photon counting detectors

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Tantalum STJ for Photon Counting Detectors

Tantalum STJ for Photon Counting Detectors

The aim is to investigate the interest of this kind of detectors for ground based astronomical applications and compare them to Hot Electron Bolometers devices (or Superconducting Single Photon Detectors, SSPD) that are also developed in our group [4]. Since the conventional detector arrays based on semi-conductor devices have recently progressed toward the direction of photon counting detectors in the visible [5], some niches have to be found for this type of detectors where

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Deep UV photon-counting detectors and applications

Deep UV photon-counting detectors and applications

Stanislav Soloviev, Alexey Vert, Peter Sandvik GE Global Research, 1 Research Circle, Niskayuna, NY 12309 ABSTRACT Photon counting detectors are used in many diverse applications and are well-suited to situations in which a weak signal is present in a relatively benign background. Examples of successful system applications of photon-counting detectors include ladar, bio-aerosol detection, communication, and low-light imaging. A variety of practical photon-counting detectors have been developed employing materials and technologies that cover the waveband from deep ultraviolet (UV) to the near-infrared. However, until recently, photoemissive detectors (photomultiplier tubes (PMTs) and their variants) were the only viable technology for photon-counting in the deep UV region of the spectrum. While PMTs exhibit extremely low dark count rates and large active area, they have other characteristics which make them unsuitable for certain applications. The characteristics and performance limitations of PMTs that prevent their use in some applications include bandwidth limitations, high bias voltages, sensitivity to magnetic fields, low quantum efficiency, large volume and high cost.
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A Radon-based criterion for the energy resolution of photon counting x-ray detectors

A Radon-based criterion for the energy resolution of photon counting x-ray detectors

2015 ). Equivalently, the standard deviation obtained by tting a Gaussian model ( Jakubek , 2011 ; Myronakis and Darambara , 2011 ; Myronakis et al. , 2012 ) or an error function ( Xu, Persson, Chen, Karlsson, Danielsson, Svensson and Bornefalk , 2013 ; Xu, Chen, Persson, Karlsson, Danielsson, Svensson and Bornefalk , 2013 ) was considered. However, the resulting energy resolution depends on the energy of the monochromatic illumination, typically as the square root of the latter ( Fredenberg et al. , 2010 ). Since photon-counting detectors aim at measuring simultaneously photons at dierent energies, the aforementioned criteria do not directly translate into image quality.
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Tantalum superconducting tunnel junctions for infrared photon counting

Tantalum superconducting tunnel junctions for infrared photon counting

2.1. Absorber epitaxy improvement Like a majority of photon counting detectors, STJ converts the incident energy into an excited charge population which gives an access to the deposited energy. Here, the photon-excited charges tunnel through the oxide barrier and the energy can be measured thanks to the integration of the induced current. Thus, the crystalline quality of the base Ta electrode (the absorber), in which the photons are absorbed, is a critical parameter and we need to maximize the lifetime of the excited charges.
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One-photon and two-photon quantum holography with bi-photon states of large spatial dimensionality

One-photon and two-photon quantum holography with bi-photon states of large spatial dimensionality

The experimental set-up for two-photon QH is illustrated in Fig. 1a. Photon pairs with a dimensionality of 1790 in the two-dimensional transverse space are generated via SPDC in a type-II geometry [9]. The crystal (i.e. near field of twin photons) is imaged with a 4 − f imaging system on a binary phase hologram and the entire flux of spontaneous down converted light illuminates the hologram. Fig. 1b shows the binary pattern engraved on a glass slide to create the phase hologram and the insert corresponds to the pattern encoded in the hologram : an array of 9 Dirac peaks. The engraving depth of the holograms is adjusted to produce a 0 − π
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Evidential combination of pedestrian detectors

Evidential combination of pedestrian detectors

2 CNRS, LIAMA, Beijing, P. R. China Abstract The importance of pedestrian detection in many applications has led to the develop- ment of many algorithms. In this paper, we address the problem of combining the outputs of several detectors. A pre-trained pedestrian detector is seen as a black box returning a set of bounding boxes with associated scores. A calibration step is first conducted to transform those scores into a probability measure. The bounding boxes are then grouped into clusters and their scores are combined. Different combination strategies using the theory of belief functions are proposed and compared to probabilistic ones. A combina- tion rule based on triangular norms is used to deal with dependencies among detectors. More than 30 state-of-the-art detectors were combined and tested on the Caltech Pedes- trian Detection Benchmark. The best combination strategy outperforms the currently best performing detector by 9% in terms of log-average miss rate.
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Improved robust T-wave alternans detectors

Improved robust T-wave alternans detectors

also considered but they are subsequently processed in two different ways in order to supply single 16 values series to the detectors. In the first case, the average over time of every T-wave was calculated and the series was composed of the received results (processing labeled M). In the second case, the singular value decomposition (SVD) was computed and the series was built by using the first eigenvector instead of T- wave itself (processing labeled S). Finally, in the simulated data section the 16 values series are directly synthesized instead of T-waves and subsequent processings.
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Performance analysis of knock detectors

Performance analysis of knock detectors

This paper examines performance of the knock detection tech- nique typically used in engine control systems, and the margin for possible improvement. We introduce a knock signal model and obtain an analytical result for the associated receiver oper- ating characteristic of the standard knock detector. To show the improvement potential, we derive the theoretical upper bound of performance. A special case with unknown model parame- ters is also considered. Numerical results stimulate the research of improved detectors.

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Counting with Population Protocols

Counting with Population Protocols

Keywords-Population protocol; Majority algorithm; Counting problem; Performance evaluation. I. I NTRODUCTION The population protocol model, introduced by Angluin et al. [2], provides theoretical foundations for analyzing global properties emerging from pairwise interactions among a large number of anonymous agents [5]. In the population protocol model, agents are modeled as identical and deterministic finite state machines, i.e each agent can be in a finite number of states while waiting to execute a transition. When two agents interact, they communicate their local state, and can move from one state to another according to a joint transi- tion function. The patterns of interaction are unpredictable, however they must be fair, in the sense that any interaction that should possibly appear cannot be avoided forever. The ultimate goal of population protocols is for all the agents to converge to a correct value independently of the interaction pattern. Examples of systems whose behavior can be modeled by population protocols range from molecule interactions of a chemical process to sensor networks in which agents, which are small devices embedded on animals, interact each time two animals are in the same radio range.
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Counting RNA pseudoknotted structures

Counting RNA pseudoknotted structures

the pseudoknot, respectively, as the set of arcs whose left (resp. right) extremities are in the left (resp. right) part of the pseudoknot, where left and right parts are defined as in S[r]

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IMPROVING RIEMANN PRIME COUNTING

IMPROVING RIEMANN PRIME COUNTING

4. Approximation of π(x) where ψ(x) is exactly known To check the validity of prime counting functions π 1 (x) and π 2 (x) it is good to compute them at values where the Chebyshev function ψ(x) is exactly known, that is, irrespectively of the knowledge of the critical zeros ρ. Exact values of ψ(x) at selected high values of x, with 10 6 ≤ x ≤ 10 15 are given in [10].

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Counting with Population Protocols

Counting with Population Protocols

This mechanism is similar to the averaging phase of the average-and-conquer algorithm of Alistarh et al. [1] for computing the majority value, and indeed our algorithm was in part inspired by this previous work. What distinguishes our algorithm from that of Alistarh et al. [1] is that we generalize the problem to counting in addition to computing majority, demonstrate that the additional mechanisms in their algorithm for propagating the majority value can be omitted without compromising correctness, and give a simpler proof of convergence of the averaging mechanism based on tracking the Euclidean distance between the vector of all agents’ values and the uniform vector.
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Consensus using Asynchronous Failure Detectors

Consensus using Asynchronous Failure Detectors

D, then D 0 is sufficient to solve a strict superset of the problems solvable by D. See [6] for details. Working entirely within an asynchronous framework allowed us to take advantage of the general results about I/O automata and to prove our results rigorously without too much difficulty. In this paper, we investigate the role of asynchronous failure detectors in circumventing the im- possibility of crash-tolerant consensus in asynchronous systems (FLP) [7]. Specifically, we demon- strate exactly how sufficiently strong AFDs circumvent the FLP impossibility. We borrow ideas from the important related result by Chandra, Hadzilacos, and Toueg [2] that says that the failure detector Ω is a “Weakest Failure Detector” that solves the consensus problem. Incidentally, the proof in [2] make certain implicit assumptions and assertions which are entirely reasonable and true, respectively. However, for the purpose of rigor, it is desirable that these assumptions be explicit and these assertions be proved. Our demonstration of how sufficiently strong AFDs circumvent FLP dovetails effortlessly with an analogous proof of “weakest AFD” for consensus.
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Counting and enumerating aggregate classifiers

Counting and enumerating aggregate classifiers

cision vectors are identical, i.e., if they define the same aggregating function. The above definitions put some useful structure on the solution space of AP. Let S sol = { (α 1 , ..., α L ) | (α 1 , ..., α L ) is a solution of AP}. For all val- ues of L and C, the set S sol contains infinitely many elements. However, the equivalence relation introduced in Definition 2 partitions the set S sol into Q equivalence classes S sol q with q ∈ {1, ..., Q}. Therefore, counting the number of distinct aggregate classifiers really amounts to computing the number Q of non equivalent solutions of AP. Formally, we define:
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Two-Photon Imaging

Two-Photon Imaging

Two-photon microscopy requires endogenous or exogenous emitting molecules. Unfortunately, while endoluminescence can be used for many tissues, it is rarely sufficient for imaging brain tissues, thus staining is necessary. For intravital brain microscopy three strategies can be used: local staining by dye injection, staining via the blood circulation after an intravenous injection and transfection of genes coding for fluorescent proteins. For instance, calcium sensitive dyes are infused locally to follow neuron activity, while non permeant plasmatic dyes are used to image the vascular network. Some dyes can cross the blood-brain-barrier (BBB) and stain the adjacent tissues. Other physico-chemical properties have also to be considered in the choice of a dye, such as the luminescent and the non linear absorption cross section efficiencies, the photochemical stability and the non toxicity. The large number of requirements explains why the development of new dyes remains an important area for fundamental research.
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ON COUNTING MEANINGFUL UNITS IN TEXTS

ON COUNTING MEANINGFUL UNITS IN TEXTS

Tenses in many languages provide other difficulties of counting procedures. The preterit form washed is one simple word, but the past tense form has washed is composed of two simple words. To make these two forms comparable both from a linguistic and a statistical point of view, several options can be considered. One consider washed to be improperly spelled: a rational spelling would separate the tense suffix from the root, as in wash-ed, so that this sequence would count as two simple words. Alternatively, we might perform a lemmatization of these forms, replacing the forms washed and have washed by a normal form (the infinitive), and attaching to it the grammatical values that differentiate the forms:
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Counting in trees for free

Counting in trees for free

Our notion of Presburger Tree Automata for ordered trees, which combines both regular constraints on the children of nodes as well as numerical constraints given by Presburger formulas, [r]

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Counting discriminants of number fields

Counting discriminants of number fields

We have generated A 4 extensions using Kummer theory of quadratic extensions over cyclic cubic fields, keeping only those extensions whose discriminant is less than the required bound (s[r]

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Counting for some convergent groups

Counting for some convergent groups

Counting for some convergent groups July 26, 2017 Marc Peign´e (1) , Samuel Tapie (2) & Pierre Vidotto (3) Abstract. We present examples of geometrically finite manifolds with pinched negative curvature, whose geodesic flow has infinite non-ergodic Bowen-Margulis measure and whose Poincar´e series converges at the critical exponent δΓ. We obtain an explicit asymptotic for their orbital growth function. Namely, for any α ∈]1, 2[ and any slowly varying function L : R → (0, +∞), we construct N-dimensional Hadamard manifolds (X, g) of negative and pinched curvature, whose group of oriented isometries admits convergent geometrically finite subgroups Γ such that, as R → +∞,
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Smoke detectors in prison cells

Smoke detectors in prison cells

• Detector location in the corridor could be directly in front of the cell or at each column between cells. Locating detectors at alternate columns (every second cell) cannot assure response times before critical conditions are reached. • The optical density readings obtained in the exhaust duct from the cell indicated that detectors could be located in these ducts and obtain a response prior to critical conditions being reached inside the cell. This application requires a reliable exhaust system in addition to the reliability of specific duct detectors to be used. Measures to prevent inmates from blocking exhaust vents must be applied. A program of upkeep and maintenance would have to be established to ensure reliable operation and to minimize false alarms.
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