The HPS electromagnetic calorimeter

The Heavy Photon Search experiment (HPS) is searching for a new gauge boson, the so-called “heavy photon.” Through its kinetic mixing with the Standard Model photon, this particle could decay into an electron-positron pair. It would then be detectable as a narrow peak in the invariant mass spectrum of such pairs, or, depending on its lifetime, by a decay downstream of the production target. The HPS experiment is installed in Hall-B of Jefferson Lab. This article presents the design and performance of one of the two detectors of the experiment, the electromagnetic calorimeter, during the runs performed in 2015–2016. The calorimeter's main purpose is to provide a fast trigger and reduce the copious background from electromagnetic processes through matching with a tracking detector. The detector is a homogeneous calorimeter, made of 442 lead-tungstate (PbWO4) scintillating crystals, each read out by an avalanche photodiode coupled to a custom trans-impedance amplifier

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

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.Comment: 14 pages, 12 figures, to be published in Nucl. Inst. Meth.

The Heavy Photon Search test detector

The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment׳s technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in the e+e− invariant mass spectrum above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW04 crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top-bottom. This arrangement provides sensitivity to low-mass heavy photons, allows clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e+e− pairs requires the first layer of silicon sensors be placed only 10 cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. Accordingly, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab

Electronique FE pour les détecteurs de physique nucléaire

International audienc

Investigation of deep submicron single and double gate SOI MOSFETs in accumulation mode for enhanced performance

The behavior of single and double gate accumulation mode silicon-on-insulator (SOI) metal oxide semiconductor field effect transistors (MOSFETs) is thoroughly investigated. Accumulation mode devices present advantages over inversion mode transistors regarding transconductance, ease of fabrication, and parasitic effects. We have concluded, from experimental results and 2D simulations, that short channel effects such as DIBL and subthreshold swing degradation are substantially reduced in the volume accumulation regime, being even lower in thin-film double gate accumulation mode SOI MOSFETs than in inversion mode double gate SOI devices for adequate technological characteristics. The potential of thin-film accumulation mode SOI MOS transistors down to sub-0.1 mum technologies and up to 125 degrees C is demonstrated. (C) 2001 The Electrochemical Society

Conception théorique d'un nouveau modulateur électrooptique sur GaAs/AlGaAs à largeur de bande commandée en tension

Dans cet article, nous présentons un nouveau type de modulateur électrooptique à onde progressive. L'originalité de ce nouveau composant réside dans l'adjonction d'une tension de commande extérieure qui a pour rôle d'accorder l'indice microonde à l'indice optique : le résultat est un élargissement considérable de la largeur de bande de modulation

Conception théorique d'un nouveau modulateur électrooptique sur GaAs/AlGaAs à largeur de bande commandée en tension

This paper addresses a new type of travelling wave electrooptic modulators. The proposed modulator is tuned by an external variable voltage. By this method one may match the microwave index to the optical one. The consequence is a significant enhancement of the bandwidth modulation.Dans cet article, nous présentons un nouveau type de modulateur électrooptique à onde progressive. L'originalité de ce nouveau composant réside dans l'adjonction d'une tension de commande extérieure qui a pour rôle d'accorder l'indice microonde à l'indice optique : le résultat est un élargissement considérable de la largeur de bande de modulation

Effet des métallisations réelles dans les lignes GaAs pour les circuits microondes monolithiques

This paper deals with the effect of metallisation thickness in GaAs lines for microwave integrated circuits. An original approach, which is an extension of the well known Spectral Domain Technique is proposed. This method is applied to a typical Metal-Insulator-Semiconductor (MIS) GaAs line. The effect of the metallization thickness and conductivity of the strip on the propagation characteristics i.e. effective permittivity, losses and characteristic impedance are discussed.Cet article traite les effets des métallisations réelles dans les lignes GaAs pour circuits intégrés microondes. Une approche théorique originale, qui est en fait une extension de la Méthode Spectrale classique, est présentée dans cette communication. Cette approche est appliquée à une ligne Metal-Isolant-Semiconducteur (MIS) sur GaAs. On montre l'effet de l'épaisseur des rubans sur les caractéristiques de propagation : permittivité effective, pertes de propagation et impédance caractéristique

A thorough analysis of self-heating effects for SOI MOSFETs on SIMOX and UNIBOND substrates

The impact of the self heating effect (SH) on the low temperature operation of MOSFET/SOI is investigated with the help of a simple self heating model. Both the SIMOX and UNIBOND substrates are analyzed. The variation with temperature of the buried oxide thermal conductivity extracted from the thermal resistance is found to be in good agreement with the experimental data for fused silica. The influence of the depletion of the thin Si film is carefully analysed and the existence of an optimum substrate temperature is demonstrated allowing better device performance to be achieved