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

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

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

Scintillating Fibers used as Profile Monitors for the CNAO HEBT Lines

The CNAO (Centro Nazionale di Adroterapia Oncologica) Foundation is the first Italian center for deep hadrontherapy with Protons and Carbon Ions. Several beam monitors exploiting the scintillation process have been designed to check the beam quality in the extraction lines, in order to guarantee patients safety. The SFH (Scintillating Fibers Harp), the QPM (Qualification Profile Monitor), and the SFP (Scintillating Fibers plus Photodiodes) are made up by two orthogonal scintillating fibers harps with not dead area for the horizontal and the vertical beam profiles measurement. The QPM and the SFH are both installed on the beam line and they use a CCD camera for the signal acquisition. The SFP is a SFH upgrade project aimed to replace the camera with two Photodiodes arrays coupled to the fibers in vacuum. The WD (Watch Dog) detector, not already installed, has been designed to check the beam position through the intensity of the beam tails. It uses two couples of scintillating fibers displaced transversally to the beam direction, coupled to four APDs (Avalanche Photodiodes). This work describes the beam detectors, their achieved performances and the most recent beam measurements

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

First measurement of the polarisation asymmetry of a gamma-ray beam between 1.7 to 74 MeV with the HARPO TPC

International audienc