK Signal Regeneration With a Dual-Pump Nondegenerate Phase-Sensitive Amplifier  

Microsoft Academic Search

We demonstrate, for the first time to our knowledge, regeneration of a 42.66-Gb\\/s differential phase-shift keyed signal using a dual-pump nondegenerate four-wave-mixing-based fiber- optic parametric amplifier. The regenerative performance of the subsystem is characterized in terms of bit-error rate against nar- rowband and wideband introduced noise. While a strong receiver sensitivity improvement, up to 20 dB, is noticed against narrow-

Paola Frascella; Stylianos Sygletos; Fatima C. Garcia Gunning; Ruwan Weerasuriya; Lars Gruener-Nielsen; Richard Phelan; James O'Gorman; Andrew D. Ellis

2011-01-01

56

Stability of pulses on optical fibers with phase-sensitive amplifiers  

NASA Astrophysics Data System (ADS)

Pulse stability is crucial to the effective propagation of information in a soliton-based optical communication system. It is shown in this paper that pulses in optical fibers, for which attenuation is compensated by phase-sensitive amplifiers, are stable over a large range of parameter values. A fourth-order nonlinear diffusion model due to Kutz and co-workers is used. The stability proof invokes a number of mathematical techniques, including the Evans function and Grillakis' functional analytic approach.

Alexander, J. C.; Grillakis, M. G.; Jones, C. K. R. T.; Sandstede, B.

57

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers.  

PubMed

We investigate the transmission performance of advanced modulation formats in nonlinear regenerative channels based on cascaded phase sensitive amplifiers. We identify the impact of amplitude and phase noise dynamics along the transmission line and show that after a cascade of regenerators, densely packed single ring PSK constellations outperform multi-ring constellations. The results of this study will greatly simplify the design of future nonlinear regenerative channels for ultra-high capacity transmission. PMID:24514694

Sorokina, Mariia; Sygletos, Stylianos; Ellis, Andrew D; Turitsyn, Sergei

2013-12-16

58

An Overload Cancellation Circuit for a Charge-Sensitive Preamplifier.  

National Technical Information Service (NTIS)

An active circuit which prevents saturation due to overloads in a charge-sensitive preamplifier is presented. Cosmic rays often produce relatively bright scintillations in a detector, especially if the crystal is large. The resulting overload may saturate...

M. M. Satterfield G. R. Dyer W. J. McClain

1969-01-01

59

The design of charge-sensitive preamplifier with differential JFET input  

NASA Astrophysics Data System (ADS)

In the highly sensitive detection field, charge-sensitive amplifier is widely used in the preamplifier of detectors, however, the high voltage applied to these detectors (such as CZT nuclear detector) often make serious noise, which may influence the sensitivity of the detector. Despite the traditional passive filter circuit to eliminate the noise of the power, but if the power supply accuracy isn't high enough and the passive circuit eliminate the power supply noise is incomplete. The noise still may affect the performance of the final system. According to the need of nuclear detection and photoelectric detection, a kind of differential JFET charge-sensitive preamplifier is proposed in this paper, which eliminates the power-supply noise and Johnson noise of bias resistance. First, theoretical analysis of the traditional JFET circuit is proved and simulation of the JFET circuit is performed with ORCAD software, which prove that power-supply noise effect the preamplifier. Next, simulation of the innovative circuit is performed with ORCAD software. Finally, the fabricated circuit board is tested with avalanche photo diode (APD). It is shown that the charge-sensitive preamplifier with differential JFET input can significantly eliminate the power-supply noise and Johnson noise of resistance (both low frequency and high frequency) and realize a high sensitivity.

Xiao, Hai-jun; Zhang, Liu-qiang; Xiao, Sha-li; Li, Xian-cang; Huang, Zhen-hua

2013-09-01

60

Charge equalizing and error estimation in position sensitive neutron detectors  

NASA Astrophysics Data System (ADS)

The conventional design of detector electronics for resistive wire position sensitive neutron detectors (PSD) using of-the-shelf charge sensitive preamplifiers and gauss-pulse shaping devices causes uncertainty in spatial position and resolution due to charge equalization between both ends of the resistive PSD. This paper describes in detail charge equalization effects and their drawbacks for a PSD system design. Error estimations for a conventional design are given. Attained results should help to better understand PSD electronics design and to provide data for system optimization.

Bönisch, Sven P.; Namaschk, Bernhard; Wulf, Friedrich

2007-01-01

61

First demonstration of high-order QAM signal amplification in PPLN-based phase sensitive amplifier.  

PubMed

We demonstrate the phase sensitive amplification of a high-order quadrature amplitude modulation (QAM) signal using non-degenerate parametric amplification in a periodically poled lithium niobate (PPLN) waveguide. The interaction between the pump, signal, and phase-conjugated idler enables us to amplify arbitrary phase components of the signal. The 16QAM signals are amplified without distortion because of the high gain linearity of the PPLN-based phase sensitive amplifier (PSA). Both the phase and amplitude noise reduction capabilities of the PSA are ensured. Phase noise cancellation is achieved by using the interaction with the phase-conjugated idler. A degraded signal-to-noise ratio (SNR) is restored by using the gain difference between a phase-correlated signal-idler pair and uncorrelated excess noise. The applicability of the simultaneous amplification of multi-carrier signals and the amplification of two independent polarization signals are also confirmed with a view to realizing ultra-high spectrally efficient signal amplification. PMID:24663539

Umeki, T; Tadanaga, O; Asobe, M; Miyamoto, Y; Takenouchi, H

2014-02-10

62

Ultra-Sensitive Biological Detection via Nanoparticle-Based Magnetically Amplified Surface Plasmon Resonance (Mag-SPR) Techniques.  

National Technical Information Service (NTIS)

The report contains final reports from four separate projects co- funded by AFOSR/AOARD and Korean MEST. The four projects were (1) Ultra- Sensitive Biological Detection via Nanoparticle-Based Magnetically Amplified Surface Plasmon Resonance (Mag-SPR) Tec...

A. P. Alivisatos D. Choi J. Cheon J. Kim K. Lee

2008-01-01

63

Highly sensitive beam quality measurements on large-mode-area fiber amplifiers.  

PubMed

The beam quality of large-mode-area fiber amplifiers was investigated at the 10 W power level using a tunable ring cavity, that is also used in the laboratory system of GEO600 as a pre-mode-cleaner for mode filtering. More than 98% of the overall output power were contained within the polarized (200:1) TEM00 mode with an appropriate choice of coiling diameter. With the high sensitivity ring cavity analysis, the beam quality improvement caused by decreasing the coiling diameter was verified, while this could not be seen within conventional M2-measurements. The results are compared with the properties of single-mode fibers. PMID:19471464

Weßels, Peter; Fallnich, Carsten

2003-12-15

64

Classicalization times of parametrically amplified “Schrödinger cat” states coupled to phase-sensitive reservoirs  

NASA Astrophysics Data System (ADS)

The exact Wigner function of a parametrically excited quantum oscillator in a phase-sensitive amplifying/attenuating reservoir is found for initial even/odd coherent states. Studying the evolution of negativity of the Wigner function we show the difference between the “initial positivization time” (IPT), which is inversely proportional to the square of the initial size of the superposition, and the “final positivization time” (FPT), which does not depend on this size. Both these times can be made arbitrarily long in maximally squeezed high-temperature reservoirs. Besides, we find the conditions when some (small) squeezing can exist even after the Wigner function becomes totally positive.

Dodonov, V. V.; Valverde, C.; Souza, L. S.; Baseia, B.

2011-10-01

65

A monolithic radiation-tolerant charge-sensitive preamplifier  

Microsoft Academic Search

A monolithic charge-sensitive preamplifier based on N-channel junction field-effect transistors (NJFETs) and P-channel MOS (PMOS) has been realized for applications with multielectrode detectors in elementary particle physics. Radiation resistance tests carried out with the preamplifier exposed to gamma-rays emitted by a 60Co source have shown no degradation in equivalent noise charge up to 150 krad absorbed dose.

W. Buttler; M. Citterio; G. Lutz; P. F. Manfredi; V. Re; V. Speziali

1990-01-01

66

Optimization of the alignment sensitivity and energy stability of the NIF regenerative amplifier cavity/011  

SciTech Connect

The work to improve the energy stability of the regenerative amplifier (`regen`) for the National Ignition Facility is described. This includes a fast feed-forward system, designed to regulate the output energy of the regen by monitoring how quickly a pulse builds up over many round trips. Shot-to-shot energy fluctuations of all elements prior to (and including) the regen may be compensated for in this way, at the expense of a loss of approximately 50%. Also included is a detailed study into the alignment sensitivity of the regen cavity, with the goal of quantifying the effect of misalignment on the output energy. This is done by calculating the displacement of the eigenmode by augmenting the cavity ABCD matrix with the misalignment matrix elements, E, F. In this way, cavity misalignment issues due to thermal loading of the gain medium are investigated. Alternative cavity designs, which reduce the alignment sensitivity and therefore the energy drift over periods of continuous operation, are considered. Alterations to the amplifier head design are also considered.

Hopps, N. W., Atomic Weapons Research Establishment, Aldermaston, Great Britain

1998-06-24

67

A simple method for rise-time discrimination of slow pulses from charge-sensitive preamplifiers  

NASA Astrophysics Data System (ADS)

Performance of a simple method of particle identification via pulse rise-time discrimination is demonstrated for slow pulses from charge-sensitive preamplifiers with rise times ranging from 10 to 500 ns. The method is based on a comparison of the amplitudes of two pulses, derived from each raw preamplifier pulse with two amplifiers with largely differing shaping times, using a fast peak-sensing ADC. For the injected charges corresponding to energy deposits in silicon detectors of a few tens of MeV, a rise-time resolution of the order of 1 ns can be achieved. The identification method is applicable in particle experiments involving large-area silicon detectors, but is easily adaptable to other detectors with a response corresponding to significantly different pulse rise times for different particle species.

Tõke, Jan; Quinlan, Michael J.; Gawlikowicz, Wojtek; Schröder, W. Udo

2008-10-01

68

Investigation of e-beam sensitive negative-tone chemically amplified resists for binary mask making  

NASA Astrophysics Data System (ADS)

Negative-tone chemically amplified resists MES-EN1G (JSR), FEN-270 (Fujifilm ARCH), EN-024M (TOK) and NEB-22 (Sumitomo) were evaluated for binary mask making. The investigations were performed on an advanced tool set comprising a 50kV e-beam writer Leica SB350, a Steag Hamatech hot/cool plate module APB5000, a Steag Hamatech developer ASP5000, an UNAXIS MASK ETCHER III and a SEM LEO1560 with integrated CD measurement option. We investigated and compared the evaluated resists in terms of resolution, e-beam sensitivity, resist profile, post exposure bake sensitivity, CD-uniformity, line edge roughness, pattern fidelity and etch resistance. Furthermore, the influence of post coating delay and post exposure delay in vacuum and air was determined.

Irmscher, Mathias; Berger, Lothar; Beyer, Dirk; Butschke, Joerg; Dress, Peter; Hoffmann, Thomas; Hudek, Peter; Koepernik, Corinna; Tschinkl, Martin; Voehringer, Peter

2003-08-01

69

Charge Sensitive Preamplifier Using Field-Effect Transistors.  

National Technical Information Service (NTIS)

A general-purpose charge-sensitive Field-Effect Transistors (FET) preamplifier for use with high-resolution solid state radiation detectors is described. The germanium-equivalent noise linewidth of the preamplifier is less than 1.5 keV at room temperature...

L. V. East

1967-01-01

70

Charge-Sensitive Preamplifier for Gas Proportional Counters.  

National Technical Information Service (NTIS)

A low noise charge-sensitive preamplifier for gas proportional counters is described. In the preamplifier a simple shaping circuit was designed to improve the baseline stability at high count rates. A low thermal coefficient of the total gain was achieved...

W. Dabrowski

1985-01-01

71

A novel charge sensitive preamplifier without the feedback resistor  

Microsoft Academic Search

A novel charge sensitive preamplifier which has no resistor in parallel with the feedback capacitor is presented. No external device or circuit is required to discharge the feedback capacitor. The detector leakage and signal current flows away through the gate of the first JFET which works with its gate to source junction slightly forward biased. The DC stabilization of the

G. Bertuccio; P. Rehak; D. Xi

1992-01-01

72

Design of a charge sensitive preamplifier on high resistivity silicon  

Microsoft Academic Search

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the

V. Radeka; P. Rehak; S. Rescia; E. Gatti; A. Longoni; M. Sampietro; P. Holl; L. Struder; J. Kemmer

1988-01-01

73

Design of a charge sensitive preamplifier on high resistivity silicon  

Microsoft Academic Search

A low noise, fast charge sensitive preamplifier was designed on high resistivity, detector grade silicon. It is built at the surface of a fully depleted region of n-type silicon. This allows the preamplifier to be placed very close to a detector anode. The preamplifier uses the classical input cascode configuration with a capacitor and a high value resistor in the

V. Radeka; P. Rehak; S. Rescia; E. Gatti; A. Longoni; M. Sampietro; P. Holl; L. Strueder; J. Kemmer

1987-01-01

74

Existence and stability of N-pulses on optical fibers with phase-sensitive amplifiers  

NASA Astrophysics Data System (ADS)

The propagation of pulses in optical communication systems in which attenuation is compensated by phase-sensitive amplifiers is investigated. A central issue is whether optical fibers are capable of carrying several pieces of information at the same time. In this paper, multiple pulses are shown to exist for a fourth-order nonlinear diffusion model due to Kutz and co-workers (1994). Moreover, criteria are derived for determining which of these pulses are stable. The pulses arise in a reversible orbit-flip, a homoclinic bifurcation investigated here for the first time. Numerical simulations are used to study multiple pulses far away from the actual bifurcation point. They confirm that properties of the multiple pulses including their stability are surprisingly well-predicted by the analysis carried out near the bifurcation.

Sandstede, B.; Jones, C. K. R. T.; Alexander, J. C.

1997-02-01

75

Asymmetric MQW semiconductor optical amplifier with low-polarization sensitivity of over 90-nm bandwidth  

NASA Astrophysics Data System (ADS)

An exhausted capacity of current Passive Optical Networks has been anticipated as bandwidth-hungry applications such as HDTV and 3D video become available to end-users. To enhance their performance, the next generation optical access networks have been proposed, using optical carriers allocated within the E-band (1360-1460 nm). It is partly motivated by the low-water peak fiber being manufactured by Corning. At these wavelengths, choices for low cost optical amplifiers, with compact size, low energy consumption and feasibility for integration with other optoelectronic components are limited, making the semiconductor optical amplifiers (SOA) a realistic solution. An experimental characterization of a broadband and low polarization sensitive asymmetric multi quantum well (MQW) SOA operating in the E-band is reported. The SOA device is composed of nine 6 nm In1-xGaxAsyP1-y 0.2% tensile strained asymmetric MQW layers sandwiched between nine latticed matched 6 nm InGaAsP barrier layers. The active region is grown on an n-doped InP substrate and buried by p-doped InGaAsP layers. The SOA devices have 7-degrees tilt anti-reflected coated facets, with 2 ?m ridge width, and a cavity length of 900 ?m. For input powers of -10 dBm and -20 dBm, a maximum gain of 20 dB at 1360 nm with a polarization insensitivity under 3 dB for over 90 nm bandwidth is measured. Polarization sensitivity of less than 0.5 dB is observed for some wavelengths. Obtained results indicate a promising SOA with broadband amplification, polarization insensitivity and high gain. These SOAs were designed and characterized at the Photonics Technology Laboratory, University of Ottawa, Canada.

Nkanta, Julie E.; Maldonado-Basilio, Ramón; Abdul-Majid, Sawsan; Zhang, Jessica; Hall, Trevor J.

2013-12-01

76

Yb 3+ sensitized Er 3+ -doped waveguide amplifiers: a theoretical approach  

Microsoft Academic Search

Silicate and phosphate glass waveguide amplifiers doped with Er3+, and co-doped with Er3+\\/Yb3+ are theoretically studied. Configurations for core and core–cladding doped waveguide amplifiers are considered. It is shown that gain in the core–cladding doped amplifiers is considerably higher than core doped amplifiers. It is also shown that with input signal power up to 1 and 200mW pump power, a

A. Shooshtari; Tahar Touam; S. I. Najafi; S. Safavi-Naeini; H. Hatami-Hanza

1998-01-01

77

Space-charge limits of ion sensitive probes  

NASA Astrophysics Data System (ADS)

Ion sensitive probes (ISPs) are used to measure ion temperature and plasma potential in magnetized plasmas. Their operation relies on the difference in electron and ion Larmor radii to preferentially collect the ion species on a recessed electrode. Because of their simple two-electrode construction and optimal geometry for heat flux handling they are an attractive probe to use in the high heat flux boundary of magnetic confinement fusion experiments. However, the integrity of its measurements is rarely, if ever, checked under such conditions. Recent measurements with an ISP in the Alcator C-Mod tokamak have shown that its ion current is space-charge limited and thus its current-voltage (I-V) response does not contain information on the ion temperature. We numerically solve a 1D Vlasov-Poisson model of ion collection to determine how much bias is needed to overcome space-charge effects and regain the classic I-V characteristic with an exponential decay. Prompted by the observations of space charge in C-Mod, we have performed a survey of ISP measurements reported in the literature. Evidence of space-charge limited current collection is found on many probes, with few authors noting its presence. Some probes are able to apparently exceed the classic 1D space-charge limit because electrons can E × B drift into the probe volume, partially reducing the net ion charge; it is argued that this does not, however, change the basic problem that space charge compromises the measurement of ion temperature. Guidance is given for design of ISPs to minimize the effects of space charge.

Brunner, D.; LaBombard, B.; Ochoukov, R.; Sullivan, R.; Whyte, D.

2013-12-01

78

Low noise charge sensitive preamplifier for fast pulse counting  

Microsoft Academic Search

A charge-sensitive preamplifier has been developed for use with photomultipliers in fast photon-counting applications. The device has the following characteristics: linear response of 1.04 x 10 to the 15th mV\\/C between 10 to the -15th and 10 to the -12th C; input noise not less than 660 rms electrons, and pulse repetition rate not greater than 3 x 10 to

G. Grainger; D. K. Bedford

1978-01-01

79

A novel charge sensitive preamplifier without the feedback resistor  

Microsoft Academic Search

A novel charge sensitive preamplifier#1#1 U.S. patent pending. which has no resistor in parallel with the feedback capacitor is presented. No external device or circuit is required to discharge the feedback capacitor. The detector leakage and signal current flows away through the gate of the input JFET which works with its gate to source junction slightly forward biased. The DC

Giuseppe Bertuccio; Pavel Rehak; Deming Xi

1993-01-01

80

Charge-sensitive preamplifier IC for silicon calorimetry at colliders  

Microsoft Academic Search

Four versions of a fast monolithic charge-sensitive preamplifier (CSP) were designed using microwave BJT-JFET technology. The best one has a 3.5 ns rise time for input detector capacitance Cd = 100 pF and approximately 8 mW power dissipation for 5 V supply voltage. The ENC performance at shaping time 30 ns is 1350 e + 17 e\\/pF for Cd up

M. A. Baturitsky; V. A. Chekhovsky; I. F. Emel'yanchik; N. M. Shumeiko; I. A. Golutvin; N. I. Zamyatin; O. V. Dvornikov

1995-01-01

81

Design of a hardened fast bipolar monolithic Charge Sensitive Preamplifier  

Microsoft Academic Search

For implementation of a high-speed, radiation hardened, Charge Sensitive Preamplifier (CSP) in the monolithic 2 ?m BiCMOS technology (called HF2CMOS), the performance of the available NPN and PNP transistors were measured, before and after neutron irradiation. Also monolithic CSPs, realized with the same technology, were irradiated and investigated. The neutron irradiation effect on the base spreading resistance (rbb') of the

A. Baschirotto; R. Castello; G. Pessina; P. G. Rancoita; M. Redaelli; A. Seidman; A. Gola

1995-01-01

82

Dry-etch characteristics of chemically amplified and onium-salt-sensitized electron-beam resists  

NASA Astrophysics Data System (ADS)

Electron beam resists having high sensitivity and high resistance to dry etching are under investigation for sub-half micron device production using 5x reticle masks. The effects of dry etch process conditions on the performance of the novolac based chemically amplified AZPN114 and onium salt sensitized EPR resist have been investigated at 20 keV and 10 keV electron beam energies using an electron beam microfabricator under a range of dose, post- exposure bake, and development conditions. Linewidths in the range from 4 micrometers down to 0.2 micrometers have been evaluated. Pattern transfer to chromium on quartz was carried out in a commercial reactive ion etcher. A comprehensive series of RIE experiments were devised and analyzed using a commercial statistical software package. CD measurements on resist lines and also on chromium lines after dry etch, were carried out both in a field emission SEM and with a calibrated optical linewidth measuring system. A focused ion beam system was used to microsection selected resist lines on chromium and dry etched chromium lines for edge profile inspection.

Huq, Syed E.; Prewett, Philip D.

1994-05-01

83

An ultralow noise current amplifier based on superconducting quantum interference device for high sensitivity applications.  

PubMed

An integrated ultrahigh sensitive current amplifier based on a niobium dc superconducting quantum interference device (SQUID) has been developed. The sensor design is based on a multiturn signal coil coupled to a suitable SQUID magnetometer. The signal coil consists of 60 square niobium turns tightly coupled to a superconducting flux transformer of a SQUID magnetometer. The primary coil (pick-up coil) of the flux transformer has been suitably designed in order to accommodate the multiturn input coil. It has a side length of 10 mm and a width of 2.4 mm. In such a way we have obtained a signal current to magnetic flux transfer coefficient (current sensitivity) as low as 62 nA??(0). The sensor has been characterized in liquid helium by using a direct coupling low noise readout electronic and a standard modulated electronic in flux locked loop configuration for the noise measurements. Beside the circuit complexity, the sensor has exhibited a smooth and free resonance voltage-flux characteristic guaranteeing a reliable and a stable working operation. Considering a SQUID magnetic flux noise of S(?)(1?2) = 1.8 ??(0)?Hz(1?2) at T = 4.2 K, a current noise as low as 110 fA?Hz(1?2) is obtained. Such a value is about a factor two less than the noise of other SQUIDs of the same category. As an application, Nyquist noise measurements of integrated test resistors using the current sensing noise thermometer technique are reported. Due to its high performance such a sensor can be employed in all applications requiring an extremely current sensitivity like the readout of the gravitational wave detectors and the current sensing noise thermometry. PMID:21280839

Granata, C; Vettoliere, A; Russo, M

2011-01-01

84

Fast-Scanning Fibre-Amplified Diode Laser Pumped cw OPO for Sensitive, MultiComponent Trace Gas Detection  

Microsoft Academic Search

An 800 mW, fast scanning (100 THz\\/s), continuous wave optical parametric oscillator (3-4 mum) pumped by a fibre-amplified diode laser is used for sensitive (1.5 times 10-8 cm-1 Hz-1\\/2), multi-component trace gas detection.

S. T. Persijn; A. K. Y. Ngai; F. J. M. Harren; L. D. Lindsay; P. Gross; B. Adhimoolam; K. J. Boiler

2007-01-01

85

Global sensitivity analyses of coherent beam combining of fiber amplifier arrays by the use of numerical space filling designs  

Microsoft Academic Search

We perform sensitivity analyses on two different array configurations of coherently combined fiber amplifiers to study the impact of residual phase errors onto the combining efficiency. The arrays studied are: a square of 16 fibers and a hexagon of 19 fibers. For the hexagon, two different shaped wavefronts are studied. In this method a global analysisis performed: we modify simultaneously

Adrian Azarian; Olivier Vasseur; Baya Bennaļ; Laurent Lombard; Guillaume Canat; Véronique Jolivet; Yves Jaouėn; Pierre Bourdon

2011-01-01

86

Low polarization-sensitive asymmetric multi-quantum well semiconductor amplifier for next-generation optical access networks.  

PubMed

A broadband and low-polarization-sensitive multi-quantum well semiconductor optical amplifier with an asymmetric structure is reported for operation in the E-band wavelength range. A gain peak of 20 dB for a bandwidth of more than 50 nm is measured for both TE and TM polarizations. A maximum polarization sensitivity of 3 dB is measured for a broad wavelength range from 1340 to 1440 nm. PMID:24104677

Nkanta, Julie E; Maldonado-Basilio, Ramón; Khan, Kaiser; Benhsaien, Abdessamad; Abdul-Majid, Sawsan; Zhang, Jessica; Hall, Trevor J

2013-08-15

87

A novel charge sensitive preamplifier without the feedback resistor  

SciTech Connect

A novel charge sensitive preamplifier which has no resistor in parallel with the feedback capacitor is presented. No external device or circuit is required to discharge the feedback capacitor. The detector leakage and signal current flows away through the gate of the first JFET which works with its gate to source junction slightly forward biased. The DC stabilization of the preamplifier is accomplished by an additional feedback loop, which permits to equalize the current flowing through the forward baised gate to source junction and the current coming from the detector. An equivalent noise charge of less than 20 electrons r.m.s. has been measured at room temperature by using an input JFET with a transconductance to gate capacitance ratio of 4 mS/5.4 pF.

Bertuccio, G. [Politecnico di Milano, Milan (Italy). Dipt. di Elettronica e Informazione; Rehak, P.; Xi, D. [Brookhaven National Lab., Upton, NY (United States)

1992-07-01

88

A novel charge sensitive preamplifier without the feedback resistor  

SciTech Connect

A novel charge sensitive preamplifier which has no resistor in parallel with the feedback capacitor is presented. No external device or circuit is required to discharge the feedback capacitor. The detector leakage and signal current flows away through the gate of the first JFET which works with its gate to source junction slightly forward biased. The DC stabilization of the preamplifier is accomplished by an additional feedback loop, which permits to equalize the current flowing through the forward baised gate to source junction and the current coming from the detector. An equivalent noise charge of less than 20 electrons r.m.s. has been measured at room temperature by using an input JFET with a transconductance to gate capacitance ratio of 4 mS/5.4 pF.

Bertuccio, G. (Politecnico di Milano, Milan (Italy). Dipt. di Elettronica e Informazione); Rehak, P.; Xi, D. (Brookhaven National Lab., Upton, NY (United States))

1992-01-01

89

Rapid and sensitive microbial analysis by capillary isotachophoresis with continuous electrokinetic injection under field amplified conditions.  

PubMed

A highly sensitive capillary isotachophoresis method with LIF detection for microbial analysis was developed. This allowed the reliable analysis of Escherichia coli bacteria with a LOD of 14 cells in a sample volume of 100 ?L, or 1.35 × 10(2) cell/mL, which is 47 times lower than reported by CE-LIF and 148 times lower than CE-UV with on-line concentration. A leading electrolyte of 50 mM Tris-HCl was used while the cells were diluted in 5 mM Tris HEPES as the terminator. To facilitate detection, cells were stained with the universal nucleic acid fluorophore SYTO 9. Continuous electrokinetic injection of the cells from the terminator under field amplified conditions concentrated cells into a single peak at the leader/terminator boundary allowing quantitation by measurement of peak height. The method was applied to water collected from two local streams, with only filtration through a 5-?m syringe filter to remove large particulate matter followed by a ten times dilution in terminator, with total analysis time approximately 40 min. The detected cell numbers in the water samples by the isotachophoresis method were 3.70 × 10(5) cell/mL and 2.62 × 10(4) cell/mL, which were slightly higher than the 9.50 × 10(4) cell/mL and 1.96 × 10(4) cell/mL obtained by conventional microbiological plate counting. PMID:23208770

Phung, Sui Ching; Nai, Yi Heng; Powell, Shane M; Macka, Mirek; Breadmore, Michael C

2013-06-01

90

Compact representation of the spatial modes of a phase-sensitive image amplifier.  

PubMed

We compute the eigenmodes of a spatially-broadband optical parametric amplifier with elliptical Gaussian pump and show that the well-amplified eigenmodes can be compactly represented by a low-dimensional subspace of the first few Laguerre- or Hermite-Gaussian (LG or HG, respectively) modes of an appropriate waist size. We also show that the first few eigenmodes are well matched to single LG or HG modes. For sufficiently large pump waists, the optimum waist size of the compact basis is in the vicinity of the geometric average of the pump waist size and the inverse spatial bandwidth of the nonlinear crystal in the parametric amplifier. The use of such compact representation can greatly simplify numerical computation of the spatial eigenmodes of the amplifier and thus lead to improving the experiments on traveling-wave image amplification and spatially-broadband vacuum squeezing. PMID:24514326

Annamalai, Muthiah; Stelmakh, Nikolai; Kumar, Prem; Vasilyev, Michael

2013-11-18

91

Phase regeneration of a star-8QAM signal in a phase-sensitive amplifier with conjugated pumps.  

PubMed

We demonstrate numerically phase regeneration of a star-8QAM signal with two amplitude and four phase states in a phase-sensitive amplifier. In a dual-stage setup, two phase-conjugated idlers are generated in a first stage consisting of two fiber-optic parametric phase-insensitive amplifiers operated in highly nonlinear gain regime. These are used as pumps in the second, phase-sensitive amplification stage which enables efficient phase regeneration via a degenerate four-wave-mixing process. The latter can be operated in two different operation modes: without format conversion or with phase-shifted amplitude levels. In both regimes, we observe high phase-regeneration efficiency for all amplitude levels: the initial phase noise with 0.2 rad standard deviation is reduced by a factor of 5. PMID:24515062

Stiller, B; Onishchukov, G; Schmauss, B; Leuchs, G

2014-01-13

92

Photogeneration of charge carrier correlated with amplified spontaneous emission in single crystals of a thiophene/phenylene co-oligomer  

NASA Astrophysics Data System (ADS)

Thiophene/phenylene co-oligomers have substantial promise for the use of not only organic electronics but also organic optical devices. However, considerably less is known about the correlation between their optical and optoelectronic properties. We have investigated the charge carrier generation in 1,4-bis(5-phenylthiophen-2-yl)benzene (AC5) single crystals by flash-photolysis time-resolved microwave conductivity (TRMC) and transient absorption spectroscopy (TAS). It was found that the dependence of photocarrier generation efficiency on excitation photon density differed from that of emission efficiency once amplified spontaneous emission (ASE) and resultant spectrally narrowed emission occur upon exposure to 355 nm. In contrast, the dependences of emission and photocarrier generation efficiencies were identical when ASE was not involved at a different excitation wavelength (193 nm). An approximated analytical solution of rate equation considering ASE or singlet-singlet annihilation was applied to the experiments, exhibiting good agreement. On the basis of TRMC, TAS, and extinction coefficient of radical cation assessed by pulse radiolysis, the minimum charge carrier mobility was estimated, without electrodes, to be 0.12 cm2 V-1 s-1. The dynamics of charge carrier and triplet excited state is discussed, accompanying with examination by time-dependent density functional theory. The present work would open the way to a deeper understanding of the fate of excited state in optically robust organic semiconducting crystals.

Saeki, Akinori; Seki, Shu; Shimizu, Yasuhiro; Yamao, Takeshi; Hotta, Shu

2010-04-01

93

Development of CdTe hybrid detector with CMOS charge integration amplifier  

NASA Astrophysics Data System (ADS)

A pixelated CdTe detector module is being developed for use in X-ray imaging application. The CdTe is expected to allow higher energy detection capability because of the high atomic number. And also, high resolution imaging becomes possible with a direct conversion method in which an incident X-ray photon is directly converted to electric charges. This paper reports the first results of a 50 ?m pitch, 64×64 pixels, CdTe hybrid imaging module with CMOS charge integration readout ASIC with a flip chip bonding technique.

Fujita, K.; Matsue, K.; Ichikawa, M.; Yamamoto, K.

2011-04-01

94

Position Determination and Resolution of Position Sensitive Neutron Detectors Limited by Charge Equalization and Noise  

Microsoft Academic Search

The conventional design of detector electronics for resistive-wire position sensitive neutron detectors (PSD) using charge sensitive preamplifiers and gauss-pulse shaping devices causes uncertainty in spatial position and resolution due to charge equalization between both ends of the resistive PSD. Errors introduced by charge equalization may be in excess of limitations given by noise, linearity, dynamic range or EMI. This paper

S. P. Bonisch; B. Namaschk; F. Wulf

2006-01-01

95

Conjugated self-doped polyaniline-DNA hybrid as trigger for highly sensitive reagentless and electrochemical self-signal amplifying DNA hybridization sensing.  

PubMed

In very recent years, polyaniline or its derivatives have been adopted to efficiently immobilize probe DNA via ?-? interaction between conjugated interface and DNA bases. In this work, self-doped polyaniline (SPAN)-DNA hybrid was adopted as the platform to construct a DNA biosensor with label-free, reagentless and electrochemical self-signal amplifying features. This was achieved by the ?-? interaction between conjugated SPAN and DNA bases, also the intrinsic differences between single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The tightly cross-linked hybrid was tethered to Au electrode, which had been anchored by p-aminothiophenol (PATP) self-assembled monolayer (SAM) previously, based on the phosphoramidate bond between PATP and ssDNA. SPAN in the recognition surface exhibited well-defined redox signals under neutral conditions. Due to the intrinsic property differences between ssDNA and dsDNA, such as rigidity, ?-stacked bases, charge distribution and long-range electron transfer, SPAN-DNA underwent a major conformational change after hybridization. The redox behaviors of SPAN were modulated by DNA, which served as signals to monitor hybridization. As an example, the gene fragment related to one of the screening genes for the genetically modified plants, cauliflower mosaic virus 35S gene was satisfactorily detected with this strategy. Under optimal conditions, the dynamic range for the DNA assay was from 1.0 × 10(-14) mol L(-1) to 1.0 × 10(-8) mol L(-1) with the detection limit of 2.3 × 10(-15) mol L(-1). This work presents the construction of a recognition surface for the highly-sensitive electrochemical DNA hybridization detection via the self-signal amplifying procedure of conjugated SPAN-DNA hybrid. Unlike most signal amplifying processes using outer indicators, complex labels or other reagents, this procedure possesses simplicity and convenience. PMID:23304697

Hu, Yuwei; Yang, Tao; Li, Qianhe; Guan, Qian; Jiao, Kui

2013-02-21

96

Sensitivity of x-ray photoconductors: Charge trapping and absorption-limited universal sensitivity curves  

NASA Astrophysics Data System (ADS)

Direct conversion flat panel x-ray sensors that are currently under development are based on stabilized a-Se (a-Se alloyed with a small percentage of As and doped with Cl in the ppm amount). There are also other potential x-ray photoconductors such as PbO, PbI2, HgI2, CdTe, etc. Indeed, good x-ray images have been reported from PbI2, HgI2, and CdTe based x-ray sensors. The present article considers the x-ray sensitivity of photoconductors in terms of the following combined effects: (i) Absorption of x-rays, controlled by the linear attenuation coefficient ?(E) and energy absorption coefficient ?en(E), both x-ray photon energy E dependent. (ii) Electric field F and x-ray photon energy dependent ionization of the medium, that is, in terms of the electron and hole creation energy W+/-(E,F). (iii) The transport and trapping of charges across the photoconductor as they drift to the collecting electrodes. (iv) The electron and hole pairs are generated with an exponentially decaying distribution across the thickness of the photoconductor. We analytically solve the continuity equation by considering the drift of electrons and holes in the presence of deep traps. We derive an expression for the amount of collected charge per unit incident radiation, defined as the x-ray sensitivity S, in terms of W+/-, ?, ?en, and the normalized parameters: normalized attenuation depth and electron and hole schubwegs per unit thickness. We obtain two- and three-dimensional universal sensitivity curves that allow x-ray sensitivity of any potential x-ray photoconductor material to be determined from the normalized parameters.

Zahangir Kabir, M.; Kasap, S. O.

2002-05-01

97

Reconstruction of a multimode entangled state using a two-photon phase-sensitive linear amplifier  

NASA Astrophysics Data System (ADS)

We propose a model for the measurement of an arbitrary multimode entangled state of the cavity field using two-photon correlated emission laser. We consider two cases: (a) The modes have different frequencies and are detected separately and (b) the modes consist of two orthogonal polarization states and are detected using a single balanced homodyne detector. The basic idea is to amplify the initial multimode state such that there is no-noise in the quadrature of interest and all the noise is fed into the conjugate quadrature component. The amplified noise-free quadrature is prepared in different phases and then corresponding quadrature distribution is measured. The Wigner function of the initial multimode entangled state is then reconstructed by using inverse Radon transformation. This scheme is insensitive to the noise associated with the nonunit efficiency of the detector in the homodyne detection measurement scheme.

Ahmad, Mashhood; Qamar, Shahid; Zubairy, M. Suhail

2003-04-01

98

Bipolar pulsed reset for AC coupled charge-sensitive preamplifiers  

Microsoft Academic Search

A new type of charge restoration is described for use particularly in Ge gamma-ray spectrometers for accelerator and space physics applications. A bipolar pulsed reset technique is applied to these applications for the first time. This technique overcomes the problems introduced by the need to AC couple detectors and the fact that very large energy depositions occur due to charged

D. A. Landis; N. W. Madden; F. S. Goulding

1997-01-01

99

Sensitivity of Carbon Nanotube Transistors to a Charged Dielectric Coating  

Microsoft Academic Search

This paper investigates the electronic properties of single-walled carbon nanotube field-effect transistors (SWCNT-FETs) in which the SWCNT element is coated with a charged dielectric. The presence of remote charge on the surface of the dielectric is considered to effect carrier transport in the nanotube as a result of both carrier-scattering and gate screening. Nanotube device characteristics are simulated using the

Gary Pennington; Matthew H. Ervin; Alma E. Wickenden

2008-01-01

100

Bipolar pulsed reset for AC coupled charge-sensitive preamplifiers  

SciTech Connect

A new type of charge restoration is described for use particularly in germanium gamma-ray spectrometers for accelerator and space physics applications. A bipolar pulsed reset technique is applied to these applications for the first time. This technique overcomes the problems introduced by the need to AC couple detectors and the fact that very large energy depositions occur due to charged particles present in substantial fluxes, particularly in space. The circuit is described and experimental results are presented and discussed.

Landis, D.A.; Madden, N.M.; Goulding, F.S.

1997-07-01

101

Analysis of DNA methylation of maize in response to osmotic and salt stress based on methylation-sensitive amplified polymorphism.  

PubMed

Water stress is known to alter cytosine methylation, which generally represses transcription. However, little is known about the role of methylation alteration in maize under osmotic stress. Here, methylation-sensitive amplified polymorphism (MSAP) was used to screen PEG- or NaCl-induced methylation alteration in maize seedlings. The sequences of 25 differentially amplified fragments relevant to stress were successfully obtained. Two stress-specific fragments from leaves, LP166 and LPS911, shown to be homologous to retrotransposon Gag-Pol protein genes, suggested that osmotic stress-induced methylation of retrotransposons. Three MSAP fragments, representing drought-induced or salt-induced methylation in leaves, were homologous to a maize aluminum-induced transporter. Besides these, heat shock protein HSP82, Poly [ADP-ribose] polymerase 2, Lipoxygenase, casein kinase (CK2), and dehydration-responsive element-binding (DREB) factor were also homologs of MSAP sequences from salt-treated roots. One MSAP fragment amplified from salt-treated roots, designated RS39, was homologous to the first intron of maize protein phosphatase 2C (zmPP2C), whereas - LS103, absent from salt-treated leaves, was homologous to maize glutathione S-transferases (zmGST). Expression analysis showed that salt-induced intron methylation of root zmPP2C significantly downregulated its expression, while salt-induced demethylation of leaf zmGST weakly upregulated its expression. The results suggested that salinity-induced methylation downregulated zmPP2C expression, a negative regulator of the stress response, while salinity-induced demethylation upregulated zmGST expression, a positive effecter of the stress response. Altered methylation, in response to stress, might also be involved in stress acclimation. PMID:19889550

Tan, Ming-pu

2010-01-01

102

A wireless and sensitive detection of octachlorostyrene using modified AuNPs as signal-amplifying tags.  

PubMed

A wireless, remote query octachlorostyrene (OCS) biosensor was fabricated by coating a mass-sensitive magnetoelastic ribbon with anti-OCS antibody. In response to a time-varying magnetic field, the magnetoelastic sensor mechanically vibrates at a characteristic resonance frequency which inversely depends on the sensor mass loading. As the magnetoelastic film is magnetostrictive itself, the vibrations launch magnetic flux that can be remotely detected using a pickup coil. Au nanoparticles (NPs) were used to amplify the mass loading. In a sample solution containing OCS target and OCS-modified AuNPs (OCS-AuNPs), both OCS and OCS-AuNPs react with the anti-OCS antibody immobilized on the sensor surface in a competition mode. The bound OCS-AuNPs amount is inversely proportional to the OCS target concentration. The reduction of bound OCS-AuNPs induced by free OCS results in significant change in mass loading, which amplifies the responses. The biosensor demonstrates a linear shift in resonance frequency with OCS concentration between 7.4 ?M and 9 nM, with a detection limit of 2.8 nM. PMID:24135481

Chen, Lan; Li, Jiezhen; ThanhThuy, T Tran; Zhou, Liping; Huang, Chen'an; Yuan, Lijuan; Cai, Qingyun

2014-02-15

103

Charge collection and equalization for position-sensitive silicon strip detector  

NASA Astrophysics Data System (ADS)

A new and complete theoretical formulation was implemented for resistive silicon strip detectors, taking into account the effects of detector time constant, finite impedance of the preamplifier and the charge equalization effect. The theoretical calculation agrees very well with the model simulation and experimental tests. Although the "ballistic deficit" effect is small for a strip detector, it is demonstrated that the charge equalization effect should be treated carefully. The present work provides a quantitative base to optimize the design of the resistive strip detector, the preamplifier and the amplifier in a consistent way.

Qiao, R.; Li, J.; Wang, J.; Dai, X.; Ye, Y. L.

2012-09-01

104

Ultimate charge sensitivity and efficiency of a quantum point contact with a superposed input state  

NASA Astrophysics Data System (ADS)

We address the ultimate charge detection scheme with a quantum point contact. It is shown that a superposed input state is necessary to exploit the full sensitivity of a quantum point contact detector. The coherence of the input state provides an improvement in charge sensitivity, and this improvement is a result of a fundamental property of the scattering matrix. Further, a quantum-limited (maximally efficient) detection is made possible by controlling the interference between the two output waves. Our scheme provides the ultimate sensitivity and efficiency of charge detection with a generic quantum point contact.

Lee, Kang-Ho; Kang, Kicheon

2013-01-01

105

Phase-and-amplitude regeneration of differential phase-shift keyed signals using a phase-sensitive amplifier.  

PubMed

DPSK phase-and-amplitude regeneration with a NOLM-based phase-sensitive amplifier is demonstrated experimentally. For a highly degraded input signal, maximum differential phase errors were reduced from 82 degrees to 41 degrees , while the SNR was improved by more than 5-dB. Differential phase Q-factor improvement was better than 6-dB. The PSA was operated free of excess noise due to stimulated Brillouin scattering by using a binary phase modulated pulse train as the pump. The impact of pump fluctuations on regeneration performance is clarified. The regenerated signal was characterized by measurement of the constellation diagram by linear optical sampling, giving the first directly measured evidence of DPSK phase regeneration. PMID:19503540

Croussore, Kevin; Kim, Inwoong; Kim, Cheolhwan; Han, Yan; Li, Guifang

2006-03-20

106

Bipolar pulsed reset for AC coupled charge-sensitive preamplifiers  

Microsoft Academic Search

A new type of charge restoration is described for use particularly in germanium gamma-ray spectrometers for accelerator and space physics applications. A bipolar pulsed reset technique is applied to these applications for the first time. This technique overcomes the problems introduced by the need here to AC couple detectors and the fact that very large energy depositions occur due to

D. A. Landis; N. W. Madden; F. S. Goulding

1998-01-01

107

Sensitive enzyme-amplified electrical immunoassay for protein A-bearing Staphylococcus aureus in foods.  

PubMed Central

An amperometric electrochemical immunoassay specific for protein A-bearing Staphylococcus aureus was developed. The method was based on a sandwich immunosorbent assay and incorporated an enzyme amplification step, using a NAD-specific redox cycle generating NADH (C. H. Stanley, A. Johannsson, and C. H. Self, J. Immunol. Methods 83:89-95, 1985). Reduction of the mediator, ferricyanide, was dependent on the initial concentration of antigen. The final potential was measured by using a Pt disk electrode polarized at +0.8 V to the Ag/AgCl reference electrode. The assay was rapid (4 h) and generated protein A- and cell (S. aureus)-dependent signals. The system was highly sensitive and could detect 10 pg of protein A ml-1 and less than 100 CFU of S. aureus ml-1. Similar sensitivities were observed with S. aureus cultures inoculated into beef and milk, but the sensitivity was reduced slightly (ca. 10(3) g-1) with samples of Cheddar cheese.

Brooks, J L; Mirhabibollahi, B; Kroll, R G

1990-01-01

108

Charge and current-sensitive preamplifiers for pulse shape discrimination techniques with silicon detectors  

NASA Astrophysics Data System (ADS)

New charge- and current-sensitive preamplifiers coupled to silicon detectors and devoted to studies in nuclear structure and dynamics have been developed and tested. For the first time shapes of current pulses from light charged particles and carbon ions are presented. Capabilities for pulse shape discrimination techniques are demonstrated.

Hamrita, H.; Rauly, E.; Blumenfeld, Y.; Borderie, B.; Chabot, M.; Edelbruck, P.; Lavergne, L.; Le Bris, J.; Legou, Th.; Le Neindre, N.; Richard, A.; Rivet, M. F.; Scarpaci, J. A.; Tillier, J.; Barbey, S.; Becheva, E.; Bocage, F.; Bougault, R.; Bzyl, R.; Grévy, S.; Carniol, B.; Cussol, D.; Désesquelles, P.; Etasse, D.; Galichet, E.; Grévy, S.; Guinet, D.; Lalu, G.; Lanzalone, G.; Lautesse, Ph.; Lopez, O.; Martinet, G.; Pierre, S.; Politi, G.; Rosato, E.; Tamain, B.; Vient, E.

2004-10-01

109

A pH-sensitive charge-conversion system for doxorubicin delivery.  

PubMed

A novel pH-sensitive charge-conversion shielding system was designed by the electrostatic binding of polyethylenimine (PEI)-poly(l-lysine)-poly(l-glutamic acid) (PELG), PEI, and cis-aconityl-doxorubicin (CAD). Doxorubicin (DOX) was modified by cis-aconityl linkage to form acid-sensitive CAD, which was then adsorbed by the positively charged PEI. The PEI/CAD complexes were subsequently shielded with the pH-responsive charge-conversion PELG. In normal tissues, the PELG/PEI/CAD complexes were negatively charged; in acidic tumor tissues, the shielding PELG was positively charged and detached from the PELG/PEI/CAD complexes. The resulting positively charged PEI/CAD complexes thus became exposed and were endocytosed. CAD was then cleaved in the acidic intracellular environment of endosomes and lysosomes, and converted back into DOX. The charge reversal of the PELG/PEI/CAD complexes was verified by zeta potential analysis at different pH values. Moreover, DOX release increased with decreasing pH. Cell uptake and confocal laser scanning microscopy analyses showed that, at pH 6.8, PELG/PEI/CAD had the highest endocytosis rate and more DOX entered cell nuclei. More importantly, the system showed remarkable cytotoxicity against cancer cells. These results revealed that the combination of pH-sensitive charge-conversion shielding with pH-sensitive drug release is a potential drug delivery system for tumor treatment. PMID:23648572

Guan, Xiuwen; Li, Yanhui; Jiao, Zixue; Chen, Jie; Guo, Zhaopei; Tian, Huayu; Chen, Xuesi

2013-08-01

110

A fast and low noise charge sensitive preamplifier in 90 nm CMOS technology  

Microsoft Academic Search

A fast charge sensitive preamplifier was designed and built in a 90 nm CMOS technology. The work is part of the R&D effort towards the read out of pixel or small strip sensors in next generation HEP experiments. The preamplifier features outstanding noise performance given its wide bandwidth, with a ENC (equivalent noise charge) of about 350 electrons RMS with

A Baschirotto; G Cocciolo; M De Matteis; A Giachero; C Gotti; M Maino; G Pessina

2012-01-01

111

Charge and current-sensitive preamplifiers for pulse shape discrimination techniques with silicon detectors  

Microsoft Academic Search

New charge- and current-sensitive preamplifiers coupled to silicon detectors and devoted to studies in nuclear structure and dynamics have been developed and tested. For the first time shapes of current pulses from light charged particles and carbon ions are presented. Capabilities for pulse shape discrimination techniques are demonstrated.

H. Hamrita; E. Rauly; Y. Blumenfeld; B. Borderie; M. Chabot; P. Edelbruck; L. Lavergne; J. Le Bris; Th. Legou; N. Le Neindre; A. Richard; M. F. Rivet; J. A. Scarpaci; J. Tillier; S. Barbey; E. Becheva; F. Bocage; R. Bougault; R. Bzyl; S. Grévy; B. Carniol; D. Cussol; P. Désesquelles; D. Etasse; E. Galichet; D. Guinet; G. Lalu; G. Lanzalone; Ph. Lautesse; O. Lopez; G. Martinet; S. Pierre; G. Politi; E. Rosato; B. Tamain; E. Vient

2004-01-01

112

Trastuzumab reverses letrozole resistance and amplifies the sensitivity of breast cancer cells to estrogen  

PubMed Central

In this study we investigated adaptive mechanisms associated with aromatase inhibitor (AI) resistance in breast cancer cells and show that sensitivity to AIs can be extended through dual inhibition of Estrogen Receptor (ER) and Human Epidermal Receptor-2 (Her-2) signaling. We utilized human ER-positive breast cancer cells stably transfected with the aromatase gene (MCF-7Ca). These cells grow as tumors in nude mice and are inhibited by AIs. Despite continued treatment, tumors eventually become insensitive to AI letrozole. The cells isolated from these Long-Term Letrozole Treated tumors (LTLT-Ca) were found to have decreased ER? levels. Our results suggest that LTLT-Ca cells survive estrogen deprivation by activation of Her-2/Mitogen Activated Protein Kinase (MAPK) pathway. Here, we demonstrate that trastuzumab (antibody against Her-2; IC50=0.4mg/ml) was very effective in restoring the ER? levels and sensitivity of LTLT-Ca cells to endocrine therapy by down-regulation of Her-2/MAPK pathway and upregulation of ER?. In contrast, trastuzumab was ineffective in the parental hormone responsive MCF-7Ca cells (IC50=4.28mg/ml) and xenografts. By blocking Her-2, trastuzumab also up-regulates ER?, aromatase expression and hyper-sensitized MCF-7Ca cells to E2. We show that trastuzumab is beneficial in hormone refractory cells and xenografts by restoring ER, implicating Her-2 as a negative regulator of ER?. In xenograft studies the combination of trastuzumab plus letrozole is equally effective in inhibiting growth of MCF-7Ca tumors as letrozole alone. However, upon the acquisition of resistance and increased Her-2 expression the combination of letrozole plus trastuzumab provided superior benefit over letrozole or trastuzumab alone.

Sabnis, Gauri; Schayowitz, Adam; Goloubeva, Olga; Macedo, Luciana; Brodie, Angela

2008-01-01

113

Sensitivity improvement of a Varian E-109 EPR spectrometer with a low noise microwave amplifier  

SciTech Connect

The installation of a low noise GaAsFET microwave preamplifier into a Varian E-109 homodyne X-band EPR spectrometer is described, and measurements of the resulting improvement in sensitivity as a function of microwave power are presented. Particular attention is paid to modification of the automatic frequency control (AFC) system to compensate for the preamplifier gain, which would otherwise result in instability of the AFC servoloop and decreased spectrometer performance at moderate microwave power levels. Specific details are provided for modification of the Varian E-102 bridge, but the general approach is applicable to other spectrometers.

Dexheimer, S.L.; Klein, M.P.

1988-05-01

114

Sensitivity and fidelity of DNA microarray improved with integration of Amplified Differential Gene Expression (ADGE)  

PubMed Central

Background The ADGE technique is a method designed to magnify the ratios of gene expression before detection. It improves the detection sensitivity to small change of gene expression and requires small amount of starting material. However, the throughput of ADGE is low. We integrated ADGE with DNA microarray (ADGE microarray) and compared it with regular microarray. Results When ADGE was integrated with DNA microarray, a quantitative relationship of a power function between detected and input ratios was found. Because of ratio magnification, ADGE microarray was better able to detect small changes in gene expression in a drug resistant model cell line system. The PCR amplification of templates and efficient labeling reduced the requirement of starting material to as little as 125 ng of total RNA for one slide hybridization and enhanced the signal intensity. Integration of ratio magnification, template amplification and efficient labeling in ADGE microarray reduced artifacts in microarray data and improved detection fidelity. The results of ADGE microarray were less variable and more reproducible than those of regular microarray. A gene expression profile generated with ADGE microarray characterized the drug resistant phenotype, particularly with reference to glutathione, proliferation and kinase pathways. Conclusion ADGE microarray magnified the ratios of differential gene expression in a power function, improved the detection sensitivity and fidelity and reduced the requirement for starting material while maintaining high throughput. ADGE microarray generated a more informative expression pattern than regular microarray.

Chen, Zhijian J; Gate, Laurent; Davis, Warren; Ile, Kristina E; Tew, Kenneth D

2003-01-01

115

Sensitive and Specific KRAS Somatic Mutation Analysis on Whole-Genome Amplified DNA from Archival Tissues  

PubMed Central

Kirsten RAS (KRAS) is a small GTPase that plays a key role in Ras/mitogen-activated protein kinase signaling; somatic mutations in KRAS are frequently found in many cancers. The most common KRAS mutations result in a constitutively active protein. Accurate detection of KRAS mutations is pivotal to the molecular diagnosis of cancer and may guide proper treatment selection. Here, we describe a two-step KRAS mutation screening protocol that combines whole-genome amplification (WGA), high-resolution melting analysis (HRM) as a prescreen method for mutation carrying samples, and direct Sanger sequencing of DNA from formalin-fixed, paraffin-embedded (FFPE) tissue, from which limited amounts of DNA are available. We developed target-specific primers, thereby avoiding amplification of homologous KRAS sequences. The addition of herring sperm DNA facilitated WGA in DNA samples isolated from as few as 100 cells. KRAS mutation screening using high-resolution melting analysis on wgaDNA from formalin-fixed, paraffin-embedded tissue is highly sensitive and specific; additionally, this method is feasible for screening of clinical specimens, as illustrated by our analysis of pancreatic cancers. Furthermore, PCR on wgaDNA does not introduce genotypic changes, as opposed to unamplified genomic DNA. This method can, after validation, be applied to virtually any potentially mutated region in the genome.

van Eijk, Ronald; van Puijenbroek, Marjo; Chhatta, Amiet R.; Gupta, Nisha; Vossen, Rolf H.A.M.; Lips, Esther H.; Cleton-Jansen, Anne-Marie; Morreau, Hans; van Wezel, Tom

2010-01-01

116

Charge movement of a voltage-sensitive fluorescent protein.  

PubMed

The N-terminus of Ciona intestinalis (Ci-VSP) is a voltage-sensing domain (VSD) controlling the activity of a phosphatase domain on the C terminus. By replacing the phosphatase domain with a tandem of fluorescent proteins, CFP and YFP, a family of fluorescence resonance energy transfer-based, genetically encoded voltage-sensing fluorescent protein (VSFP) was created. VSFP2.3, one of the latest versions of this family, showed large changes in YFP emission upon changes in membrane potential with CFP excitation when expressed in Xenopus laevis oocytes. The time course of the fluorescence has two components: the fast component correlates with the time course of sensing current produced by the charge movement, while the slow component is at least one order-of-magnitude slower than the sensing current. This suggests that the tandem of fluorescent proteins reports a secondary conformational transition of the VSD which resembles the relaxation of the VSD of Ci-VSP described in detail for the Ci-VSP. This observation indicates that the relaxation of the VSD of VSFP2.3 is a global conformational change that encompasses the entire S4 segment. PMID:19167283

Villalba-Galea, Carlos A; Sandtner, Walter; Dimitrov, Dimitar; Mutoh, Hiroki; Knöpfel, Thomas; Bezanilla, Francisco

2009-01-01

117

Charge Movement of a Voltage-Sensitive Fluorescent Protein  

PubMed Central

Abstract The N-terminus of Ciona intestinalis (Ci-VSP) is a voltage-sensing domain (VSD) controlling the activity of a phosphatase domain on the C terminus. By replacing the phosphatase domain with a tandem of fluorescent proteins, CFP and YFP, a family of fluorescence resonance energy transfer-based, genetically encoded voltage-sensing fluorescent protein (VSFP) was created. VSFP2.3, one of the latest versions of this family, showed large changes in YFP emission upon changes in membrane potential with CFP excitation when expressed in Xenopus laevis oocytes. The time course of the fluorescence has two components: the fast component correlates with the time course of sensing current produced by the charge movement, while the slow component is at least one order-of-magnitude slower than the sensing current. This suggests that the tandem of fluorescent proteins reports a secondary conformational transition of the VSD which resembles the relaxation of the VSD of Ci-VSP described in detail for the Ci-VSP. This observation indicates that the relaxation of the VSD of VSFP2.3 is a global conformational change that encompasses the entire S4 segment.

Villalba-Galea, Carlos A.; Sandtner, Walter; Dimitrov, Dimitar; Mutoh, Hiroki; Knopfel, Thomas; Bezanilla, Francisco

2009-01-01

118

Space charge instabilities in gyrotron beams and theory of gyro-traveling-wave-amplifiers at cyclotron harmonics  

SciTech Connect

This dissertation concerns itself with two important issues in the study of gyrotrons. In Part I, the authors study the space charge instabilities in gyrotron electron beams via both solution of the linear dispersion equation and the nonlinear particle simulation. The linear analysis addressed the stabilizing effects of energy spread in the beams and the gradient of the external magnetic field. The nonlinear multi-frequency simulation demonstrates that the energy spread induced by multiple unstable waves in the nonlinear saturation stage is more significant than the corresponding spread induced by a single unstable wave. This indicates that the deleterious effect on the quality of the beam will be greater than previously expected, and emphasizes the need to design electron guns which are stable to this wave mode. In Part II, the authors develop a generalized theory of gyro-traveling-wave tubes (gyro-TWTs) operating at arbitrary cyclotron harmonics. In the framework of small signal theory, the authors obtain and analyze the dispersion equation and discuss a problem of spurious counterpropagating waves excitation. In the large-signal study, the authors predict the possibility of achieving high efficiency of operation at the first four cyclotron harmonics and show that the orbital efficiency of the relativistic gyro-TWT operating at the second cyclotron harmonic with large frequency up-conversion may exceed 60%. The results obtained also demonstrate that the sensitivity of the harmonic gyro-TWT efficiency with respect to the electron velocity spread strongly depends on axial wavenumbers of the travelling waves.

Li, H.

1993-01-01

119

A silicon nanowire ion-sensitive field-effect transistor with elementary charge sensitivity  

Microsoft Academic Search

We investigate the mechanisms responsible for the low-frequency noise in liquid-gated nanoscale silicon nanowire field-effect transistors (SiNW-FETs) and show that the charge-noise level is lower than elementary charge. Our measurements also show that ionic strength of the surrounding electrolyte has a minimal effect on the overall noise. Dielectric polarization noise seems to be at the origin of the 1\\/f noise

N. Clément; K. Nishiguchi; J. F. Dufreche; D. Guerin; A. Fujiwara; D. Vuillaume

2011-01-01

120

Method and apparatus for detection of charge on ions and particles  

DOEpatents

The present invention provides a tessellated array detector with charge collecting plate (or cup) electrode pixels and amplifying circuitry integrated into each pixel making it sensitive to external electrostatic charge; a micro collector/amplifier pixel design possessing a small capacitance to ensure a high charge to voltage signal conversion for low noise/high sensitivity operation; a micro-fabricated array of such pixels to create a useful macroscopic target area for ion and charged particle collection.

Fuerstenau, Stephen Douglas (3938 Park Pl., Montrose, CA 91020); Soli, George Arthur (4003 Wanna Vista Dr., Vancouver, WA 98661)

2002-01-01

121

A silicon nanowire ion-sensitive field-effect transistor with elementary charge sensitivity  

NASA Astrophysics Data System (ADS)

We investigate the mechanisms responsible for the low-frequency noise in liquid-gated nanoscale silicon nanowire field-effect transistors (SiNW-FETs) and show that the charge-noise level is lower than elementary charge. Our measurements also show that ionic strength of the surrounding electrolyte has a minimal effect on the overall noise. Dielectric polarization noise seems to be at the origin of the 1/f noise in our devices. The estimated spectral density of charge noise Sq=1.6×10-2 e/Hz1/2 at 10 Hz opens the door to metrological studies with these SiNW-FETs for the electrical detection of a small number of molecules.

Clément, N.; Nishiguchi, K.; Dufreche, J. F.; Guerin, D.; Fujiwara, A.; Vuillaume, D.

2011-01-01

122

Performance of a new monolithic eight channel charge sensitive preamplifier-shaper  

Microsoft Academic Search

A monolithic eight channel CMOS time-invariant preamplifier\\/shaper has been designed and built by Chuck Britton of ORNL in collaboration with Ray Yarema and Tom Zimmerman of Fermilab. Each of the eight channels incorporates a charge sensitive preamplifier and two shaping stages. The resultant weighting function is similar to CR-RC(exp 3). The peaking time is approx. 200 ns, and the charge

T. Zimmerman

1991-01-01

123

Non-coalescence of oppositely charged droplets in pH-sensitive emulsions  

PubMed Central

Like charges stabilize emulsions, whereas opposite charges break emulsions. This is the fundamental principle for many industrial and practical processes. Using micrometer-sized pH-sensitive polymeric hydrogel particles as emulsion stabilizers, we prepare emulsions that consist of oppositely charged droplets, which do not coalesce. We observe noncoalescence of oppositely charged droplets in bulk emulsification as well as in microfluidic devices, where oppositely charged droplets are forced to collide within channel junctions. The results demonstrate that electrostatic interactions between droplets do not determine their stability and reveal the unique pH-dependent properties of emulsions stabilized by soft microgel particles. The noncoalescence can be switched to coalescence by neutralizing the microgels, and the emulsion can be broken on demand. This unusual feature of the microgel-stabilized emulsions offers fascinating opportunities for future applications of these systems.

Liu, Tingting; Seiffert, Sebastian; Thiele, Julian; Abate, Adam R.; Weitz, David A.; Richtering, Walter

2012-01-01

124

New light-amplifier-based detector designs for high spatial resolution and high sensitivity CBCT mammography and fluoroscopy  

PubMed Central

New cone-beam computed tomographic (CBCT) mammography system designs are presented where the detectors provide high spatial resolution, high sensitivity, low noise, wide dynamic range, negligible lag and high frame rates similar to features required for high performance fluoroscopy detectors. The x-ray detectors consist of a phosphor coupled by a fiber-optic taper to either a high gain image light amplifier (LA) then CCD camera or to an electron multiplying CCD. When a square-array of such detectors is used, a field-of-view (FOV) to 20 × 20 cm can be obtained where the images have pixel-resolution of 100 µm or better. To achieve practical CBCT mammography scan-times, 30 fps may be acquired with quantum limited (noise free) performance below 0.2 µR detector exposure per frame. Because of the flexible voltage controlled gain of the LA’s and EMCCDs, large detector dynamic range is also achievable. Features of such detector systems with arrays of either generation 2 (Gen 2) or 3 (Gen 3) LAs optically coupled to CCD cameras or arrays of EMCCDs coupled directly are compared. Quantum accounting analysis is done for a variety of such designs where either the lowest number of information carriers off the LA photo-cathode or electrons released in the EMCCDs per x-ray absorbed in the phosphor are large enough to imply no quantum sink for the design. These new LA- or EMCCD-based systems could lead to vastly improved CBCT mammography, ROI-CT, or fluoroscopy performance compared to systems using flat panels.

Rudin, Stephen; Kuhls, Andrew T.; Yadava, Girijesh K.; Josan, Gaurav C.; Wu, Ye; Chityala, Ravishankar N.; Rangwala, Hussain S.; Ciprian Ionita, N.; Hoffmann, Kenneth R.; Bednarek, Daniel R.

2011-01-01

125

New light-amplifier-based detector designs for high spatial resolution and high sensitivity CBCT mammography and fluoroscopy  

NASA Astrophysics Data System (ADS)

New cone-beam computed tomographic (CBCT) mammography system designs are presented where the detectors provide high spatial resolution, high sensitivity, low noise, wide dynamic range, negligible lag and high frame rates similar to features required for high performance fluoroscopy detectors. The x-ray detectors consist of a phosphor coupled by a fiber-optic taper to either a high gain image light amplifier (LA) then CCD camera or to an electron multiplying CCD. When a square-array of such detectors is used, a field-of-view (FOV) to 20 x 20 cm can be obtained where the images have pixel-resolution of 100 ?m or better. To achieve practical CBCT mammography scan-times, 30 fps may be acquired with quantum limited (noise free) performance below 0.2 ?R detector exposure per frame. Because of the flexible voltage controlled gain of the LA's and EMCCDs, large detector dynamic range is also achievable. Features of such detector systems with arrays of either generation 2 (Gen 2) or 3 (Gen 3) LAs optically coupled to CCD cameras or arrays of EMCCDs coupled directly are compared. Quantum accounting analysis is done for a variety of such designs where either the lowest number of information carriers off the LA photo-cathode or electrons released in the EMCCDs per x-ray absorbed in the phosphor are large enough to imply no quantum sink for the design. These new LA- or EMCCD-based systems could lead to vastly improved CBCT mammography, ROI-CT, or fluoroscopy performance compared to systems using flat panels.

Rudin, Stephen; Kuhls, Andrew T.; Yadava, Girijesh K.; Josan, Gaurav C.; Wu, Ye; Chityala, Ravishankar N.; Rangwala, Hussain S.; Ionita, N. Ciprian; Hoffmann, Kenneth R.; Bednarek, Daniel R.

2006-03-01

126

Development of large area pSi surface barrier detectors and the associated charge sensitive preamplifier  

Microsoft Academic Search

Large area Si Surface Barrier Detectors (SBD), with 95 cmĀ² sensitive area, and a charge sensitive preamplifier, for use up to 10āµ pF input capacity were developed. Noise width of the preamplifier had a slope of 7eV\\/pF with respect to the input capacitance. The p-Si detectors were made of MCZ Si of 1.7-3.6 kohms in resistivity. Detector Characteristics, the detailed

Y. Takami; F. Shiraishi; H. Murakami; M. Sieminski; N. Isawa

1989-01-01

127

A wide bandwidth, high linearity hybrid charge-sensitive preamplifier for high-capacitance silicon detectors  

Microsoft Academic Search

A new hybrid charge-sensitive preamplifier with a sensitivity of 5 mV\\/MeV has been specifically designed to operate in conjunction with high-capacitance silicon detectors. The shape of the leading edge of its impulse response keeps fast (20 ns) and unchanged over the full output voltage swing (7 V), as is required in nuclear-physics experiments in which Pulse-Shape Analysis is used for

Roberto Bassini; Ciro Boiano; Angelo Pagano; Alberto Pullia

2003-01-01

128

A high molar extinction coefficient charge transfer sensitizer and its application in dye-sensitized solar cell  

Microsoft Academic Search

A high molar extinction coefficient charge transfer sensitizer tetrabutylammonium [Ru(4,-carboxylic acid-4?-carboxylate-2,2?-bipyridine)(4,4?-di-(2-(3,6-dimethoxyphenyl)ethenyl)-2,2?-bipyridine)(NCS)2], is developed which upon anchoring onto nanocrystalline TiO2 films exhibit superior power conversion efficiency compared to the standard sensitizer bistetrabutylammonium cis-dithiocyanatobis(4,4?-dicarboxylic acid-2,2?-bipyridine)ruthenium(II) (N719). The new sensitizer anchored TiO2 films harvest visible light very efficiently over a large spectral range and produce a short-circuit photocurrent density of 18.84mA\\/cm2, open-circuit voltage

T. Bessho; Le Cevey; S. Ito; C. Klein; F. De Angelis; S. Fantacci; P. Comte; P. Liska; H. Imai; M. Graetzel

2007-01-01

129

Performance of a new monolithic eight channel charge sensitive preamplifier-shaper.  

National Technical Information Service (NTIS)

A monolithic eight channel CMOS time-invariant preamplifier/shaper has been designed and built by Chuck Britton of ORNL in collaboration with Ray Yarema and Tom Zimmerman of Fermilab. Each of the eight channels incorporates a charge sensitive preamplifier...

T. Zimmerman

1991-01-01

130

A low noise CMOS charge sensitive preamplifier for MEMS capacitive accelerometer readout  

Microsoft Academic Search

This paper describes a low noise CMOS charge sensitive preamplifier for MEMS capacitive accelerometer readout circuit. This structure utilizes a feedback capacitance and switch's technique to cancel the input parasitic capacitance and the offset voltage, and also uses an optimized noise input buffer stage to reduce low frequency noises, especially the flicker noise without increasing the complexity of the proposed

Jianghua Chen; Xuewen Ni; Bangxian Mo

2007-01-01

131

CMOS low noise switched charge sensitive preamplifier for CdTe X-ray detection  

Microsoft Academic Search

A CdTe detector readout based on MOS switched charge sensitive preamplifier without feedback resistor is presented. CMOS technology allows high integration level, relatively low power consumption and provides a nearly ideal switch that does not introduce significant drift current to the integration capacitor. No external components are required. CdTe detectors combine low current with high resistivity and low capacitance that

CLAUDIO G. JAKOBSON; D. Lavie; YAEL NEMIROVSKY

1995-01-01

132

Low noise charge sensitive preamplifier DC stabilized without a physical resistor  

Microsoft Academic Search

The invention is a novel charge sensitive preamplifier (CSP) which has no resistor in parallel with the feedback capacitor. No resetting circuit is required to discharge the feedback capacitor. The DC stabilization of the preamplifier is obtained by means of a second feedback loop between the preamplifier output and the common base transistor of the input cascode. The input transistor

Giuseppe Bertuccio; Pavel Rehak; Deming Xi

1994-01-01

133

A charge sensitive preamplifier made with SiGe bipolar transistors  

Microsoft Academic Search

We have characterized some commercial SiGe bipolar transistors to be used at low injection level and in a wide temperature range, in view of their possible application in experiments with large number of channels. After having observed that they are very suitable for low noise and high-speed applications we have designed and built a charge sensitive preamplifier able to work

Claudio Arnaboldi; Giuliano Boella; Gianluigi Pessina

2004-01-01

134

Experimental comparison of discrete and CMOS charge sensitive preamplifiers for CZT radiation detectors  

Microsoft Academic Search

During recent years, many readout integrated circuits for CZT radiation detectors have been studied particularly for use on pixilated detectors in imaging applications. The main challenge is to keep noise performance similar to discrete preamplifiers, even with lower power. This paper presents the design and the experimental evaluation of CMOS integrated charge sensitive preamplifiers intended for CZT radiation detectors. A

Guillaume Montémont; Jean-Pierre Rostaing; Loļck Verger

2002-01-01

135

A LOW-NOISE CHARGE-SENSITIVE PREAMPLIFIER FOR SEMI-CONDUCTOR IONIZATION CHAMBERS  

Microsoft Academic Search

A low-noise charge-sensitive preamplifier for particle spectroscopy with ; junction detectors is described. Using an E 280 F as input tube a noise width of ; 2.9 kev (fwhm) is achieved. The open-loop gain is in excess of 1800. The noise ; width as a function of the external input capacity is measured. Without a ; feedback capacitor the circuit

J. Moritz; H. J. Tauffenbach

1962-01-01

136

Sensitivity of Cased Charges of Molten and Solid Composition B to Impact by Primary Steel Fragments.  

National Technical Information Service (NTIS)

An experimental program was conducted to establish the sensitivity of cased charges of Composition B, in the molten and solid state, to impact by high velocity steel fragments. Primary fragments having a square cross-sectional area and weighing 0.5, 1.0 a...

G. Petino D. DeMella

1976-01-01

137

Experimental comparison of discrete and CMOS charge sensitive preamplifiers for CZT radiation detectors  

Microsoft Academic Search

During recent years, many readout integrated circuits for CdZnTe (CZT) radiation detectors have been studied particularly for use on pixellated detectors in imaging applications. The fundamental challenge is to keep noise performance similar to discrete preamplifiers, even with lower power. This paper presents an experimental evaluation of CMOS integrated charge sensitive preamplifiers intended for CZT radiation detectors using a comparison

Guillaume Montémont; Jean-Pierre Rostaing; Loļck Verger

2003-01-01

138

Enhanced laboratory sensitivity to variation of the fine-structure constant using highly charged ions.  

PubMed

We study atomic systems that are in the frequency range of optical atomic clocks and have enhanced sensitivity to potential time variation of the fine-structure constant ?. The high sensitivity is due to coherent contributions from three factors: high nuclear charge Z, high ionization degree, and significant differences in the configuration composition of the states involved. Configuration crossing keeps the frequencies in the optical range despite the large ionization energies. We discuss a few promising examples that have the largest ? sensitivities seen in atomic systems. PMID:20867622

Berengut, J C; Dzuba, V A; Flambaum, V V

2010-09-17

139

Gated charged-particle trap  

DOEpatents

The design and operation of a new type of charged-particle trap provides simultaneous measurements of mass, charge, and velocity of large electrospray ions. The trap consists of a detector tube mounted between two sets of center-bored trapping plates. Voltages applied to the trapping plates define symmetrically-opposing potential valleys which guide axially-injected ions to cycle back and forth through the charge-detection tube. A low noise charge-sensitive amplifier, connected to the tube, reproduces the image charge of individual ions as they pass through the detector tube. Ion mass is calculated from measurement of ion charge and velocity following each passage through the detector.

Benner, W. Henry (Danville, CA)

1999-01-01

140

Reverberation Controlled Gain Amplifier.  

National Technical Information Service (NTIS)

The amplifier is used in underwater echo-ranging apparatus associated with a homing-type torpedo. A signal amplifier is provided which automatically adjusts its sensitivity-time characteristic according to the rate of reverberation decoy of the signal ret...

J. W. Flowers E. J. Wade

1964-01-01

141

Composite Tin and Zinc oxide nanocrystalline particles for enhanced charge separation in sensitized degradation of dyes  

Microsoft Academic Search

Composite ZnO\\/SnO2 catalyst has been studied for the sensitized degradation of dyes e.g. Eosin Y (2?,4?,5?,7?-tetrabromofluorescein disodium salt) in relation to efficient charge separation properties of the catalyst. Improved photocatalytic activity was observed in the case of ZnO\\/SnO2 composite catalyst compared to the catalytic activity of ZnO, SnO2 or TiO2 powder. The suppression of charge recombination in the composite ZnO\\/SnO2

J. Bandara; K. Tennakone; P. P. B. Jayatilaka

2002-01-01

142

Short communication: Naturally sensitive Bacillus thuringiensis EG10368 produces thurincin H and acquires immunity after heterologous expression of the one-step-amplified thurincin H gene cluster.  

PubMed

Heterologous expression of bacteriocin genetic determinants (or operons) has long been a research interest for the functional analysis of genes involved in bacteriocin biosynthesis, regulation, modification, and immunity. Previously, construction of genomic libraries of the bacteriocin producer strains was usually required to identify new bacteriocin operons, a method that is tedious and time consuming. For the first time, we directly amplified an 8.14-kb bioinformatically identified thurincin H gene cluster using a one-step PCR method with 100% accuracy. This amplified gene cluster was cloned into plasmid pHT315, resulting in plasmid pGW139, and subsequently transformed to Bacillus thuringiensis EG10368, a strain naturally sensitive to thurincin H. Heterologous expression of the gene cluster makes the sensitive B. thuringiensis EG10368 produce thurincin H at a higher level compared with the wild-type producer, B. thuringiensis SF361. Moreover, B. thuringiensis EG10368pGW139 acquired complete immunity to thurincin H. The results indicated that one-step PCR is a promising tool to accurately amplify long bacteriocin gene clusters used in bacteriocin functional analysis studies and it is an effective way to produce bacteriocins at a higher level, without the need to clone large chromosomal fragments. PMID:24767890

Wang, G; Manns, D C; Churey, J J; Worobo, R W

2014-07-01

143

Characteristics of Highly Sensitive pH Sensors with Charge Accumulation Operation  

NASA Astrophysics Data System (ADS)

A charge-transfer-type pH sensor operated by charge accumulation was demonstrated, and it was confirmed that its pH sensitivity was 1130 mV/pH with five signal integration cycles. The most familiar pH sensor using a semiconductor is the ion-sensitive field effect transistor (ISFET). The sensitivity of our pH sensor was 20 times higher than that of the ISFET. The sensitivity of the ISFET, which is similar in structure to a metal-insulator-semiconductor (MIS) structure, is restricted by the Nernst equation (59 mV/pH at room temperature). The output signal from an ISFET disappears into its noise as pH variation becomes small. The charge-transfer-type pH sensor increases the pH output signal to integrate signals in the time domain that are noise-free. It is expected that with this sensor it is possible to measure small pH signal variations.

Hizawa, Takeshi; Sawada, Kazuaki; Takao, Hidekuni; Ishida, Makoto

2006-12-01

144

Surface charge and properties of cardiac ATP-sensitive K+ channels  

PubMed Central

ATP-sensitive K+ (KATP) channels are present in a wide variety of tissues. The sensitivity of these channels to closure by cytosolic ATP (ATPi) varies significantly among different tissues and even within the same tissue. The purpose of this study was to test the hypothesis that negative surface charges modulate the sensitivity of the KATP channels to ATPi by influencing surface potential in the vicinity of the ATP- binding site(s) of the channel. Unitary currents through KATP channels were measured in inside-out membrane patches excised from rabbit ventricular myocytes using the patch-clamp technique. Agents known to be effective at screening negative surface charges were applied to the cytosolic surface of the patches, and their effects on ATP sensitivity were examined. These agents included Mg2+ (2-15 mM), Ba2+ (2-10 mM), and the polycations protamine (0.01-10 microM), poly-L-lysine (500 microM), and poly-L-arginine (0.5 microM). The divalent cations and the various polycations all dramatically reduced the concentration of ATPi required to half-maximally suppress current through KATP channels (Kd), from approximately 100 microM in the absence of these agents to 1.6-8 microM in their presence. The effects were dose dependent. Protamine also reduced the sensitivity of KATP channels to block by cytosolic ADP. The sensitivity of KATP channels to block by ATP was independent of membrane potential, suggesting that the ATP-binding site is not located within the transmembrane voltage field. The effects of the polycation poly-L-lysine on ATP sensitivity were also independent of membrane potential or the direction (inward or outward) of current through KATP channels. In addition to increasing ATP sensitivity, Mg2+, Ba2+, and the polycations all caused dose-dependent block of inward and outward currents through KATP channels over similar concentration ranges as their effects on ATP sensitivity. The block of inward current by polycations was not associated with reduction of single-channel conductance or evidence of fast open channel block. However, the polycations did cause a modest reduction in single-channel conductance of outward current. These results are consistent with the presence of negative surface charges that reduce the local ATP concentration at the ATP-binding site(s) on the channel, relative to the bulk cytosolic ATP concentration. Screening these negative surface charges with divalent cations or polycations decreases the local ATP gradient, resulting in a decrease in the apparent Kd for ATP.(ABSTRACT TRUNCATED AT 400 WORDS)

1994-01-01

145

Development of large area P-Si surface barrier detectors and the associated charge sensitive preamplifier  

SciTech Connect

Large area Si Surface Barrier Detectors (SBD), with 95 cm/sup 2/ sensitive area, and a charge sensitive preamplifier, for use up to 10/sup 5/ pF input capacity were developed. Noise width of the preamplifier had a slope of 7eV/pF with respect to the input capacitance. The p-Si detectors were made of MCZ Si of 1.7-3.6 kohms in resistivity. Detector Characteristics, the detailed fabrication technique including the surface treatment and passivation are described.

Takami, Y.; Shiraishi, F.; Murakami, H.; Sieminski, M.; Isawa, N.

1989-02-01

146

Sensitive gas sensor embedded in a vertical polymer space-charge-limited transistor  

NASA Astrophysics Data System (ADS)

We report a very sensitive gas sensor embedded in a vertical polymer space-charge-limited transistor. The oxidizing and reducing gases act as electron dedoping and electron doping agents on the transistor active layer to change the potential distribution in the vertical channel and hence to change the output current density. With a 30-ppb detection limit to ammonia, the sensor can be used for non-invasive breath monitor in point-of-care applications. The integration of a sensitive gas sensor and a low-operation-voltage transistor in one single device also facilitates the development of low-cost and low-power-consumption sensor array.

Zan, Hsiao-Wen; Li, Chang-Hung; Yu, Chih-Kuan; Meng, Hsin-Fei

2012-07-01

147

Modeling of trap assisted interfacial charge transfer in dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

This paper presents a model for charge transport in dye sensitized solar cells based on the physics of electron capture, electron emission, oxidation, and reduction processes mediated by deep interfacial trap states at TiO2/dye/electrolyte interfaces. This model suggests that electron back injection from the conduction band of TiO2 to electrolyte is due to trapping of conduction band electrons by deep states followed by reduction processes at the interface. The simulated dark IV, illuminated IV, and quantum efficiency characteristics of dye sensitized solar cells based on this model are consistent with experimental results.

Nepal, Jeevan; Sadegh Mottaghian, Seyyed; Biesecker, Matt; Farrokh Baroughi, Mahdi

2013-05-01

148

Development of Charge Sensitive Infrared Phototransistors for the Far-Infrared Wavelength  

NASA Astrophysics Data System (ADS)

Ultra-highly-sensitive far-infrared detectors are developed for potential application to astronomy. The detectors exploit a novel mechanism called Charge Sensitive Infrared Phototransistors (CSIPs), in which an upper quantum well (QW) in GaAs/AlGaAs double QW structures is positively charged up by photo-excitation via inter-subband transition. This causes the conductance of the lower QW channel to increase. The device is effectively a phototransistor, in which the upper QW serves as a photo-sensitive gate to the source-drain channel provided by the lower QW. Resultant extraordinary high photoconductive gain makes CSIPs so sensitive as to detect single photons. CSIPs are well established in the mid-infrared ( = 12-20 m), achieving noise equivalent power around 1.9 10 W/Hz with a quantum efficiency of 7 %. CSIPs have been demonstrated to work in longer wavelengths up to 45 m, but the sensitivity was not as high as in the shorter wavelengths, probably due to lower quantum efficiency. Reported here is a remarkable improvement in the performance of longer wavelength CSIPs (45 m), achieved primarily by optimizing the doping concentration in the upper QW. This work indicates that longer wavelength CSIPs are promising detectors for the astronomical application.

Nihei, R.; Komiyama, S.; Kawada, M.; Matsuura, S.; Doi, Y.; Satoh, T.; Nakagawa, T.

2014-08-01

149

Charge sensitivity approach to mutual polarization of reactants: molecular mechanics perspective.  

PubMed

Charge sensitivity analysis (CSA) in force-field atoms resolution was applied to describe the mutual polarization of reactants as well as charge-transfer (CT) effects. An inclusion complex of ?-cyclodextrin with salicylic acid was used as a model system. Three CSA models were taken into account and verified on a Born-Oppenheimer molecular dynamics (BOMD) trajectory. The models differed in terms of the equilibrium conditions imposed on the system. It was demonstrated that mutual polarization is an important source of stabilization, in contrast to the results obtained from static charge calculations. The energy lowering induced by CT was small and comparable to the CT stabilization that occurs in hydrogen-bonded systems. All models correctly described the main topological features of the BOMD energy surface. CSA in force-field atoms resolution qualitatively reproduced the charge reorganization accompanying hydrogen-bond formation. It was shown that CSA parameters are very sensitive to the bond formation process, which suggests that they could be applied in reactive force fields as detectors of newly formed chemical bonds. PMID:23392762

Stachowicz, Anna; Rogalski, Marek; Korchowiec, Jacek

2013-10-01

150

A JFET-CMOS radiation-tolerant charge-sensitive preamplifier  

Microsoft Academic Search

A monolithic charge-sensitive preamplifier based on n-channel junction field-effect transistors (JFETs) and p-channel MOS has been realized for applications with microelectrode detectors in elementary particle physics. Radiation resistance tests carried out with the preamplifier exposed to gamma rays emitted by a Co-60 source have shown no significant increase of the equivalent noise source up to 150-krd absorbed dose.

Werner Buttler; Bedrich J. Hosticka; Gerhard Lutz; Pier F. Manfredi

1990-01-01

151

Radiation damage study of a fast bipolar monolithic charge sensitive preamplifier  

Microsoft Academic Search

A fast bipolar monolithic Charge Sensitive Preamplifier (CSP) implemented in the monolithic 2 ?m BiCMOS technology (called HF2CMOS), was studied after neutron irradiation at fluences between 1.26 × 1012 and 1.09 × 1014 n\\/cm2. Neutron fluence effects on the base spreading resistance, rbb?, and the parallel noise of the bipolar npn input device and on the PMOS transistor in the

A. Baschirotto; R. Castello; A. Gola; C. Onado; G. Pessina; P. G. Rancoita; M. Redaelli; A. Seidman

1996-01-01

152

A low noise charge sensitive preamplifier with switch control feedback resistance  

Microsoft Academic Search

In this paper, the design and analysis of a new low noise charge sensitive preamplifier for silicon strip, Si(Li), CdZnTe and CsI detectors etc. with switch control feedback resistance were described, the entire system to be built using the CMOS transistors. The circuit configuration of the CSP proposed in this paper can be adopted to develop CMOS-based Application Specific Integrated

Evariste WEMBE TAFO; Hong SU; Yu PENG; Ming WU; Yi QIAN

2008-01-01

153

The AGATA charge-sensitive preamplifiers with built-in active-reset device and pulser  

Microsoft Academic Search

New charge-sensitive preamplifiers for the highly segmented HPGe detectors of AGATA have been designed and built, as developed to read out simultaneously the segment- and the core-electrode signals. A new fast-reset circuitry is used to reduce the dead time brought about by a background of energetic particles in the 10 to 100 MeV range that could hit the detectors in

A. Pullia; G. Pascovici; B. Cahan; D. Weisshaar; C. Boiano; R. Bassini; M. Petcu; F. Zocca

2004-01-01

154

Automatic Offset Cancellation and Time-Constant Reduction in Charge-Sensitive Preamplifiers  

Microsoft Academic Search

A circuit technique is presented which eliminates the offset at the output of charge-sensitive preamplifiers and optionally reduces the resistive reset time-constant. Offset cancellation as well as time-constant reduction are obtained with no trimming. Offset cancellation is obtained actively through a negative feedback path whose ??error?? variable is the offset itself. As a result the output voltage offset is automatically

Alberto Pullia; Francesca Zocca

2010-01-01

155

Low-noise gallium-arsenide charge-sensitive preamplifiers for low-temperature particle detectors  

Microsoft Academic Search

Charge-sensitive preamplifiers for operation between 1 K and 120 K have been developed and evaluated. They use double-gate GaAs MESFETs selected for their low 1\\/f noise. These devices are operated with both gates interconnected, emulating single-gate MESFETs of double gate-length, obtaining in this way a value of Af, (the coefficient of the 1\\/f noise spectral power density), of 1.7×10-13 V2

A. Alessandrello; C. Brofferio; D. V. Camin; A. Giuliani; G. Pessina; E. Previtali

1990-01-01

156

A double-gate double-feedback JFET charge-sensitive preamplifier  

Microsoft Academic Search

A new Charge-Sensitive Preamplifier (CSP) without a physical resistance in the feedback is presented. The input device has to be a double-gate JFET. In this new preamplifier configuration the feedback capacitor is continuously discharged by means of a second DC current feedback loop closed through the bottom gate of the input JFET. The top gate-channel junction works as usual in

Alberto Fazzi; Pavel Rehak

1996-01-01

157

Design and Characterization of CMOS Avalanche Photodiode With Charge Sensitive Preamplifier  

Microsoft Academic Search

The CMOS Avalanche Photodiodes (APDs) and Charge Sensitive Preamplifiers (CSAs) were fabricated using the commercially available AMIS 0.7 mum high voltage process without any process modifications. The APDs have an N+\\/P-substrate structure with the diameters of their active areas equal to 25 mum, 50 mum, 100 mum, 400 mum, and 800 mum. The CSAs with three different input transistor sizes

Young Soo Kim; In Sub Jun; Kwang Hyun Kim

2008-01-01

158

A charge sensitive preamplifier made with SiGe bipolar transistors  

NASA Astrophysics Data System (ADS)

We have characterized some commercial SiGe bipolar transistors to be used at low injection level and in a wide temperature range, in view of their possible application in experiments with large number of channels. After having observed that they are very suitable for low noise and high-speed applications we have designed and built a charge sensitive preamplifier able to work at tens of nsec shaping time. In this paper, the preamplifier performances at room temperature are described.

Arnaboldi, Claudio; Boella, Giuliano; Pessina, Gianluigi

2004-02-01

159

A ultra fast hybrid charge-sensitive preamplifier for high-capacitance detectors  

Microsoft Academic Search

In order to improve performances of pulse shape methods for the particles identification in large area silicon detectors of typical large capacitance (1 nF), a new ultra fast hybrid charge-sensitive preamplifier has been designed and built. It is arranged to operate with typically nF range input capacitance. An excellent rise time of less then 2 ns has been reached with

C. Boiano; R. Bassini; A. Pagano; A. Pullia; S. Riboldi

2007-01-01

160

A JFET-CMOS radiation-tolerant charge-sensitive preamplifier  

Microsoft Academic Search

A monolithic charge-sensitive preamplifier based on n-channel junction field-effect transistors (JFETs) and p-channel MOS has been realized for applications with microelectrode detectors in elementary particle physics. Radiation resistance tests carried out with the preamplifier exposed to ?-rays emitted by a 60Co source have shown no significant increase of the equivalent noise source up to 150-krd absorbed dose

WERNER BUTTLER; BEDRICH J. HOSTICKA; GERHARD LUTZ; PIER F. MANFREDI

1990-01-01

161

Gallium-arsenide charge-sensitive preamplifier for operation in a wide low-temperature range  

Microsoft Academic Search

A charge-sensitive preamplifier for temperature operation between 1 and 120 K has been developed and evaluated. It uses double-gate GaAs MESFETs selected for their low 1\\/f; noise. These devices are operated with both gates interconnected emulating single-gate MESFETs of double gate-length, obtaining in this way a value for Af;, the coefficient of the 1\\/f; noise spectral power density, of 1.7

A. Alessandrello; C. Brofferio; D. V. Camin; A. Giuliani; G. Pessina; E. Previtali

1990-01-01

162

A versatile high-speed bipolar charge-sensitive preamplifier for calorimeter applications  

Microsoft Academic Search

A high-speed charge-sensitive preamplifier (CSP) to be used in silicon calorimeters has been realized. The main features of this circuit are: high slew rate (larger than 500 V\\/?s), low noise, large output swing (5 V), high dynamic range (of the order of 90 dB), and 50-? output drive capability. In addition, the CSP is designed to allow adaptation of its

A. Baschirotto; R. Castello; G. Pessina; P. G. Rancoita; A. Seidman

1998-01-01

163

Radiation damage investigation for the design of a hardened fast bipolar monolithic charge sensitive preamplifier  

Microsoft Academic Search

In order to implement a high-speed, radiation hardened, charge sensitive preamplifier (CSP) in the monolithic 2 ?m BiCMOS technology (called HF2CMOS), the performance of the available NPN and PNP transistors were measured, before and after neutron irradiation. Furthermore, also monolithic CSPs, realized with the same technology, were irradiated and investigated. Results on the neutron irradiation effect on the base spreading

A. Baschirotto; R. Castello; A. Gola; G. Pessina; P. G. Rancoita; M. Rattaggi; M. Redaelli; A. Seidman

1995-01-01

164

Design for a Versatile Charge Sensitive Preamplifier for Nuclear Radiation Detectors  

Microsoft Academic Search

The design of the high-gain, low-noise, charge-sensitive preamplifier discussed in this paper was prompted by the need for a unit that would fulfill many experimental requirements without modification and\\/or redesign. This transistorized preamplifier has good versatility without sacrificing performance characteristics. The maximum gain is about 650 volts\\/picocoulomb, but can be reduced by a factor of 1200. The noise figure is

Arne E. Bradley

1966-01-01

165

A CMOS charge sensitive preamplifier for CdZnTe detector  

Microsoft Academic Search

In this work, a low noise and low power charge sensitive preamplifier (CSA) based on CSMC 0.6 ?m double poly mix CMOS technology was designed and simulated. In this design, two MOSFETs were used as a feedback resistor and a feedback capacitor respectively to replace an on-chip resistor in parallel and an on-chip capacitor in a conventional CSA. Simulation results

Zhubin Shi; Lan Peng; Linjun Wang; Kaifeng Qin; Jiahua Min; Jijun Zhang; Xiaoyan Liang; Yiben Xia

2010-01-01

166

Realization of a versatile high-speed bipolar charge sensitive preamplifier for calorimeter applications  

Microsoft Academic Search

A versatile high-speed Charge Sensitive Preamplifier (CSP) to be used in silicon calorimeters is presented. The main features of this circuit are low noise, high slew-rate (larger than 500V\\/æs), high dynamic range (of the order of 90dB), and 100æ output drive capability. The bias current of the CSP can be adjusted, in order to optimise the trade-off between power and

A. Baschirotto; R. Castello; A. Gola; G. Pessina; P. G. Rancoita; M. Redaelli; A. Seidman; M. Volpi

1995-01-01

167

A fully integrated, monolithic, cryogenic charge sensitive preamplifier using N-channel JFETs and polysilicon resistors  

Microsoft Academic Search

An N-channel JFET process technology for integrated charge sensitive preamplifiers has been developed. The process integrates multiple pinch-off voltage JFETs fabricated in an n-type epitaxial layer on a low resistivity p-type substrate. The process also incorporates polysilicon resistors integrated on the same die as the JFETs. The optimized polysilicon resistors exhibit 1\\/f noise nearly as good as metal film resistors

T. S. Jung; H. Guckel; J. Seefeldt; G. Ott; Y. C. Ahn

1994-01-01

168

Ultrafast interfacial charge transfer dynamics in dye-sensitized and quantum dot solar cell  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cell (DSSC) appeared to be one of the good discovery for the solution of energy problem. We have been involved in studying ultrafast interfacial electron transfer dynamics in DSSC using femtosecond laser spectroscopy. However it has been realized that it is very difficult to design and develop higher efficient one, due to thermodynamic limitation. Again in DSSC most of the absorbed photon energy is lost as heat within the cell, which apart from decreasing the efficiency also destabilizes the device. It has been realized that quantum dot solar cell (QDSC) are the best bet where the sensitizer dye molecules can be replaced by suitable quantum dot (QD) materials in solar cell. The quantum-confinement effect in semiconductors modifies their electronic structure, which is a very important aspect of these materials. For photovoltaic applications, a long-lived charge separation remains one of the most essential criteria. One of the problems in using QDs for photovoltaic applications is their fast charge recombination caused by nonradiative Auger processes, which occur predominantly at lower particle sizes due to an increase in the Coulomb interaction between electrons and holes. Various approaches, such as the use of metal-semiconductor composites, semiconductor-polymer composite, and semiconductor core-shell heterostructures, have been attempted to minimize the fast recombination between electrons and holes. To make higher efficient solar devices it has been realised that it is very important to understand charge carrier and electron transfer dynamics in QD and QD sensitized semiconductor nanostructured materials. In the present talk, we are going to discuss on recent works on ultrafast electron transfer dynamics in dye-sensitized TiO2 nanoparticles/film [1-12] and charge (electron/hole) transfer dynamics in quantum dot core-shell nano-structured materials [13-17].

Ghosh, Hirendra N.

2013-02-01

169

Intercellular Communication Amplifies Stressful Effects in High-Charge, High-Energy (HZE) Particle-Irradiated Human Cells  

PubMed Central

Understanding the mechanisms that underlay the biological effects of particulate radiations is essential for space exploration and for radiotherapy. Here, we investigated the role of gap junction intercellular communication (GJIC) in modulating harmful effects induced in confluent cultures wherein most cells are traversed by one or more radiation tracks. We focused on the effect of radiation quality (linear energy transfer; LET) on junctional propagation of DNA damage and cell death among the irradiated cells. Confluent normal human fibroblasts were exposed to graded doses of 1 GeV protons (LET ~0.2 keV/?m) or 1 GeV/u iron ions (LET ~151 keV/?m) and were assayed for clonogenic survival and for micronucleus formation, a reflection of DNA damage, shortly after irradiation and following longer incubation periods. Iron ions were ~2.7 fold more effective than protons at killing 90% of the cells in the exposed cultures when assayed within 5–10 minutes after irradiation. When cells were held in the confluent state for several hours after irradiation, substantial repair of potentially lethal damage (PLDR), coupled with a reduction in micronucleus formation, occurred in cells exposed to protons, but not in those exposed to iron ions. In fact, such confluent holding after exposure to a similarly toxic dose of iron ions enhanced the induced toxic effect. However, following iron ion irradiation, inhibition of GJIC by 18-?-glycyrrhetinic acid eliminated the enhanced toxicity and reduced micronucleus formation to levels below those detected in cells assayed shortly after irradiation. The data show that low LET radiation induces strong PLDR within hours, but that high LET radiation with similar immediate toxicity does not induce PLDR and its toxicity increases with time following irradiation. The results also show that GJIC among irradiated cells amplifies stressful effects following exposure to high, but not LET radiation, and that GJIC has only minimal effect on cellular recovery following low LET irradiation.

AUTSAVAPROMPORN, Narongchai; DE TOLEDO, Sonia M.; BUONANNO, Manuela; JAY-GERIN, Jean-Paul; HARRIS, Andrew L.; AZZAM, Edouard I.

2014-01-01

170

Relationship between Resolution, Line Edge Roughness, and Sensitivity in Chemically Amplified Resist of Post-Optical Lithography Revealed by Monte Carlo and Dissolution Simulations  

NASA Astrophysics Data System (ADS)

The simultaneous achievement of high resolution and low line width (edge) roughness (LWR, LER) at acceptable sensitivity (RLS) in chemically-amplified resist (CAR) is in strong demand to realize the mass production of ultra-small electric circuit using extreme ultraviolet. We performed Monte Carlo and dissolution simulations of positive-tone CAR of electron beam lithography to clarify this RLS formation. The trade-off RLS relationship was successfully reproduced and discussed in terms of non-scaling law of exposed line width. It was demonstrated that LER follows the inverse of square root of exposure dose at moderate acid diffusion length.

Saeki, Akinori; Kozawa, Takahiro; Tagawa, Seiichi

2009-07-01

171

High Speed Multichannel Charge Sensitive Data Acquisition System with Self-Triggered Event Timing  

PubMed Central

A number of modern experiments require simultaneous measurement of charges on multiple channels at > MHz event rates with an accuracy of 100-1000 e? rms. One widely used data processing scheme relies on application of specific integrated circuits enabling multichannel analog peak detection asserted by an external trigger followed by a serial/sparsified readout. Although this configuration minimizes the back end electronics, its counting rate capability is limited by the speed of the serial readout. Recent advances in analog to digital converters and FPGA devices enable fully parallel high speed multichannel data processing with digital peak detection enhanced by finite impulse response filtering. Not only can accurate charge values be obtained at high event rates, but the timing of the event on each channel can also be determined with high accuracy. We present the concept and first experimental tests of fully parallel 128-channel charge sensitive data processing electronics capable of measuring charges with accuracy of ~1000 e- rms. Our system does not require an external trigger and, in addition to charge values, it provides the event timing with an accuracy of ~1 ns FWHM. One of the possible applications of this system is high resolution position sensitive event counting detectors with microchannel plates combined with cross strip readout. Implementation of fast data acquisition electronics increases the counting rates of those detectors to multi-MHz level, preserving their unique capability of virtually noiseless detection of both position (with accuracy of ~10 ?m FWHM) and timing (~1 ns FWHM) of individual particles, including photons, electrons, ions, neutrals, and neutrons.

Tremsin, Anton S.; Siegmund, Oswald H.W.; Vallerga, John V.; Raffanti, Rick; Weiss, Shimon; Michalet, Xavier

2010-01-01

172

Charge transport through split photoelectrodes in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Charge transport and recombination are relatively ignored parameters while upscaling dye-sensitized solar cells (DSCs). Enhanced photovoltaic parameters are anticipated by merely widening the devices physical dimensions, viz., thickness and area as evident from the device design adopted in reported large area DSCs. These strip designs lead to ?50% loss in photocurrent compared to the high efficiency lab scale devices. Herein, we report that the key to achieving higher current density (JSC) is optimized diffusion volume rather than the increased photoelectrode area because kinetics of the devices is strongly influenced by the varied choices of diffusion pathways upon increasing the electrode area. For a given electrode area and thickness, we altered the photoelectrode design by splitting the electrode into multiple fractions to restrict the electron diffusion pathways. We observed a correlation between the device physical dimensions and its charge collection efficiency via current-voltage and impedance spectroscopy measurements. The modified electrode designs showed >50% increased JSC due to shorter transport time, higher recombination resistance and enhanced charge collection efficiency compared to the conventional ones despite their similar active volume (˜3.36 × 10-4 cm3). A detailed charge transport characteristic of the split devices and their comparison with single electrode configuration is described in this article.

Fakharuddin, Azhar; Ahmed, Irfan; Khalidin, Zulkeflee; Yusoff, Mashitah M.; Jose, Rajan

2014-04-01

173

Energy-sensitive X-ray radiography and charge sharing effect in pixelated detector  

NASA Astrophysics Data System (ADS)

The semiconductor pixel detector TimePix (256×256 pixels with a pitch of 55 ?m) is a newly developed successor of the Medipix2 device. Each Timepix pixel can be operated in Time-over-Threshold mode allowing direct energy measurement. The possibility of per pixel energy measurement presents a substantial advantage for X-ray radiography with polychromatic X-ray sources (tubes) allowing material identification (colour X-ray radiography) via analysis of transmission energy spectra. The energy resolution of the pixelated planar detector is, however, influenced by charge sharing. The ionization charge generated by the particle (X-ray photon) can be collected by several pixels, forming a cluster. If the fraction of the charge collected by a particular pixel drops below the energy threshold it is not counted and therefore it is lost. This fact, together with the presence of noise, limits the energy resolution of the device. A simplified model of the charge sharing effect is studied in this work and compared with experimental data. The application of a (per-pixel) energy-calibrated TimePix detector in the field of energy-sensitive X-ray radiography enables the recognition of soft biological materials (fat and muscle tissue) which is presented here.

Jakubek, Jan

2009-08-01

174

Highly stable biased amplifier and stretcher system  

NASA Technical Reports Server (NTRS)

Amplifier and stretcher system, which minimizes thermal effects and compensates for repetition-rate effects, maintains resolution levels in spectrum analysis. An additional inverting amplifier is used in the system to provide a noiseless charge restorer.

Roddick, R. G.

1970-01-01

175

A sensitive enzyme-linked immunosorbent assay amplified by biotin-streptavidin system for detecting non-steroidal anti-inflammatory drug ketoprofen.  

PubMed

A sensitive biotin-streptavidin-amplified enzyme-linked immunosorbent assay (BA-ELISA) method was developed for detecting non-steroidal anti-inflammatory drug ketoprofen. Compared with traditional ELISA method, the sensitivity of proposed immunoassay was enhanced by the biotin-streptavidin system. Under the optimal condition, the median inhibitory concentration (IC50) was 0.25 ng mL(-1), with minor cross-reactivity to a number of structural analogs. This developed assay was successfully applied to detect the ketoprofen residues in different fish samples, and good recoveries (72.6-105.5%) were obtained. The results indicated that this immunoassay method could specifically detect trace ketoprofen residues and could be widely used for routine monitoring of food samples. PMID:24762178

Bu, Dan; Zhuang, Hui S; Yang, Guang X

2014-06-01

176

A low-noise, wide-band CMOS charge-sensitive preamplifier for use with APD/LSO PET detectors  

SciTech Connect

The recent emergence of LSO as a potential scintillator for positron emission tomography (PET) and recent improvements in avalanche photodiode (APD) technology offer encouragement that an APD/LSO based PET detector may be commercially viable in the near future. An important component of any APD/LSO based PET detector will be the preamplifier used to read out the low-level detector signals. Due to the large number of detectors (>18,000) in a high-resolution PET scanner, the preamplifier must be implemented as a monolithic integrated circuit. Additionally, in order to achieve the timing resolution required for high resolution PET, the preamplifier must have a large band-width and a low equivalent input noise voltage. This paper presents a CMOS charge-sensitive preamplifier design which uses local feedback to improve the performance of the common gate transistor. The modified cascode circuit is analyzed and compared with a previously reported simple folded cascode circuit. A prototype circuit was fabricated in a 2 {micro}m NWELL CMOS process. The prototype amplifier has a measured 10--90% rise-time of 7 ns with an external input capacitance of {approximately}6 pF and has an equivalent input noise voltage of {approximately}1.1 nV/rt-Hz above the flicker noise corner. A pulse height resolution of 14.3% FWHM and a timing resolution of 1.57 ns FWHM (vs. plastic) were obtained with the preamplifier, an Advanced Photonix 5 mm diameter beveled-edge APD and a 3.5 x 3.5 x 22 mm{sup 3} Teflon wrapped LSO crystal.

Paulus, M.J.; Andreaco, M.S.; Binkley, D.M. [CTI, Inc., Knoxville, TN (United States)] [CTI, Inc., Knoxville, TN (United States); Rochelle, J.M. [Univ. of Tennessee, Knoxville, TN (United States). Electrical and Computing Engineering Dept.] [Univ. of Tennessee, Knoxville, TN (United States). Electrical and Computing Engineering Dept.

1996-06-01

177

Visualizing interfacial charge transfer in dye sensitized nanoparticles using x-ray transient absorption spectroscopy.  

SciTech Connect

A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy){sub 2}(NCS){sub 2} (RuN3) dye adsorbed to TiO{sub 2} nanoparticle surfaces. The results show that the average Ru-NCS bond length reduces by 0.06 {angstrom}, whereas the average Ru-N(dcbpy) bond length remains nearly unchanged after the electron injection. The differences in bond-order change and steric hindrance between two types of ligands are attributed to their structural response in the charge separation. This study extends the application of XTA into optically opaque hybrid interfacial systems relevant to the solar energy conversion.

Zhang, X. Y.; Smolentsev, G.; Guo, J.; Attenkofer, K.; Kurtz, C.; Jennings, G.; Lockard, J. V.; Stickrath, A. B.; Chen, L. X. (X-Ray Science Division); (Southern Federal Univ.); (Lund Univ.); (Northwestern Univ.)

2011-01-01

178

Composite tin and zinc oxide nanocrystalline particles for enhanced charge separation in sensitized degradation of dyes.  

PubMed

Composite ZnO/SnO2 catalyst has been studied for the sensitized degradation of dyes e.g. Eosin Y (2', 4', 5', 7'-tetrabromofluorescein disodium salt) in relation to efficient charge separation properties of the catalyst. Improved photocatalytic activity was observed in the case of ZnO/SnO2 composite catalyst compared to the catalytic activity of ZnO, SnO2 or TiO2 powder. The suppression of charge recombination in the composite ZnO/SnO2 catalyst led to higher catalytic activity for the degradation of Eosin Y. Degradation of Eosin follows concomitant formation of CO2 and formation of CO2 followed a pseudo-first-order rate. Photoelectrochemical cells constructed using SnO2, ZnO, ZnO/SnO2 sensitized with Eosin Y showed V(oc) of 175, 306, 512 mV/cm2 and I(sc) of 50, 70, 200 microA/cm2 respectively. A higher irreversible degradation of Eosin Y and higher V(oc) observed on composite ZnO/SnO2 than ZnO and SnO2 separately can be considered as a proof of enhanced charge separation of ZnO/SnO2 catalyst. Eosin Y showed a higher emission decreases on ZnO/SnO2 composite than on individual ZnO, SnO2 or TiO2 indicating dominance of the charge injection process. Photoinjected electrons are tunneled from ZnO to SnO2 particles accumulating injected electrons in the conduction bands allowing wider separation of excited carriers. PMID:12365841

Bandara, J; Tennakone, K; Jayatilaka, P P B

2002-10-01

179

Development and evaluation of charge-sensitive preamplifier for CsI calorimeter in the KEK B-factory  

Microsoft Academic Search

We developed a charge-sensitive preamplifier for the electromagnetic calorimeter (CsI(Tl)) in the KEK B-factory. We examined noise characteristic, dynamic range and power-supply ripple-rejection ratio on power rails

Manobu Tanaka; Hirokazu Ikeda; Kunio Tamai; Megumi Takemoto; Hisashi Hayashii

1994-01-01

180

Characterization of a new charge sensitive preamplifier (CSP) for the electromagnetic calorimeters of the ALICE experiment  

NASA Astrophysics Data System (ADS)

The ALICE calorimeters PHOS and EMCal (including its extension DCal) are based on Avalanche Photo-Diode (APD) photosensors with Charge Sensitive Preamplifiers (CSPs) for readout of the scintillating elements. A new CSP has been developed on the basis of the design of the PHOS CSP, but modified to meet the requirements of the EMCal and DCal. Modifications were made specifically for a different APD choice with different characteristics, and also with the goals of less noise, faster rise time, and reduced cost. This paper presents a detailed description of the new CSP features and the test results.

Wang, Yaping; Muller, Hans; Cai, Xu; Zhou, Daicui; Awes, Terry C.; Yin, Zhongbao

2012-09-01

181

Characterization of a New Charge Sensitive Preamplifier (CSP) for the Electromagnetic Calorimeters of the ALICE Experiment  

SciTech Connect

The ALICE calorimeters PHOS and EMCal (including its extension DCal) are based on Avalanche Photo-Diode (APD) photosensors with Charge Sensitive Preamplifiers (CSPs) for readout of the scintillating elements. A new CSP has been developed on the basis of the design of the PHOS CSP, but modified to meet the requirements of the EMCal and DCal. Modifications were made specifically for a different APD choice with different characteristics, and also with the goals of less noise, faster rise time, and reduced cost. This paper presents a detailed description of the new CSP features and the test results.

Wang, Yaping [Inst. of Particle Physics/Key Lab. of Quark and Lepton Physics, Central China Normal Univ., Wuhan, C; Muller, Hans [CERN, Geneva, Switzerland; Cai, Xu [Inst. of Particle Physics/Key Lab. of Quark and Lepton Physics, Central China Normal Univ., Wuhan, C; Zhou, Daicui [Inst. of Particle Physics/Key Lab. of Quark and Lepton Physics, Central China Normal Univ., Wuhan, C; Awes, Terry C [ORNL; Yin, Zhongbao [Inst. of Particle Physics/Key Lab. of Quark and Lepton Physics, Central China Normal Univ., Wuhan, C

2012-01-01

182

A Low-Noise Charge-Sensitive Preamplifier with a Field-Effect Transistor in the Input Stage  

Microsoft Academic Search

The excellent energy resolution of semiconductor radiation detectors has generated a need for charge-sensitive transistorized preamplifiers which have low values of noise line-widths. The application of field-effect transistors in charge-sensitive configurations was investigated, and a low-noise preamplifier was consequently developed. The preamplifier has a junction field-effect transistor in the input stage. The field-effect transistor is connected in cascode with the

T. V. Blalock

1964-01-01

183

Photoinduced charge transfer and acetone sensitivity of single-walled carbon nanotube-titanium dioxide hybrids.  

PubMed

The unique physical and chemical properties of single-walled carbon nanotubes (SWNTs) make them ideal building blocks for the construction of hybrid nanostructures. In addition to increasing the material complexity and functionality, SWNTs can probe the interfacial processes in the hybrid system. In this work, SWNT-TiO2 core/shell hybrid nanostructures were found to exhibit unique electrical behavior in response to UV illumination and acetone vapors. By experimental and theoretical studies of UV and acetone sensitivities of different SWNT-TiO2 hybrid systems, we established a fundamental understanding on the interfacial charge transfer between photoexcited TiO2 and SWNTs as well as the mechanism of acetone sensing. We further demonstrated a practical application of photoinduced acetone sensitivity by fabricating a microsized room temperature acetone sensor that showed fast, linear, and reversible detection of acetone vapors with concentrations in few parts per million range. PMID:23734594

Ding, Mengning; Sorescu, Dan C; Star, Alexander

2013-06-19

184

Mu2e: A High-Sensitivity Charged Lepton Flavor-Violating Search at Fermilab  

NASA Astrophysics Data System (ADS)

The Mu2e Experiment at Fermilab will search for coherent, neutrino-less conversion of a muon into an electron in the field of a nucleus, -circ;+A->A+e^-, with a sensitivity improvement of a factor of 10,000 over existing limits. Such a charged lepton flavor-violating reaction probes new physics complementary to the LHC and can reach a scale unavailable by direct searches at either present or planned high energy colliders. The physics motivation for Mu2e will be presented, as well as the design of the muon beamline and spectrometer. The beamline employs a new design consisting of superconducting solenoids that will produce muons at high efficiency. A scheme by which the experiment can be mounted in the present Fermilab accelerator complex will be described. Prospects for increased sensitivity at future very high intensity sources, such as the Project X linac that is being proposed by Fermilab, will be discussed.

Miller, James

2012-03-01

185

45 GHz transimpedance 32 dB limiting amplifier and 40 Gb\\/s 1:4 high-sensitivity demultiplexer with decision circuit using SiGe HBTs for 40 Gb\\/s optical receiver  

Microsoft Academic Search

A preamplifier with 45 GHz bandwidth and 50.2 dB? transimpedance gain, a limiting amplifier with 32 dB gain and 49 GHz bandwidth, and a 40 Gb\\/s 1:4 high-sensitivity demultiplexer (HS-DEMUX) combined with a decision circuit are for use in a 40 Gb\\/s optical receiver. The bandwidth in the preamplifier and the maximum gain at 40 GHz in the limiting amplifier

Toru Masuda; Ken-ichi Ohhata; Fumihiko Arakawa; Nobuhiro Shiramizu; Eiji Ohue; Katsuya Oda; Reiko Hayami; Masamichi Tanabe; Hiromi Shimamoto; Masao Kondo; Takashi Harada; Katsuyoshi Washio

2000-01-01

186

Chemical reactivity trends of ergotamine and butenolide from electrostatic potentials and charge sensitivities  

SciTech Connect

A set of reactivity indices, including maps of the electrostatic potential and local and condensed Fukui function (FF) indices in the atomic resolution, are reported for two vasoconstricting mycotoxins: butenolide and ergotamine; both the finite difference approach of Parr and Yan as well as charge sensitivity analysis, determining the charge responses via the inversion of the hardness tensor, have been used to generate the FF data. These two routes of arriving at the atomic FF indices provide an opportunity to evaluate the available parametrizations of the semiempirical NDDO-type of methods which have been used to determine the input charge distribution; namely, the best parametrization should generate consistent FF predictions resulting from both approaches. For butenolide, the MNDO parametrization was found to fulfill this consistency requirement. The chemical reactivity information has been used to trace possible similarities in reactivity trends of the butenolide molecule and the related fragment of ergotamine, toward hypothetical nucleophilic, electrophilic, and radical attacks. These predictions have been compared to experimental data available for other unsaturated lactones. 13 refs., 18 figs., 1 tab.

Mrozek, J.; Michalak, A. [Jagiellonian Univ., Cracow (Poland)

1995-12-05

187

A fast charge-sensitive preamplifier for soft X-ray astronomy applications of multiwire proportional chambers  

Microsoft Academic Search

An inexpensive charge-sensitive preamplifier circuit with total dissipation of 38 mW and sensitivity of 3.2 × 10^8 volts\\/electron has been developed and tested for a soft X-rays multiwire proportional chamber.

G. Auriemma; F. Giovannelli; C. Mengucci

1973-01-01

188

A low-cost sensitizer based on a phenolic resin for charge-transfer type photocatalysts working under visible light.  

PubMed

Phenolic resin (denoted as PR) was used as an economical sensitizer of titania to achieve efficient visible light photocatalytic activity. Through the surface complexation of PR with TiO(2), we demonstrate that the complexed PR layer sensitizes TiO(2) under visible light through the ligand-to-metal charge transfer (LMCT) mechanism. PMID:23011117

Zhang, Guan; Choi, Wonyong

2012-11-01

189

Composite space charge density functions for the calculation of gamma sensitivity of self-powered neutron detectors, using Warren's model  

Microsoft Academic Search

In the calculational model developed by Warren and Shah for the computation of the gamma sensitivity (Sgamma) it has been observed that the computed Sgamma value is quite sensitive to the space charge distribution function assumed for the insulator region and the energy of the gamma photons. The Sgamma of SPNDs with Pt, Co and V emitters (manufactured by Thermocoax,

A. K. Mahant; P. S. Rao; S. C. Misra

1994-01-01

190

Charge behaviour and power consumption in ball mills: sensitivity to mill operating conditions, liner geometry and charge composition  

Microsoft Academic Search

Discrete element method (DEM) modelling has been used to systematically study the effects of changes in mill operating parameters and particle properties on the charge shape and power draw of a 5-m ball mill. Specifically, changes in charge fill level, lifter shape (either by design or wear) and lifter pattern are analysed. The effects of changes to the properties of

Paul W Cleary

2001-01-01

191

DEPTH-CHARGE static and time-dependent perturbation/sensitivity system for nuclear reactor core analysis. Revision I. [DEPTH-CHARGE code  

SciTech Connect

This report provides the background theory, user input, and sample problems required for the efficient application of the DEPTH-CHARGE system - a code black for both static and time-dependent perturbation theory and data sensitivity analyses. The DEPTH-CHARGE system is of modular construction and has been implemented within the VENTURE-BURNER computational system at Oak Ridge National Laboratory. The DEPTH module (coupled with VENTURE) solves for the three adjoint functions of Depletion Perturbation Theory and calculates the desired time-dependent derivatives of the response with respect to the nuclide concentrations and nuclear data utilized in the reference model. The CHARGE code is a collection of utility routines for general data manipulation and input preparation and considerably extends the usefulness of the system through the automatic generation of adjoint sources, estimated perturbed responses, and relative data sensitivity coefficients. Combined, the DEPTH-CHARGE system provides, for the first time, a complete generalized first-order perturbation/sensitivity theory capability for both static and time-dependent analyses of realistic multidimensional reactor models. This current documentation incorporates minor revisions to the original DEPTH-CHARGE documentation (ORNL/CSD-78) to reflect some new capabilities within the individual codes.

White, J.R.

1985-04-01

192

Phase-sensitive manipulations of the two-mode entangled state by a type-II nondegenerate optical parametric amplifier inside an optical cavity  

NASA Astrophysics Data System (ADS)

The quantum fluctuations and correlations of the output signal and idler beams from a type-II polarization nondegenerate optical parametric amplifier (NOPA) inside an optical cavity are investigated theoretically, which is driven by the different kinds of quantized fields such as the two-mode thermal field, the phase-conjugate state, and a pair of EPR beams at the signal and idler frequency. Spectral line shapes due to quantum interferences between the input quantum fields and the generated down-converted subharmonic fields of NOPA are studied by scanning the length of the NOPA cavity. The entanglement degree of the EPR entangled beams injected into the NOPA as signal and idler beams can be increased or decreased, which are realized by controlling the relative phase between the pump beam and the injected beams for the NOPA. The results demonstrate coherent phenomena of NOPA in the quantum regime and show phase-sensitive manipulations of quantum entanglement for quantum information processing.

Chen, Haixia; Zhang, Jing

2009-06-01

193

Switching Amplifiers  

NSDL National Science Digital Library

Created by Work-Ready Electronics, a project of the Advanced Technological Education, this module walks visitors through switching amplifiers. The site content is divided up into four sections: Switching Amplifiers Introduction, Class D Switching Amplifiers, Switching RF Power Amplifiers, and Troubleshooting. There is a quiz for each section to test what students learned in the module in the Knowledge Probe section, and the Learning Resources section contains four activities to help cement student understanding. There are also further resources - both print and Web based - for more information and two Questor games, a Flash quiz that reiterates the material covered. The Notebook function allows visitors to take notes and review them at any time. This is an excellent resource students and educators in electronics technician programs to introduce and explore switching amplifiers.

2008-09-04

194

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)

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.

Kuzyuta, E. I.

1974-01-01

195

Overexpression of the Adiponectin Receptor AdipoR1 in Rat Skeletal Muscle Amplifies Local Insulin Sensitivity  

PubMed Central

Adiponectin is an adipokine whose plasma levels are inversely related to degrees of insulin resistance (IR) or obesity. It enhances glucose disposal and mitochondrial substrate oxidation in skeletal muscle and its actions are mediated through binding to receptors, especially adiponectin receptor 1 (AdipoR1). However, the in vivo significance of adiponectin sensitivity and the molecular mechanisms of muscle insulin sensitization by adiponectin have not been fully established. We used in vivo electrotransfer to overexpress AdipoR1 in single muscles of rats, some of which were fed for 6 wk with chow or high-fat diet (HFD) and then subjected to hyperinsulinemic-euglycemic clamp. After 1 wk, the effects on glucose disposal, signaling, and sphingolipid metabolism were investigated in test vs. contralateral control muscles. AdipoR1 overexpression (OE) increased glucose uptake and glycogen accumulation in the basal and insulin-treated rat muscle and also in the HFD-fed rats, locally ameliorating muscle IR. These effects were associated with increased phosphorylation of insulin receptor substrate-1, Akt, and glycogen synthase kinase-3?. AdipoR1 OE also caused increased phosphorylation of p70S6 kinase, AMP-activated protein kinase, and acetyl-coA carboxylase as well as increased protein levels of adaptor protein containing pleckstrin homology domain, phosphotyrosine binding domain, and leucine zipper motif-1 and adiponectin, peroxisome proliferator activated receptor-? coactivator-1?, and uncoupling protein-3, indicative of increased mitochondrial biogenesis. Although neither HFD feeding nor AdipoR1 OE caused generalized changes in sphingolipids, AdipoR1 OE did reduce levels of sphingosine 1-phosphate, ceramide 18:1, ceramide 20:2, and dihydroceramide 20:0, plus mRNA levels of the ceramide synthetic enzymes serine palmitoyl transferase and sphingolipid ?-4 desaturase, changes that are associated with increased insulin sensitivity. These data demonstrate that enhancement of local adiponectin sensitivity is sufficient to improve skeletal muscle IR.

Patel, S. A.; Hoehn, K. L.; Lawrence, R. T.; Sawbridge, L.; Talbot, N. A.; Tomsig, J. L.; Turner, N.; Cooney, G. J.; Whitehead, J. P.; Kraegen, E. W.

2012-01-01

196

The operational amplifier in linear active networks  

Microsoft Academic Search

In this article the two-port characteristics, the gain stability, and the sensitivity of the nonideal operational amplifier are presented. A unified approach is taken to cover both the inverting and the noninverting modes of amplifier operation. Some of the sensitivity aspects pertaining to network synthesis using operational amplifiers are also discussed.

G. S. Moschytz

1970-01-01

197

Ultra-low noise charge sensitive preamplifier for scintillation detection with avalanche photodiodes in PET applications  

SciTech Connect

The need for compact, fast, low-noise front-end electronics in high resolution positron emission tomography (PET) has prompted this effort to design a preamplifier suitable for avalanche photodiode-based scintillation detectors. Due to the small signals from the detectors (< .03 rhoC/meV), a preamplifier with ultra-low noise performance in the 5 to 20 MHz range is essential to achieve the timing resolution required by the PET application. Out of many available technologies, a new third generation MOSFET was selected and implemented as input transistor in an original charge sensitive (CSP) design. Performance among the best reported to date are obtained. The new design was implemented as a dual-channel preamplifier in high density hybrid (thick film) technology.

Schmitt, D.; Lecomte, R.; Lapointe, M.; Martel, G.; Carrier, C.; Karuta, B.; Duval, F.

1987-02-01

198

Extreme chemical sensitivity of nonlinear conductivity in charge-ordered LuFe2O4  

PubMed Central

Nonlinear transport behaviors are crucial for applications in electronic technology. At the nonlinear critical turning point, the nonequilibrium states cause rich physics responses to environment. The corresponding study in this field is crucial for physics and industry application. Here nonlinear conductivity in charge-ordered (CO) LuFe2O4 has been demonstrated. Remarkable resistivity switching behavior was observed and the gas-sensing property can be reversibly tuned by a small alternation of partial pressure and/or chemical components of the environment. These facts allow us to use LuFe2O4 materials as a sensitive chemical gas sensor in technological applications. Careful analysis of the gas sensing process in LuFe2O4 suggests a novel sensing mechanism in sharp contrast with that discussed for the conventional gas sensors which depend fundamentally on surface chemical reactions.

Cao, Shi; Li, Jun; Wang, Zhen; Tian, Huanfang; Qin, Yuanbin; Zeng, Lunjie; Ma, Chao; Yang, Huaixin; Li, Jianqi

2012-01-01

199

A fast and low noise charge sensitive preamplifier in 90 nm CMOS technology  

NASA Astrophysics Data System (ADS)

A fast charge sensitive preamplifier was designed and built in a 90 nm CMOS technology. The work is part of the R&D effort towards the read out of pixel or small strip sensors in next generation HEP experiments. The preamplifier features outstanding noise performance given its wide bandwidth, with a ENC (equivalent noise charge) of about 350 electrons RMS with a detector of 1 pF capacitance. With proper filtering, the ENC drops to less than 200 electrons RMS. Power consumption is 5 mW for one channel, and the closed loop bandwith is about 180 MHz, for a risetime down to 2 ns in the fastest operation mode. Thanks to some freedom left to the user in setting the open loop gain, detectors with larger source capacitance can be read out without significant loss in bandwidth, being the rise time still 5.5 ns for a 5.6 pF detector. The output can drive a 50 ? terminated transmission line.

Baschirotto, A.; Cocciolo, G.; De Matteis, M.; Giachero, A.; Gotti, C.; Maino, M.; Pessina, G.

2012-01-01

200

Interpretation of optoelectronic transient and charge extraction measurements in dye-sensitized solar cells.  

PubMed

Tools that assess the limitations of dye sensitized solar cells (DSSCs) made with new materials are critical for progress. Measuring the transient electrical signals (voltage or current) after optically perturbing a DSSC is an approach which can give information about electron concentration, transport and recombination. Here we describe the theory and practice of this class of optoelectronic measurements, illustrated with numerous examples. The measurements are interpreted with the multiple trapping continuum model which describes electrons in a semiconductor with an exponential distribution of trapping states. We review standard small perturbation photocurrent and photovoltage transients, and introduce the photovoltage time of flight measurement which allows the simultaneous derivation of both effective diffusion and recombination coefficients. We then consider the utility of large perturbation measurements such as charge extraction and the current interrupt technique for finding the internal charge and voltage within a device. Combining these measurements allows differences between DSSCs to be understood in terms such as electron collection efficiency, semiconductor conduction band edge shifts and recombination kinetics. PMID:23404656

Barnes, Piers R F; Miettunen, Kati; Li, Xiaoe; Anderson, Assaf Y; Bessho, Takeru; Gratzel, Michael; O'Regan, Brian C

2013-04-01

201

Performance of a new monolithic eight channel charge sensitive preamplifier-shaper  

SciTech Connect

A monolithic eight channel CMOS time-invariant preamplifier/shaper has been designed and built by Chuck Britton of ORNL in collaboration with Ray Yarema and Tom Zimmerman of Fermilab. Each of the eight channels incorporates a charge sensitive preamplifier and two shaping stages. The resultant weighting function is similar to CR-RC{sup 3}. The peaking time is approximately 200 ns, and the charge gain approximately in the range of 50--70 mv/fc. The layout was done on a Tinychip pad frame and the device was fabricated in a 2{mu} P-well process by Orbit. Figure 1 shows the chip layout. The channels are on an 84{mu} pitch to fit on a Tinychip without folding the layout. The design can be easily expanded to a larger number of channels. This paper describes results of tests performed on this device at Fermilab. The tests were done with a bare die which was directly wirebonded to a printed circuit board. This minimizes parasitic effects which can become significant when using large packages. Results may be somewhat different when using the standard 40 pin package. 6 figs.

Zimmerman, T.

1991-08-01

202

Sensitive identification of bluetongue virus serogroup by a colorimetric dual oligonucleotide sorbent assay of amplified viral nucleic acid.  

PubMed Central

A polymerase chain reaction (PCR) procedure coupled to an enzyme-linked oligonucleotide sorbent assay (ELOSA; a PCR-ELOSA) identified all 24 serotypic variants of bluetongue virus (BTV) without identifying any of six viruses belonging to the related epizootic hemorrhagic disease virus serogroup. The PCR-ELOSA detected 0.01 50% cell culture infectious doses of each serotype of BTV. The sensitivity and serogroup-wide specificity of the PCR-ELOSA may enable it to replace the more expensive, time-consuming, and biohazardous methods used in the identification of BTV. Images

Katz, J B; Alstad, A D; Gustafson, G A; Moser, K M

1993-01-01

203

Enhanced performance CCD output amplifier  

DOEpatents

A low-noise FET amplifier is connected to amplify output charge from a che coupled device (CCD). The FET has its gate connected to the CCD in common source configuration for receiving the output charge signal from the CCD and output an intermediate signal at a drain of the FET. An intermediate amplifier is connected to the drain of the FET for receiving the intermediate signal and outputting a low-noise signal functionally related to the output charge signal from the CCD. The amplifier is preferably connected as a virtual ground to the FET drain. The inherent shunt capacitance of the FET is selected to be at least equal to the sum of the remaining capacitances.

Dunham, Mark E. (Los Alamos, NM); Morley, David W. (Santa Fe, NM)

1996-01-01

204

Cryogenic charge-sensitive preamplifiers, for high dynamic range and fast speed of response using GaAs technology  

Microsoft Academic Search

Charge-sensitive preamplifiers using GaAs MESFETs have been designed to satisfy requirements of high dynamic range, low power dissipation, and low noise at short shaping times. They use SGM20006M MESFETs, a replacement type for the 3SK164. The main parameters of the preamplifiers with a detector capacitance of 400 pF are an equivalent noise charge (ENC) of 5500 RMS electrons at 77

D. V. Camin; G. Pessina; E. Previtali

1991-01-01

205

Cryogenic Charge-sensitive Preamplifiers For High Dynamic Range And Fast Speed Of Response Using GaAs Technology  

Microsoft Academic Search

Charge sensitive preamplifiers using GaAs MESFETs have been designed to satisfy requirements of high dynamic range , low power dissipation and low noise at short shap ing times. They use SGM20006M MESFETS, a replacement type for the 3SK164. The main parameters of the preamplifiers with a detector capacitance of 400pF are the following ones: the equivalent noise charge (ENC) is

D. V. Carnin; G. Pessina; E. Previtali

1990-01-01

206

Nanostructured materials and their charge transport properties in photoanodes of dye sensitized solar cells  

NASA Astrophysics Data System (ADS)

Since the big progress of dye sensitized solar cells (DSCs) by adopting TiO2 nanoparticles for a photoanode in 1991, DSCs have been intensively studied as an alternative to conventional Si-based solar cells. As a main component of DSCs, a photoanode composed of a nanostructured semiconducting oxide network plays a significant role in determining performances of DSCs in terms of light harvesting efficiency (LHE) and charge collection efficiency related to charge transport and recombination. Nanomaterials with various morphologies, such as particles, rods and tubes have been fabricated and investigated to improve performances of DSCs. Among them, submicrometer-sized aggregates of nanocrystallites have demonstrated to be promising as a photoanode of DSCs for higher power conversion efficiency. Such hierarchical structures make it possible to have both high specific surface area for dye molecule adsorption and internal light scattering within the photoanode, leading to a much enhanced LHE. This work focused on the surface modification and charge transport characterization of such hierarchically structured photoanodes. First, a core-shell configuration was fabricated by atomic layer deposition (ALD) process, which was achieved by depositing ultrathin TiO2 layer on inner surface of ZnO aggregate film in which the TiO2 shell was anticipated to act as a chemical and energy barrier. Although the ALD-TiO2 coating failed to improve chemical stability of the ZnO aggregate against to an acidic dye solution due to the ultrathin thickness (< 1 nm), the ALD-TiO2 shell layer effectively suppressed charge recombination at the interface. As a result of the reduced charge recombination, Voc, and FF of DSCs were increased, leading to 20 % enhancement of power conversion efficiency. Second, effects of annealing temperatures on ALD-TiO2 coated aggregates of ZnO nanocrystallites were investigated in terms of sintering behavior and charge transport. 350 °C as the maximum temperature was typically used to preserve the specific surface area of ZnO aggregates. Nitrogen sorption analyses revealed that the ALD-TiO2 layer improved thermal stability of ZnO aggregates at high temperature, ALD-TiO2 coated ZnO aggregates retained the same specific surface area even annealed at 450 °C. The higher annealing temperature resulted in an improved crystallinity, resulting in the highest charge transfer resistance when annealed at 450 °C. As a result, the DSC with photoanode made of ALD-TiO2 coated ZnO aggregates annealed at 450 °C showed the highest Voc and FF, with a little reduced Jsc and thus, the highest power conversion efficiency. Third, charge transport properties such as electron lifetime, chemical diffusion coefficient and diffusion length of ZnO nanorod aggregates were investigated. Electrochemical impedance spectroscopy (EIS) was used to characterize charge transport properties, and it was found that increased crystal sizes and widened necks with higher annealing temperature reduced charge diffusion resistance (Rd), and increased diffusion length from 50 microm to 140 microm. As a result, the power conversion efficiency increased 25 %. Lastly, TiO2 nanoparticles were added into TiO2 aggregates with different ratios; 10 wt% and 20 wt% nanoparticle. As a result, diffusion resistance was found to be reduced and the corresponding diffusion length was increased by filling the bottlenecks between adjacent aggregates with nanoparticles, while additional reduction of diffusion resistance was not observed when the amount of the added TiO 2 nanoparticles increased from 10 to 20 wt%, indicating that there is a saturation point for charge transport. Even though there was no significant impact of the added nanoparticles on electron lifetime despite of the increase of surface area, admixing TiO2 aggregates with TiO2 nanoparticles improved Jsc and eventually leaded to the enhanced efficiency by 30 % as a result of the improved diffusion length and increased surface area.

Ponsaing, Anita Kristine

207

Hydraulic Amplifier.  

National Technical Information Service (NTIS)

The proposed hydraulic amplifier differs from those already known for increasing accuracy, simplifying the design and ensuring the independence of the output parameter from a change in pressure and drainage head; the throttle valve in it is incorporated i...

A. A. Lyubimov E. D. Magner M. V. Shevyakov

1969-01-01

208

Gyromagnetron Amplifier.  

National Technical Information Service (NTIS)

Document describes a gyromagnetron amplifier for radiation at millimeter wavelengths comprising a tapered waveguide tube with longitudinally running vanes in the walls of the tube with the number of vanes chosen to coincide with a desired cyclotron harmon...

Y. Y. Lau L. R. Barnett

1983-01-01

209

Ultrafast Charge Separation Dynamics of Twisted Intramolecular Charge Transfer State (TICT) in Coumarin Dye Sensitized TiO2 Film: A New Route to Achieve Higher Efficient Dye-Sensitized Solar Cell  

NASA Astrophysics Data System (ADS)

Ultrafast transient spectroscopy of 7-diethyl amino coumarin 3-carboxylic acid (D-1421) sensitized TiO2 film reveals that TICT states facilitate higher charge separation and slow recombination and proved to be new route to design higher efficient solar cell.

Verma, Sandeep; Ghosh, Hirendra N.

2013-03-01

210

Probing the charge-collection sensitivity profile using a picosecond pulsed laser at a range of wavelengths  

Microsoft Academic Search

A new empirical methodology is defined and demonstrated in which the charge collection sensitivity profile of single-event effect (SEE)-susceptible nodes in microcircuits is calculated on the basis of laser pulse measurements of the upset threshold at a range of wavelengths.

A. M. Chugg; R. Jones; A. Moutrie; C. S. Dyer; C. Sanderson; A. Wraight

2002-01-01

211

A low-noise charge sensitive preamplifier for Ge spectroscopy operating at cryogenic temperature in the GERDA experiment  

Microsoft Academic Search

Front-end electronics for ionizing radiation detectors signal read-out must sometimes operate at cryogenic temperatures. The classical solution based on cold input transistor and subsequent warm electronics is sometimes not suitable due to the physical constraints of the experimental setup, so the entire front-end circuit has to operate at cryogenic temperature. The proposed multi-channel charge sensitive preamplifiers (\\

Stefano Riboldi; Carla Cattadori; Alessio D'Andragora; Alberto Pullia; Francesca Zocca; Marik Barnabe-Heider; Dusan Budjas

2010-01-01

212

Performance of resistive-charge position sensitive detectors for RBS/Channeling applications  

NASA Astrophysics Data System (ADS)

The performance of two types of 1×1 cm2 photodiode position sensitive detectors (PSDs) based on resistive charge division was evaluated for their use in Rutherford Backscattering/Channeling (RBS/C) experiments in blocking geometry. Their energy resolution was first determined for ~5.5 MeV alpha particles from a radioactive sources, and values of full width half maximum (FWHM) of 22 keV and 33 keV were achieved using a shaping time constant of ?=2.0 ?s. Additional tests were performed using backscattered 4He particles from the 2.0 MeV beam of a Van de Graaff accelerator. While the 22 keV FWHM detector failed after exposure to less than 5×106 cm-24He particles, the other did not show any noticeable deterioration due to radiation damage for a fluence of 4×108 cm-2. For this type of PSD position resolution (?=0.5 ?s) standard deviations of ?L=0.072 mm at ~5.5 MeV and ?L=0.247 mm at 1.1 MeV were achieved. RBS/Channeling experiments using PSD were performed on several crystalline samples, showing that this setup seems suitable for lattice location studies, particularly for heavy ions implantation (D ? 1015 at/cm2) on light substrates like Si, SiC, and AlN.

Miranda, P. A.; Wahl, U.; Catarino, N.; Ribeiro da Silva, M.; Alves, E.

2014-10-01

213

Bidirectional amplifier  

DOEpatents

A bilateral circuit is operable for transmitting signals in two directions without generation of ringing due to feedback caused by the insertion of the circuit. The circuit may include gain for each of the signals to provide a bidirectional amplifier. The signals are passed through two separate paths, with a unidirectional amplifier in each path. A controlled sampling device is provided in each path for sampling the two signals. Any feedback loop between the two signals is disrupted by providing a phase displacement between the control signals for the two sampling devices.

Wright, James T. (Cedarcrest, NM)

1986-01-01

214

Bidirectional amplifier  

DOEpatents

A bilateral circuit is operable for transmitting signals in two directions without generation of ringing due to feedback caused by the insertion of the circuit. The circuit may include gain for each of the signals to provide a bidirectional amplifier. The signals are passed through two separate paths, with a unidirectional amplifier in each path. A controlled sampling device is provided in each path for sampling the two signals. Any feedback loop between the two signals is disrupted by providing a phase displacement between the control signals for the two sampling devices.

Wright, J.T.

1984-02-02

215

Experimental observation of sub-femtosecond charge transfer in a model water splitting dye-sensitized solar cell.  

PubMed

Charge transfer from photoexcited dye molecules to a semiconductor substrate forms the basis of dye sensitized solar cells (DSCs); the overall effectiveness of a DSC device is critically dependent upon the efficiency of this process due to competition with other de-excitation channels. In this paper, we experimentally derive timescales for the charge transfer process in model water splitting DSCs. We studied two organometallic dye complexes adsorbed onto a rutile TiO(2)(110) substrate, the dye molecules were deposited in ultra-high vacuum using electrospray deposition. DFT simulations were used to calculate the spatial distribution of orbitals relevant to the charge transfer process. The core-hole clock implementation of resonant photoemission spectroscopy was used to determine upper limits on charge transfer timescales for previously unoccupied orbitals, which were found to be in the low-femtosecond regime apart from one orbital found to have an upper limit in the sub-femtosecond regime. PMID:23249025

Weston, Matthew; Handrup, Karsten; Reade, Thomas J; Champness, Neil R; O'Shea, James N

2012-12-14

216

The Compressibility of pH-Sensitive Microgels at the Oil-Water Interface: Higher Charge Leads to Less Repulsion.  

PubMed

pH-responsive microgels are unique stabilizers for stimuli-sensitive emulsions that can be broken on demand by changing the pH?value. However, recent experiments have indicated that electrostatic interactions play a different role to that in conventional Pickering emulsions. The influence of charges on the interactions between microgels at the oil-water interface is now described. Compression isotherms of microgels with different charge density and architecture were determined in a Langmuir trough, and counter-intuitive results were obtained: Charged microgels can be compressed more easily than uncharged microgels. The compressibility of microgels is thus not determined by direct Coulomb repulsion. Instead, the different swelling of the microgels in the charged and the uncharged states is proposed to be the key parameter. PMID:24683109

Geisel, Karen; Isa, Lucio; Richtering, Walter

2014-05-01

217

Highly selective and sensitive adenosine aptasensor based on platinum nanoparticles as catalytical label for amplified detection of biorecognition events through H2O2 reduction.  

PubMed

Based on a combination of aptamer and platinum nanoparticles a new sensitive and selective adenosine aptasensor was fabricated. Functionalized thiol-terminated adenosine aptamer (5'-AGAGAACCTGGGGGAGTATTGCGGAGGAAGGT-SH-3') with Pt Nanoparticles (Pt-NPs) was employed as highly catalytic label for electrochemical detection of adenosine based on electrocatalytic activity of Pt-NPs toward H2O2 reduction. Multiwalled carbon nanotubes/ionic liquid/chitosan (MWCNTs/IL/CHIT) nanocomposite was applied as the interface for covalent attachment of 3'-amine-terminated capture probe (3'-NH2-(CH2)6-TCTCTTGGACCC-5'). The presence of Pt nanoparticles improvement the conductivity and performance characteristics of the biosensor as well as incensement in the loading amount of the aptamer DNA sequence. The interaction of adenosine with the aptamer causes the releasing of aptamer with PtNPs into solution which resulted in a decreasing of hydrogen peroxide reduction peak current. Sensitive quantitative detection of adenosine was achieved by monitoring the decrease of voltammetric responses of H2O2 peak current. The peak current of H2O2 decreased with increase in the concentration of adenosine over a range of 1-750 nM with detection limit 1 nM. In addition the proposed aptasensor showed excellent selectivity toward adenosine in compared to some other nucleosides such as guanosine, cytidine and uridine. The proposed aptasensor was successfully used to detect adenosine in human serum samples. The elimination of enzymes or antibodies for the amplified detection of adenosine and the use of platinum nanoparticles as inorganic catalytic label, are the advantage of the proposed aptasensor. PMID:24176972

Shahdost-fard, Faezeh; Salimi, Abdollah; Khezrian, Somayeh

2014-03-15

218

Improved Current and Charge Amplifiers for Driving Piezoelectric Loads, and Issues in Signal Processing Design for Synthesis of Shunt Damping Circuits  

Microsoft Academic Search

Piezoelectric transducers are known to exhibit less hysterisis when driven with current or charge rather than voltage. Despite this advantage, such methods have found little practical application due to the poor low-frequency response of present current and charge driver designs. This paper introduces the compliance feedback current driver containing a secondary voltage feedback loop to prevent DC charging of capacitive

A. J. Fleming; S. O. R. Moheimani

2004-01-01

219

Highly sensitive measurement of ?-rays in NaI(Tl) scintillator by pulse shape discrimination with charge-sensitive analog-to-digital converter  

Microsoft Academic Search

In order to investigate the contamination due to the radioactive isotopes (RIs) in NaI(Tl) scintillator for dark matter search, a simple method of pulse shape discrimination (PSD) to extract ?-rays energy spectrum was developed. Two linear signals of different timings were input into a single module charge-sensitive analog-to-digital converter. The ?- and the ?-rays were discriminated by comparing the total

K. Ichihara; K. Fushimi; N. Koori; S. Nakayama; K. Takahisa; S. Umehara; S. Yoshida

2003-01-01

220

Highly sensitive measurement of alpha-rays in NaI(Tl) scintillator by pulse shape discrimination with charge-sensitive analog-to-digital converter  

Microsoft Academic Search

In order to investigate the contamination due to the radioactive isotopes (RIs) in NaI(Tl) scintillator for dark matter search, a simple method of pulse shape discrimination (PSD) to extract alpha-rays energy spectrum was developed. Two linear signals of different timings were input into a single module charge-sensitive analog-to-digital converter. The alpha- and the gamma-rays were discriminated by comparing the total

K. Ichihara; K. Fushimi; N. Koori; S. Nakayama; K. Takahisa; S. Umehara; S. Yoshida

2003-01-01

221

Differential Amplifier.  

National Technical Information Service (NTIS)

In an embodiment, a pair of push-pull amplifier stages are balanced with respect to ground. A pair of resistors are inserted between the cathode of the electron tube in each stage and ground. The A.C. potential variation across the load resistance of each...

T. R. Williams

1964-01-01

222

Gated charged-particle trap  

DOEpatents

The design and operation of a new type of charged-particle trap provides simultaneous measurements of mass, charge, and velocity of large electrospray ions. The trap consists of a detector tube mounted between two sets of center-bored trapping plates. Voltages applied to the trapping plates define symmetrically-opposing potential valleys which guide axially-injected ions to cycle back and forth through the charge-detection tube. A low noise charge-sensitive amplifier, connected to the tube, reproduces the image charge of individual ions as they pass through the detector tube. Ion mass is calculated from measurement of ion charge and velocity following each passage through the detector. 5 figs.

Benner, W.H.

1999-03-09

223

Differential transimpedance amplifier circuit for correlated differential amplification  

DOEpatents

A differential transimpedance amplifier circuit for correlated differential amplification. The amplifier circuit increase electronic signal-to-noise ratios in charge detection circuits designed for the detection of very small quantities of electrical charge and/or very weak electromagnetic waves. A differential, integrating capacitive transimpedance amplifier integrated circuit comprising capacitor feedback loops performs time-correlated subtraction of noise.

Gresham, Christopher A. (Albuquerque, NM); Denton, M. Bonner (Tucson, AZ); Sperline, Roger P. (Tucson, AZ)

2008-07-22

224

Cryomicroscopy of radiation sensitive specimens on unmodified graphene sheets: Reduction of electron-optical effects of charging?  

PubMed Central

Images of radiation-sensitive specimens obtained by electron microscopy suffer a reduction in quality beyond that expected from radiation damage alone due to electron beam-induced charging or movement of the specimen. For biological specimens, charging and movement are most severe when they are suspended in an insulating layer of vitreous ice, which is otherwise optimal for preserving hydrated specimens in a near native state. We image biological specimens, including a single particle protein complex and a lipid-enveloped virus in thin, vitreous ice films over suspended sheets of unmodified graphene. We show that in such preparations, the charging of ice, as assessed by electron-optical perturbation of the imaging beam, is eliminated. We also use the same specimen supports to record high resolution images at liquid nitrogen temperature of monolayer paraffin crystals grown over graphene.

Sader, Kasim; Stopps, Martyn; Calder, Lesley J.; Rosenthal, Peter B.

2013-01-01

225

Composite space charge density functions for the calculation of gamma sensitivity of self-powered neutron detectors, using Warren's model  

NASA Astrophysics Data System (ADS)

In the calculational model developed by Warren and Shah for the computation of the gamma sensitivity ( S?) it has been observed that the computed S? value is quite sensitive to the space charge distribution function assumed for the insulator region and the energy of the gamma photons. The S? of SPNDs with Pt, Co and V emitters (manufactured by Thermocoax, France) has been measured at 60Co photon energy and a good correlation between the measured and computed values has been obtained using a composite space charge density function (CSCD), the details of which are presented in this paper. The arguments are extended for evaluating the S? values of several SPNDs for which Warren and Shah reported the measured values for a prompt fission gamma spectrum obtained in a swimming pool reactor. These results are also discussed.

Mahant, A. K.; Rao, P. S.; Misra, S. C.

1994-07-01

226

Phase properties of multicomponent superposition states in various amplifiers  

NASA Technical Reports Server (NTRS)

There have been theoretical studies for generation of optical coherent superposition states. Once the superposition state is generated it is natural to ask if it is possible to amplify it without losing the nonclassical properties of the field state. We consider amplification of the superposition state in various amplifiers such as a sub-Poissonian amplifier, a phase-sensitive amplifier and a classical amplifier. We show the evolution of phase probability distribution functions in the amplifier.

Lee, Kang-Soo; Kim, M. S.

1994-01-01

227

Integrated low noise, low power, fast charge-sensitive preamplifier for avalanche photodiodes in JFET-CMOS-technology  

Microsoft Academic Search

To take advantage on the compactness of APD arrays, low noise, power efficient, fast charge sensitive preamplifier chips with differential current drivers have been developed. A 16-channel and a single channel version are available. The chips were adapted for low capacitance 4×8 APD arrays produced by Hamamatsu, Japan. A mixed JFET-CMOS production process yielded high quality integrated JFETs for the

B. J. Pichler; W. Pimpl; W. Buttler; L. Kotoulas; G. Boning; M. Rafecas; E. Lorenz; S. I. Ziegler

2000-01-01

228

Integrated low-noise low-power fast charge-sensitive preamplifier for avalanche photodiodes in JFET-CMOS technology  

Microsoft Academic Search

To take advantage of the compactness of avalanche photodiode (APD) arrays, low-noise power-efficient fast charge-sensitive preamplifier chips with differential current drivers have been developed. A 16-channel and a single-channel version are available. The chips were adapted for low-capacitance 4×8 APD arrays produced by Hamamatsu, Japan. A mixed junction field-effect transistor (JFET)-CMOS production process yielded high-quality integrated JFETs for the input

Bernd J. Pichler; Wendelin Pimpl; Werner Buttler; Leonidas Kotoulas; Guido Böning; Magdalena Rafecas; Eckart Lorenz; Sibylle I. Ziegler

2001-01-01

229

Signal and noise performance of large-area PIN photodiodes and charge-sensitive preamplifiers for gamma radiography  

Microsoft Academic Search

Using 5 cm long CsI (Tl) crystal scintillators, large-area PIN-type photodiodes of 1 cm×1 cm, and a low-noise charge-sensitive preamplifier, two gamma-ray detectors were manufactured. One detector used PIN-type photodiodes fabricated in the process of Electronics and Telecommunications Research Institute (ETRI) and the other one was based on Hamamatsu PIN-type photodiodes of S-3590-01. Gamma spectroscopies were performed and analyzed for

Kwang Hyun Kim; Young Soo Kim; Jung Soo Kim

2008-01-01

230

Visualizing interfacial charge transfer in Ru-dye sensitized TiO nanoparticles using x-ray transient absorption spectroscopy  

Microsoft Academic Search

A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy)(NCS) (RuN3) dye adsorbed to TiO nanoparticle surfaces. The results show

X. Zhang; G. Smolentsev; J. Guo; K. Attenkofer; C. Kurtz; G. Jennings; J. V. Lockard; A. B. Stickrath; L. X. Chen

2011-01-01

231

The effect of temperature on the charge transport and transient absorption properties of K27 sensitized DSSC  

Microsoft Academic Search

The charge transport and transient absorption properties of K27 dye-sensitized solar cell have been investigated. The current–voltage (I–V) characteristics of the solar cell were analyzed by the thermionic emission theory. The ideality factor, barrier height and series resistance values of the solar cell were determined. The ideality factor higher than unity indicated the presence of non-ideal behavior in current–voltage characteristics

Kasim Ocakoglu; Fahrettin Yakuphanoglu; James R. Durrant; Siddik Icli

2008-01-01

232

A varied shaping time noise analysis of Al0.8Ga0.2As and GaAs soft X-ray photodiodes coupled to a low-noise charge sensitive preamplifier  

NASA Astrophysics Data System (ADS)

The noise sources affecting Al0.8Ga0.2As and GaAs spectroscopic X-ray photon counting p+-i-n+ photodiodes connected to a custom low-noise charge sensitive preamplifier are quantified by analysing the system's response to pulses from a signal generator and varying the system's shaping amplifier's shaping time (from 0.5 ?s to 10 ?s). The system is investigated at three temperatures (-10 °C, +20 °C and +50 °C) in order to characterise the variation of the component noise sources and optimum shaping time with temperature for Al0.8Ga0.2As and GaAs diodes. The analysis shows that the system is primarily limited by dielectric noise, hypothesised to be mainly from the packaging surrounding the detector, for both types of diode and at each temperature.

Barnett, A. M.; Lees, J. E.; Bassford, D. J.; Ng, J. S.

2012-05-01

233

Selective Acylation Enhances Membrane Charge Sensitivity of the Antimicrobial Peptide Mastoparan-X  

PubMed Central

The partitioning of the wasp venom peptide mastoparan-X (MPX) into neutral and negatively charged lipid membranes has been compared with two new synthetic analogs of MPX where the N?-terminal of MPX was acylated with propanoic acid (PA) and octanoic acid (OA). The acylation caused a considerable change in the membrane partitioning properties of MPX and it was found that the shorter acylation with PA gave improved affinity and selectivity toward negatively charged membranes, whereas OA decreased the selectivity. Based on these findings, we hypothesize that minor differences in the embedding and positioning of the peptide in the membrane caused by either PA or OA acylation play a critical role in the fine-tuning of the effective charge of the peptide and thereby the fine-tuning of the peptide's selectivity between neutral and negatively charged lipid membranes. This finding is unique compared to previous reports where peptide acylation enhanced membrane affinity but also resulted in impaired selectivity. Our result may provide a method of enhancing selectivity of antimicrobial peptides toward bacterial membranes due to their high negative charge—a finding that should be investigated for other, more potent antimicrobial peptides in future studies.

Etzerodt, Thomas; Henriksen, Jonas R.; Rasmussen, Palle; Clausen, Mads H.; Andresen, Thomas L.

2011-01-01

234

High precision wavelength measurements of QED-sensitive forbidden transitions in highly charged argon ions.  

PubMed

We present the results of an experimental study of magnetic dipole (M1) transitions in highly charged argon ions (Ar X, Ar XI, Ar XIV, Ar XV) in the visible spectral range using an electron beam ion trap. Their wavelengths were determined with, for highly charged ions, unprecedented accuracy up to the sub-ppm level and compared with theoretical calculations. The QED contributions, calculated in this Letter, are found to be 4 orders of magnitude larger than the experimental error and are absolutely indispensable to bring theory and experiment to a good agreement. This method shows great potential for the study of QED effects in relativistic few-electron systems. PMID:14611279

Dragani?, I; Crespo López-Urrutia, J R; DuBois, R; Fritzsche, S; Shabaev, V M; Orts, R Soria; Tupitsyn, I I; Zou, Y; Ullrich, J

2003-10-31

235

A charge sensitive preamplifier for high peak stability in spectroscopic measurements at high counting rates  

Microsoft Academic Search

In this work a charge preamplifier designed to achieve high stability in spectroscopic measurements at different counting rates is presented. The preamplifier operates with the input JFET and the feedback capacitor directly integrated on the detector, in the specific case a silicon drift detector (SDD). The motivation of the work is to overcome the peak shift, typically in the order

C. Fiorini

2004-01-01

236

A charge sensitive preamplifier for high peak stability in spectroscopic measurements at high counting rates  

Microsoft Academic Search

In this paper, a charge preamplifier designed to achieve high stability in spectroscopic measurements at different counting rates is presented. The preamplifier operates with the input JFET and the feedback capacitor directly integrated on the silicon detector, in the specific case a Silicon Drift Detector (SDD). The motivation of the work is to overcome the peak shift, typically in the

Carlo Fiorini

2005-01-01

237

Design and simulation of charge sensitive preamplifier with CMOS FET implemented as feedback capacitor C fp  

Microsoft Academic Search

In this paper, to design a new preamplifier for optimum performances with charged-particle or heavy-ion detectors, the CMOS FET is implemented as a feedback capacitor Cfp. so that the entire system should be built only with MOSFET. This work is a revolution design because to realize an ASIC for a preamplifier circuit, the capacitor will also be included. We succeed

Evariste WEMBE TAFO; Hong SU; Yanni GAO; Ming WU

2008-01-01

238

Direct Method of Determining the Sensitivity of Microcrystals to Charge Particles.  

National Technical Information Service (NTIS)

As we know from literature which is devoted to founding and developing semiconductor radiation detectors, a charged particle, braked in a solid, expends on the formation of an unbalanced pair of carriers the same amount of energy, regardless of its mass, ...

A. P. Zhdanov I. M. Kuks

1968-01-01

239

Micrometre resolution of a charge integrating microstrip detector with single photon sensitivity  

PubMed Central

A synchrotron beam has been used to test the spatial resolution of a single-photon-resolving integrating readout-chip coupled to a 320?µm-thick silicon strip sensor with a dedicated readout system. Charge interpolation methods have yielded a spatial resolution of ?x ? 1.8?µm for a 20?µm-pitch strip.

Schubert, A.; Bergamaschi, A.; David, C.; Dinapoli, R.; Elbracht-Leong, S.; Gorelick, S.; Graafsma, H.; Henrich, B.; Johnson, I.; Lohmann, M.; Mozzanica, A.; Radicci, V.; Rassool, R.; Schadler, L.; Schmitt, B.; Shi, X.; Sobott, B.

2012-01-01

240

High dynamic range charge measurements  

DOEpatents

A charge amplifier for use in radiation sensing includes an amplifier, at least one switch, and at least one capacitor. The switch selectively couples the input of the switch to one of at least two voltages. The capacitor is electrically coupled in series between the input of the amplifier and the input of the switch. The capacitor is electrically coupled to the input of the amplifier without a switch coupled therebetween. A method of measuring charge in radiation sensing includes selectively diverting charge from an input of an amplifier to an input of at least one capacitor by selectively coupling an output of the at least one capacitor to one of at least two voltages. The input of the at least one capacitor is operatively coupled to the input of the amplifier without a switch coupled therebetween. The method also includes calculating a total charge based on a sum of the amplified charge and the diverted charge.

De Geronimo, Gianluigi

2012-09-04

241

Beam cleanup of a multimode Yb-doped fiber amplifier with an infrared sensitive Rh:BaTiO3 crystal  

Microsoft Academic Search

Summary form only given. Single-mode, Er or Yb doped fiber lasers and amplifiers have made great progress in the last few years since output power exceeding 100 W have been demonstrated with a nearly diffraction limited beam quality. However, a further increase of the power is limited by nonlinear effects and by material damage. To limit the contribution of these

A. Brignon; Y. Louyer; J.-P. Huignard; E. Lallier

2001-01-01

242

KPiX, An Array of Self Triggered Charge Sensitive Cells Generating Digital Time and Amplitude Information  

SciTech Connect

The Silicon Detector proposed for the International Linear Collider (ILC) requires electronic read-out that can be tightly coupled to the silicon detectors envisioned for the tracker and the electromagnetic calorimeter. The KPiX is a 1024-channel read-out chip that bump-bonds to the detector and communicates through a few digital signals, power, and detector bias. The KPiX front-end is a low-noise dual-range charge-amplifier with a dynamic range of 17 bit, achieved by autonomous switching of the feedback capacitor. The device takes advantage of the ILC duty cycle of 1 ms trains at 5 Hz rate by lowering the supply current after the data acquisition cycle for an average power consumption of <20 {micro}W/channel. During the 1 ms train, up to four events exceeding a programmable threshold can be stored, the amplitude as a voltage on a capacitor for subsequent digitization, the event time in digital format. The chip can be configured for other than ILC applications.

Freytag, D.; Herbst, R.; /SLAC; Brau, J.; /Oregon U.; Breidenbach, M.; /SLAC; Frey, R.; /Oregon U.; Haller, G.; /SLAC; Holbrook, B.; Lander, R.; /UC, Davis; Nelson, T.; /SLAC; Radeka, V.; /Brookhaven; Strom, D.; /Oregon U.; Tripathi, M.; /UC, Davis

2008-12-11

243

Development and evaluation of charge-sensitive preamplifier for CsI calorimeter in the KEK B-factory  

SciTech Connect

In the KEK B-factory the barrel part of the electromagnetic calorimeter comprises 7,000 CsI(Tl) crystals. Each crystal has two photodiodes (HAMAMATSU S2744-03) and two preamplifiers. The capacitance of the photodiode is 100 pF at a bias voltage of 60 V and the leakage current is less than 4 nA. The authors developed a charge-sensitive preamplifier for the electromagnetic calorimeter (CsI(Tl)) in the KEK B-factory. They examined noise characteristic, dynamic range and power-supply ripple-rejection ratio on power rails.

Tanaka, Manobu; Ikeda, Hirokazu; Tamai, Kunio (National Lab. for High Energy Physics, Tsukuba (Japan)); Takemoto, Megumi; Hayashii, Hisashi (Nara Women's Univ. (Japan))

1994-08-01

244

Signal and noise performance of large-area PIN photodiodes and charge-sensitive preamplifiers for gamma radiography  

Microsoft Academic Search

Using 5cm long CsI (Tl) crystal scintillators, large-area PIN-type photodiodes of 1cm×1cm, and a low-noise charge-sensitive preamplifier, two gamma-ray detectors were manufactured. One detector used PIN-type photodiodes fabricated in the process of Electronics and Telecommunications Research Institute (ETRI) and the other one was based on Hamamatsu PIN-type photodiodes of S-3590-01. Gamma spectroscopies were performed and analyzed for both Co-60 and

Kwang Hyun Kim; Young Soo Kim; Jung Soo Kim

2008-01-01

245

Effect of the photoinduced charge exchange of Ag+ ions on the sensitized luminescence of Eu3+ in oxide films  

NASA Astrophysics Data System (ADS)

It has been found that the excitation of silver ions by ultraviolet radiation in GeO2-Eu2O3-Ag and SiO2-Eu2O3-Ag films is accompanied by the weakening of silver-ion-sensitized luminescence of Eu3+ ions. The degree and rate of such weakening vary in wide ranges depending on the nature of the matrix, thermal treatment temperature, and energy of an exciting photon. The revealed effect has been explained by the photoinduced charge exchange of silver ions in complex Ag-Eu centers.

Malashkevich, G. E.; Shevchenko, G. P.; Stupak, A. P.; Bokshits, Yu. V.; Sukhodola, A. A.; Stanishevsky, I. V.

2014-02-01

246

Promoting charge-separation in p-type dye-sensitized solar cells using bodipy.  

PubMed

The viability of applying bodipy sensitisers to NiO-based p-type dye-sensitised solar cells (p-DSCs) has been successfully demonstrated. The triphenylamine donor-bodipy acceptor design promotes a long-lived charge-separated state which is difficult to achieve with NiO-based devices. The current was above 3 mA cm(-2) and the IPCE was 28%. PMID:24129545

Lefebvre, Jean-Franēois; Sun, Xue-Zhong; Calladine, James A; George, Michael W; Gibson, Elizabeth A

2014-05-25

247

X-ray sensitive charge-coupled device instrumentation for short and ultrashort pulse laser-produced plasma experiments  

SciTech Connect

We describe the use of x-ray sensitive charge-coupled device (CCD) detectors for measuring the 1--15 A emission from high temperature plasmas produced at the [ital L]-Division JANUS and USP (pulse length[similar to]100 fs) laser facilities. Instruments based upon commercially available video format cameras have been designed to replace x-ray film, as the two-dimensional recording medium, for imaging and x-ray spectroscopic applications. Used in conjunction with a high sensitivity x-ray pinhole camera, magnification 5--20, the CCD detectors can give spatial resolution approaching 5 [mu]m and energy band information by the use of edge filters. A compact wavelength dispersive spectrometer equipped with the CCD detector and a flat Bragg crystal analyzer can record survey spectra.

Dunn, J.; Young, B.K.F.; Shiromizu, S.J. (L-Division, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States))

1995-01-01

248

Mu2e: A high-sensitivity search for charged lepton flavor violation at Fermilab  

NASA Astrophysics Data System (ADS)

The Mu2e collaboration proposes to search for the coherent, neutrinoless conversion of muons into electrons in the field of a nucleus, ?N?eN, with a single-event sensitivity of ˜10, an improvement of a factor of 10,000 over existing limits. This lepton flavor-violating reaction probes mass scales unavailable by direct searches at either present or planned high energy colliders. The apparatus is described as well as a scheme by which the experiment can be mounted in the present Fermilab accelerator complex. Prospects for increased sensitivity using the Project X accelerator upgrades that are being proposed by Fermilab are briefly discussed.

Dukes, E. Craig

2011-09-01

249

The effect of molecular aggregates over the interfacial charge transfer processes on dye sensitized solar cells  

SciTech Connect

The electron transfer reaction between the photoinjected electrons in the nanocrystalline TiO{sub 2} mesoporous sensitized films and the oxidized electrolyte in dye sensitized solar cells (DSSC) plays a major role on the device efficiency. In this communication we show that, although the presence of molecular aggregates on the free base porphyrin DSSC limits the device photocurrent response under illumination, they form an effective hydrophobic barrier against the oxidized electrolyte impeding fast back-electron transfer kinetics. Therefore, their drawback can be overcome by designing dyes with peripheral moieties that prevent the formation of the aggregates and are able to achieve efficiencies as high as 3.2% under full sun.

Planells, Miquel; Forneli, Amparo; Martinez-Ferrero, Eugenia; Sanchez-Diaz, Antonio; Sarmentero, Maria Angeles [Institute of Chemical Research of Catalonia (ICIQ). Avda. Paiesos Catalans, 16 Tarragona 43007 (Spain); Ballester, Pablo; Palomares, Emilio [Institute of Chemical Research of Catalonia (ICIQ). Avda. Paiesos Catalans, 16 Tarragona 43007 (Spain); Institucio Catalana de Recerca i Estudis Avancats (ICREA), Passeig Lluis Companys, 23 08010 Barcelona (Spain); O'Regan, Brian C. [Centre for Electronic Materials and Devices, Imperial College of London, Exhibition Road, SW7 2AZ London (United Kingdom)

2008-04-14

250

Instantaneous generation of charge-separated state on TiO? surface sensitized with plasmonic nanoparticles.  

PubMed

Photoexcitation of the plasmon band in metallic nanoparticles adsorbed on a TiO2 surface initiates many important photovoltaic and photocatalytic processes. The traditional view on the photoinduced charge separation involves excitation of a surface plasmon, its subsequent dephasing into electron-hole pairs, followed by electron transfer (ET) from the metal nanoparticle into TiO2. We use nonadiabatic molecular dynamics combined with time-domain density functional theory to demonstrate that an electron appears inside TiO2 immediately upon photoexcitation with a high probability (~50%), bypassing the intermediate step of electron-hole thermalization inside the nanoparticle. By providing a detailed, atomistic description of the charge separation, energy relaxation, and electron-hole recombination processes, the simulation rationalizes why the experimentally observed ultrafast photoinduced ET in an Au-TiO2 system is possible in spite of the fast energy relaxation. The simulation shows that the photogenerated plasmon is highly delocalized onto TiO2, and thus, it is shared by the electron donor and acceptor materials. In the 50% of the cases remaining after the instantaneous photogeneration of the charge-separated state, the electron injects into TiO2 on a sub-100 fs time scale by the nonadiabatic mechanism due to high density of acceptor states. The electron-phonon relaxation parallels the injection and is slower, resulting in a transient heating of the TiO2 surface by 40 K. Driven by entropy, the electron moves further into TiO2 bulk. If the electron remains trapped at the TiO2 surface, it recombines with the hole on a picosecond time scale. The obtained ET and recombination times are in excellent agreement with the experiment. The delocalized plasmon state observed in our study establishes a novel concept for plasmonic photosensitization of wide band gap semiconductors, leading to efficient conversion of photons to charge carriers and to hybrid materials with a wide variety of applications in photocatalysis and photovoltaics. PMID:24568726

Long, Run; Prezhdo, Oleg V

2014-03-19

251

Charge dynamics in new architectures for dye-sensitized solar cells  

Microsoft Academic Search

The promise of a clean, renewable, and abundant energy supply make the efficient conversion of solar energy to electricity a compelling scientific and societal goal. In the following chapters, I will describe my efforts to advance one class of photovoltaic technology, dye-sensitized solar cells, by demonstration and characterization of unexplored device architectures. Chapter 1 provides an introduction to the origin

Alex Brandon Fletcher Martinson

2008-01-01

252

High-surface-area architectures for improved charge transfer kinetics at the dark electrode in dye-sensitized solar cells.  

PubMed

Dye-sensitized solar cell (DSC) redox shuttles other than triiodide/iodide have exhibited significantly higher charge transfer resistances at the dark electrode. This often results in poor fill factor, a severe detriment to device performance. Rather than moving to dark electrodes of untested materials that may have higher catalytic activity for specific shuttles, the surface area of platinum dark electrodes could be increased, improving the catalytic activity by simply presenting more catalyst to the shuttle solution. A new copper-based redox shuttle that experiences extremely high charge-transfer resistance at conventional Pt dark electrodes yields cells having fill-factors of less than 0.3. By replacing the standard Pt dark electrode with an inverse opal Pt electrode fabricated via atomic layer deposition, the dark electrode surface area is boosted by ca. 50-fold. The resulting increase in interfacial electron transfer rate (decrease in charge-transfer resistance) nearly doubles the fill factor and therefore the overall energy conversion efficiency, illustrating the utility of this high-area electrode for DSCs. PMID:24828106

Hoffeditz, William L; Katz, Michael J; Deria, Pravas; Martinson, Alex B F; Pellin, Michael J; Farha, Omar K; Hupp, Joseph T

2014-06-11

253

Solvent dipole modulation of conduction band edge shift and charge recombination in robust dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Molecular modification is certified as a powerful strategy to adjust the energy alignment and electron transfer dynamics of dye-sensitized solar cells (DSCs). Herein, devices are assembled with three robust solvent (3-methoxypropionitrile, N,N-dimethylformamide and ?-butyrolactone) based electrolytes to elucidate the solvent dipole effects at the semiconductor-dye-electrolyte interface. Photovoltaic results demonstrate that open-circuit photovoltages of the devices vary linearly with the dipole moment of the solvents, along with an adverse dependence of the short-circuit photocurrent density under simulated irradiation. Impedance analysis reveals an apparent dipole moment-modulated conduction band edge shift of the nanocrystalline TiO2 electrodes with respect to the redox potential of the electrolyte. Furthermore, the adverse shifts of the short-circuit photocurrent are explained by a dipole dependence of the driving force for electron injection and the interfacial charge recombination, together with a notably changed charge collection efficiency. Therefore, this study draws attention to the feasibility of tuning the electron transfer dynamics and energy alignment in photoelectrochemical devices by judiciously selecting the electrolyte solvents for further efficiency improvement, especially for those alternative organic sensitizers or quantum dots with inadequate electron injection driven forces.

Hao, Feng; Jiao, Xingjian; Li, Jianbao; Lin, Hong

2012-12-01

254

Micron resolution of MÖNCH and GOTTHARD, small pitch charge integrating detectors with single photon sensitivity  

NASA Astrophysics Data System (ADS)

MÖNCH, a charge integrating readout ASIC (Application Specific Integrated Circuit) prototype with a pixel pitch of 25 ?m developed at PSI, allows new imaging applications in the field of micron resolution and spectral imaging. The small pixel size of this system facilitates charge sharing between pixels, which then can be exploited to gain additional information about the photon absorption position and photon energy. However, for reconstructing complete images from this information, sufficient hits need to be recorded and therefore acquisition times are potentially long. We present a fast read-out system, that is capable of acquiring enough statistics for an image in a few hours in combination with a position reconstruction algorithm, which has the potential to run in a similar amount of time on a fast computing node. We further present results of experiments with a comparable strip detector (small-pitch GOTTHARD system) showing that with the aid of single photon interpolation algorithms micron resolution is achievable. Additionally, we show that a similar position reconstruction algorithm works in the two dimensional case for MÖNCH.

Cartier, S.; Bergamaschi, A.; Dinapoli, R.; Greiffenberg, D.; Johnson, I.; Jungmann, J. H.; Mezza, D.; Mozzanica, A.; Schmitt, B.; Shi, X.; Stampanoni, M.; Sun, J.; Tinti, G.

2014-05-01

255

Thermally sensitive reversible microgels formed by poly(N-Isopropylacrylamide) charged chains: A Hofmeister effect study.  

PubMed

In this study, we present a new method to obtain anionic and cationic stable colloidal nanogels from PNIPAM charged chains. The stability of the particles formed by inter-chain aggregation stems from the charged chemical groups attached at the sides of PNIPAM polymer chains. The particle formation is fully reversible-that is, it is possible to change from stable polymer solutions to stable colloidal dispersions and vice versa simply by varying temperature. In addition, we also demonstrate that the polymer LCST (lower critical solution temperature), the final particle size and the electrokinetic behavior of the particles formed are highly dependent on the electrolyte nature and salt concentration. These latter results are related to Hofmeister effects. The analysis of these results provides more insights about the origin of this ionic specificity, confirming that the interaction of ions with interfaces is dominated by the chaotropic/kosmotropic character of the ions and the hydrophobic/hydrophilic character of the surface in solution. PMID:24863797

López-León, Teresa; Ortega-Vinuesa, Juan L; Bastos-Gonzįlez, Delfi; Elaissari, Abdelhamid

2014-07-15

256

Surpassing the Amplifier Limit for Force Detection  

NASA Astrophysics Data System (ADS)

A force-measuring system composed of a macroscopic harmonic oscillator, mechanical-electrical transducer, and linear amplifier is described and the sensitivity is calculated for a "back-action evasion" mode of operation. It is shown that it is possible to surpass the standard amplifier limit with this device, and the specific requirements to do so are given. These results may also apply to a quantum-limited amplifier and thus give the requirements to perform quantum-nondemolition measurements.

Bocko, Mark F.; Johnson, Warren W.

1982-05-01

257

Charge collection and pore filling in solid-state dye-sensitized solar cells  

Microsoft Academic Search

The solar to electrical power conversion efficiency for dye-sensitized solar cells (DSCs) incorporating a solid-state organic hole-transporter can be over 5%. However, this is for devices significantly thinner than the optical depth of the active composites and by comparison to the liquid electrolyte based DSCs, which exhibit efficiencies in excess of 10%, more than doubling of this efficiency is clearly

Henry J. Snaith; Robin Humphry-Baker; Peter Chen; Ilkay Cesar; Shaik M. Zakeeruddin; Michael Grätzel

2008-01-01

258

Charge separation in solid-state dye-sensitized heterojunction solar cells  

Microsoft Academic Search

Dye-sensitized nanocrystalline solar cells are presently under intensive investigation, as they offer an attractive alternative to conventional p--n junction devices. Solid-state versions have been described where the electrolyte present in the pores of the malodorous oxide film is replaced by a large band gap p-type semiconductor. In this way, a solid-state heterojunction of very large contact area is formed. Light

Udo Bach; Yasuhiro Tachibana; Jacques-E. Moser; Saif A. Haque; James R. Durrant; M. Graetzel; David R. Klug

1999-01-01

259

An Acoustic Charge Transport Imager for High Definition Television Applications: Low-Voltage SAW Amplifiers on Multilayer GaAs/ZnO Substrates  

NASA Technical Reports Server (NTRS)

This thesis addresses the acoustoelectric issues concerning the amplification of surface acoustic waves (SAWs) and the reflection of SAWs from slanted reflector gratings on GaAs, with application to a novel acoustic charge transport (ACT) device architecture. First a simple model of the SAWAMP was developed, which was subsequently used to define the epitaxially grown material structure necessary to provide simultaneously high resistance and high electron mobility. In addition, a segmented SAWAMP structure was explored with line widths on the order of an acoustic wavelength. This resulted in the demonstration of SAWAMPS with an order of magnitude less voltage and power requirements than previously reported devices. A two-dimensional model was developed to explain the performance of devices with charge confinement layers less then 0.5 mm, which was experimentally verified. This model was extended to predict a greatly increased gain from the addition of a ZnO overlay. These overlays were experimentally attempted, but no working devices were reported due to process incompatibilities. In addition to the SAWAMP research, the reflection of SAWs from slanted gratings on GaAs was also studied and experimentally determined reflection coefficients for both 45 deg grooves and Al stripes on GaAs have been reported for the first time. The SAWAMp and reflector gratings were combined to investigate the integrated ring oscillator for application to the proposed ACT device and design parameters for this device have been provided.

Hunt, W. D.; Brennan, K. F.; Summers, C. J.; Cameron, Thomas P.

1996-01-01

260

Understanding sensitization behavior of lead selenide photoconductive detectors by charge separation model  

NASA Astrophysics Data System (ADS)

We introduce a charge separation model in this work to explain the mechanism of enhanced photoconductivity of polycrystalline lead salt photoconductors. Our results show that this model could clarify the heuristic fabrication processes of such lead salt detectors that were not well understood and often considered mysterious for nearly a century. The improved lifetime and performance of the device, e.g., responsivity, are attributed to the spatial separation of holes and electrons, hence less possibility of carrier recombination. This model shows that in addition to crystal quality the size of crystallites, the depth of outer conversion layer, and doping concentration could all affect detector performance. The simulation results agree well with experimental results and thus offer a very useful tool for further improvement of lead salt detectors. The model was developed with lead salt family of photoconductors in mind, but may well be applicable to a wider class of semiconducting films.

Zhao, Lihua; Qiu, Jijun; Weng, Binbin; Chang, Caleb; Yuan, Zijian; Shi, Zhisheng

2014-02-01

261

Shot-Noise-Limited Operation of a Fast Quantum-Point-Contact Charge Sensor  

Microsoft Academic Search

We have operated a quantum point contact (QPC) charge detector in a radio frequency (RF) mode that allows fast charge detection in a bandwidth of tens of megahertz. We find that the charge sensitivity of the RF-QPC is limited not by the noise of a secondary amplifier, but by non-equilibrium noise f the QPC itself. We have performed frequency-resolved measurements

Madhu Thalakulam; W. W. Xue; Feng Pan; Z. Ji; J. Stettenheim; Loren Pfeiffer; K. W. West; A. J. Rimberg

2007-01-01

262

Improvement in light harvesting in a dye sensitized solar cell based on cascade charge transfer  

NASA Astrophysics Data System (ADS)

Dye sensitized solar cells (DSSCs) offer the potential of being low-cost, high-efficiency photovoltaic devices. However, the power conversion efficiency is limited as they cannot utilize all photons of the visible solar spectrum. A novel design of a core-shell photoanode is presented herein where a thin shell of infrared dye is deposited over the core of a sensitized TiO2 nanofiber. Specifically, a ruthenium based dye (N719) sensitized TiO2 nanofiber is wrapped by a thin shell of copper phthalocyanine (CuPc). In addition to broadening the absorption spectrum, this core-shell configuration further suppresses the electron-hole recombination process. Instead of adopting the typical Förster resonance energy transfer, upon photons being absorbed by the infrared dye, electrons are transferred efficiently through a cascade process from the CuPc to the N719 dye, the conduction band of TiO2, the FTO electrode and finally the external circuit. Concurrently, photons are also absorbed by the N719 dye with electrons being transferred in the cell. These additive effects result in a high power conversion efficiency of 9.48% for the device. The proposed strategy provides an alternative method for enhancing the performance of DSSCs for low-cost renewable energy in the future.Dye sensitized solar cells (DSSCs) offer the potential of being low-cost, high-efficiency photovoltaic devices. However, the power conversion efficiency is limited as they cannot utilize all photons of the visible solar spectrum. A novel design of a core-shell photoanode is presented herein where a thin shell of infrared dye is deposited over the core of a sensitized TiO2 nanofiber. Specifically, a ruthenium based dye (N719) sensitized TiO2 nanofiber is wrapped by a thin shell of copper phthalocyanine (CuPc). In addition to broadening the absorption spectrum, this core-shell configuration further suppresses the electron-hole recombination process. Instead of adopting the typical Förster resonance energy transfer, upon photons being absorbed by the infrared dye, electrons are transferred efficiently through a cascade process from the CuPc to the N719 dye, the conduction band of TiO2, the FTO electrode and finally the external circuit. Concurrently, photons are also absorbed by the N719 dye with electrons being transferred in the cell. These additive effects result in a high power conversion efficiency of 9.48% for the device. The proposed strategy provides an alternative method for enhancing the performance of DSSCs for low-cost renewable energy in the future. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01868g

Yang, Lijun; Leung, Wallace Woon-Fong; Wang, Jingchuan

2013-07-01

263

Highly Sensitive Determination of the Polaron-Induced Optical Absorption of Organic Charge-Transport Materials  

NASA Astrophysics Data System (ADS)

We examine polaron-induced absorption in organic transport materials using a highly sensitive measurement technique. A hole only device is embedded into a low-loss TE2 waveguide structure, and the current induced change of the waveguide absorption is measured. The exemplary study of 2,2',7,7'-tetrakis(N,N-diphenylamine)-9,9'-spiro-bifluorene (S-TAD) reveals a very low polaron absorption cross section of ?p?2.6×10-18cm2 for 560 nm ???660nm. The accuracy of this data is unsurpassed by other techniques used for the unambiguous study of polaronic species in organic thin films.

Rabe, T.; Görrn, P.; Lehnhardt, M.; Tilgner, M.; Riedl, T.; Kowalsky, W.

2009-04-01

264

Applications of position sensitive germanium detectors for X-ray spectroscopy of highly charged heavy ions  

NASA Astrophysics Data System (ADS)

The spectroscopy of atomic transitions in the hard X-ray regime above 15 keV utilizing position-sensitive solid state detectors is discussed. Special emphasis is given to the current detector developments for X-ray spectroscopy of heavy ions at the ESR storage ring where applications for precision spectroscopy as well as for polarization studies are of particular interest. For both cases, the advantages and new possibilities which are opened up by position and energy resolving solid state detectors are illustrated by the presentation of first experiments.

Stöhlker, Th.; Banas, D.; Beyer, H. F.; Gumberidze, A.; Kozhuharov, C.; Kanter, E.; Krings, T.; Lewoczko, W.; Ma, X.; Protic, D.; Sierpowski, D.; Spillmann, U.; Tachenov, S.; Warczak, A.

2003-05-01

265

Quantum dynamics simulations of interfacial charge-transfer in organic dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

We describe a novel time-dependent quantum-mechanics/molecular-mechanics method for studying electron transfer in dye sensitized semiconductor interfaces, that takes into account the interacting electron-hole quantum dynamics, the underlying nuclear fluctuations and solvation dynamics. We provide a comprehensive investigation of the quantum dynamics, the electronic and the structural properties of prototypical D-?-A organic dyes sensitizing the TiO2 anatase surface, both in vacuum and solvated by liquid acetonitrile. The organic dyes are comprised of an electron donating moiety and an anchoring acceptor moiety, conjugated by thiophene bridges. Although interfacial electron transfer is very efficient, it is demonstrated that the coupling between the photoexcited electron and the hole delays the electron injection. Simulations demonstrate that the solvent screens the dye from the surface, narrowing the absorption peaks and delaying the electron injection. We have also studied several aspects that are relevant for the recombination process, such as the role played by surface defects and the interaction of redox species with the TiO2 surface, and the effect of additives.

Rego, Luis G. C.; da Silva, R.; Hoff, D. A.

2013-03-01

266

Holographic modification of TiO2 nanostructure for enhanced charge transport in dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

We show that the photocurrent and energy conversion efficiency of dye-sensitized solar cells can be greatly enhanced with holographic modification to the morphology of TiO2 electrode. The nanoporous electrode coated onto conducting glass was irradiated by three interfering laser beams at 1064 nm incident from the backside of the substrate. This generated two-dimensional periodic pillars of higher density in the electrode, through which the photoexcited electrons could be extracted more effectively. The cells fabricated with modified electrodes exhibited average photocurrent and efficiency of 17.14 mA/cm2 and 9.03%, while 14.91 mA/cm2 and 7.83% were obtained from the reference cells. It was attributed to the enhanced charge transport accompanied by the reduction of internal resistance of the electrode.

Lee, Jinsoo; Yoon, Junghwan; Jin, Minhea; Lee, Myeongkyu

2012-08-01

267

Control of charge recombination dynamics in dye sensitized solar cells by the use of conformally deposited metal oxide blocking layers.  

PubMed

We report herein a methodology for conformally coating nanocrystalline TiO2 films with a thin overlayer of a second metal oxide. SiO2, Al2O3, and ZrO2 overlayers were fabricated by dipping mesoporous, nanocrystalline TiO2 films in organic solutions of their respective alkoxides, followed by sintering at 435 degrees C. These three metal oxide overlayers are shown in all cases to act as barrier layers for interfacial electron transfer processes. However, experimental measurements of film electron density and interfacial charge recombination dynamics under applied negative bias were vary significantly for the overlayers. A good correlation was observed between these observations and the point of zero charge of the different metal oxides. On this basis, it is found that the most basic overlayer coating, Al2O3 (pzc = 9.2), is optimal for retarding interfacial recombination losses under negative applied bias. These observations show good correlation with current/voltage analyses of dye sensitized solar cell fabricated from these films, with the Al2O3 resulting in an increase in V(oc) of up to 50 mV and a 35% improvement in overall device efficiency. These observations are discussed and compared with an alternative TiCl4 posttreatment of nanocrystalline TiO2 films with regard to optimizing device efficiency. PMID:12517161

Palomares, Emilio; Clifford, John N; Haque, Saif A; Lutz, Thierry; Durrant, James R

2003-01-15

268

Temperature sensitive mutants of influenza A virus generated by reverse genetics and clustered charged to alanine mutagenesis.  

PubMed

Temperature sensitive (ts) mutants of influenza A virus have the potential to serve as live attenuated (att) virus vaccines. Previously, ts mutants were isolated by chemical mutagenesis or arose spontaneously, and most likely contained point mutations in one or more genes. While sufficiently attenuated, even the most genetically stable of these viruses was found to revert to a more virulent form in a seronegative vaccinee. Recently developed technology, however, allows the introduction of engineered mutations into the genome of influenza A and B viruses, permitting the rational design of attenuated mutants with the potential for increased genetic stability. To accomplish this goal, we have introduced ts mutations into the PB2 gene of A/Los Angeles/2/87 (H3N2) and rescued the mutated genes into infectious viruses. We have used clustered charged to alanine mutagenesis (substitution of alanine for charged amino acid residues which are present in clusters) of the PB2 gene to generate novel ts mutants. Viruses containing such ts PB2 genes were attenuated in mice and ferrets. This approach has thus yielded several vaccine candidates with ts and attenuated characteristics in animal models. Combination of these mutations with each other or with other ts mutations may lead to a high level of genetic stability. PMID:9029775

Parkin, N T; Chiu, P; Coelingh, K L

1996-12-01

269

Signal and noise analysis of a-Si:H radiation detector-amplifier system  

SciTech Connect

Hydrogenated amorphous silicon (a-Si:H) has potential advantages in making radiation detectors for many applications because of its deposition capability on a large-area substrate and its high radiation resistance. Position-sensitive radiation detectors can be made out of a 1d strip or a 2-d pixel array of a Si:H pin diodes. In addition, signal processing electronics can be made by thin-film transistors on the same substrate. The calculated radiation signal, based on a simple charge collection model agreed well with results from various wave length light sources and 1 MeV beta particles on sample diodes. The total noise of the detection system was analyzed into (a) shot noise and (b) 1/f noise from a detector diode, and (c) thermal noise and (d) 1/f noise from the frontend TFT of a charge-sensitive preamplifier. the effective noise charge calculated by convoluting these noise power spectra with the transfer function of a CR-RC shaping amplifier showed a good agreement with the direct measurements of noise charge. The derived equations of signal and noise charge can be used to design an a-Si:H pixel detector amplifier system optimally. Signals from a pixel can be readout using switching TFTs, or diodes. Prototype tests of a double-diode readout scheme showed that the storage time and the readout time are limited by the resistances of the reverse-biased pixel diode and the forward biased switching diodes respectively. A prototype charge-sensitive amplifier was made using poly-Si TFTs to test the feasibility of making pixel-level amplifiers which would be required in small-signal detection. The measured overall gain-bandwidth product was {approximately}400 MHz and the noise charge {approximately}1000 electrons at a 1 {mu}sec shaping time. When the amplifier is connected to a pixel detector of capacitance 0.2 pF, it would give a charge-to-voltage gain of {approximately}0.02 mV/electron with a pulse rise time less than 100 nsec and a dynamic range of 48 dB.

Cho, Gyuseong.

1992-03-01

270

Power booster audio amplifier  

Microsoft Academic Search

A novel power booster amplifier is based on a modified half-bridge topology using separated switches and a floating bridge capacitor. The power booster amplifier provides four times higher peak power at the loudspeaker than the peak power of a class-D amplifier using the same power supply. Total harmonic distortion and amplifier efficiency are similar to a class-D amplifier. A universal

Milan Prokin

2002-01-01

271

Highly sensitive potentiometric strip test for detecting high charge density impurities in heparin.  

PubMed

Contamination of heparin with oversulfated chondroitin sulfate (OSCS) became a matter of grave concern in the medical field after many fatal responses to OSCS tainted heparin products occurred during the 2007-2008 period. Even though standard lab-based analytical techniques such as nuclear magnetic resonance (NMR) and strong anion-exchange high performance liquid chromatography (SAX-HPLC) have proven useful for monitoring the OSCS content in heparin products, an easy-to-use, quick, portable, and cost-efficient method is still needed for on-site monitoring during and after the heparin production. In this report, a disposable strip-type electrochemical polyion sensor is described for detection of low levels of OSCS contamination in heparin. A magnetic actuator is incorporated into this simple electrode-based microfluidic device in order to create the mixing effect necessary to achieve equilibrium potential changes of the sensor within a microfluidic channel. The planar membrane electrode detector within the sample channel is prepared with a tridodecylmethylammonium chloride (TDMAC)-doped poly(vinyl chloride) (PVC) membrane essentially equivalent to previously reported polyanion-sensitive electrodes. When the concentration of heparin applied to the single-use strip device is 57 mg/mL (in only 20 ?L of sample), the same concentration recommended in the NMR analysis protocol for detecting OSCS in heparin, the detection limit is 0.005 wt % of OSCS, which is ca. 20 times lower than the reported detection limit of the NMR method. PMID:21500820

Kang, Youngjea; Gwon, Kihak; Shin, Jae Ho; Nam, Hakhyun; Meyerhoff, Mark E; Cha, Geun Sig

2011-05-15

272

Simulation and modelling of charge transport in dye-sensitized solar cells based on carbon nano-tube electrodes  

NASA Astrophysics Data System (ADS)

For a better understanding of the mechanisms of dye-sensitized solar cells (DSSCs), based on carbon nano-tube (CNT) electrodes, a phenomenological model is proposed. For modelling purposes, the meso-scopic porous CNT electrode is considered as a homogeneous nano-crystalline structure with thickness L. The CNT electrode is covered with light-absorbing dye molecules, and interpenetrated by the tri-iodide (I-/I3-) redox couple. A simulation platform, designed to study coupled charge transport in such cells, is presented here. The work aims at formulating a mathematical model that describes charge transfer and charge transport within the porous CNT window electrode. The model is based on a pseudo-homogeneous active layer using drift-diffusion transport equations for free electron and ion transport. Based on solving the continuity equation for electrons, the model uses the numerical finite difference method. The numerical solution of the continuity equation produces current-voltage curves that fit the diode equation with an ideality factor of unity. The calculated current-voltage (J-V) characteristics of the illuminated idealized DSSCs (100 mW cm-2, AM1.5), and the different series resistances of the transparent conductor oxide (TCO) layer were introduced into the idealized simulated photo J-V characteristics. The results obtained are presented and discussed in this paper. Thus, for a series resistance of 4 ? of the TCO layer, the conversion efficiency (?) was 7.49% for the CNT-based cell, compared with 6.11% for the TiO2-based cell. Two recombination kinetic models are used, the electron transport kinetics within the nano-structured CNT film, or the electron transfer rate across the CNT-electrolyte interface. The simulations indicate that both electron and ion transport properties should be considered when modelling CNT-based DSSCs and other similar systems. Unlike conventional polycrystalline solar cells which exhibit carrier recombination, which limits their efficiency, the CNT matrix (in CNT-based cells) serves as the conductor for majority carriers and prevents recombination. This is because of special conductivity and visible-near-infrared transparency of the CNT. Charge transfer mechanisms within the porous CNT matrix and at the semiconductor-dye-electrolyte interfaces are described in this paper.

Gacemi, Yahia; Cheknane, Ali; Hilal, Hikmat S.

2013-03-01

273

Modulation on charge recombination and light harvesting toward high-performance benzothiadiazole-based sensitizers in dye-sensitized solar cells: A theoretical investigation  

NASA Astrophysics Data System (ADS)

Factors associated with short circuit current density (Jsc) and open circuit photovoltage (Voc) of dye sensitized solar cells (DSSCs) have been analyzed through DFT and TDDFT calculations to explore the origin of the significant performance differences with only tiny structure difference (1.24% for 1 and 8.21% for 2) (Advanced Functional Materials 2012, 22, 1291-1302). Our results reveal that the insertion of phenyl ring in 2 enlarges the distance between the dye cation hole and the semiconductor surface and makes the benzothiadiazole (BTDA) unit, which has strong interaction with the electrolyte, far away from the semiconductor, resulting in a decreased charge recombination rate compared with that of 1. However, the insertion of phenyl ring also results in a distortion of the molecular structure, leading to a decreased light harvesting ability. Hence, two dyes (6 and 7) derived from 2 with better conjugation degree, farther position of BTDA unit and longer molecular length have been designed to keep the advantages and overcome the disadvantages of 2 simultaneously. The results demonstrate that we get the desired properties of dyes through reasonable molecular design, and these two dyes could be promising candidates in DSSC field and further improve the performance of the cell.

Zhang, Jian-Zhao; Zhang, Ji; Li, Hai-Bin; Wu, Yong; Xu, Hong-Liang; Zhang, Min; Geng, Yun; Su, Zhong-Min

2014-12-01

274

Amplified OTDR Systems for Multipoint Corrosion Monitoring  

PubMed Central

We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR) technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

Nascimento, Jehan F.; Silva, Marcionilo J.; Coelho, Isnaldo J. S.; Cipriano, Eliel; Martins-Filho, Joaquim F.

2012-01-01

275

Amplified OTDR systems for multipoint corrosion monitoring.  

PubMed

We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR) technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations. PMID:22737017

Nascimento, Jehan F; Silva, Marcionilo J; Coźlho, Isnaldo J S; Cipriano, Eliel; Martins-Filho, Joaquim F

2012-01-01

276

Simple, sensitive and selective spectrophotometric methods for the determination of atenolol in pharmaceuticals through charge transfer complex formation reaction.  

PubMed

Three rapid, selective and sensitive spectrophotometric methods have been proposed for the quantitative determination of atenolol (ATN) in pure form as well as in its pharmaceutical formulation. The methods are based on charge transfer complexation reaction of ATN as n-electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,4-dinitrophenol (DNP) and 2,4,6-trinitrophenol (picric acid; PA) as pi-acceptors to give highly colored radical anion species. The colored products were quantified spectrophotometrically at 590 nm with DDQ (method A) and at 420 nm with both DNP (method B) and PA (method C). Under the optimized experimental conditions, Beer's law is obeyed over the concentration ranges of 3-48, 2-24 and 1.5-18 ?g/mL ATN for method A, method B and method C, respectively. The molar absorptivity, Sandell sensitivity, limits of detection and quantification are also reported. The effects of reaction medium, reaction time and reagent concentration on the sensitivity and stability of the complexes formed have been examined. The proposed methods were successfully applied to the determination of ATN in pure form and commercial tablets with good accuracy and precision. Statistical comparison of the results was performed using Student's t-test and F-ratio at 95% confidence level and the results showed no significant difference between the reference and proposed methods with regard to accuracy and precision. Further, the accuracy and reliability of the methods were confirmed by recovery studies via standard addition technique. PMID:22568035

Prashanth, Kudige Nagaraju; Basavaiah, Kanakapura

2012-01-01

277

Terahertz wave parametric amplifier.  

PubMed

The importance of terahertz (THz) wave techniques has been demonstrated in various fields, and the range of applications is now expanding rapidly. However, the practical implementation of THz science to solve the real-world problems is restricted due to the lack not only of convenient high power THz wave emitters and sensitive detectors but also of efficient quasi-optical active devices such as amplifiers. In this work, we demonstrate the direct amplification of THz waves in room temperature using magnesium oxide-doped lithium niobate (MgO:LiNbO3) crystals as the nonlinear gain medium. The input THz wave is injected as a seed beam along with the pump beam into the nonlinear crystal and it is amplified by the optical parametric process. We report gain in excess of 30 dB with an input THz pulse energy of less than 1 pJ. We believe that this demonstration will contribute to the convenience and further applicability of THz frequency techniques. PMID:24690860

Tripathi, Saroj R; Taira, Yuusuke; Hayashi, Shin'ichiro; Nawata, Kouji; Murate, Kousuke; Minamide, Hiroaki; Kawase, Kodo

2014-03-15

278

Cross-differential amplifier  

NASA Technical Reports Server (NTRS)

A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

2011-01-01

279

Cross-differential amplifier  

NASA Technical Reports Server (NTRS)

A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

2010-01-01

280

Hybrid matrix amplifier  

DOEpatents

The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N.times.M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise.

Martens, Jon S. (Sunnyvale, CA); Hietala, Vincent M. (Placitas, NM); Plut, Thomas A. (Albuquerque, NM)

1995-01-01

281

Hybrid matrix amplifier  

DOEpatents

The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N[times]M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise. 6 figures.

Martens, J.S.; Hietala, V.M.; Plut, T.A.

1995-01-03

282

Cross-differential amplifier  

NASA Technical Reports Server (NTRS)

A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

2008-01-01

283

Cross-differential amplifier  

NASA Technical Reports Server (NTRS)

A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

2013-01-01

284

Progress on diamond amplified photo-cathode  

SciTech Connect

Two years ago, we obtained an emission gain of 40 from the Diamond Amplifier Cathode (DAC) in our test system. In our current systematic study of hydrogenation, the highest gain we registered in emission scanning was 178. We proved that our treatments for improving the diamond amplifiers are reproducible. Upcoming tests planned include testing DAC in a RF cavity. Already, we have designed a system for these tests using our 112 MHz superconducting cavity, wherein we will measure DAC parameters, such as the limit, if any, on emission current density, the bunch charge, and the bunch length. The diamond-amplified photocathode, that promises to support a high average current, low emittance, and a highly stable electron beam with a long lifetime, is under development for an electron source. The diamond, functioning as a secondary emitter amplifies the primary current, with a few KeV energy, that comes from the traditional cathode. Earlier, our group recorded a maximum gain of 40 in the secondary electron emission from a diamond amplifier. In this article, we detail our optimization of the hydrogenation process for a diamond amplifier that resulted in a stable emission gain of 140. We proved that these characteristics are reproducible. We now are designing a system to test the diamond amplifier cathode using an 112MHz SRF gun to measure the limits of the emission current's density, and on the bunch charge and bunch length.

Wang, E.; Ben-Zvi, I.; Burrill, A.; Kewisch, J.; Chang, X.; Rao, T.; Smedley, J.; Wu, Q.; Muller, E.; Xin, T.

2011-03-28

285

Optically Isolated Amplifier.  

National Technical Information Service (NTIS)

The design presented was used for biomedical signal detection and monitoring. The amplifier was successfully applied for EMG and ECG research studies. The patient is safely isolated from the processing equipment when using the amplifier. This opto-isolate...

C. J. Smith

1982-01-01

286

Portable musical instrument amplifier  

DOEpatents

The present invention relates to a musical instrument amplifier which is particularly useful for electric guitars. The amplifier has a rigid body for housing both the electronic system for amplifying and processing signals from the guitar and the system's power supply. An input plug connected to and projecting from the body is electrically coupled to the signal amplifying and processing system. When the plug is inserted into an output jack for an electric guitar, the body is rigidly carried by the guitar, and the guitar is operatively connected to the electrical amplifying and signal processing system without use of a loose interconnection cable. The amplifier is provided with an output jack, into which headphones are plugged to receive amplified signals from the guitar. By eliminating the conventional interconnection cable, the amplifier of the present invention can be used by musicians with increased flexibility and greater freedom of movement.

Christian, David E. (Danbury, CT)

1990-07-24

287

Boost bridge audio amplifier  

Microsoft Academic Search

The main difference in topology of a boost bridge amplifier and state-of-the-art class-D amplifier is in the connection of a loudspeaker between a power supply and a switching bridge. The boost bridge amplifier provides four times higher peak power at the loudspeaker than the power, which can be achieved by a class-D amplifier from the same power supply. Total harmonic

Milan Prokin

2001-01-01

288

Exploring the bond topological properties and the charge depletion-impact sensitivity relationship of high energetic TNT molecule via theoretical charge density analysis  

Microsoft Academic Search

To understand the energetic properties of 2,3,4-Trinitrotolune (TNT) molecule, a quantum chemical calculation and the electronic charge density analysis have been performed. The density functional theory (B3P86\\/6-311G??) calculation was carried out using Gaussian03 software. The energy-minimized wave function obtained from DFT was used for the charge density analysis. The inductive and steric effects of methyl and nitro substituents are not

Arputharaj David Stephen; Rajesh B. Pawar; Poomani Kumaradhas

2010-01-01

289

Measurements of fluxes of thermal neutrons using detector 6 LiI(Eu)-Si-Pin-Pd and a charge-sensitive preamplifier  

Microsoft Academic Search

A method is described for measurement of the flux of thermal neutrons using detectors based on a 6LiI:Eu single crystal, a Hamamatsu Si-PIN-PD of S-3590-01 type and a fast charge-sensitive preamplifier

V. D. Ryzhikov; E. A. Danshin; W. R. Lubimskii; N. N. Smirnov; O. V. Zelenskaya; A. E. Filimonov; V. V. Chernikov

1997-01-01

290

TECHNICAL NOTE: Use of a monolithic dual JFET in a low cost, low noise, charge-sensitive preamplifier for semiconductor radiation detectors (medical application)  

Microsoft Academic Search

A charge-sensitive preamplifier can be simply constructed utilising a 2N5566 monolithic dual JFET with the two FET connected in parallel. The noise performance for this preamplifier is comparable to that for a commercial low noise preamplifier under normal operating conditions. The circuit is unsophisticated, requiring few components, facilitating ease of construction provided attention is paid to the points mentioned. The

D. M. Raymond; M. F. Cottrall

1988-01-01

291

Charge sensitive preamplifier with continuous reset by means of the gate-to-drain current of the JFET integrated on the detector  

Microsoft Academic Search

In this paper we present a charge sensitive preamplifier for a Si drift detector where both the input n-JFET and feedback capacitor are integrated directly on the detector chip. This solution allows to minimize the stray capacitances of the connections and to obtain a capacitive matching between detector and front-end transistor. A continuous discharging mechanism for the leakage current and

C. Fiorini; P. Lechner

2001-01-01

292

Rapid Charge Transport in Dye-Sensitized Solar Cells Made from Vertically Aligned Single-Crystal Rutile TiO2 Nanowires  

SciTech Connect

A rapid solvothermal approach was used to synthesize aligned 1D single-crystal rutile TiO2 nanowire (NW) arrays on transparent conducting substrates as electrodes for dye-sensitized solar cells. The NW arrays showed a more than 200 times faster charge transport (see picture) and a factor four lower defect state density than conventional rutile nanoparticle films.

Feng, X.; Zhu, K.; Frank, A. J.; Grimes, C. A.; Mallouk, T. E.

2012-03-12

293

Semiconductor hierarchically structured flower-like clusters for dye-sensitized solar cells with nearly 100% charge collection efficiency.  

PubMed

By combining the ease of producing ZnO nanoflowers with the advantageous chemical stability of TiO2, hierarchically structured hollow TiO2 flower-like clusters were yielded via chemical bath deposition (CBD) of ZnO nanoflowers, followed by their conversion into TiO2 flower-like clusters in the presence of TiO2 precursors. The effects of ZnO precursor concentration, precursor amount, and reaction time on the formation of ZnO nanoflowers were systematically explored. Dye-sensitized solar cells fabricated by utilizing these hierarchically structured ZnO and TiO2 flower clusters exhibited a power conversion efficiency of 1.16% and 2.73%, respectively, under 100 mW cm(-2) illumination. The intensity modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) studies suggested that flower-like structures had a fast electron transit time and their charge collection efficiency was nearly 100%. PMID:24081015

Xin, Xukai; Liu, Hsiang-Yu; Ye, Meidan; Lin, Zhiqun

2013-11-21

294

Signal and noise performance of large-area PIN photodiodes and charge-sensitive preamplifiers for gamma radiography  

NASA Astrophysics Data System (ADS)

Using 5 cm long CsI (Tl) crystal scintillators, large-area PIN-type photodiodes of 1 cm×1 cm, and a low-noise charge-sensitive preamplifier, two gamma-ray detectors were manufactured. One detector used PIN-type photodiodes fabricated in the process of Electronics and Telecommunications Research Institute (ETRI) and the other one was based on Hamamatsu PIN-type photodiodes of S-3590-01. Gamma spectroscopies were performed and analyzed for both Co-60 and Cs-137 gamma sources. The first detector showed energy resolutions (FWHM) of 6.4% and 5.5% for 1.17 and 1.33 MeV, which were similar to energy resolutions of the second detector for Co-60, but the second detector showed 6.6% better resolution than the first detector's 11.8% for Cs-137. For 10 h exposure of Co-60 (14.5 ?Ci), noise equivalent quanta (NEQ) and spectroscopy for both detectors have been investigated in detail. The NEQ of 25% increased after the exposure and degradations of the FWHMs of 26% and 11% have been found for 1.17 and 1.33 MeV, respectively.

Kim, Kwang Hyun; Kim, Young Soo; Kim, Jung Soo

2008-06-01

295

Laser amplifier chain  

DOEpatents

A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain. 6 figs.

Hackel, R.P.

1992-10-20

296

Laser amplifier chain  

DOEpatents

A laser amplifier chain has a plurality of laser amplifiers arranged in a chain to sequentially amplify a low-power signal beam to produce a significantly higher-power output beam. Overall efficiency of such a chain is improved if high-gain, low efficiency amplifiers are placed on the upstream side of the chain where only a very small fraction of the total pumped power is received by the chain and low-gain, high-efficiency amplifiers are placed on the downstream side where a majority of pumping energy is received by the chain.

Hackel, Richard P. (Livermore, CA)

1992-01-01

297

Proton induced damage in JFET transistors and charge preamplifiers on high-resistivity silicon  

Microsoft Academic Search

The results discussed in this paper are relevant to junction field effect transistors and JFET based charge sensitive amplifiers fabricated in a detector compatible process. Such structures were irradiated with 27 MeV protons to evaluate the suitability of the technology for space applications and high energy physics experiments from the standpoint of radiation tol- erance. The process investigated in this

G. F. Dalla Betta; M. Manghisoni; L. Ratti; V. Re; Valeria Speziali; Gianluca Traversi; Andrea Candelori

2003-01-01

298

A sensitive and selective mercury(II) sensor based on amplified fluorescence quenching in a conjugated polyelectrolyte/spiro-cyclic rhodamine system.  

PubMed

A novel fluorescence-based sensor for mercury(II) ion is described consisting of a water-soluble, anionic-conjugated polyelectrolyte (CPE) and spiro-cyclic rhodamine derivative (1). A solution containing the CPE (0.1 × 10(-6) M repeat unit concentration) and 1 (1 × 10(-6) M concentration) in aqueous solution exhibits a sensitive and selective turn-off fluorescence response to Hg(II). The Stern-Volmer quenching constant for quenching of the fluorescence of the system by Hg(II) is ?1.5 × 10(7) M(-1) , and Hg(II) can be sensed with a detection limit <10 × 10(-9) M. A mechanism for the sensor response is proposed and it consists of efficient and selective complex formation between 1 and Hg(II), along with a very high association between the 1-Hg(II) complex and the anionic CPE. PMID:23529859

Lee, Seoung Ho; Parthasarathy, Anand; Schanze, Kirk S

2013-05-14

299

Influence of polymer size, liposomal composition, surface charge, and temperature on the permeability of pH-sensitive liposomes containing lipid-anchored poly(2-ethylacrylic acid)  

PubMed Central

Background Liposomes containing pH-sensitive polymers are promising candidates for the treatment of tumors and localized infection. This study aimed to identify parameters influencing the extent of contents release from poly(ethylacrylic acid) (PEAA) vesicles, focusing on the effects of polymer size, lipid composition, vesicle surface charge, and temperature. Methods Anchored lipid pH-sensitive PEAA was synthesized using PEAA with a molecular weight of 8.4 kDa. PEAA vesicles were prepared by insertion of the lipid-anchored PEAA into preformed large unilamellar vesicles. The preformed liposomes were manipulated by varying the phosphocholine and cholesterol content, and by adding negative or positive charges to the liposomes. A calcein release assay was used to evaluate the effects of polymer size, liposome composition, surface charge, and temperature on liposomal permeability. Results The release efficiency of the calcein-entrapped vesicles was found to be dependent on the PEAA polymer size. PEAA vesicles containing a phosphatidylcholine to cholesterol ratio of 60:40 (mol/mol) released more than 80% of their calcein content when the molecular weight of PEAA was larger than 8.4 kDa. Therefore, the same-sized polymer of 8.4 kDa was used for the rest of study. The calcein release potential was found to decrease as the percentage of cholesterol increased and with an increase in the phosphocholine acyl chain length (DMPC DPPC DSPC). Negatively charged and neutral vesicles released similar amounts of calcein, whereas positively charged liposomes released a significant amount of their contents. pH-sensitive release was dependent on temperature. Dramatic content release was observed at higher temperatures. Conclusion The observed synergistic effect of pH and temperature on release of the contents of PEAA vesicles suggests that this pH-sensitive liposome might be a good candidate for intracellular drug delivery in the treatment of tumors or localized infection.

Lu, Tingli; Wang, Zhao; Ma, Yufan; Zhang, Yang; Chen, Tao

2012-01-01

300

Primer on the Lock-in Amplifier  

NSDL National Science Digital Library

This is an experiment designed to measure the resistance of copper and gold nanowires using a lock-in amplifier. Students learn: 1. about different types of noise, 2. the principles of phase-sensitive techniques, 3. to extract signals buried in noise using a lock-in amplifier, 4. to operate optical chopper to measure weak optical signals modulated at a certain frequency. 4. to measure the minute resistance of a conducting nanowires.

Farooq, Sidra; Salman, Rabiya; Zia, Wasif; Hassan, Umer; Anwar, Muhammad S.

2012-02-10

301

Characteristic features of charge transfer in the interaction between sensitizer molecules and AgCl(I) molecules  

NASA Astrophysics Data System (ADS)

We have used flash luminescence stimulation and photoinduced emission methods to study deep impurity states of AgCl(I) microcrystals with adsorbed organic cationic and anionic dye molecules. We have observed that when these molecules interact with the crystal, charge transfer occurs simultaneously from different orbitals and the transfer occurs differently from each orbital: some orbitals of the molecule pick up a negative charge, others at the same time give up a negative charge. We hypothesize that the type of transfer is determined by the overall charge.

Latyshev, A. N.; Chung, Nguyen Thi Kim; Suvorova, T. I.; Ovchinnikov, O. V.; Smirnov, M. S.; Egorushina, E. A.

2011-07-01

302

Multipass optical parametric amplifier  

NASA Astrophysics Data System (ADS)

A compact, low-threshold, multipass optical parametric amplifier has been developed for the conversion of short-pulse (360-ps) 1064-nm Nd:YAG laser radiation into eye-safe 1572-nm radiation for laser ranging and radar applications. The amplifier had a threshold pump power of as low as 45 mu J , and at three to four times this threshold pump power the amplifier converted 30% of the input 1064-nm radiation into 1572-nm output radiation.

Jeys, T. H.

1996-08-01

303

Ultra-sensitive detection of mutated papillary thyroid carcinoma DNA using square wave stripping voltammetry method and amplified gold nanoparticle biomarkers.  

PubMed

This study presents an ultra-sensitive technique for the electrochemical detection of the mutated BRAF gene associated with papillary thyroid carcinomas (PTC). In the proposed approach, a biotinylated 30-nucleotides probe DNA was immobilized in a streptavidin-modified 96-well microtiter plate and the free active sites of the streptavidin were blocked using biotinylated bovine serum albumin (BSA). The biotinylated target DNA was then added and allowed to hybridize with the immobilized probe DNA for 30min. Subsequently, streptavidin-labeled gold nanoparticles were added, and a nanoparticle enlargement process was performed using gold ion solution and formaldehyde reductant. The gold particles were then dissolved in bromide and DNA hybridization detection process was performed using a square wave stripping voltammetry (SWSV) technique. The results indicated a stable SWSV response in differential detection between blank solution and target DNA solution with a concentration of 130aM. Moreover, the coefficient of determination (R(2)) of the semi-log plot of the SWSV response current against the target DNA concentration (0.52-1300aM) was found to be 0.9982. The detection limit was estimated to be 0.35aM (based on a signal-to-noise ratio of 3:1). This value was approximately three orders of magnitude lower than that obtained using the same method but without gold amplification process. Finally, the proposed approach is successful in differentiating between the mutant and wildtype BRAF sequences that are present in genuine 224-nucleotides DNA. PMID:19010660

Liao, Kuo-Tang; Cheng, Jiin-Tsuey; Li, Chun-Liang; Liu, Rue-Tsuan; Huang, Hsuan-Jung

2009-03-15

304

Simulation of intramolecular hydrogen bond dynamics in manzamine A as a sensitive test for charge distribution quality.  

PubMed

Subtle balance of inter- and intramolecular hydrogen bond strength in aqueous solutions often governs the structure and dynamics of molecular species used as potential drugs and in supramolecular applications. In silico molecular dynamics study of water solution of manzamine A has been performed with different atomic charges in order to investigate the influence of charge distribution choice on predicting qualitative and quantitative features of the simulated systems. Various well known charge schemes (MK-ESP, RESP, Mulliken, AMI-BCC, Gasteiger-Hückel, Gasteiger-Marsili, MMFF94, and Dynamic Electronegativity Relaxation - DENR) led to qualitatively different pictures of dynamic behavior of the intramolecular hydrogen bond. The reported calculation framework represents a relatively rare case where differences in charge distributions lead to noticeable differences in simulated properties, thus providing a useful test case for force field and charge distribution development, provided high quality experiments are conducted to use as references. PMID:22545399

Shulga, Dmitry A; Osolodkin, Dmitry I; Palyulin, Vladimir A; Zefirov, Nikolay S

2012-03-01

305

Amplifiers and Active Systems  

NSDL National Science Digital Library

Created by Tony R. Kuphaldt, this chapter of All About Circuit's third volume on Semiconductors describes amplifiers and active devices. The chapter is divided into seven sections: From electric to electronic, Active versus passive devices, Amplifiers, Amplifier gain, Decibels, Absolute dB scales, and Attenuators. Each section has clear illustrations and a concise, bulleted review of what was covered at the end. There is also a link to the All About Circuits forums, where contributors and other visitors discuss the material presented. This is an excellent resource for educators in physics and electronic engineering classrooms to introduce lessons or units on amplifiers.

Kuphaldt, Tony R.

2008-07-03

306

Note: A high dynamic range, linear response transimpedance amplifier.  

PubMed

We have built a high dynamic range (nine decade) transimpedance amplifier with a linear response. The amplifier uses junction-gate field effect transistors (JFETs) to switch between three different resistors in the feedback of a low input bias current operational amplifier. This allows for the creation of multiple outputs, each with a linear response and a different transimpedance gain. The overall bandwidth of the transimpedance amplifier is set by the bandwidth of the most sensitive range. For our application, we demonstrate a three-stage amplifier with transimpedance gains of approximately 10(9)?, 3 × 10(7)?, and 10(4)? with a bandwidth of 100 Hz. PMID:22380140

Eckel, S; Sushkov, A O; Lamoreaux, S K

2012-02-01

307

Sensitivity of combustion and ignition characteristics of the solid-fuel charge of the microelectromechanical system of a microthruster to macrokinetic and design parameters  

NASA Astrophysics Data System (ADS)

We have developed a sensitivity analysis permitting effective estimation of the change in the impulse responses of a microthrusters and in the ignition characteristics of the solid-fuel charge caused by the variation of the basic macrokinetic parameters of the mixed fuel and the design parameters of the microthruster's combustion chamber. On the basis of the proposed sensitivity analysis, we have estimated the spread of both the propulsive force and impulse and the induction period and self-ignition temperature depending on the macrokinetic parameters of combustion (pre-exponential factor, activation energy, density, and heat content) of the solid-fuel charge of the microthruster. The obtained results can be used for rapid and effective estimation of the spread of goal functions to provide stable physicochemical characteristics and impulse responses of solid-fuel mixtures in making and using microthrusters.

Futko, S. I.; Ermolaeva, E. M.; Dobrego, K. V.; Bondarenko, V. P.; Dolgii, L. N.

2012-07-01

308

Theoretical investigation of the charge-transfer properties in different meso-linked zinc porphyrins for highly efficient dye-sensitized solar cells.  

PubMed

The charge transfer effect of different meso-substituted linkages on porphyrin analogue 1 (A1, B1 and C1) was theoretically investigated using density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The calculated geometry parameters and natural bond orbital analysis reveal that the twisted conformation between porphyrin macrocycle and meso-substituted linkages leads to blocking of the conjugation of the conjugated backbone, and the frontier molecular orbital plot shows that the intramolecular charge transfer of A1, B1 and C1 hardly takes place. In an attempt to improve the photoinduced intramolecular charge transfer ability of the meso-linked zinc porphyrin sensitizer, a strong electron-withdrawing group (CN) was introduced into the anchoring group of analogue 1 forming analogue 2 (A2, B2 and C2). The density difference plot of A2, B2 and C2 shows that the charge transfer properties dramatically improved. The electron injection process has been performed using TDDFT; the direct charge-transfer transition in the A2-(TiO2)38 interacting system takes place; our results strongly indicated that introducing electron-withdrawing groups into the acceptor part of porphyrin dyes can fine-tune the effective conjugation length of the ?-spacer and improve intramolecular charge transfer properties, consequently inducing the electron injection process from the anchoring group of the porphyrin dye to the (TiO2)38 surface which may improve the conversion efficiency of the DSSCs. Our calculated results can provide valuable information and a promising outlook for computation-aided sensitizer design with anticipated good properties in further experimental synthesis. PMID:24810141

Namuangruk, Supawadee; Sirithip, Kanokkorn; Rattanatwan, Rattanawelee; Keawin, Tinnagon; Kungwan, Nawee; Sudyodsuk, Taweesak; Promarak, Vinich; Surakhot, Yaowarat; Jungsuttiwong, Siriporn

2014-06-28

309

Charge-sensitive preamplifier with continuous reset by means of the gate-to-drain current of the JFET integrated on the detector  

Microsoft Academic Search

In this paper, we present a charge-sensitive preamplifier designed for a silicon drift detector (SDD), where both input n-JFET and feedback capacitor are integrated directly on the detector chip. The integration of these devices allows obtaining a capacitive matching between detector and front-end transistor and to minimize the stray capacitances of the connections. A continuous discharging mechanism for the leakage

C. Fiorini; P. Lechner

2002-01-01

310

A low-noise charge-sensitive preamplifier for an X-ray detector of a Nb-based superconducting tunnel junction  

Microsoft Academic Search

A low-noise charge-sensitive preamplifier with cooled 4-JFETs was developed for an X-ray detector of a Nb-based superconducting tunnel junction with a large capacitance and a low leakage current. The low-noise characteristics for a wide range of shaping times were obtained by using a selected JFET, 2SK 190 in the first stage of the preamplifier. A new formula to simulate the

M. Ukibe; M. Kishimoto; M. Katagiri; M. Kurakado; M. Nakazawa

1997-01-01

311

Electron donor-acceptor distance dependence of the dynamics of light-induced interfacial charge transfer in the dye-sensitization of nanocrystalline oxide semiconductors  

Microsoft Academic Search

The effect of electronic and nuclear factors on the dynamics of dye-to-semiconductor electron transfer was studied employing RuII(terpy)(NCS)3 sensitizers grafted onto transparent films made of titanium dioxide nanoparticles. Various approaches were strived to understand the dependence of the kinetics of charge injection and recombination processes upon the distance separating the dye molecules and the redox active surface. A series of

Bernard Wenger; Christophe Bauer; Mohammad K. Nazeeruddin; Pascal Comte; Shaik M. Zakeeruddin; Michael Grätzel; Jacques-E. Moser

2006-01-01

312

Ultrafast polarisation spectroscopy of photoinduced charges in a conjugated polymer  

SciTech Connect

Tunable optical parametric generators and amplifiers (OPA), proposed and developed by Akhmanov and his colleagues, have become the working horses in exploration of dynamical processes in physics, chemistry, and biology. In this paper, we demonstrate the possibility of using ultrafast polarisation-sensitive two-colour spectroscopy, performed with a set of two OPAs, to study charge photogeneration and transport in conjugated polymers and their donor-acceptor blends. (special issue devoted to the 80th birthday of S.A. Akhmanov)

Bakulin, A A; Loosdrecht, P van; Pshenichnikov, M S [Zernike Institute for Advanced Materials, University of Groningen, Groningen (Netherlands); Parashchuk, D Yu [M. V. Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation)

2009-07-31

313

Dye laser amplifier  

DOEpatents

An improved dye laser amplifier is disclosed. The efficiency of the dye laser amplifier is increased significantly by increasing the power of a dye beam as it passes from an input window to an output window within the dye chamber, while maintaining the intensity of the dye beam constant. 3 figs.

Moses, E.I.

1992-12-01

314

Universal signal conditioning amplifier  

NASA Technical Reports Server (NTRS)

A state-of-the-art instrumentation amplifier capable of being used with most types of transducers has been developed at the Kennedy Space Center. This Universal Signal Conditioning Amplifier (USCA) can eliminate costly measurement setup item and troubleshooting, improve system reliability and provide more accurate data than conventional amplifiers. The USCA can configure itself for maximum resolution and accuracy based on information read from a RAM chip attached to each transducer. Excitation voltages or current are also automatically configured. The amplifier uses both analog and digital state-of-the-art technology with analog-to-digital conversion performed in the early stages in order to minimize errors introduced by offset and gain drifts in the analog components. A dynamic temperature compensation scheme has been designed to achieve and maintain 12-bit accuracy of the amplifier from 0 to 70 C. The digital signal processing section allows the implementation of digital filters up to 511th order. The amplifier can also perform real-time linearizations up to fourth order while processing data at a rate of 23.438 kS/s. Both digital and analog outputs are available from the amplifier.

Medelius, Pedro J.; Hallberg, Carl; Cecil, Jim

1994-01-01

315

Gyrotron Travelling-Wave Amplifier.  

National Technical Information Service (NTIS)

An apparatus for amplifying coherent radiation at millimeter and submillimeter wavelengths includes the combination of a travelling-wave-tube cyclotron-maser-amplifier structure and a magnetron-injection electron gun. The amplifier structure includes a fa...

V. L. Granatstein P. Sprangle A. T. Drobot

1978-01-01

316

Charged particle identification using difference in track length detected by two-dimensional multi-wire proportional counter  

Microsoft Academic Search

It is important to measure each kind of charged particle individually in radiation fields because each particle has different characteristic in human body. We propose a method of charged particle identification using difference in track length detected by a two-dimensional position sensitive gas detector. This system consists of a multi-wire detection head, amplifier-shaper- discriminator circuits, a logic circuit for calculation

H. Tanaka; T. Nakamura; K. Toh; H. Yamagishi; K. Soyama; K. Ochiai; C. Konno; K. Aizawa; A. Maruhashi

2007-01-01

317

Structure-property relationships for three indoline dyes used in dye-sensitized solar cells: TDDFT study of visible absorption and photoinduced charge-transfer processes.  

PubMed

The electronic structures of three D-A-?-A indoline dyes (WS-2, WS-6, and WS-11) used in dye-sensitized solar cells (DSSCs) were studied by performing quantum chemistry calculations. The coplanarity of the A-?-A segment and distinct noncoplanarity of the indoline donor part of each dye were confirmed by checking the calculated geometric parameters. The relationships between molecular modifications and the optical properties of the dyes were derived in terms of the partial density of states, absorption spectrum, frontier molecular orbital, and excited-state charge transfer. 3D real-space analysis of the transition density (TD) and charge difference density (CDD) was also performed to further investigate the excited-state features of the molecular systems, as they provide visualized physical pictures of the charge separation and transfer. It was found that modifying the alkyl chain of the bridge unit near the acceptor unit is an efficient way to decrease dye aggregation and improve DSSC efficiency. Inserting a hexylthiophene group next to the donor unit leads to a complicated molecular structure and a decrease in the charge-transfer ability of the system, which has an unfavorable impact on DSSC performance. PMID:24154611

Li, Huixing; Chen, Maodu

2013-12-01

318

Use of commercial operational amplifiers in a low cost multi-channel preamplifier system  

NASA Astrophysics Data System (ADS)

We report on a simple, compact-size and cost-effective multi-channel charge-sensitive preamplifier system using the commercial IC operational amplifiers. An energy resolution of 5.6% at 511 keV is achieved with a large size (10×10×1 mm3) planar CdTe detector. The system is well suited for use with the compound semiconductor detectors in the applications in which the rather high power consumption of the system (320 mW per channel) can be tolerated.

Nakhostin, M.; Kikuchi, Y.; Ishii, K.; Matsuyama, S.; Yamazaki, H.

2013-04-01

319

Fully relayed regenerative amplifier  

DOEpatents

A regenerative laser apparatus and method using the optical relay concept to maintain high fill factors, to suppress diffraction effects, and to minimize phase distortions in a regenerative amplifier.

Glass, Alexander J. (Berkeley, CA) [Berkeley, CA

1981-01-01

320

Amplify Interest in STS.  

ERIC Educational Resources Information Center

Presents activities in which students construct simple crystal radio sets and amplifiers out of diodes, transistors, and integrated circuits. Provides conceptual background, materials needed, instructions, diagrams, and classroom applications. (MDH)

Chiappetta, Eugene L; Mays, John D.

1992-01-01

321

CGE Rod Amplifier Modules.  

National Technical Information Service (NTIS)

The performance and development history of the neodymium glass laser rod amplifiers in use at NRL on the Pharos II laser system is reviewed. The impact of possible future modifications is assessed. (Author)

J. M. McMahon

1978-01-01

322

Visualizing interfacial charge transfer in Ru-dye sensitized TiO{sub 2} nanoparticles using x-ray transient absorption spectroscopy.  

SciTech Connect

A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy){sub 2}(NCS){sub 2} (RuN3) dye adsorbed to TiO{sub 2} nanoparticle surfaces. The results show that the average Ru-NCS bond length reduces by 0.06 {angstrom}, whereas the average Ru?N(dcbpy) bond length remains nearly unchanged after the electron injection. The differences in bond-order change and steric hindrance between two types of ligands are attributed to their structural response in the charge separation. This study extends the application of XTA into optically opaque hybrid interfacial systems relevant to the solar energy conversion.

Zhang, X.; Smolentsev, G.; Guo, J.; Attenkofer, K.; Kurtz, C.; Jennings, G.; Lockard, J. V.; Stickrath, A. B.; Chen, L. X. (Chemical Sciences and Engineering Division); ( XSD); (Southern Federal Univ.); (Lund Univ.); (Northwestern Univ.)

2011-03-01

323

Superfunctions for amplifiers  

NASA Astrophysics Data System (ADS)

An amplifier is characterized by its transfer function T, which expresses the dependence of the output signal on the input signal. This signal may be related to power, intensity, energy of a pulse, or its fluence, or any similar physical quantity. The internal structure of the amplified signal (e.g., its spectral content, polarization, temporal behavior, and spatial distribution) is not taken into account. The amplifier is considered to be spatially homogeneous and uniformly pumped. The transfer function is supposed to be known (measured in an experiment). The problem of reconstruction of the behavior of the signal inside the amplifier is formulated. For a given transfer function T, the evolution of the signal inside is interpreted as the superfunction F, satisfying the transfer equation F( z + 1) T(F(z)), where z is of coordinate along the propagation direction, while the length of the amplifier is used as a unit of measurement. (For simplicity, distances are measured in units of the length of the amplifier.) Two examples of realistic transfer function T are considered; they correspond to amplification of continuous wave and to amplification of pulses. In these examples, the transfer function and the distribution of the signal along the amplifier can be expressed in terms of special functions. The iterative procedure is suggested as a general method of reconstructing the signal along the amplifier, if neither the transfer function T, nor the superfunction F can be expressed with a simple combination of special functions. The examples show that the iterations converge to a physically meaningful solution. This method is expected to be useful for the characterization of laser materials from the measurement of the transfer function of a bulk sample.

Kouznetsov, Dmitrii

2013-07-01

324

Amplified DNA Biosensors  

Microsoft Academic Search

\\u000a Amplified detection of DNA is a central research topic in modern bioanalytical science. Electronic or optical transduction\\u000a of DNA recognition events provides readout signals for DNA biosensors. Amplification of the DNA analysis is accomplished by\\u000a the coupling of nucleic acid-functionalized enzymes or nucleic acid-functionalized nanoparticles (NP) as labels for the DNA\\u000a duplex formation. This chapter discusses the amplified amperometric analysis

Itamar Willner; Bella Shlyahovsky; Bilha Willner; Maya Zayats

2009-01-01

325

Noise in chi (3) and photorefractive amplifiers  

NASA Astrophysics Data System (ADS)

A comparison of the noise characteristics of chi (3) and photorefractive coherent amplifiers reveals basic differences in their dependence on operating parameters. Unlike all types of chi (3) amplifiers, which are shown to have a well-defined optimum working point in the region of the self-stimulated scattering threshold, the photorefractive amplifier can be made increasingly quieter by lowering the pump power. This is demonstrated by use of highly doped Co:BaTiO3 in a tight-focus reflection grating geometry. It is shown that scattering from inhomogeneities in the crystal is the major limiting noise source and is significantly higher than predictions resulting from fundamental considerations such as random space-charge noise. An extremely high small-signal gain of 107 was measured with this crystal and geometry. To our knowledge this is the highest photorefractive gain reported to date.

Sternklar, Shmuel; Glick, Yaakov

1995-12-01

326

Wideband Raman Amplifiers  

NASA Astrophysics Data System (ADS)

This chapter describes designs and experiments that apply the Raman effect to wideband amplifiers (WBAs). In the context of this chapter, wideband corresponds to a bandwidth of approximately 50 to 100 nm or more. We start by explaining the need for WBAs, and briefly review some of the key enabling technologies for wideband systems. Section 14.2 describes several approaches for WBA, including the erbium-doped fiber amplifier (EDFA) and Raman amplifier combinations as well as all-Raman amplifiers. Section 14.3 summarizes the advantages and challenges of the all-Raman approach, the focus of this chapter. Section 14.4 identifies the key physical principles that need to be considered in the design of all-Raman WBAs. Then, perhaps the most important section of this chapter, Section 14.5 describes engineering design rules for construction of all-Raman WBAs that satisfy gain and noise figure performance requirements of typical long-haul and ultra-long-haul fiber-optic transmission systems. Several WBA experiments that use either EDFA/Raman amplifier combinations or all-Raman amplifiers are illustrated in Section 14.6, and exemplary wideband system experiments are described in Section 14.7. Finally, we summarize and conclude the chapter in Section 14.8.

Islam, Mohammed N.; De Wilde, Carl; Kuditcher, Amos

327

Solid state radiographic image amplifiers, part C  

NASA Technical Reports Server (NTRS)

The contrast sensitivity of the radiographic amplifiers, both the storage type and nonstorage type, their absolute sensitivity, and the reproducibility of fabrication were investigated. The required 2-2T quality level was reached with the radiographic storage screen. The sensitivity threshold was 100 to 200 mR with 45 to 100 kV filtered X-rays. The quality level of the radiographic amplifier screen (without storage) was 4-4T; for a 6 mm (0.25 in.) thick aluminum specimen, a 1 mm (0.040 in.) diameter hole in a 0.25 mm (0.010 in.) thick penetrameter was detected. Its sensitivity threshold was 2 to 6 mR/min. The developed radiographic screens are applicable for uses in nondestructive testing.

Szepesi, Z.

1971-01-01

328

Single-stage transimpedance amplifier for advanced DVD systems  

NASA Astrophysics Data System (ADS)

For digital versatile disk (DVD) applications, amplifiers with high bandwidth and high sensitivity in the red spectral range are required. The presented optoelectronic integrated circuit (OEIC) achieves a bandwidth of 265MHz and a transimpedance of 210k? due to an advanced feedback network. This is an improvement by a factor of 4 compared to the same amplifier with a simple feedback resistor.

Seidl, Christoph; Knorr, Johannes; Swoboda, Robert; Zimmermann, Horst

2004-06-01

329

Charge-sensitive vibrations in p-chloranil: the strange case of the C=C antisymmetric stretching.  

PubMed

We have combined DFT calculations with single-crystal polarized infrared spectra to reinvestigate the assignment of the C=C antisymmetric stretching mode b(2u)nu(18) of p-chloranil (CA). The frequency of this mode indeed seems to display a nonlinear dependence on the average charge on the CA molecule (rho), at variance with the behavior of the antisymmetric C=O stretching frequency. The DFT calculations show that the origin of the problem is a drastic, 2 orders of magnitude decrease of the infrared intensity of the C=C antisymmetric stretching upon electron addition. Therefore, no infrared band can be easily associated to this mode in charge-transfer (CT) solids with rho approximately > 0.5. On the other hand, a linear relationship between rho and the b(2u)nu(18) frequency is found in quasi-neutral CT complexes of CA. PMID:17941667

Ranzieri, Paolo; Masino, Matteo; Girlando, Alberto

2007-11-01

330

A 3.3-to-25V all-digital charge pump based system with temperature and load compensation for avalanche photodiode cameras with fixed sensitivity  

NASA Astrophysics Data System (ADS)

This paper presents a digitally controlled charge pump (DCP) to supply high voltages, while ensuring temperature and load current independence of excess bias in cameras based on avalanche photodiodes. This is achieved through a single-photon avalanche diode (SPAD) based monitoring mechanism that continuously reconfigures the DCP using a feedback loop to compensate breakdown voltage variations by temperature and load current in real time. The sensitivity of the SPADs, or photon detection probability (PDP), is maintained to within 1.9% when the temperature shifts from 28°C to 65°C and the load current changes from 0 ?A to 100 ?A.

Mandai, S.; Charbon, E.

2013-03-01

331

Electrochemical characterization of Prussian blue type nickel hexacyanoferrate redox mediator for potential application as charge relay in dye-sensitized solar cells  

Microsoft Academic Search

A polynuclear electronically\\/ionically (redox) conducting mixed-valent inorganic material such as nickel(II) hexacyanoferrate(II,III),\\u000a NiHCF, was considered for potential application as a redox mediator (charge relay) in dye-sensitized solar cell (DSSC). The\\u000a NiHCF redox reactions were found fast and reversible not only when the system was studied as thin film exposed to an aqueous\\u000a supporting electrolyte but also as bulk material (pasted

Iwona A. Rutkowska; Adam Andrearczyk; Sylwia Zoladek; Monika Goral; Kazimierz Darowicki; Pawel J. Kulesza

332

Measuring momentum for charged particle tomography  

Microsoft Academic Search

Methods, apparatus and systems for detecting charged particles and obtaining tomography of a volume by measuring charged particles including measuring the momentum of a charged particle passing through a charged particle detector. Sets of position sensitive detectors measure scattering of the charged particle. The position sensitive detectors having sufficient mass to cause the charged particle passing through the position sensitive

Christopher Morris; Andrew Mcleod Fraser; Larry Joe Schultz; Konstantin N. Borozdin; Alexei Vasilievich Klimenko; Michael James Sossong; Gary Blanpied

2010-01-01

333

Laser amplifier and method  

DOEpatents

Laser amplifiers and methods for amplifying a laser beam are disclosed. A representative embodiment of the amplifier comprises first and second curved mirrors, a gain medium, a third mirror, and a mask. The gain medium is situated between the first and second curved mirrors at the focal point of each curved mirror. The first curved mirror directs and focuses a laser beam to pass through the gain medium to the second curved mirror which reflects and recollimates the laser beam. The gain medium amplifies and shapes the laser beam as the laser beam passes therethrough. The third mirror reflects the laser beam, reflected from the second curved mirror, so that the laser beam bypasses the gain medium and return to the first curved mirror, thereby completing a cycle of a ring traversed by the laser beam. The mask defines at least one beam-clipping aperture through which the laser beam passes during a cycle. The gain medium is pumped, preferably using a suitable pumping laser. The laser amplifier can be used to increase the energy of continuous-wave or, especially, pulsed laser beams including pulses of femtosecond duration and relatively high pulse rate. 7 figs.

Backus, S.; Kapteyn, H.C.; Murnane, M.M.

1997-07-01

334

Influence of TiO2 nanotube morphology and TiCl4 treatment on the charge transfer in dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Dye-sensitized solar cells (DSSCs) were fabricated using TiO2 nanoparticles (NPs), TiO2 nanotube arrays (NTAs), and surface-modified NTAs with a TiCl4 treatment. The photovoltaic efficiencies of the DSSCs using TiO2 NP, NTA, and TiCl4-treated NTA electrodes are 4.25, 4.74, and 7.47 %, respectively. The highest performance was observed with a TiCl4-treated TiO2 NTA photoanode, although in the case of the latter two electrodes, the amounts of N719 dye adsorbed were similar and 68 % of that of the NP electrode. Electrochemical impedance measurements show that the overall resistance, including the charge-transfer resistance, was smaller with NTA morphologies than with NP morphologies. We suggest that a different electron transfer mechanism along the one-dimensional nanostructure of the TiO2 NTAs contributes to the smaller charge-transfer resistance, resulting in a higher short circuit current ( J sc), even at lower dye adsorption. Furthermore, the TiCl4-treated NTAs showed even smaller charge-transfer resistance, resulting in the highest J sc value, because the downward shift in the conduction band edge improves the electron injection efficiency from the excited dye into the TiCl4-treated TiO2 electrodes.

Lee, Sun Hong; Chae, Sang Youn; Hwang, Yun Jeong; Koo, Kee-Kahb; Joo, Oh-Shim

2013-09-01

335

Functional assessment for predicting charge-transfer excitations of dyes in complexed state: a study of triphenylamine-donor dyes on titania for dye-sensitized solar cells.  

PubMed

Time-dependent density functional theory (TD-DFT) was employed to calculate the UV/vis spectra for three of the triphenylamine (TPA)-donor dyes, TC1, L1, and LJ1, in isolation as well as when complexed with a titania nanoparticle. TPA-donor dyes are a class of promising organic dyes for use in dye-sensitized solar cells (DSSCs). The three dyes studied here are among the smallest of these molecules and provide important insight into the entire series of TPA dyes that are being explored as possible sensitizers in titania-based DSSCs. An attempt to calculate the optical spectra for these dyes within the B3LYP approximation to the exchange correlation functional produces erroneous results. However, Coulomb attenuated approximation (CAM-B3LYP) captures the correct photophysics of the dyes and produces more accurate charge-transfer excitation energies of their complexes with titania. This work shows that the extent to which a given approximation fails or succeeds to correctly predict the charge-transfer excitation energies in the isolated dyes is propagated in that it fails (or succeeds) to correctly predict the values of the excitation energies for the complexes. It is, therefore, important to determine the most appropriate functional for a dye before considering it in more complicated structures such as dye-titania complexes. PMID:23237270

Dev, Pratibha; Agrawal, Saurabh; English, Niall J

2013-03-14

336

Analog Electronics: Basic Circuits of Operational Amplifiers  

NSDL National Science Digital Library

This site offers a set of interactive operational amplifiers (OAs) simulators with detailed lessons and basic circuit schematics (including theory). The Java applets provided include an inverting amplifier, summing amplifier, difference amplifier, differentiator, and integrator circuit amplifier.

2009-11-02

337

Dispersive Readout of a Superconducting Qubit Using a SLUG Amplifier  

NASA Astrophysics Data System (ADS)

Developing a fast, high-fidelity readout of superconducting quantum bits (qubits) makes significant demands of the cryogenic amplification chain, where the first stage amplifier must have sufficient sensitivity to resolve the state of the qubit and enough gain to overcome the noise of subsequent stages of amplification. Additionally, the architecture of a scalable quantum computer requires an amplifier with a large enough bandwidth and dynamic range to simultaneously measure multiple qubits without sacrificing performance. In this thesis, we describe a novel low-noise phase-insensitive linear amplifier at microwave frequencies based on the Superconducting Low-Inductance Undulatory Galvanometer (SLUG), an amplifier capable of meeting the demands of the superconducting qubit community. We discuss the numerical optimization of the SLUG amplifier and calculate the expected amplifier gain and noise temperature. We walk through the amplifier design and fabrication process before discussing how to fully characterize the fabricated device. We report on amplifiers with measured gain of 10 to 15 dB, bandwidths from 50 to 100 MHz, and added system noise below 2 quanta. Next, we describe the qubit- cavity system and the limits of a dispersive quantum measurement using circuit quantum electrodynamics. Finally, we report on experiments where a SLUG amplifier is used to measure the state of a superconducting qubit, demonstrating improved measurement signal-to-noise ratios of 10 dB and a dynamic range that is an order of magnitude better than any available amplifier currently being developed.

Hover, David James

338

Universal signal conditioning amplifier  

NASA Technical Reports Server (NTRS)

Engineers at NASA's Kennedy Space Center have designed a signal conditioning amplifier which automatically matches itself to almost any kind of transducer. The product, called Universal Signal Conditioning Amplifier (USCA), uses state-of-the-art technologies to deliver high accuracy measurements. USCA's features which can be either programmable or automated include: voltage, current, or pulsed excitation, unlimited resolution gain, digital filtering and both analog and digital output. USCA will be used at Kennedy Space Center's launch pads for environmental measurements such as vibrations, strains, temperatures and overpressures. USCA is presently being commercialized through a co-funded agreement between NASA, the State of Florida, and Loral Test and Information Systems, Inc.

Larson, William E.; Hallberg, Carl; Medelius, Pedro J.

1994-01-01

339

Novel pH-sensitive charge-reversal cell penetrating peptide conjugated PEG-PLA micelles for docetaxel delivery: In vitro study.  

PubMed

In order to create a pH-sensitive charge-reversal system for cell penetrating peptides (CPP) to prevent non-specific internalization of the drug; and concomitantly enhance the physical stability and tumor targetability of poly(ethylene glycol)-poly(d,l-lactide) (PEG-PLA) micelles, two sets of novel PEG-PLA micelles were developed. Cell penetrating decapeptide arginine-glycine (RG)5 and a pH-sensitive masking decapeptide histidine-glutamic acid (HE)5 were conjugated at the PEG free end to produce pH sensitive with peptides outside micelles (PHPO), while the pH sensitive with peptides inside micelles (PHPI) are the micelles obtained with the two peptides conjugated to the free end of the PLA block. The polymers were successfully synthesized and characterized by (1)H NMR and GPC. The mixed micelles were prepared and characterized for their loading efficiency, particle size and zeta potential. The surface charge of PHPO was greatly affected by the pH of the solution and (RG)5:(HE)5 ratio at the surface. The pH value of the solution at which the surface charge of PHPO reversed could be manipulated by the feed ratio of (RG)5-PEG-PLA (RGO) and (HE)5-PEG-PLA (HEO), hence, HEO:RGO molar ratio of 45:55 was selected for tumor targeting. Docetaxel (DTX) was sufficiently solubilized by DTX-PHPO with a loading efficiency of 90.18±1.65%. At pH 7.4, DTX loaded mPEG-PLA (DTX-PM) (41.2±0.3nm), DTX-PHPO (195.3±1.9nm) and DTX-PHPI (190.9±4.5nm) showed sustained DTX release of less than 55% within 48h. However, at pH 6.8 DTX-PHPI released 87.29±0.24%, while DTX-PHPO released 70.49±0.39% of the initial DTX amount within 48h. Moreover, the physical stability of DTX-PHPO was increased due to the electrostatic interaction of the two peptides. The cellular uptake of DTX-PHPO in SGC-7901 cells and the cell killing effect tested on MCF-7 cells were enhanced by 2 folds at pH 6.8 compared to pH 7.4. Hence, DTX-PHPO is highly pH-sensitive in mildly acidic pH and exhibited higher internalization, but DTX-PHPI exhibited accelerated release. Meanwhile, both formulations displayed low internalization and release at pH greater than 7. This pH sensitive charge reversal design can offer a promising safe carrier using both CPPs and PEG-PLA micelles. PMID:24614579

Ouahab, Ammar; Cheraga, Nihad; Onoja, Vitus; Shen, Yan; Tu, Jiasheng

2014-05-15

340

Charge-carrier transport and photogeneration processes in pyronine (G) (PYR) sensitized-TiO 2 photovoltaic device  

Microsoft Academic Search

Steady-state current–voltage characteristics in dark and under illumination, along with impedance characteristics at different biasing voltages, were investigated on solid film of pyronine (PYR) sensitized-TiO2, sandwiched between ITO and Al electrodes. The J–V characteristics of the material in dark were explained by the formation of percolation network of nano particles between the electrodes. The device ITO\\/TiO2–PYR\\/Al device shows rectification below

G. D. Sharma; Shailendra Sharma; M. S. Roy

2004-01-01

341

Multipass amplifiers of POLARIS  

NASA Astrophysics Data System (ADS)

Advanced high intensity laser matter interaction experiments always call for optimized laser performance. In order to further enhance the POLARIS laser system, operational at the University of Jena and the Helmholtz-Institute Jena, in particular its energy, bandwidth and focusability, new amplifier technologies have been developed and are reported here. Additionally, existing sections were considerably improved. A new multi-pass amplification stage, which is able to replace two currently used ones, was developed in close collaboration with the MPQ (Garching). The new basic elements of this amplifier are well homogenized pump modules and the application of a successive imaging principle. By operating the amplifier under vacuum conditions a top hat beam profile with an output energy of up to 1.5 J per pulse is foreseen. The already implemented POLARIS amplifier A4 was further improved by adapting an advanced method for the homogenization of the multi-spot composed pump profile. The new method comprises a computer-based evolutionary algorithm which optimizes the position of the different spots regarding its individual size, shape and intensity. The latter allowed a better homogenization of the POLARIS near field profile.

Keppler, S.; Wandt, C.; Hornung, M.; Bödefeld, R.; Kessler, A.; Sävert, A.; Hellwing, M.; Schorcht, F.; Hein, J.; Kaluza, M. C.

2013-05-01

342

Fourier plane image amplifier  

DOEpatents

A solid state laser is frequency tripled to 0.3 {micro}m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only about 1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power. 1 fig.

Hackel, L.A.; Hermann, M.R.; Dane, C.B.; Tiszauer, D.H.

1995-12-12

343

Fourier plane image amplifier  

DOEpatents

A solid state laser is frequency tripled to 0.3 .mu.m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only .about.1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power.

Hackel, Lloyd A. (Livermore, CA); Hermann, Mark R. (San Ramon, CA); Dane, C. Brent (Livermore, CA); Tiszauer, Detlev H. (Tracy, CA)

1995-01-01

344

Novel sulfur-doped niobium pentoxide nanoparticles: fabrication, characterization, visible light sensitization and redox charge transfer study  

Microsoft Academic Search

Novel sulfur-modified niobium(V) oxide nanoparticles (SNON) that firstly exhibited good visible light sensitization were fabricated\\u000a by a modified sol–gel technique using a very stable sol containing niobium(V) chloride, oxalic acid, isopropanol as chelating\\u000a agent and thiourea as sulfur source. The resulting S-doped Nb2O5 nanomaterials were characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy\\u000a (EDAX), scanning electron microscope

Mohammad Hossein Habibi; Reza Mokhtari

345

Highly sensitive and positively charged precolumn derivatization reagent for amines and amino acids in liquid chromatography/electrospray ionization tandem mass spectrometry.  

PubMed

We have developed a highly sensitive and positively charged precolumn derivatization reagent, (5-N-succinimidoxy-5-oxopentyl)triphenylphosphonium bromide (SPTPP), for amines and amino acids in liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). The handling of the derivatization reaction is quite simple and the reagent reacts with the analytes rapidly and with high efficiency. The derivatized analytes were observed to form regular and intense product ions upon MS/MS analysis; thus, highly sensitive and selective detection was possible in the selected reaction monitoring (SRM) mode. The limits of detection of the SPTPP-derivatized analytes were less than sub-femtomole levels. The sensitivities of the derivatized analytes increased about 500-fold compared to those of underivatized analytes. Since the hydrophobicities of the samples increased after their derivatization, the resolution of the analytes improved dramatically when a reversed-phase system was used. The relative standard deviations of intra-day and inter-day variations were below 10.6% and 13.3%, respectively. The accuracy ranged between 86.6-113% and 83.4-113%, respectively. Furthermore, the developed reagent was used for the analysis of the neurotransmitter 4-aminobutanoic acid (GABA) and oxidative stress markers such as oxidized, nitrated, and halogenated tyrosines in rat serum. PMID:20391609

Inagaki, Shinsuke; Tano, Yuma; Yamakata, Yusuke; Higashi, Tatsuya; Min, Jun Zhe; Toyo'oka, Toshimasa

2010-05-15

346

Beam propagation in direct nuclear pumped laser amplifiers  

NASA Astrophysics Data System (ADS)

Thermal distortions in transverse flow, direct nuclear pumped laser amplifiers and the resulting effect on beam propagation is investigated. Nuclear pumping occurs from surfaces, either from plates parallel to the flow direction, from screens or porous material perpendicular to the flow direction, or from the combination of the two. The analysis presented is topically divided into the analysis of the energy deposition of the energetic charged particles in the amplifying media and the analysis of the beam propagation in the amplifier and to the far field. The spatially varying energy deposition produces large index of refraction variations in the nuclear pumped amplifier. These variations are modeled by a Zernike polynomial expansion and their effect on the propagation of a uniform intensity plane wave is discussed. For purposes of illustration, an amplifier with a 1 m gain length and a 1 atm (101 kPa) argon gas flowing at 100 m/s is presented. With approximately 150 W/cu cm average charged particle pumping in the amplifier the beam qualities range from 7 to 27 times diffraction limited when the primary (tilt and focus) aberrations in the amplifier are corrected.

Neuman, W. A.; Fincke, J. R.; Lassahn, G. D.; Montierth, L. M.

347

Study of the sensitivity of neutron sensors consisting of a converter plus Si charged-particle detector  

NASA Astrophysics Data System (ADS)

With the aim of improving neutron sensors for monitoring external neutron exposure, we have analysed the workings of a converter plus silicon PIN diode detector arrangement. A phenomenological analysis of the conversion and signal generation of different converter materials and their effectiveness is given. The results are compared with experimental measurements. Because of the fundamentally different interactions of thermal neutrons versus high energy neutrons, we study the two species separately. For thermal neutrons, two types of neutron converters were examined, 6LiF (crystalline) and Kodak 10B films. For fast neutrons in the energy range from 1 to 20 MeV hydrogen rich Lucite—PMMA (H 8C 5O 2) and Polyethylene—PE (CH 2) converters were studied. For thermal neutrons and a pure 10B-converter the theoretical response in counts/neutron reaches a value of BS TOT=0.0684 and for a pure 6LiF-converter LiFS TOT=0.0543 . The corresponding experimental responses are 0.0062 for KODAK 10B film and 0.0223 for 6LiF converters. The difference between theory and experiment is understood by the necessity to use a lower level discriminator to eliminate unwanted counts coming from electrons and gammas. In the case of the 10B converter impurities in the converter material reduce the signal. Our analysis for fast neutrons allows us to calculate the ratio of sensitivity for Polyethylene to Lucite, for which we predict a value of 1.6. For the measured sensitivities for PE and PMMA, using an 241Am-Be neutron source, we obtain the values of 0.00225 and 0.0015 respectively, the ratio being 1.5.

Wielunski, M.; Schütz, R.; Fantuzzi, E.; Pagnamenta, A.; Wahl, W.; Palfįlvi, J.; Zombori, P.; Andrasi, A.; Stadtmann, H.; Schmitzer, Ch.

2004-01-01

348

Fractional charge search  

SciTech Connect

A device to search for fractional charge in matter is described. The sample is coupled to a low-noise amplifier by a periodically varying capacitor and the resulting signal is synchronously detected. The varying capacitor is constructed as a rapidly spinning wheel. Samples of any material in volumes of up to 0.05 ml may be searched in less than an hour.

Innes, W.; Klein, S.; Perl, M.; Price, J.C.

1982-06-01

349

Total Temperature Probe Buffer Amplifier.  

National Technical Information Service (NTIS)

The elimination of undesirable thermally induced changes of electrical characteristics of signal components is accomplished three operational amplifier circuits. The first operational amplifier provides electrical power to a system critical component and ...

W. E. Ott

1984-01-01

350

IonCCD™ for Direct Position-Sensitive Charged-Particle Detection: from Electrons and keV Ions to Hyperthermal Biomolecular Ions  

NASA Astrophysics Data System (ADS)

A novel, low-cost, pixel-based detector array (described elsewhere Sinha and Wadsworth (76(2), 1) is examined using different charged particles, from electrons to hyperthermal (<100 eV) large biomolecular positive and negative ions, including keV small atomic and molecular ions. With this in mind, it is used in instrumentation design (beam profiling), mass spectrometry, and electron spectroscopy. The array detector is a modified light-sensitive charge-coupled device (CCD) that was engineered for direct charged-particle detection by replacing the semiconductor part of the CCD pixel with a conductor Sinha and Wadsworth (76(2), 1). The device is referred to as the IonCCD. For the first time, we show the direct detection of 250-eV electrons, providing linearity response of the IonCCD to the electron beam current. We demonstrate that the IonCCD detection efficiency is virtually independent from the particle energy (250 eV, 1250 eV), impact angle (45o, 90o) and flux. By combining the IonCCD with a double-focusing sector field mass spectrometer (MS) of Mattauch-Herzog geometry (MH-MS), we demonstrate fast data acquisition. Detection of hyperthermal biomolecular ions produced using an electrospray ionization source (ESI) is also presented. In addition, the IonCCD was used as a beam profiler to characterize the beam shape and intensity of 15 eV protonated and deprotonated biomolecular ions at the exit of an rf-only collisional quadrupole. This demonstrates an ion-beam profiling application for instrument design. Finally, we present simultaneous detection of 140 eV doubly protonated biomolecular ions when the IonCCD is combined with the MH-MS. This demonstrates the possibility of simultaneous separation and micro-array deposition of biological material using a miniature MH-MS.

Hadjar, Omar; Johnson, Grant; Laskin, Julia; Kibelka, Gottfried; Shill, Scott; Kuhn, Ken; Cameron, Chad; Kassan, Scott

2011-04-01

351

Highly efficient ZnO/Au Schottky barrier dye-sensitized solar cells: Role of gold nanoparticles on the charge-transfer process  

PubMed Central

Summary Zinc oxide (ZnO) nanorods decorated with gold (Au) nanoparticles have been synthesized and used to fabricate dye-sensitized solar cells (DSSC). The picosecond-resolved, time-correlated single-photon-count (TCSPC) spectroscopy technique was used to explore the charge-transfer mechanism in the ZnO/Au-nanocomposite DSSC. Due to the formation of the Schottky barrier at the ZnO/Au interface and the higher optical absorptions of the ZnO/Au photoelectrodes arising from the surface plasmon absorption of the Au nanoparticles, enhanced power-conversion efficiency (PCE) of 6.49% for small-area (0.1 cm2) ZnO/Au-nanocomposite DSSC was achieved compared to the 5.34% efficiency of the bare ZnO nanorod DSSC. The TCSPC studies revealed similar dynamics for the charge transfer from dye molecules to ZnO both in the presence and absence of Au nanoparticles. A slower fluorescence decay associated with the electron recombination process, observed in the presence of Au nanoparticles, confirmed the blocking of the electron transfer from ZnO back to the dye or electrolyte by the Schottky barrier formed at the ZnO/Au interface. For large area DSSC (1 cm2), ~130% enhancement in PCE (from 0.50% to 1.16%) was achieved after incorporation of the Au nanoparticles into the ZnO nanorods.

Bora, Tanujjal; Kyaw, Htet H; Sarkar, Soumik; Pal, Samir K

2011-01-01

352

Ab initio Simulations of charge transfer properties at Quantum Dot/TiO2 Interface in Quantum Dot-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

Quantum dot-sensitized solar cells (QDSSCs) have emerged as a very promising solar architecture for next generation photovoltaics. The QDSSCs exhibit a remarkably fast electron transfer from the quantum dot (QD) donor to the TiO2 acceptor with size quantization properties that allows for the modulation of QD band gaps to control the photoresponse and photoconversion efficiency of QDSSCs. To understand the mechanisms that underpin this rapid charge transfer, the electronic properties of CdSe and PbSe QDs on the TiO2 substrate were simulated using a rigorous ab initio method. In contrast to the plane wave approaches, this method capitalized on localized orbital basis set that is computationally less intensive, and provides excellent electronic structure of the constituent systems. We consider QDs grown on TiO{2 }without functional ligands passivating the QD surface. We find a remarkable set of electron bridging states between QDs and TiO2 occurring via the strong bonding between the conduction bands of QDs and TiO2. Such bridging states account for the fast adiabatic charge transfer from the QD donor to the TiO2 acceptor, and may be a general feature for other strongly coupled donor/acceptor systems and nanostructured semiconductor interfaces.

Xin, Xukai; Biswas, Rana; Lin, Zhiqun

2013-03-01

353

Molecular engineering of simple phenothiazine-based dyes to modulate dye aggregation, charge recombination, and dye regeneration in highly efficient dye-sensitized solar cells.  

PubMed

A series of simple phenothiazine-based dyes, namely, TP, EP, TTP, ETP, and EEP have been developed, in which the thiophene (T), ethylenedioxythiophene (E), their dimers, and mixtures are present to modulate dye aggregation, charge recombination, and dye regeneration for highly efficient dye-sensitized solar cell (DSSC) applications. Devices sensitized by the dyes TP and TTP display high power conversion efficiencies (PCEs) of 8.07 (Jsc =15.2?mA?cm(-2) , Voc =0.783?V, fill factor (FF)=0.679) and 7.87?% (Jsc =16.1?mA?cm(-2) , Voc =0.717?V, FF=0.681), respectively; these were measured under simulated AM 1.5 sunlight in conjunction with the I(-) /I3 (-) redox couple. By replacing the T group with the E unit, EP-based DSSCs had a slightly lower PCE of 7.98?% with a higher short-circuit photocurrent (Jsc ) of 16.7?mA?cm(-2) . The dye ETP, with a mixture of E and T, had an even lower PCE of 5.62?%. Specifically, the cell based on the dye EEP, with a dimer of E, had inferior Jsc and Voc values and corresponded to the lowest PCE of 2.24?%. The results indicate that the photovoltaic performance can be finely modulated through structural engineering of the dyes. The selection of T analogues as donors can not only modulate light absorption and energy levels, but also have an impact on dye aggregation and interfacial charge recombination of electrons at the interface of titania, electrolytes, and/or oxidized dye molecules; this was demonstrated through DFT calculations, electrochemical impedance analysis, and transient photovoltage studies. PMID:24715494

Hua, Yong; Chang, Shuai; He, Jian; Zhang, Caishun; Zhao, Jianzhang; Chen, Tao; Wong, Wai-Yeung; Wong, Wai-Kwok; Zhu, Xunjin

2014-05-19

354

Proton-induced damage in JFET transistors and charge preamplifiers on high-resistivity silicon  

Microsoft Academic Search

The results discussed in this paper are relevant to junction field effect transistors (JFETs) and JFET-based charge sensitive amplifiers fabricated in a detector compatible process. Such structures were irradiated with 27 MeV protons to evaluate the suitability of the technology for space applications and high-energy physics experiments from the standpoint of radiation tolerance. The process investigated in this work, originally

G. F. D. Betta; Massimo Manghisoni; Lodovico Ratti; Valerio Re; Valeria Speziali; Gianluca Traversi; Andrea Candelori

2004-01-01

355

Amplifying genetic logic gates.  

PubMed

Organisms must process information encoded via developmental and environmental signals to survive and reproduce. Researchers have also engineered synthetic genetic logic to realize simpler, independent control of biological processes. We developed a three-terminal device architecture, termed the transcriptor, that uses bacteriophage serine integrases to control the flow of RNA polymerase along DNA. Integrase-mediated inversion or deletion of DNA encoding transcription terminators or a promoter modulates transcription rates. We realized permanent amplifying AND, NAND, OR, XOR, NOR, and XNOR gates actuated across common control signal ranges and sequential logic supporting autonomous cell-cell communication of DNA encoding distinct logic-gate states. The single-layer digital logic architecture developed here enables engineering of amplifying logic gates to control transcription rates within and across diverse organisms. PMID:23539178

Bonnet, Jerome; Yin, Peter; Ortiz, Monica E; Subsoontorn, Pakpoom; Endy, Drew

2013-05-01

356

Monolithic dye laser amplifier  

DOEpatents

A fluid dye laser amplifier for amplifying a dye beam by pump beams has a channel structure defining a channel through which a laseable fluid flows and the dye and pump beams pass transversely to one another through a lasing region. The channel structure is formed with two pairs of mutually spaced-apart and mutually confronting glass windows, which are interlocked and make surface-contacts with one another and surround the lasing region. One of the glass window pairs passes the dye beam and the other passes the pump beams therethrough and through the lasing region. Where these glass window pieces make surface-contacts, glue is used to join the pieces together to form a monolithic structure so as to prevent the dye in the fluid passing through the channel from entering the space between the mutually contacting glass window pieces.

Kuklo, T.C.

1993-03-30

357

Monolithic dye laser amplifier  

DOEpatents

A fluid dye laser amplifier for amplifying a dye beam by pump beams has a channel structure defining a channel through which a laseable fluid flows and the dye and pump beams pass transversely to one another through a lasing region. The channel structure is formed with two pairs of mutually spaced-apart and mutually confronting glass windows, which are interlocked and make surface-contacts with one another and surround the lasing region. One of the glass window pairs passes the dye beam and the other passes the pump beams therethrough and through the lasing region. Where these glass window pieces make surface-contacts, glue is used to join the pieces together to form a monolithic structure so as to prevent the dye in the fluid passing through the channel from entering the space between the mutually contacting glass window pieces.

Kuklo, Thomas C. (Ripon, CA)

1993-01-01

358

Helical Fiber Amplifier  

SciTech Connect

A multi-mode gain fiber is provided which affords substantial improvements in the maximum pulse energy, peak power handling capabilities, average output power, and/or pumping efficiency of fiber amplifier and laser sources while maintaining good beam quality (comparable to that of a conventional single-mode fiber source). These benefits are realized by coiling the multimode gain fiber to induce significant bend loss for all but the lowest-order mode(s).

Koplow, Jeffrey P. (Washington, DC); Kliner, Dahy (San Ramon, CA); Goldberg, Lew (Fairfax, VA)

2002-12-17

359

HEMT 60 GHz amplifier  

NASA Technical Reports Server (NTRS)

A high electron mobility transistor (HEMT) amplifier has been fabricated which exhibits 7.5 dB gain at 61 GHz. This result was obtained with a quarter-micrometre gate-length depletion-mode HEMT. Reduction of source-gate resistance and gate length are primarily responsible for this performance. The letter describes the materials and device processing technology developed for fabricating these devices.

Berenz, J.; Nakano, K.; Hsu, T.-I.; Goel, J.

1985-01-01

360

Saturated Operational Amplifier  

NSDL National Science Digital Library

This animated gif illustrates the changing voltages when an operational amplifier (op-amp) becomes saturated. This animation would be useful for visually respresenting Finley's law. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations.Other 3-D Circuit Animations can be seen here.

2009-11-27

361

Gas amplified ionization detector for gas chromatography  

DOEpatents

A gas-amplified ionization detector for gas chromatrography which possesses increased sensitivity and a very fast response time. Solutes eluding from a gas chromatographic column are ionized by UV photoionization of matter eluting therefrom. The detector is capable of generating easily measured voltage signals by gas amplification/multiplication of electron products resulting from the UV photoionization of at least a portion of each solute passing through the detector.

Huston, Gregg C. (LaBelle, PA)

1992-01-01

362

CMOS low-noise switched charge sensitive preamplifier for CdTe and CdZnTe X-ray detectors  

SciTech Connect

CdTe and CdZnTe X-ray detector arrays for imaging and spectroscopy provide low capacitance current sources with low leakage currents. The optimal shaping time for low-noise operation is relatively high in CMOS analog channels that provide the readout for these detectors. The shaper is centered at lower frequencies, and thus the l/f noise from the electronics is the main noise source that limits the resolution of the channel. The optimal dimensions of the input stage MOSFET are determined by this noise. In this paper a design criterion for the optimization of the resolution and the power consumption in a l/f noise dominated readout is introduced. A readout based on CMOS switched charge sensitive preamplifier without feedback resistor has been designed and fabricated in the CMOS 2-{mu} low-noise analog process provided by MOSIS. This design provides high sensitivity and the possibility to integrate a large number of channels with low power consumption. Measurements of the performance of a first prototype chip are presented.

Jakobson, C.G.; Nemirovsky, Y. [Technion-Israel Inst. of Tech., Haifa (Israel)] [Technion-Israel Inst. of Tech., Haifa (Israel)

1997-02-01

363

Time-domain ab initio study of charge relaxation and recombination in dye-sensitized TiO2.  

PubMed

In order to investigate the electron dynamics at the alizarin/I2-/TiO2 interface this study uses a novel state-of-the-art quantum-classical approach that combines time-dependent density functional theory with surface hopping in the Kohn-Sham basis. Representing the dye-sensitized semiconductor Grätzel cell with the I-/I3- mediator, the system addresses the problems of an organic/inorganic, molecule/bulk interface that are commonly encountered in molecular electronics, photovoltaics, and photoelectrochemistry. The processes studied include the relaxation of the injected electron inside the TiO2 conduction band (CB), the back electron transfer (ET) from TiO2 to alizarin, the ET from the surface to the electrolyte, and the regeneration of the neutral chromophore by ET from the electrolyte to alizarin. Developing a theoretical understanding of these processes is crucial for improving solar cell design and optimizing photovoltaic current and voltage. The simulations carried out for the entire system that contains many electronic states reproduce the experimental time scales and provide detailed insights into the ET dynamics. In particular, they demonstrate the differences between the optimized geometric and electronic structure of the system at 0 K and the experimentally relevant structure at ambient temperature. The relaxation of the injected electron inside the TiO2 CB, which affects the solar cell voltage, is shown to occur on a 100 fs time scale and occurs simultaneously with the electron delocalization into the semiconductor bulk. The transfer of the electron trapped at the surface to the ground state of alizarin proceeds on a 1 ps time scale and is facilitated by vibrational modes localized on alizarin. If the electrolyte mediator is capable of approaching the semiconductor surface, it can form a stable complex and short-circuit the cell by accepting the photoexcited electron on a subpicosecond time scale. The ET from TiO2 to both alizarin and the electrolyte diminishes the solar cell current. Finally, the simulations show that the electrolyte can efficiently regenerate the neutral chromophore. This is true even though the two species do not form a chemical bond and, therefore, the electronic coupling between them is weaker than in the TiO2-chromophore and TiO2-electrolyte donor-acceptor pairs. The chromophore-electrolyte coupling can occur both directly through space and indirectly through bonding to the semiconductor surface. The ET events involving the electrolyte are promoted primarily by the electrolyte vibrational modes. PMID:17579405

Duncan, Walter R; Craig, Colleen F; Prezhdo, Oleg V

2007-07-11

364

Implementation of a preamplifier-amplifier system for radiation detectors used in Mössbauer spectroscopy  

NASA Astrophysics Data System (ADS)

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.

Velįsquez, A. A.; Arroyave, M.

2014-01-01

365

Effective amplifier noise for an optical receiver based on linear mode avalanche photodiodes  

NASA Technical Reports Server (NTRS)

The rms noise charge induced by the amplifier for an optical receiver based on the linear-mode avalanche photodiode (APD) was analyzed. It is shown that for an amplifier with a 1-pF capacitor and a noise temperature of 100 K, the rms noise charge due to the amplifier is about 300. Since the noise charge must be small compared to the signal gain, APD gains on the order of 1000 will be required to operate the receiver in the linear mode.

Chen, C.-C.

1989-01-01

366

Method and apparatus for providing pulse pile-up correction in charge quantizing radiation detection systems  

DOEpatents

A radiation detection method and system for continuously correcting the quantization of detected charge during pulse pile-up conditions. Charge pulses from a radiation detector responsive to the energy of detected radiation events are converted to voltage pulses of predetermined shape whose peak amplitudes are proportional to the quantity of charge of each corresponding detected event by means of a charge-sensitive preamplifier. These peak amplitudes are sampled and stored sequentially in accordance with their respective times of occurrence. Based on the stored peak amplitudes and times of occurrence, a correction factor is generated which represents the fraction of a previous pulses influence on a preceding pulse peak amplitude. This correction factor is subtracted from the following pulse amplitude in a summing amplifier whose output then represents the corrected charge quantity measurement.

Britton, Jr., Charles L. (Alcoa, TN); Wintenberg, Alan L. (Knoxville, TN)

1993-01-01

367

Ways to suppress click and pop for class D amplifiers  

NASA Astrophysics Data System (ADS)

Undesirable audio click and pop may be generated in a speaker or headphone. Compared to linear (class A/B/AB) amplifiers, class D amplifiers that comprise of an input stage and a modulation stage are more prone to producing click and pop. This article analyzes sources that generate click and pop in class D amplifiers, and corresponding ways to suppress them. For a class D amplifier with a single-ended input, click and pop is likely to be due to two factors. One is from a voltage difference (VDIF) between the voltage of an input capacitance (VCIN) and a reference voltage (VREF) of the input stage, and the other one is from the non-linear switching during the setting up of the bias and feedback voltages/currents (BFVC) of the modulation stage. In this article, a fast charging loop is introduced into the input stage to charge VCIN to roughly near VREF. Then a correction loop further charges or discharges VCIN, substantially equalizing it with VREF. Dummy switches are introduced into the modulation stage to provide switching signals for setting up BFVC, and the power switches are disabled until the BFVC are set up successfully. A two channel single-ended class D amplifier with the above features is fabricated with 0.5 ?m Bi-CMOS process. Road test and fast Fourier transform analysis indicate that there is no noticeable click and pop.

Haishi, Wang; Bo, Zhang; Jiang, Sun

2012-08-01

368

Amplifying Electrochemical Indicators  

NASA Technical Reports Server (NTRS)

Dendrimeric reporter compounds have been invented for use in sensing and amplifying electrochemical signals from molecular recognition events that involve many chemical and biological entities. These reporter compounds can be formulated to target specific molecules or molecular recognition events. They can also be formulated to be, variously, hydrophilic or amphiphilic so that they are suitable for use at interfaces between (1) aqueous solutions and (2) electrodes connected to external signal-processing electronic circuits. The invention of these reporter compounds is expected to enable the development of highly miniaturized, low-power-consumption, relatively inexpensive, mass-producible sensor units for diverse applications.

Fan, Wenhong; Li, Jun; Han, Jie

2004-01-01

369

Nanoclay gelation approach toward improved dye-sensitized solar cell efficiencies: an investigation of charge transport and shift in the TiO2 conduction band.  

PubMed

Nanoclay minerals play a promising role as additives in the liquid electrolyte to form a gel electrolyte for quasi-solid-state dye-sensitized solar cells, because of the high chemical stability, unique swelling capability, ion exchange capacity, and rheological properties of nanoclays. Here, we report the improved performance of a quasi-solid-state gel electrolyte that is made from a liquid electrolyte and synthetic nitrate-hydrotalcite nanoclay. Charge transport mechanisms in the gel electrolyte and nanoclay interactions with TiO(2)/electrolyte interface are discussed in detail. The electrochemical analysis reveals that the charge transport is solely based on physical diffusion at the ratio of [PMII]:[I(2)] = 10:1 (where PMII is 1-propyl-3-methylimidazolium iodide). The calculated physical diffusion coefficient shows that the diffusion of redox ions is not affected much by the viscosity of nanoclay gel. The addition of nitrate-hydrotalcite clay in the electrolyte has the effect of buffering the protonation process at the TiO(2)/electrolyte interface, resulting in an upward shift in the conduction band and a boost in open-circuit voltage (V(OC)). Higher V(OC) values with undiminished photocurrent is achieved with nitrate-hydrotalcite nanoclay gel electrolyte for organic as well as for inorganic dye (D35 and N719) systems. The efficiency for hydrotalcite clay gel electrolyte solar cells is increased by 10%, compared to that of the liquid electrolyte. The power conversion efficiency can reach 10.1% under 0.25 sun and 9.6% under full sun. This study demonstrates that nitrate-hydrotalcite nanoclay in the electrolyte not only solidifies the liquid electrolyte to prevent solvent leakage, but also facilitates the improvement in cell efficiency. PMID:23252392

Wang, Xiu; Kulkarni, Sneha A; Ito, Bruno Ieiri; Batabyal, Sudip K; Nonomura, Kazuteru; Wong, Chee Cheong; Grätzel, Michael; Mhaisalkar, Subodh G; Uchida, Satoshi

2013-01-23

370

3-D TiO2 nanoparticle/ITO nanowire nanocomposite antenna for efficient charge collection in solid state dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposites for use as photoelectrode materials were fabricated to improve the charge collection efficiency in solid state dye sensitized solar cells (ss-DSSCs). The average current density for ss-DSSCs containing TiO2 NP/ITO NW arrays was 7.2 mA cm-2 that was 98% higher than that for the conventional TiO2 NP ss-DSSCs. The intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) studies exhibited that the electron diffusion length of TiO2 NP/ITO-NW nanocomposite ss-DSSCs was in the range of 4.3-5.6 ?m, longer than that of TiO2 NP solar cells (2.6-4.1 ?m). The longer diffusion length was responsible for the boosted current densities of TiO2 NP/ITO NW nanocomposite ss-DSSCs. We also employed the TiO2 NP/ITO NW nanocomposite photoelectrode to inorganic-organic perovskite solar cells whose energy conversion efficiency was 7.5%.TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposites for use as photoelectrode materials were fabricated to improve the charge collection efficiency in solid state dye sensitized solar cells (ss-DSSCs). The average current density for ss-DSSCs containing TiO2 NP/ITO NW arrays was 7.2 mA cm-2 that was 98% higher than that for the conventional TiO2 NP ss-DSSCs. The intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) studies exhibited that the electron diffusion length of TiO2 NP/ITO-NW nanocomposite ss-DSSCs was in the range of 4.3-5.6 ?m, longer than that of TiO2 NP solar cells (2.6-4.1 ?m). The longer diffusion length was responsible for the boosted current densities of TiO2 NP/ITO NW nanocomposite ss-DSSCs. We also employed the TiO2 NP/ITO NW nanocomposite photoelectrode to inorganic-organic perovskite solar cells whose energy conversion efficiency was 7.5%. Electronic supplementary information (ESI) available: SEM images of a 3-D TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposite photoelectrode, photovoltaic properties, J-V curves for the best performance cells, and the plot of dye loading vs. active layer thickness. See DOI: 10.1039/c4nr00621f

Han, Gill Sang; Lee, Sangwook; Noh, Jun Hong; Chung, Hyun Suk; Park, Jong Hoon; Swain, Bhabani Sankar; Im, Jeong-Hyeok; Park, Nam-Gyu; Jung, Hyun Suk

2014-05-01

371

DIAMOND AMPLIFIED PHOTOCATHODES.  

SciTech Connect

High-average-current linear electron accelerators require photoinjectors capable of delivering tens to hundreds of mA average current, with peak currents of hundreds of amps. Standard photocathodes face significant challenges in meeting these requirements, and often have short operational lifetimes in an accelerator environment. We report on recent progress toward development of secondary emission amplifiers for photocathodes, which are intended to increase the achievable average current while protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic (few keV) primary electrons into hundreds of electron-hole pairs via secondary electron emission. The electrons drift through the diamond under an external bias and are emitted into vacuum via a hydrogen-terminated surface with negative electron affinity (NEA). Secondary emission gain of over 200 has been achieved. Two methods of patterning diamond, laser ablation and reactive-ion etching (RIE), are being developed to produce the required geometry. A variety of diagnostic techniques, including FTIR, SEM and AFM, have been used to characterize the diamonds.

SMEDLEY,J.; BEN-ZVI, I.; BOHON, J.; CHANG, X.; GROVER, R.; ISAKOVIC, A.; RAO, T.; WU, Q.

2007-11-26

372

Universal Signal Conditioning Amplifier  

NASA Technical Reports Server (NTRS)

The Technological Research and Development Authority (TRDA) and NASA-KSC entered into a cooperative agreement in March of 1994 to achieve the utilization and commercialization of a technology development for benefiting both the Space Program and U.S. industry on a "dual-use basis". The technology involved in this transfer is a new, unique Universal Conditioning Amplifier (USCA) used in connection with various types of transducers. The project was initiated in partnership with I-Net Corporation, Lockheed Martin Telemetry & Instrumentation (formerly Loral Test and Information Systems) and Brevard Community College. The project consists of designing, miniaturizing, manufacturing, and testing an existing prototype of USCA that was developed for NASA-KSC by the I-Net Corporation. The USCA is a rugged and field-installable self (or remotely)- programmable amplifier that works in combination with a tag random access memory (RAM) attached to various types of transducers. This summary report comprises performance evaluations, TRDA partnership tasks, a project summary, project milestones and results.

Kinney, Frank

1997-01-01

373

Zero-Net-Charge Air Ionizer  

NASA Technical Reports Server (NTRS)

Instrument monitors air supplied by air ionizer and regulates ionizer to ensure net charge neutral. High-impedance electrometer and nulling control amplifier regulate output of air ionizer. Primarily intended to furnish ionized air having no net charge, instrument adaptable to generating air with positive or negative net charge is so desired. Useful where integrated circuit chips are manufactured, inspected, tested or assembled.

Woods, W. R., Jr.

1985-01-01

374

SQUID linear amplifier circuit simulations  

SciTech Connect

This paper presents numerical simulations of a single stage of a linear SQUID amplifier. The amplifier stage is fabricated in thin film technology, and consists of two asymmetric SQUIDs placed in the push-pull configuration. It was found that the Q of the tank circuit formed by SQUID inductance and a parasitic strip-line capacitance must be reduced to unity to avoid hysteretic operation. A load line analysis has determined the amplifier operating point and SQUID inductance which yield optimum linearity.

Gershenson, M.; Hastings, R.; Schneider, R.; Sorensen, E.; Sweeny, M.

1983-09-01

375

Dynamical theory of polariton amplifiers.  

PubMed

We present the theory of the dynamics of the polariton amplifier in the region of small polariton densities. We give an analytical solution for the polariton condensate density matrix and show that the formation of a coherent quantum state is possible. Once the condensate is formed, the coherence becomes macroscopically long living. Polariton amplifier represents, therefore, an optical memory element, where the input weak coherent signal can be amplified and kept. PMID:14611482

Rubo, Yuri G; Laussy, F P; Malpuech, G; Kavokin, A; Bigenwald, P

2003-10-10

376

A sensitive and selective fluorescent probe for cysteine based on a new response-assisted electrostatic attraction strategy: the role of spatial charge configuration.  

PubMed

A new strategy for fast fluorescent detection of cysteine (Cys), based on a response-assisted electrostatic attraction, is demonstrated. By utilizing this strategy, we designed and synthesized three fluorescent probes for the specific detection of Cys under actual physiological conditions. The probe m-CP, a coumarin fluorophore conjugated with a substituted methyl pyridinium group through an unsaturated ketone unit, showed highly selective and sensitive detection for cysteine (Cys) over homocysteine (Hcy) and glutathione (GSH). The kinetic analysis indicated that the sensing process was highly accelerated (a response time less than 1?min) by the response-assisted electrostatic attraction. More importantly, control experiments with isomeric probes first demonstrated that the spatial charge configuration of the probe played an important role in Cys-preferred selectivity and kinetic rate acceleration. Furthermore, the practical utility of the probe m-CP in the fluorescent labeling of Cys residues within proteins was demonstrated. Finally, these probes were employed in living cell imaging with HeLa cells, in which it displayed satisfactory cell permeability and enabled us to distinguish active thiols in the cytoplasm, nucleus, and mitochondria. PMID:23595979

Zhou, Xin; Jin, Xuejun; Sun, Guangyan; Wu, Xue

2013-06-10

377

3-D TiO2 nanoparticle/ITO nanowire nanocomposite antenna for efficient charge collection in solid state dye-sensitized solar cells.  

PubMed

TiO2 nanoparticle (NP)/ITO nanowire (NW) nanocomposites for use as photoelectrode materials were fabricated to improve the charge collection efficiency in solid state dye sensitized solar cells (ss-DSSCs). The average current density for ss-DSSCs containing TiO2 NP/ITO NW arrays was 7.2 mA cm(-2) that was 98% higher than that for the conventional TiO2 NP ss-DSSCs. The intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) studies exhibited that the electron diffusion length of TiO2 NP/ITO-NW nanocomposite ss-DSSCs was in the range of 4.3-5.6 ?m, longer than that of TiO2 NP solar cells (2.6-4.1 ?m). The longer diffusion length was responsible for the boosted current densities of TiO2 NP/ITO NW nanocomposite ss-DSSCs. We also employed the TiO2 NP/ITO NW nanocomposite photoelectrode to inorganic-organic perovskite solar cells whose energy conversion efficiency was 7.5%. PMID:24788946

Han, Gill Sang; Lee, Sangwook; Noh, Jun Hong; Chung, Hyun Suk; Park, Jong Hoon; Swain, Bhabani Sankar; Im, Jeong-Hyeok; Park, Nam-Gyu; Jung, Hyun Suk

2014-06-01

378

TiO2 Nanorods: A Facile Size- and Shape-Tunable Synthesis and Effective Improvement of Charge Collection Kinetics for Dye-Sensitized Solar Cells.  

PubMed

In this paper, we present a novel, high-yield, and cost-effective hydrothermal method for the preparation of single crystal-like anatase TiO2 nanorods (NRs) with specific {101} exposed crystal planes and preferred [001] growth direction, which is governed by the "oriented attachment" mechanism. The successful synthesis of TiO2 NRs and fine tuning on their size and shape could be easily accomplished by adjusting the solvent compositions. The salient feature of these NRs, in lieu of traditional nanoparticles as building blocks of photoanodes in dye-sensitized solar cell (DSSC) system, rests with their significantly reduced grain boundaries. The electron diffusion and recombination kinetics have been critically compared for the first time with respect to the size and shape of the novel building blocks. A high efficiency of 8.87% has finally been achieved for DSSC based on long-thin NRs rather than short-thin or long-thick NRs, which possesses balanced optimizations on charge collection and light-harvesting properties. PMID:24833257

Zhang, Wenjun; Xie, Yan; Xiong, Dehua; Zeng, Xianwei; Li, Zhihong; Wang, Mingkui; Cheng, Yi-Bing; Chen, Wei; Yan, Keyou; Yang, Shihe

2014-06-25

379

Optical amplifier for space applications.  

PubMed

We describe an optical amplifier designed to amplify a spatially sampled component of an optical wavefront to kilowatt average power. The goal is means for implementing a strategy of spatially segmenting a large aperture wavefront, amplifying the individual segments, maintaining the phase coherence of the segments by active means, and imaging the resultant amplified coherent field. Applications of interest are the transmission of space solar power over multi-megameter distances, as to distant spacecraft, or to remote sites with no preexisting power grid. PMID:19401734

Fork, R L; Cole, S; Diffey, W; Gamble, L; Keys, A

1999-12-01

380

Reflex ring laser amplifier system  

SciTech Connect

A laser pulse is injected into an unstable ring resonator-amplifier structure. Inside this resonator the laser pulse is amplified, spatially filtered and magnified. The laser pulse is recirculated in the resonator, being amplified, filtered and magnified on each pass. The magnification is chosen so that the beam passes through the amplifier in concentric non-overlapping regions similar to a single pass MOPA. After a number of passes around the ring resonator the laser pulse is spatially large enough to exit the ring resonator system by passing around an output mirror.

Summers, M.A.

1985-10-22

381

Optical Amplifier for Space Applications  

NASA Technical Reports Server (NTRS)

We describe an optical amplifier designed to amplify a spatially sampled component of an optical wavefront to kilowatt average power. The goal is means for implementing a strategy of spatially segmenting a large aperture wavefront, amplifying the individual segments, maintaining the phase coherence of the segments by active means, and imaging the resultant amplified coherent field. Applications of interest are the transmission of space solar power over multi-megameter distances, as to distant spacecraft, or to remote sites with no preexisting power grid.

Fork, Richard L.; Cole, Spencer T.; Gamble, Lisa J.; Diffey, William M.; Keys, Andrew S.

1999-01-01

382

Regulation of cloned ATP-sensitive K channels by adenine nucleotides and sulfonylureas: interactions between SUR1 and positively charged domains on Kir6.2.  

PubMed

K(ATP) channels, comprised of the pore-forming protein Kir6.x and the sulfonylurea receptor SURx, are regulated in an interdependent manner by adenine nucleotides, PIP2, and sulfonylureas. To gain insight into these interactions, we investigated the effects of mutating positively charged residues in Kir6.2, previously implicated in the response to PIP2, on channel regulation by adenine nucleotides and the sulfonylurea glyburide. Our data show that the Kir6.2 "PIP2-insensitive" mutants R176C and R177C are not reactivated by MgADP after ATP-induced inhibition and are also insensitive to glyburide. These results suggest that R176 and R177 are required for functional coupling to SUR1, which confers MgADP and sulfonylurea sensitivity to the K(ATP) channel. In contrast, the R301C and R314C mutants, which are also "PIP2-insensitive," remained sensitive to stimulation by MgADP in the absence of ATP and were inhibited by glyburide. Based on these findings, as well as previous data, we propose a model of the K(ATP) channel whereby in the presence of ATP, the R176 and R177 residues on Kir6.2 form a specific site that interacts with NBF1 bound to ATP on SUR1, promoting channel opening by counteracting the inhibition by ATP. This interaction is facilitated by binding of MgADP to NBF2 and blocked by binding of sulfonylureas to SUR1. In the absence of ATP, since K(ATP) channels are not blocked by ATP, they do not require the counteracting effect of NBF1 interacting with R176 and R177 to open. Nevertheless, channels in this state remain activated by MgADP. This effect may be explained by a direct stimulatory interaction of NBF2/MgADP moiety with another region of Kir6.2 (perhaps the NH2 terminus), or by NBF2/MgADP still promoting a weak interaction between NBF1 and Kir6.2 in the absence of ATP. The region delimited by R301 and R314 is not involved in the interaction with NBF1 or NBF2, but confers additional PIP2 sensitivity. PMID:11585851

John, S A; Weiss, J N; Ribalet, B

2001-10-01

383

Vertical charge transport in junction charge-coupled devices  

NASA Astrophysics Data System (ADS)

Vertical charge transport in junction charge coupled devices (JCCD's) and its application in logic circuits were analyzed. Charge can be vertically injected into the JCCD transport channel through the steering gates by applying a vertical NPN transistor (injector), which can be made without any additional fabrication processing steps. The substrate PNP transistor, formed by the steering gate, the transport channel, and the substrate, can be used for the detection of surplus charge. The substrate PNP transistor was applied in a very simple, amplifying JCCD output structure, having a gain more than 100 while harmonic distortion is less than - 50 dB. Circuits based on vertical charge injection and vertical charge overflow of surplus charge were realized. And-or-invert circuits were operated at more than 50 MHz. A Full Adder was operated at 5 MHz. Performance can be improved by a fast charge-normalizing stage and a thinner epilayer.

Vanderklauw, Cornelis Leonardus Maria

384

Sensitivity of a Strained C-C Single Bond to Charge Transfer: Redox Activity in Mononuclear and Dinuclear Ruthenium Complexes of Bis(arylimino)acenaphthene (BIAN) Ligands.  

PubMed

The new compounds [Ru(acac)2(BIAN)], BIAN = bis(arylimino)acenaphthene (aryl = Ph (1a), 4-MeC6H4 (2a), 4-OMeC6H4 (3a), 4-ClC6H4 (4a), 4-NO2C6H4 (5a)), were synthesized and structurally, electrochemically, spectroscopically, and computationally characterized. The ?-diimine sections of the compounds exhibit intrachelate ring bond lengths 1.304 Å < d(CN) < 1.334 and 1.425 Å < d(CC) < 1.449 Å, which indicate considerable metal-to-ligand charge transfer in the ground state, approaching a Ru(III)(BIAN(•-)) oxidation state formulation. The particular structural sensitivity of the strained peri-connecting C-C bond in the BIAN ligands toward metal-to-ligand charge transfer is discussed. Oxidation of [Ru(acac)2(BIAN)] produces electron paramagnetic resonance (EPR) and UV-vis-NIR (NIR = near infrared) spectroelectrochemically detectable Ru(III) species, while the reduction yields predominantly BIAN-based spin, in agreement with density functional theory (DFT) spin-density calculations. Variation of the substituents from CH3 to NO2 has little effect on the spin distribution but affects the absorption spectra. The dinuclear compounds {(?-tppz)[Ru(Cl)(BIAN)]2}(ClO4)2, tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine; aryl (BIAN) = Ph ([1b](ClO4)2), 4-MeC6H4 ([2b](ClO4)2), 4-OMeC6H4 ([3b](ClO4)2), 4-ClC6H4 ([4b](ClO4)2), were also obtained and investigated. The structure determination of [2b](ClO4)2 and [3b](ClO4)2 reveals trans configuration of the chloride ligands and unreduced BIAN ligands. The DFT and spectroelectrochemical results (UV-vis-NIR, EPR) indicate oxidation to a weakly coupled Ru(III)Ru(II) mixed-valent species but reduction to a tppz-centered radical state. The effect of the ? electron-accepting BIAN ancillary ligands is to diminish the metal-metal interaction due to competition with the acceptor bridge tppz. PMID:24983788

Mondal, Prasenjit; Agarwala, Hemlata; Jana, Rahul Dev; Plebst, Sebastian; Grupp, Anita; Ehret, Fabian; Mobin, Shaikh M; Kaim, Wolfgang; Lahiri, Goutam Kumar

2014-07-21

385

Transverse Bragg resonance laser amplifier  

Microsoft Academic Search

We propose and analyze a new type of optical amplifier that is formed by addition of gain in the periodic cladding of a transverse Bragg resonance waveguide [Opt. Lett. 27, 936 (2002)]. Using the coupled-wave formalism, we calculate the mode profiles, the exponential gain constant, and, for comparison, the gain enhancement compared with those of conventional semiconductor optical amplifiers. In

Amnon Yariv; Yong Xu; Shayan Mookherjea

2003-01-01

386

Deflection amplifier for image dissectors  

NASA Technical Reports Server (NTRS)

Balanced symmetrical y-axis amplifier uses zener-diode level shifting to interface operational amplifiers to high voltage bipolar output stages. Nominal voltage transfer characteristic is 40 differential output volts per input volt; bandwidth, between -3-dB points, is approximately 8 kHz; loop gain is nominally 89 dB with closed loop gain of 26 dB.

Salomon, P. M.

1977-01-01

387

Laser amplifier developments at Mercury  

SciTech Connect

Electron-beam pumped laser amplifiers have been modified to address the mission of krypton-fluoride excimer laser technology development. Methods are described for improving the performance and reliability of two pre-existing amplifiers at minimal cost and time. Preliminary performance data are presented to support the credibility of the approach.

Rose, E.A.; Brucker, J.P.; Honig, E.M.; McCown, A.W.; Romero, V.O.; York, G.W.

1993-09-01

388

Ytterbium-doped fiber amplifiers  

Microsoft Academic Search

The ytterbium-doped fiber amplifier offers a number of attractive features, including a broad-gain bandwidth and a high efficiency, due in large part to its freedom from various competing processes seen in other rare-earth dopants. Here we discuss the main features that influence design and possible applications of ytterbium-doped fiber amplifiers

R. Paschotta; J. Nilsson; A. C. Tropper; D. C. Hanna

1997-01-01

389

Absolute linearity characterization of lock-in amplifiers  

NASA Astrophysics Data System (ADS)

In applications where low signal-to-noise ratios are encountered, the use of phase-sensitive detection (PSD) is highly advantageous and is applied widely. However, the characteristics of lock-in amplifiers that utilize the PSD technique, such as the linearity of the output and the gain of these instruments, have not been extensively evaluated. The author proposes a method for measuring the linearity characteristics of lock-in amplifiers and describes how this method was used to measure the linearity factor of three nominally identical commercially available digital lock-in amplifiers. The results of this study show that the linearity factor of these lock-in amplifiers can deviate from unity by more than 0.1% over a factor of 2 change in output. Moreover, the linearity characteristics of these lock-in amplifiers vary from one instrument to the next. The linearity characteristics were shown to be independent of the reference frequency, the time constant, and the temporal profile of the signal being analyzed. However, they were found to be dependent on the sensitivity settings of these instruments. The linearity characteristics of these instruments were observed not to change with time. This implies that, where the uncertainty contribution due to the nonlinearity of a lock-in amplifier is significant, the nonlinearity can be evaluated by using the method described in this article and can be used to apply corrections.

Theocharous, E.

2008-03-01

390

Fluid pressure amplifier and system  

NASA Technical Reports Server (NTRS)

A flueric beam-deflection amplifier and a method of controlling the same are described. Either a single or a series of cascaded fluid amplifier units are provided and each one of which may include the usual power nozzle, control nozzles, outlet passages and vent passages. All vent passages of each fluid amplifier unit lead to an enclosed vent outlet chamber which is connected to the ambient environment or to a return manifold through a variably restricted passage. To control the fluid amplifier unit, power and control stream pressures are first established, after which the restricted passage is reduced to regulate the input bias, the gain and the input impedance of the fluid amplifier unit.

Garner, H. D.; Hellbaum, R. F. (inventors)

1973-01-01

391

Charge transport versus recombination in dye-sensitized solar cells employing nanocrystalline TiO2 and SnO2 films.  

PubMed

We report a comparison of charge transport and recombination dynamics in dye-sensitized solar cells (DSSCs) employing nanocrystalline TiO(2) and SnO(2) films and address the impact of these dynamics upon photovoltaic device efficiency. Transient photovoltage studies of electron transport in the metal oxide film are correlated with transient absorption studies of electron recombination with both oxidized sensitizer dyes and the redox couple. For all three processes, the dynamics are observed to be 2-3 orders of magnitude faster for the SnO(2) electrode. The origins of these faster dynamics are addressed by studies correlating the electron recombination dynamics to dye cations with chronoamperometric studies of film electron density. These studies indicate that the faster recombination dynamics for the SnO(2) electrodes result both from a 100-fold higher electron diffusion constant at matched electron densities, consistent with a lower trap density for this metal oxide relative to TiO(2), and from a 300 mV positive shift of the SnO(2) conduction band/trap states density of states relative to TiO(2). The faster recombination to the redox couple results in an increased dark current for DSSCs employing SnO(2) films, limiting the device open-circuit voltage. The faster recombination dynamics to the dye cation result in a significant reduction in the efficiency of regeneration of the dye ground state by the redox couple, as confirmed by transient absorption studies of this reaction, and in a loss of device short-circuit current and fill factor. The importance of this loss pathway was confirmed by nonideal diode equation analyses of device current-voltage data. The addition of MgO blocking layers is shown to be effective at reducing recombination losses to the redox electrolyte but is found to be unable to retard recombination dynamics to the dye cation sufficiently to allow efficient dye regeneration without resulting in concomitant losses of electron injection efficiency. We conclude that such a large acceleration of electron dynamics within the metal oxide films of DSSCs may in general be detrimental to device efficiency due to the limited rate of dye regeneration by the redox couple and discuss the implications of this conclusion for strategies to optimize device performance. PMID:16852549

Green, Alex N M; Palomares, Emilio; Haque, Saif A; Kroon, Jan M; Durrant, James R

2005-06-30

392

Measuring momentum for charged particle tomography  

DOEpatents

Methods, apparatus and systems for detecting charged particles and obtaining tomography of a volume by measuring charged particles including measuring the momentum of a charged particle passing through a charged particle detector. Sets of position sensitive detectors measure scattering of the charged particle. The position sensitive detectors having sufficient mass to cause the charged particle passing through the position sensitive detectors to scatter in the position sensitive detectors. A controller can be adapted and arranged to receive scattering measurements of the charged particle from the charged particle detector, determine at least one trajectory of the charged particle from the measured scattering; and determine at least one momentum measurement of the charged particle from the at least one trajectory. The charged particle can be a cosmic ray-produced charged particle, such as a cosmic ray-produced muon. The position sensitive detectors can be drift cells, such as gas-filled drift tubes.

Morris, Christopher (Los Alamos, NM); Fraser, Andrew Mcleod (Los Alamos, NM); Schultz, Larry Joe (Los Alamos, NM); Borozdin, Konstantin N. (Los Alamos, NM); Klimenko, Alexei Vasilievich (Maynard, MA); Sossong, Michael James (Los Alamos, NM); Blanpied, Gary (Lexington, SC)

2010-11-23

393

Optical back-action-evading amplifiers  

NASA Astrophysics Data System (ADS)

A detection strategy called 'black-action evasion' has been developed for following one component of the motion x(t) of the mass of a harmonic oscillator. In the present investigtion, attention is given to the general mode transformations appropriate for an optical device capable of back-action-evading amplification. A general description is presented of the ideal input-output relations for a back-action-evading measuring device. Back-action evasion in a parametric-gain medium is considered along with back-action evasion via parametric amplifiers and frequency converters, back-action evasion via beam splitters and degenerate-parametric amplifiers, and back-action evasion via degenerate-four-wave mixers. It is hoped that some of the schemes presented are sufficiently realistic to make the experimental demonstration of optical back-action evasion feasible. Perhaps some of the low-frequency realizations of the presented schemes will be useful as first-stage amplifiers for sensitive detectors, such as gravitational antennas of the Weber-bar type.

Yurke, B.

1985-05-01

394

Protonation Sites in Chemically Amplified Resists for Electron-Beam Lithography  

NASA Astrophysics Data System (ADS)

In chemically amplified resists that utilize acid-catalytic reactions for pattern formation, proton dynamics is important from the viewpoints of the insoluble layer formation due to acid loss, the resolution decrease due to acid diffusion, and the image quality improvement due to base-quencher effects. For electron-beam lithography, the protons and anions of the acid are initially generated at different places. Protons migrate in the resist matrix toward counter anions, attracted by the opposite electric charges. However, the details of proton migration are still unclear. In this study, we investigated proton quenching in poly(4-hydroxystyrene) films using base quenchers with different proton affinities. When the proton affinity of the base quencher was increased, the equimolecular proton adduct of the acid-sensitive dye was quenched without postexposure bake. Although the proton affinity is a gas-phase value, the quenching effect correlated well with the proton affinity.

Natsuda, Kenichiro; Kozawa, Takahiro; Okamoto, Kazumasa; Tagawa, Seiichi

2006-12-01

395

A high-speed low-noise CMOS 16-channel charge-sensitive preamplifier ASIC for APD-based PET detectors  

Microsoft Academic Search

A high-speed low-noise 16-channel amplifier integrated circuit (IC) has been fabricated in a 0.5 ?m CMOS process. It is a prototype for use with a PET detector that uses a 4×4 avalanche photodiode (APD) array having 3 pF of capacitance and 75 nA of leakage current per pixel. The preamplifier must have a fast rise time (a few ns) in

M. Weng; E. Mandelli; W. W. Moses; S. E. Derenzo

2003-01-01

396

A high-speed, low-noise CMOS 16-channel charge-sensitive preamplifier ASIC for APD-based PET detectors  

Microsoft Academic Search

A high-speed, low-noise 16-channel amplifier IC has been fabricated in the UP 0.5 ?m CMOS process. It is a prototype for use with a PET detector which uses a 4×4 avalanche photodiode (APD) array having 3 pF of capacitance and 75 nA of leakage current. This requires that the preamplifier have a fast rise time (a few ns) in order

M. Weng; E. Mandelli; W. W. Moses; S. E. Derenzo

2002-01-01

397

Fundamentals of Electronics. Volume 2. Power Supplies and Amplifiers.  

National Technical Information Service (NTIS)

Contents: Power transformers; Electron tube rectifier circuits; Filter circuits; Regulator circuits; Triode amplifiers; Tetrode and pentode amplifiers; Paraphase amplifier circuits; Audio power amplifier; Decibles, microphones, and speakers.

1965-01-01

398

MOSFET's for Cryogenic Amplifiers  

NASA Technical Reports Server (NTRS)

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.

Dehaye, R.; Ventrice, C. A.

1987-01-01

399

Spontaneous Separation of Charged Grains  

NASA Astrophysics Data System (ADS)

In 1867, Lord Kelvin described an experiment in which two streams of water droplets were connected so that each stream amplified the charge on the second stream [W. Thomson, Proc. R. Soc. LondonPRSLAZ0370-1662 16, 67 (1867).10.1098/rspl.1867.0019]. We present here a complementary effect in flowing grains that spontaneously separates similar and well-mixed grains into two charged streams of demixed grains. This effect has important consequences for industrial and natural processes.

Mehrotra, Amit; Muzzio, Fernando J.; Shinbrot, Troy

2007-08-01

400

Spontaneous separation of charged grains.  

PubMed

In 1867, Lord Kelvin described an experiment in which two streams of water droplets were connected so that each stream amplified the charge on the second stream [W. Thomson, Proc. R. Soc. London 16, 67 (1867)]. We present here a complementary effect in flowing grains that spontaneously separates similar and well-mixed grains into two charged streams of demixed grains. This effect has important consequences for industrial and natural processes. PMID:17930794

Mehrotra, Amit; Muzzio, Fernando J; Shinbrot, Troy

2007-08-01

401

Dispersive liquid-liquid microextraction prior to field-amplified sample injection for the sensitive analysis of 3,4-methylenedioxymethamphetamine, phencyclidine and lysergic acid diethylamide by capillary electrophoresis in human urine.  

PubMed

A novel capillary zone electrophoresis (CZE) with ultraviolet detection method has been developed and validated for the analysis of 3,4-methylenedioxymethamphetamine (MDMA), lysergic acid diethylamide (LSD) and phencyclidine (PCP) in human urine. The separation of these three analytes has been achieved in less than 8 min in a 72-cm effective length capillary with 50-?m internal diameter. 100 mM NaH(2)PO(4)/Na(2)HPO(4), pH 6.0 has been employed as running buffer, and the separation has been carried out at temperature and voltage of 20°C, and 25kV, respectively. The three drugs have been detected at 205 nm. Field amplified sample injection (FASI) has been employed for on-line sample preconcentration. FASI basically consists in a mismatch between the electric conductivity of the sample and that of the running buffer and it is achieved by electrokinetically injecting the sample diluted in a solvent of lower conductivity than that of the carrier electrolyte. Ultrapure water resulted to be the better sample solvent to reach the greatest enhancement factor. Injection voltage and time have been optimized to 5 kV and 20s, respectively. The irreproducibility associated to electrokinetic injection has been correcting by using tetracaine as internal standard. Dispersive liquid-liquid microextraction (DLLME) has been employed as sample treatment using experimental design and response surface methodology for the optimization of critical variables. Linear responses were found for MDMA, PCP and LSD in presence of urine matrix between 10.0 and 100 ng/mL approximately, and LODs of 1.00, 4.50, and 4.40 ng/mL were calculated for MDMA, PCP and LSD, respectively. The method has been successfully applied to the analysis of the three drugs of interest in human urine with satisfactory recovery percentages. PMID:23141624

Airado-Rodrķguez, Diego; Cruces-Blanco, Carmen; Garcķa-Campańa, Ana M

2012-12-01

402

Amplifier arrays for CMB polarization  

NASA Technical Reports Server (NTRS)

Cryogenic low noise amplifier technology has been successfully used in the study of the cosmic microwave background (CMB). MMIC (Monolithic Millimeter wave Integrated Circuit) technology makes the mass production of coherent detection receivers feasible.

Gaier, Todd; Lawrence, Charles R.; Seiffert, Michael D.; Wells, Mary M.; Kangaslahti, Pekka; Dawson, Douglas

2003-01-01

403

Thieno-Pyrrole-Fused 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene-Fullerene Dyads: Utilization of Near-Infrared Sensitizers for Ultrafast Charge Separation in Donor-Acceptor Systems.  

PubMed

Donor-acceptor dyads featuring near-IR sensitizers derived from thieno-pyrrole-fused BODIPY (abbreviated as SBDPiR) and fullerene, C60 have been newly synthesized and characterized. Occurrence of ultrafast photoinduced electron transfer (PET) leading to the formation of charge-separated state in these dyads, capable of harvesting light energy from the near-IR region, is established from femtosecond transient absorption studies. PMID:24820034

Bandi, Venugopal; Das, Sushanta K; Awuah, Samuel G; You, Youngjae; D'Souza, Francis

2014-05-28

404

Charge-to-Alanine Mutagenesis of the Adeno-Associated Virus Type 2 Rep78/68 Proteins Yields Temperature-Sensitive and Magnesium-Dependent Variants  

PubMed Central

The adeno-associated virus type 2 (AAV) replication (Rep) proteins Rep78 and 68 (Rep78/68) exhibit a number of biochemical activities required for AAV replication, including specific binding to a 22-bp region of the terminal repeat, site-specific endonuclease activity, and helicase activity. Individual and clusters of charged amino acids were converted to alanines in an effort to generate a collection of conditionally defective Rep78/68 proteins. Rep78 variants were expressed in human 293 cells and analyzed for their ability to mediate replication of recombinant AAV vectors at various temperatures. The biochemical activities of Rep variants were further characterized in vitro by using Rep68 His-tagged proteins purified from bacteria. The results of these analyses identified a temperature-sensitive (ts) Rep protein (D40,42,44A-78) that exhibited a delayed replication phenotype at 32°C, which exceeded wild-type activity by 48 h. Replication activity was reduced by more than threefold at 37°C and was undetectable at 39°C. Stability of the Rep78 protein paralleled replication levels at each temperature, further supporting a ts phenotype. Replication differences resulted in a 3-log-unit difference in virus yields between the permissive and nonpermissive temperatures (2.2 × 106 and 3 × 103, respectively), demonstrating that this is a relatively tight mutant. In addition to the ts Rep mutant, we identified a nonconditional mutant with a reduced ability to support viral replication in vivo. Additional characterization of this mutant demonstrated an Mg2+-dependent phenotype that was specific to Rep endonuclease activity and did not affect helicase activity. The two mutants described here are unique, in that Rep ts mutants have not previously been described and the D412A Rep mutant represents the first mutant in which the helicase and endonuclease functions can be distinguished biochemically. Further understanding of these mutants should facilitate our understanding of AAV replication and integration, as well as provide novel strategies for production of viral vectors.

Gavin, Denise K.; Young, Samuel M.; Xiao, Weidong; Temple, Brenda; Abernathy, Corinne R.; Pereira, Daniel J.; Muzyczka, Nicholas; Samulski, Richard Jude

1999-01-01

405

High current CMOS operational amplifier  

Microsoft Academic Search

This paper describes a low voltage CMOS operational amplifier, which is capable of driving heavy resistive and capacitive loads. Robust and power efficient compensation is achieved by using Miller compensation together with a high bandwidth stage. Measurements show that the amplifier achieves 5.7 MHz unity gain frequency and 61° phase margin when driving 1nF||1k? load, while drawing 2.4mA from 1.5V

Mikko Loikkanen; Juha Kostamovaara

2005-01-01

406

RF Single Electron Transistor Readout Amplifiers for Superconducting Astronomical Detectors for X-Ray to Sub-mm Wavelengths  

NASA Technical Reports Server (NTRS)

We report progress on using a new type of amplifier, the Radio-Frequency Single-Electron Transistor (RF-SET), to develop multi-channel sensor readout systems for fast and sensitive readout of high impedance cryogenic photodetectors such as Superconducting Tunnel Junctions and Single Quasiparticle Photon Counters. Although cryogenic, these detectors are desirable because of capabilities not other-wise attainable. However, high impedances and low output levels make low-noise, high-speed readouts challenging, and large format arrays would be facilitated by compact, low-power, on-chip integrated amplifiers. Well-suited for this application are RF-SETs, very high performance electrometers which use an rf readout technique to provide 100 MHz bandwidth. Small size, low power, and cryogenic operation allow direct integration with detectors, and using multiple rf carrier frequencies permits simultaneous readout of 20-50 amplifiers with a common electrical connection. We describe both the first 2-channel demonstration of this wavelength division multiplexing technique for RF-SETs, and Charge-Locked-Loop operation with 100 kHz of closed-loop bandwidth.

Stevenson, Thomas; Aassime, Abdelhanin; Delsing, Per; Frunzio, Luigi; Li, Li-Qun; Prober, Daniel; Schoelkopf, Robert; Segall, Ken; Wilson, Chris; Stahle, Carl

2000-01-01

407

Gyrotron Traveling Wave Amplifier with a Helical Interaction Waveguide  

Microsoft Academic Search

A new microwave system in the form of a cylindrical waveguide with a helical corrugation of the inner surface is proposed for a gyrotron traveling wave tube (gyro-TWT). The corrugation radically changes the wave dispersion in the region of small axial wave numbers. This allows significant reduction in the sensitivity of the amplifier to the electron velocity spread and an

G. G. Denisov; V. L. Bratman; A. W. Cross; W. He; A. D. R. Phelps; K. Ronald; S. V. Samsonov; C. G. Whyte

1998-01-01

408

Chemically amplified molecular resists for e-beam lithography  

Microsoft Academic Search

Current resist materials are unable to simultaneously meet the resolution, sensitivity and line width roughness specifications of the 32nm node. Molecular resists have small carbon rich molecules and have generated significant recent interest with their potential for high resolution and etch durability and lower linewidth roughness than conventional polymeric materials. A chemically amplified fullerene derivative based resist is presented here.

F. P. Gibbons; J. Manyam; S. Diegoli; M. Manickam; J. A. Preece; R. E. Palmer; A. P. G. Robinson

2008-01-01

409

Single Ion Quantum Lock-In Amplifier  

NASA Astrophysics Data System (ADS)

Invented by Dicke, the lock-in measurement is a phase-sensitive detection scheme that can extract a signal with a known carrier frequency from an extremely noisy environment. Here we report on the implementation of a quantum analog to the classical lock- in amplifier. All the lock-in operations: modulation, detection and mixing, are performed via the application of non-commuting quantum operators on the electronic spin state of a single trapped Sr+ ion. We increase its sensitivity to external fields while extending phase coherence by three orders of magnitude, to more than one second. With this technique we measure magnetic fields with sensitivity of 25 pT/?Hz, and light shifts with an uncertainty below 140 mHz after 1320 seconds of averaging. These sensitivities are limited by quantum projection noise and, to our knowledge, are more than two orders of magnitude better than with other single-spin probe technologies. As a first application we perform light shift spectroscopy of a narrow optical quadruple transition. We remark that the quantum lock-in technique is generic and can potentially enhance the sensitivity of any quantum sensor. (http://arxiv.org/abs/1101.4885)

Kotler, Shlomi; Akerman, Nitzan; Glickman, Yinnon; Keselman, Anna; Ozeri, Roee

2011-06-01

410

Beam quality of direct nuclear pumped laser amplifiers  

NASA Astrophysics Data System (ADS)

Beam quality attainable in transverse-flow gas-laser amplifiers subject to heavy charged-particle pumping is analyzed. The charged particles are generated by nuclear reactions in either B4C or UO2 coated on plates parallel to the lasant flow. Several variations in gas conditions and cavity geometry are used to investigate potential improvements in beam quality. It is shown that a simple correction of the cylindrical focus can improve the beam quality of plate-fueled amplifiers; a reduction in the aperture size also can improve the beam quality. The beam quality is also affected by variations in gas pressure and inlet flow velocity. The index of refraction aberrations in the fission fragment pumped argon medium is found to be larger than in the light particle pumped helium medium primarily due to the large index of refraction of argon.

Neuman, W. A.; Fincke, J. R.

1991-05-01

411

Fully differential cryogenic transistor amplifier  

NASA Astrophysics Data System (ADS)

We have constructed a dc-coupled differential amplifier capable of operating in the 4.2 K-300 K temperature range. The amplifier can be operated at high-bias setting, where it dissipates 5 mW, has noise temperature TN ? 0.7 K at RS ? 5 k? and >40 MHz bandwidth at 4.2 K bath temperature. The bias setting can be adjusted: at our lowest tested setting the amplifier dissipates <100 ?W, has noise temperature TN ? 2 K at RS ? 25 k? and >2 MHz bandwidth. The 1/f noise corner frequency is a few times 10 kHz. We foresee the amplifier to have an application in the readout of Superconducting Quantum Interference Devices (SQUIDs), Superconducting Tunnel Junction Detectors (STJs) and Transition Edge Sensors (TESes). We have verified the practical use of the amplifier by reading out a 4.2 K 480-SQUID array with 40 MHz bandwidth and <8 × 10-8 ?0/Hz1/2 flux noise.

Beev, Nikolai; Kiviranta, Mikko

2013-10-01

412

Reflex ring laser amplifier system  

DOEpatents

The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

Summers, M.A.

1983-08-31

413

Piezoelectric rubber films for highly sensitive impact measurement  

NASA Astrophysics Data System (ADS)

We have successfully demonstrated the microfabrication of piezoelectric rubber films and their application in impact measurement. To realize the desired piezoelectricity and stretchability, cellular polydimethylsiloxane (PDMS) structures with micrometer-sized voids are internally implanted with bipolar charges, which function as dipoles and respond promptly to electromechanical stimuli. In the prototype demonstration, 300 µm thick cellular PDMS films are fabricated and internally coated with a thin polytetrafluoroethylene (PTFE) layer to secure the implanted charges. Meanwhile, the top and bottom surfaces of the cellular PDMS films are deposited with stretchable gold electrodes. An electric field up to 35 MV m-1 is applied across the gold electrodes to ionize the air in the voids and to implant charges on the inner surfaces. The resulting composite structures behave like rubber (with an elastic modulus of about 300 kPa) and show strong piezoelectricity (with a piezoelectric coefficient d33 higher than 1000 pC N-1). While integrated with a wide bandwidth and large dynamic-range charge amplifier, highly sensitive impact measurement (with a stress sensitivity of about 10 mV Pa-1) is demonstrated. As such, the demonstrated piezoelectric rubber films could potentially serve as a sensitive electromechanical material for low-frequency stimuli, and fulfill the needs of a variety of physiological monitoring and wearable electronics applications.

Wang, Jhih-Jhe; Tsai, Jui-Wei; Su, Yu-Chuan

2013-07-01

414

Charged Conjugated Polymers  

NASA Astrophysics Data System (ADS)

Signal amplification property and versatility in molecular design of conjugated polymers make them attractive as signal transduction materials. Cationic conjugated polymers (CCP) have demonstrated great potential as DNA-sensing materials since electrostatic interactions between CCP and negatively charged DNA have been well developed to modify optical properties and thereby detect hybridization states. In this chapter, we focus on the state-of-art of CCP-based non-amplified genomic DNA detection in homogenous solution as well as on microarray format. Representative applications of poly(thiophene)-based DNA sensors which display colorimetric output due to conformational changes, and poly(fluorene)-based DNA sensors which utilize CCP as energy donors are highlighted. The developments of amplified single nucleotide polymorphisms and DNA methylation detection employing CCP as sensory signal are briefly discussed. Integrated signal amplification effect of CCP with high-throughput DNA microarray format will yield superior platform for genomic DNA detection.

Lv, Fengting; Wang, Shu

415

Inverting amplifier genetic circuit performance.  

PubMed

A synthetic genetic circuit has been designed whose topology and function echo those of an electronic inverting amplifier. Several variants of this circuit have been built in our laboratory. This paper reports on the testing of one of these variants and contributes to the field both in terms of evaluating the specific amplifier performance and in terms of providing a methodology for performance evaluation of analog genetic circuits. An input source was created and partially calibrated. It was then used to test the circuit through both fluorometer measurements and flow cytometry. In the discussion, consideration is given to cellular loading by the synthetic circuits and the resulting impact on circuit performance. Models developed earlier are compared with the experimental results. The circuit does indeed perform as an inverting amplifier. PMID:17947009

Nagaraj, S; Davies, S W

2006-01-01

416

Laser system using regenerative amplifier  

DOEpatents

High energy laser system is disclosed using a regenerative amplifier, which relaxes all constraints on laser components other than the intrinsic damage level of matter, so as to enable use of available laser system components. This can be accomplished by use of segmented components, spatial filters, at least one amplifier using solid state or gaseous media, and separated reflector members providing a long round trip time through the regenerative cavity, thereby allowing slower switching and adequate time to clear the spatial filters, etc. The laser system simplifies component requirements and reduces component cost while providing high energy output. 10 figs.

Emmett, J.L.

1980-03-04

417

Quantum optical state comparison amplifier.  

PubMed

It is a fundamental principle of quantum theory that an unknown state cannot be copied or, as a consequence, an unknown optical signal cannot be amplified deterministically and perfectly. Here we describe a protocol that provides nondeterministic quantum optical amplification in the coherent state basis with high gain and high fidelity and which does not use quantum resources. The scheme is based on two mature quantum optical technologies: coherent state comparison and photon subtraction. The method compares favorably with all previous nondeterministic amplifiers in terms of fidelity and success probability. PMID:24313486

Eleftheriadou, Electra; Barnett, Stephen M; Jeffers, John

2013-11-22

418

Optical amplifiers for coherent lidar  

NASA Technical Reports Server (NTRS)

We examine application of optical amplification to coherent lidar for the case of a weak return signal (a number of quanta of the return optical field close to unity). We consider the option that has been explored to date, namely, incorporation of an optical amplifier operated in a linear manner located after reception of the signal and immediately prior to heterodyning and photodetection. We also consider alternative strategies where the coherent interaction, the nonlinear processes, and the amplification are not necessarily constrained to occur in the manner investigated to date. We include the complications that occur because of mechanisms that occur at the level of a few, or one, quantum excitation. Two factors combine in the work to date that limit the value of the approach. These are: (1) the weak signal tends to require operation of the amplifier in the linear regime where the important advantages of nonlinear optical processing are not accessed, (2) the linear optical amplifier has a -3dB noise figure (SN(out)/SN(in)) that necessarily degrades the signal. Some improvement is gained because the gain provided by the optical amplifier can be used to overcome losses in the heterodyned process and photodetection. The result, however, is that introduction of an optical amplifier in a well optimized coherent lidar system results in, at best, a modest improvement in signal to noise. Some improvement may also be realized on incorporating more optical components in a coherent lidar system for purely practical reasons. For example, more compact, lighter weight, components, more robust alignment, or more rapid processing may be gained. We further find that there remain a number of potentially valuable, but unexplored options offered both by the rapidly expanding base of optical technology and the recent investigation of novel nonlinear coherent interference phenomena occurring at the single quantum excitation level. Key findings are: (1) insertion of linear optical amplifiers in well optimized conventional lidar systems offers modest improvements, at best, (2) the practical advantages of optical amplifiers, especially fiber amplifiers, such as ease of alignment, compactness, efficiency, lightweight, etc., warrant further investigation for coherent lidar, (3) the possibility of more fully optical lidar systems should be explored, (4) advantages gained by use of coherent interference of optical fields at the level of one, or a few, signal quanta should be explored, (5) amplification without inversion, population trapping, and use of electromagnetic induced transparency warrant investigation in connection with coherent lidar, (6) these new findings are probably more applicable to earth related NASA work, although applications to deep space should not be excluded, and (7) our own work in the Ultrafast Laboratory at UAH along some of the above lines of investigation, may be useful.

Fork, Richard

1996-01-01

419

Nuclear magnetic resonance experiments with dc SQUID amplifiers  

SciTech Connect

The development and fabrication of dc SQUIDs (Superconducting QUantum Interference Devices) with Nb/Al{sub 2}O{sub 3}/Nb Josephson junctions is described. A theory of the dc SQUID as a radio-frequency amplifier is presented, with an optimization strategy that accounts for the loading and noise contributions of the postamplifier and maximizes the signal-to-noise ratio of the total system. The high sensitivity of the dc SQUID is extended to high field NMR. A dc SQUID is used as a tuned radio-frequency amplifier to detect pulsed nuclear magnetic resonance at 32 MHz from a metal film in a 3.5 Tesla static field. A total system noise temperature of 11 K has been achieved, at a bath temperature of 4.2 K. The minimum number of nuclear Bohr magnetons observable from a free precession signal after a single pulse is about 2 {times} 10{sup 17} in a bandwidth of 25 kHz. In a separate experiment, a dc SQUID is used as a rf amplifier in a NQR experiment to observe a new resonance response mechanism. The net electric polarization of a NaClO{sub 3} crystal due to the precessing electric quadrupole moments of the Cl nuclei is detected at 30 MHz. The sensitivity of NMR and NQR spectrometers using dc SQUID amplifiers is compared to the sensitivity of spectrometers using conventional rf amplifiers. A SQUID-based spectrometer has a voltage sensitivity which is comparable to the best achieved by a FET-based spectrometer, at these temperatures and operating frequencies.

Heaney, M.B. (California Univ., Berkeley, CA (USA). Dept. of Physics Lawrence Berkeley Lab., CA (USA))

1990-11-01

420

The PreAmplifier ShAper for the ALICE TPC detector  

NASA Astrophysics Data System (ADS)

In this paper the PreAmplifier ShAper (PASA) for the Time Projection Chamber (TPC) of the ALICE experiment at LHC is presented. The ALICE TPC PASA is an ASIC that integrates 16 identical channels, each consisting of Charge Sensitive Amplifiers (CSA) followed by a Pole-Zero network, self-adaptive bias network, two second-order bridged-T filters, two non-inverting level shifters and a start-up circuit. The circuit is optimized for a detector capacitance of 18-25 pF. For an input capacitance of 25 pF, the PASA features a conversion gain of 12.74 mV/fC, a peaking time of 160 ns, a FWHM of 190 ns, a power consumption of 11.65 mW/ch and an equivalent noise charge of 244e+17e/pF. The circuit recovers smoothly to the baseline in about 600 ns. An integral non-linearity of 0.19% with an output swing of about 2.1 V is also achieved. The total area of the chip is 18 mm2 and is implemented in AMS's C35B3C1 0.35 ?m CMOS technology. Detailed characterization tests were performed on about 48 000 PASA circuits before mounting them on the ALICE TPC front-end cards. After more than two years of operation of the ALICE TPC with p-p and Pb-Pb collisions, the PASA has demonstrated to fulfill all requirements.

Soltveit, H. K.; Stachel, J.; Braun-Munzinger, P.; Musa, L.; Gustafsson, H. A.; Bonnes, U.; Oeschler, H.; Osterman, L.; Lang, S.; ALICE TPC Collaboration

2012-06-01

421

Temporal mode structure of a regenerative amplifier with intracavity etalons  

SciTech Connect

The effects of intracavity etalons on the temporal-mode structure of a regenerative amplifier are studied both theoretically and experimentally. The analysis predicts the temporal profile of the regenerative amplifier output pulse given the temporal profile of the input pulse, the laser-cavity parameters, the etalon parameters, and the number of round trips that the injected pulse makes in the laser cavity. Several experiments were performed. The output pulse width of a regenerative amplifier with a single etalon was measured as we varied the thickness of the etalon and the number of round trips that the injected pulse makes in the laser cavity. With two etalons an injected 70-ps pulse width was stretched to 7 ns with no temporal modulation. The thermal sensitivity of an intracavity etalon was analyzed and measured. All experimental results agree well with theory.

Skeldon, M.D.; Bui, S.T. (Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States))

1993-04-01

422

Increased Sensitivity to Broadly Neutralizing Antibodies of End-Stage Disease R5 HIV1 Correlates with Evolution in Env Glycosylation and Charge  

Microsoft Academic Search

BackgroundInduction of broadly neutralizing antibodies, such as the monoclonal antibodies IgGb12, 2F5 and 2G12, is the objective of most antibody-based HIV-1 vaccine undertakings. However, despite the relative conserved nature of epitopes targeted by these antibodies, mechanisms underlying the sensitivity of circulating HIV-1 variants to broadly neutralizing antibodies are not fully understood. Here we have studied sensitivity to broadly neutralizing antibodies

Marie Borggren; Johanna Repits; Jasminka Sterjovski; Hannes Uchtenhagen; Melissa J. Churchill; Anders Karlsson; Jan Albert; Adnane Achour; Paul R. Gorry; Eva Maria Fenyö; Marianne Jansson

2011-01-01

423

Stroke amplifier for deformable mirrors  

PubMed Central

We demonstrate a simple optical configuration that amplifies the usable stroke of a deformable mirror. By arranging for the wavefront to traverse the deformable mirror more than once, we correct it more than once. The experimental implementation of the idea demonstrates a doubling of 2.0 and 2.04 by two different means.

Webb, Robert H.; Albanese, Marc J.; Zhou, Yaopeng; Bifano, Thomas; Burns, Stephen A.

2010-01-01

424

Tunnel diode amplifier SGEMP response  

Microsoft Academic Search

The paper discusses the SGEMP response of an X-band tunnel diode amplifier design in a flash X-ray environment due to particular cavity design characteristics. SGEMP currents are not limited, and thus can result in tunnel diode damage because of its low burnout energy threshold. Eight diodes were damaged due to SGEMP and their damage threshold energies were calculated, using tunnel

J. L. Andrews; D. H. Swant; B. L. Beers

1979-01-01

425

Tunnel Diode Amplifier SGEMP Response  

Microsoft Academic Search

An X-band tunnel diode amplifier (TDA) has been studied for SGEMP response. This study has involved analytical modeling and predictions, tunnel diode electrical pulsing to develop damage statistics, and experimental measurements in an 800 kvp flash X-ray environment. In contrast to photocurrent limited TREE response, significant SGEMP replacement currents can flow through the tunnel diode. This response is associated with

J. L. Andrews; D. H. Swant; B. L. Beers

1979-01-01

426

Cryogenic MMIC Low Noise Amplifiers  

NASA Technical Reports Server (NTRS)

Monolithic (MMIC) and discrete transistor (MIC) low noise amplifiers are compared on the basis of performance, cost, and reliability. The need for cryogenic LNA's for future large microwave arrays for radio astronomy is briefly discussed and data is presented on a prototype LNA for the 1 to 10 GZH range along with a very wideband LNA for the 1 to 60 GHz range.

Weinreb, S.; Gaier, T.; Fernandez, J.; Erickson, N.; Wielgus, J.

2000-01-01

427

Graphene terahertz sources and amplifiers  

Microsoft Academic Search

Plasmons in population inverted graphene can experience extremely large gain through the process of stimulated emission at terahertz frequencies. The large gain values and the small plasmon wavelengths can lead to compact terahertz plasmon lasers and amplifiers that are only a few microns in size. We present optical and terahertz spectroscopy results for carrier relaxation and recombination dynamics in graphene

F. Rana; P. A. George; J. H. Strait; J. Dawlaty

2008-01-01

428

Planar position sensitive Ge(i)- and Si(Li)-detector systems for Compton Polarimetry in Atomic Physics with Highly Charged Ions  

NASA Astrophysics Data System (ADS)

Planar position-, energy-, and time-dispersive semiconductor detector systems have shown their excellent performance in Compton Polarimetry and X-ray Imaging in the realm of Atomic Physics Experiments with Highly Charged Ions. We report on two of these detector systems and discuss the importance of this kind of detector systems for the present and future experimental programm of the SPARC collaboration at GSI and FAIR.

Spillmann, U.; Blumenhagen, K.-H.; Bräuning, H.; Weber, G.; Stöhlker, Th

2012-11-01

429

Two important factors influencing shock sensitivity of nitro compounds: Bond dissociation energy of X–NO 2 (X = C, N, O) and Mulliken charges of nitro group  

Microsoft Academic Search

DFT\\/BLYP\\/DNP is employed to calculate bond dissociation energy of X–NO2 (X=C, N, O) and Mulliken charges of nitro group of 14 kinds of nitro compounds, and partial least squares approximation is applied to linearly fit their shock initiation pressure (p90%,TMD). It is found that the fitted values are in good agreement with the experimental shock initiation pressures. The fitted model

Bisheng Tan; Xinping Long; Rufang Peng; Hongbo Li; Bo Jin; Shijin Chu; Haishan Dong

2010-01-01

430

Positive-tone chemically amplified fullerene resist  

NASA Astrophysics Data System (ADS)

With continuing efforts to achieve higher lithographic resolution there has been on-going interest in the development of low molecular weight resists, such as molecular glasses. Here we present the initial results of a study into the development of a positive tone two component chemically amplified resist based on methanofullerene derivatives (MF) with acid labile groups (tert-butyl acetate (tBAC); tert-butoxycarbonyl (tBOC)). Mono, di, tris and hexa adducts of MFtBAC together with mono and di adducts of MF-tBOC have been evaluated with several photoacid generators. Sensitivities as high as 11 ?C/cm2 have been achieved in some cases and sub-100 nm features have been patterned.

Manyam, J.; Frommhold, A.; Yang, D. X.; McClelland, A.; Manickam, M.; Preece, J. A.; Palmer, R. E.; Robinson, A. P. G.

2012-03-01

431

Particle-Charge Spectrometer  

NASA Technical Reports Server (NTRS)

An instrument for rapidly measuring the electric charges and sizes (from approximately 1 to approximately 100 micrometers) of airborne particles is undergoing development. Conceived for monitoring atmospheric dust particles on Mars, instruments like this one could also be used on Earth to monitor natural and artificial aerosols in diverse indoor and outdoor settings for example, volcanic regions, clean rooms, powder-processing machinery, and spray-coating facilities. The instrument incorporates a commercially available, low-noise, ultrasensitive charge-sensing preamplifier circuit. The input terminal of this circuit--the gate of a field-effect transistor--is connected to a Faraday-cage cylindrical electrode. The charged particles of interest are suspended in air or other suitable gas that is made to flow along the axis of the cylindrical electrode without touching the electrode. The flow can be channeled and generated by any of several alternative means; in the prototype of this instrument, the gas is drawn along a glass capillary tube (see upper part of figure) coaxial with the electrode. The size of a particle affects its rate of acceleration in the flow and thus affects the timing and shape of the corresponding signal peak generated by the charge-sensing amplifier. The charge affects the magnitude (and thus also the shape) of the signal peak. Thus, the signal peak (see figure) conveys information on both the size and electric charge of a sensed particle. In experiments thus far, the instrument has been found to be capable of measuring individual aerosol particle charges of magnitude greater than 350 e (where e is the fundamental unit of electric charge) with a precision of +/- 150 e. The instrument can sample particles at a rate as high as several thousand per second.

Fuerstenau, Stephen; Wilson, Gregory R.

2008-01-01

432

Gold Nanoparticle Labels Amplify Ellipsometric Signals  

NASA Technical Reports Server (NTRS)

The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

Venkatasubbarao, Srivatsa

2008-01-01

433

Development of a low-noise, two-dimensional amplifier array  

NASA Astrophysics Data System (ADS)

This paper describes the recent development of a low-noise, two-dimensional analog front-end ASIC for hybrid pixel imaging detectors. Based on the Open-IP LSI project, the ASIC is designed to meet a low-noise requirement of better than 100e- (rms) with self-triggering capability. The ASIC is intended for the readout of pixel sensors utilizing silicon (Si) and cadmium telluride (CdTe) as detector materials for spectroscopic imaging observations in the X-ray and gamma-ray regions. The readout chip consists of a 4×4 matrix of identical 270 ?m×270 ?m pixel cells and was implemented with TSMC 0.35-?m CMOS technology. Each pixel cell contains a charge-sensitive amplifier, pole-zero cancellation circuit, shaper, comparator, and peak hold circuit. Preliminary testing of the ASIC achieved an 88e- (rms) equivalent noise charge and a 25e-/pF noise slope with power consumption of 150 ?W per pixel.

Kishishita, Tetsuichi; Ikeda, Hirokazu; Sakumura, Takuto; Tamura, Ken-ichi; Takahashi, Tadayuki

2009-01-01

434

NIF Capsule Sensitivity to Drive Asymmetry  

SciTech Connect

Proposed NIF ICF capsules are sensitive to asymmetries resulting from radiation drive and capsule imperfections. Capsule imperfections are amplified by the Rayleigh-Taylor and Richtmeyer-Meshkoff instabilities, and pose a risk at mode numbers in the range of 20 to 100. Radiation drive asymmetries are also amplified by these hydrodynamic instabilities, and pose a danger at modes below 10. Previous work has mostly concentrated on quantifying the sensitivity to capsule imperfections. Here we concentrate on characterizing the sensitivity to drive asymmetries.

Pollaine, S; Amendt, P; Haan, S; Herrmann, M; Jones, O; Suter, L

2003-09-19

435

Magnetic Bubble Traveling-Wave Amplifier.  

National Technical Information Service (NTIS)

A theoretical investigation is presented that exploits the magnetic bubble phenomena for producing a new type of traveling-wave amplifier (TWA) called the Magnetic Bubble Traveling-Wave Amplifier (MBTWA). The theoretical analysis follows the method used b...

L. J. Jasper

1979-01-01

436

Unconditionally Stable Microwave Si-IMPATT Amplifiers.  

National Technical Information Service (NTIS)

The purpose of this investigation has been the development of an improved understanding of the design and analysis of microwave reflection amplifiers employing the negative resistance property of the IMPATT devices. Unconditionally stable amplifier circui...

M. M. Seddik

1986-01-01

437

A high-power, traveling wave tube amplifier  

SciTech Connect

High-power X-band traveling wave tube amplifiers (TWT's) have been fabricated and tested. The tubes have gains ranging from 13 to 35 dB at 8.76 GHz and output powers ranging from 3 to 100 MW. The amplifiers are driven by the interaction of a slow space-charge wave, propagating on an electron beam, with an electromagnetic wave supported by the structure. The electron beam, which is produced from a magnetic-field-immersed field-emission cathode, has an energy of 850 keV, a current in the 1-kA range, and a pulse duration of 100 ns. The amplifiers are designed to operate as narrow-band devices in the TM{sub 01} mode. In this paper the authors report on the amplifier characteristics and compare their performance with those calculated using conventional TWT theory. The scaling of the gain and bandwidth with the beam current are approximately as expected from theory, but the absolute magnitude of the gain is somewhat greater than expected.

Shiffler, D.; Nation, J.A.; Kerslick, G.S. (Cornell Univ., Ithaca, NY (USA). Lab. of Plasma Studies)

1990-06-01

438

Power amplifier linearization using cubic spline interpolation  

Microsoft Academic Search

An adaptive RF power amplifier linearization technique is presented. The demodulated amplifier output is compared with the baseband input signal to estimate the amplifier's AM-AM and AM-PM characteristics, using cubic spline interpolation. The input signal is predistorted using these estimated characteristics to compensate for the amplifier's nonlinearity. The proposed technique has nearly 14 dB better suppression of the intermodulation products

Anit Lohtia; Paul A. Goud; Colin G. Englefield

1993-01-01

439

A CMOS Integrating Amplifier for the PHENIX Ring Imaging Cherenkov detector  

SciTech Connect

A CMOS integrating amplifier has been developed for use in the PHENIX Ring Imaging Cherenkov (RICH) detector. The amplifier, consisting of a charge-integrating amplifier followed by a variable gain amplifier (VGA), is an element of a photon measurement system comprising a photomultiplier tube, a wideband, gain of 10 amplifier, the integrating amplifier, and an analog memory followed by an ADC and double correlated sampling implemented in software. The integrating amplifier is designed for a nominal full scale input of 160 pC with a gain of 20 mV/pC and a dynamic range of 1000:1. The VGA is used for equalizing gains prior to forming analog sums for trigger purposes. The gain of the VGA is variable over a 3:1 range using a 5 bits digital control, and the risetime is held to approximately 20 ns using switched compensation in the VGA. Details of the design and results from several prototype devices fabricated in 1.2 {micro}m Orbit CMOS are presented. A complete noise analysis of the integrating amplifier and the correlated sampling process is included as well as a comparison of calculated, simulated and measured results.

Wintenberg, A.L.; Jones, J.P. Jr.; Young, G.R. [Oak Ridge National Lab., TN (United States); Moscone, C.G. [Tennessee Univ., Knoxville, TN (United States)

1997-11-01

440

Design of hysteresis circuits using differential amplifiers  

NASA Technical Reports Server (NTRS)

Design equations for hysteresis circuit are based on the following assumptions: amplifier input impedance is larger than source impedance; amplifier output impedance is less than load impedance; and amplifier switches state when differential input voltage is approximately zero. Circuits are designed to any given specifications.

Cooke, W. A.

1971-01-01

441

Quasi-Optical Constrained Lens Amplifiers.  

National Technical Information Service (NTIS)

A major goal in the field of quasi-optics is to increase the power available from solid state sources by combining the power of individual devices in free space, as demonstrated with grid oscillators and grid amplifiers. Grid amplifiers and most amplifier...

J. S. Schoenberg

1995-01-01

442

Solid state ku-band power amplifier  

NASA Technical Reports Server (NTRS)

The design, fabrication, and testing of two types of IMPATT diode reflection amplifiers and a transmission amplifier are given. The Ku-band IMPATT diode development is discussed. Circuitry and electrical performance of the final version of the Ku-band amplifier is described. Construction details and an outline and mounting drawing are presented.

Bowers, H. C.; Lockyear, W. H.

1972-01-01

443

Cooled Low-Noise HEMT Microwave Amplifiers  

NASA Technical Reports Server (NTRS)

Prototype cooled low-noise microwave amplifiers based on high-electron-mobility transistors (HEMT's) considered as replacements for cooled ruby masers used as low-noise receiver-front-end amplifiers in communications, radio science, radar systems, radio astronomy, and telemetry. HEMT amplifier operates at 12 K, requires less cooling power and operates at lower cost with simpler, more-reliable cooling system.

Bautista, J. Javier; Ortiz, Gerardo G.; Duh, Kuanghann George

1992-01-01

444

Modeling erbium-doped fiber amplifiers  

Microsoft Academic Search

Erbium-doped fiber amplifiers are modeled using the propagation and rate equations of a homogeneous two-level laser medium. Numerical methods are used to analyze the effects of optical modes and erbium confinement on amplifier performance, and to calculate both the gain and amplified spontaneous emission (ASE) spectra. Fibers with confined erbium doping are completely characterized from easily measured parameters: the ratio

C. Randy Giles; Emmanuel Desurvire

1991-01-01

445

Erbium-doped fiber amplifiers: linear approximations  

Microsoft Academic Search

In this paper, we show that there is a simple linear model for an erbium-doped fiber amplifier. Specifically, we show that the amplifier gain, raised to a wavelength-dependent power, is strongly linear with respect to the amplifier-induced increase in signal power

I. M. I. Habbab; A. A. M. Saleh; P. K. Runge

1995-01-01

446

Nonlinear predistortion for dynamic power amplifiers linearization  

Microsoft Academic Search

Signal predistortion is suitable for linearizing amplifier nonlinearity in high speed wireless applications. Volterra series provide an input-output relationship for nonlinear system with memory. The paper presents a new digital predistortion approach for the power amplifier linearization when we use the Volterra series for dynamic nonlinear modeling of the power amplifier comportment. The major advantage of the method is that

Ovidiu Leulescu; Teodor Petrescu

2005-01-01

447

Two stage double layer microstrip spatial amplifiers  

Microsoft Academic Search

Several two stage spatial amplifiers are presented. The amplifiers were constructed on double layer back to back microstrip circuits with a shared ground plane. The ground plane provides an effective isolation between the receiving antenna array and the transmitting antenna array. Furthermore, it serves as a heat sink in high-power amplifier design. The coupling between the two stages is accomplished

Toni Ivanov; Arnir Mortazawi

1995-01-01

448

Amplifier pumping optimization (in French)  

NASA Astrophysics Data System (ADS)

Slabs in NIF/LMJ large-aperture amplifiers are set at Brewster angle between two lamp arrays. A 2D+ ray-trace code is used to predict pump and gain coefficients profiles in the aperture. Code predictions, in good agreement with experimental results, show the high decay rate due to amplification of spontaneous emission leads to a strong depletion of the stored energy on the edges of the slabs. To compensate for this roll-off, shaped reflectors were calculated at CEL-V, using a dedicated routine added to the ray-trace code. They were fabricated and tested on the modified beamlet amplifier at LLNL. Numerical and experimental results agree to show that it is possible to redirect light using shaped reflectors, and that directing the pump radiation towards the edges of the aperture leads to a more uniform gain.

Le Touze, Geoffroy; Cabourdin, Olivier; Guenet, Mireille; Mengue, J. F.; Jancaitis, Kenneth S.; Rotter, Mark D.

1997-12-01

449

Analyse du bruit des transistors a effet de champ en technologie complementaire MOS et application a la realisation d'un amplificateur integre sensible au courant. (Analysis of the background noise of field effect transistors in MOS complementary technology and application in the construction of a current-sensitive integrated amplifier).  

National Technical Information Service (NTIS)

A low noise amplifier for use in high energy physics is developed. The origin and the mechanisms of the noise in MOSFET transistors is carried out with the aim of minimizing such effects in amplifiers. The research is applied in the construction of a curr...

E. Beuville

1989-01-01

450

Operational Amplifiers Animation/Presentation  

NSDL National Science Digital Library

This presentation, by Arizona State University, addresses operational amplifiers; their structure, construction and applications of the technology. The site is broken down into ten sections; these are: an introduction, terminal connections, op-amp internals, ideal op-amp equations, circuit analysis example, voltage follower, inverting configuration, non-inverting configuration, differentiators, and integrators. Overall, the site is flashy, but still informative presentation of this technology.

Holbert, Keith E.

2010-03-18

451

High power gas laser amplifier  

DOEpatents

A high power output CO.sub.2 gas laser amplifier having a number of sections, each comprising a plurality of annular pumping chambers spaced around the circumference of a vacuum chamber containing a cold cathode, gridded electron gun. The electron beam from the electron gun ionizes the gas lasing medium in the sections. An input laser beam is split into a plurality of annular beams, each passing through the sections comprising one pumping chamber.

Leland, Wallace T. (Los Alamos, NM); Stratton, Thomas F. (Los Alamos, NM)

1981-01-01

452

338-GHz Semiconductor Amplifier Module  

NASA Technical Reports Server (NTRS)

Research findings were reported from an investigation of new gallium nitride (GaN) monolithic millimeter-wave integrated circuit (MMIC) power amplifiers (PAs) targeting the highest output power and the highest efficiency for class-A operation in W-band (75-110 GHz). W-band PAs are a major component of many frequency multiplied submillimeter-wave LO signal sources. For spectrometer arrays, substantial W-band power is required due to the passive lossy frequency multipliers.

Samoska, Lorene A.; Gaier, Todd C.; Soria, Mary M.; Fung, King Man; Rasisic, Vesna; Deal, William; Leong, Kevin; Mei, Xiao Bing; Yoshida, Wayne; Liu, Po-Hsin; Uyeda, Jansen; Lai, Richard

2010-01-01

453

High power regenerative laser amplifier  

DOEpatents

A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.

Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.

1994-02-08

454

High power regenerative laser amplifier  

DOEpatents

A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse.

Miller, John L. (Livermore, CA) [Livermore, CA; Hackel, Lloyd A. (Livermore, CA) [Livermore, CA; Dane, Clifford B. (Dublin, CA) [Dublin, CA; Zapata, Luis E. (Livermore, CA) [Livermore, CA

1994-01-01

455

NIF/LMJ prototype amplifier mechanical design  

SciTech Connect

Amplifier prototypes for the National Ignition Facility and the Laser Megajoule will be tested at Lawrence Livermore National Laboratory. The prototype amplifier, which is an ensemble of modules from LLNL and Centre d`Etudes de Limeil-Valenton, is cassette-based with bottom access for maintenance. A sealed maintenance transfer vehicle which moves optical cassettes between the amplifier and the assembly cleanroom, and a vacuum gripper which holds laser slabs during cassette assembly will also be tested. The prototype amplifier will be used to verify amplifier optical performance, thermal recovery time, and cleanliness of mechanical operations.

Horvath, J.

1996-10-01

456

NIF Capsule Sensitivity to Drive Asymmetry  

Microsoft Academic Search

Proposed NIF ICF capsules are sensitive to asymmetries resulting from radiation drive and capsule imperfections. Capsule imperfections are amplified by the Rayleigh-Taylor and Richtmeyer-Meshkoff instabilites, and pose a risk at mode numbers in the range of 20 to 100. Radiation drive asymmetries are also amplified by these hydrodynamic instabilities, and pose a danger at modes below 10. Previous work has

Stephen Pollaine; Peter Amendt; Steven Haan; Mark Herrmann; Ogden Jones; Lawrence Suter

2003-01-01

457

HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.  

SciTech Connect

Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.

BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

2005-08-21

458

Direct solar-pumped iodine laser amplifier  

NASA Technical Reports Server (NTRS)

This semiannual progress report covers the period from April 1, 1985 to Sept. 30, 1985 under NASA grant NAS1-441 entitled direct solar pumped iodine laser amplifier. During this period the parametric studies of the iodine laser oscillator pumped by a Vortek simulator was carried out before the amplifier studies. The amplifier studies are postponed to the extended period following completion of the parametric studies. In addition, the kinetic modeling of a solar pumped iodine laser amplifier, and the experimental work for a solar pumped dye laser amplifier are in progress. This report contains three parts: (1) the radiation characteristics of solar simulator and the parametric characteristics of photodissociation iodine laser continuously pumped by a Vortek solar simulator; (2) kinetic modeling of a solar pumped iodine laser amplifier; and (3) the study of the dye laser amplifier pumped by a Tamarack solar simulator.

Han, K. S.

1985-01-01

459

Slow interfacial charge recombination in solid-state dye-sensitized solar cell using Al 2O 3-coated nanoporous TiO 2 films  

Microsoft Academic Search

Al2O3-coated TiO2 porous films were used to fabricate solid-state dye-sensitized solar cells using CuI as hole conductor. Investigation with transient photovoltage measurements showed that the Al2O3 interlayer slowed down the interfacial recombination of electrons in TiO2 with holes in CuI by forming a potential barrier at the TiO2\\/CuI interface. As a consequence, the cell made from Al2O3-coated TiO2 film showed

Xin-Tong Zhang; Hong-Wu Liu; Taketo Taguchi; Qing-Bo Meng; Osamu Sato; Akira Fujishima

2004-01-01

460

The spectacular human nose: an amplifier of individual quality?  

PubMed Central

Amplifiers are signals that improve the perception of underlying differences in quality. They are cost free and advantageous to high quality individuals, but disadvantageous to low quality individuals, as poor quality is easier perceived because of the amplifier. For an amplifier to evolve, the average fitness benefit to the high quality individuals should be higher than the average cost for the low quality individuals. The human nose is, compared to the nose of most other primates, extraordinary large, fragile and easily broken—especially in male–male interactions. May it have evolved as an amplifier among high quality individuals, allowing easy assessment of individual quality and influencing the perception of attractiveness? We tested the latter by manipulating the position of the nose tip or, as a control, the mouth in facial pictures and had the pictures rated for attractiveness. Our results show that facial attractiveness failed to be influenced by mouth manipulations. Yet, facial attractiveness increased whe