HARPO: a TPC as a gamma-ray telescope and polarimeter

A gas Time Projection Chamber can be used for gamma-ray astronomy with excellent angular-precision and sensitivity to faint sources, and for polarimetry, through the measurement of photon conversion to $e^+e^-$ pairs. We present the expected performance in simulations and the recent development of a demonstrator for tests in a polarized photon beam.Comment: SPIE Astronomical Telescopes + Instrumentation, Ultraviolet to gamma ray, Montr\'eal, Canada 2014. v2: note added in proof. Copyright 2014 SPIE. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibite

The CMS Electromagnetic Calorimeter Data Acquisition System at the 2006 Test Beam

The Electromagnetic Calorimeter of the CMS experiment at the CERN LHC is an homogeneous calorimeter made of about 80000 Lead Tungstate crystals. From June to November 2006, eleven barrel Supermodules (1700 crystals each) were exposed to beam at CERN SPS, both in stand-alone and in association with portions of the Hadron Calorimeter. We present the description of the system used to configure and readout the calorimeter during this period. The full set of final readout electronics boards was employed, together with the pre-series version of the data acquisition software. During this testbeam, the hardware and software concepts for the final system were validated and the successfull operation of all the ten supermodules was ensured

Energy Resolution Performance of the CMS Electromagnetic Calorimeter

The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals

New development in the CMS ECAL Level-1 trigger system to meet the challenges of LHC Run 2

International audienceAbstract - The CMS Electromagnetic Calorimeter (ECAL) provides energy sums to the Level-1Calorimeter Trigger at a rate of 40 MHz. The processing of these trigger primitives (TPs) isperformed by dedicated trigger concentrator cards (TCCs) located in the CMS service cavern.Updates to the functionality of the TCCs were required to respond to the challengingexperimental conditions of LHC Run 2, where the center-of-mass of proton-proton collisionenergy was 13 TeV and the peak instantaneous luminosity of the proton beams reached 2x1034cm$^{-2}$ s$^{-1}$. A new algorithm, termed the Cumulative Overflow Killing Engine (COKE), has beendeveloped and implemented via software and firmware updates to the TCCs in order toautomatically detect and mask noisy or problematic TPs via configurable thresholds. The autorecovery of the TCCs has also been improved, to manage the Single Event Upsets (SEUs) fromthe front-end electronics. This allows the detector to trigger efficiently without direct expertintervention, and the thresholds can evolve with evolving LHC conditions

First Results of PEPITES, A New Transparent Profiler Based on Secondary Electrons Emission for Charged Particle Beams

International audienceThe PEPITES project* consists of a brand new operational prototype of an ultra-thin, radiation-resistant profiler capable of continuous operation on mid-energy (O(100 MeV)) charged particle accelerators. Secondary electron emission (SEE) is used for the signal because it only requires a small amount of material (10 nm); very linear, it also offers good dynamics. The lateral beam profile is sampled using segmented electrodes, constructed by thin film methods. Gold strips, as thin as the electrical conductivity allows (~ 50 nm), are deposited on an insulating substrate as thin as possible. While crossing the gold, the beam ejects the electrons by SEE, the current thus formed in each strip allows the sampling. SEE was characterized at ARRONAX with 68 MeV proton beams and at medical energies at CPO**. Electrodes were subjected to doses of up to 10⁹ Gy without showing significant degradation. A demonstrator with dedicated electronics (CEA) is installed at ARRONAX and will be used routinely with proton beams of 17-68 MeV for intensities of 100fA to 100nA. An overview of the design and first measurements will be presented, and system performances will be assessed

Development of a Transparent Profiler Based on Secondary Electrons Emission for Charged Particle Beams

International audienceThe PEPITES project* aims at realizing an operational prototype of an ultra-thin, radiation-resistant profiler able to permanently operate on mid-energy (O(100 MeV)) charged particle accelerators. PEPITES uses secondary electron emission (SEE) for the signal because it requires only a minimal thickness of material (10 nm); very linear, it also offers a great dynamic. The lateral beam profile is sampled using segmented electrodes, constructed by thin film methods. Gold strips, as thin as the electrical conductivity allows (~ 50 nm), are deposited on an as thin as possible insulating substrate. When crossing the gold, the beam ejects the electrons by SEE, the current thus formed in each strip allows the sampling. The technique was validated at ARRONAX with 68 MeV proton beams for intensities from 100 fA to 10 nA. SEE is characterized up to 100 nA at ARRONAX and medical energies at CPO**. Electrodes were subjected to doses of up to 10⁹ Gy without showing significant degradation. A demonstrator with dedicated electronics (CEA) will be installed at ARRONAX and used routinely. The performances of the system and its behavior over time will thus be characterized

Electromagnetic Calorimeter Raw Data Format

This document describes the Electromagnetic Calorimeter (ECAL) raw data format, which is generated by the ECAL Data Concentrator Card (DCC) sitting on the ECAL Off-Detector electronics crates. The DCC actions in response to possible errors in the input data are discussed. A software package responsible for the event decoding and data integrity monitoring, developed for the ECAL On-line and Off-line systems, is presented

Electronics for HARPO: Design, development and validation of electronics for a high performance polarised-Gamma-ray detector

International audienceWe designed and built an experimental apparatus based on a time projection chamber, a novel scheme for high performance γ-ray astronomy and polarimetry in the γ → e+e- regime. This presentation focuses on the electronics aspect of the detector and, in particular, on the versatile dedicated trigger system that we have developed which allowed us to take data on beam with a high γ-conversion signal efficiency and a high rejection factor for single tracks and upstream conversion background events. Our scheme allows for the selective collection of γ conversions in a high-background-rate environment, such as that which is present in orbit, with a fine 3D imaging of the events and very low (in particular electronics) background, at a mild cost in terms of the number of electronics channels and therefore of electrical power consumption