The high-acceptance dielectron spectrometer HADES

Abstract

HADES is a versatile magnetic spectrometer aimed at studying dielectron production in pion, proton and heavy-ion induced collisions. Its main features include a ring imaging gas Cherenkov detector for electron-hadron discrimination, a tracking system consisting of a set of 6 superconducting coils producing a toroidal field and drift chambers and a multiplicity and electron trigger array for additional electron-hadron discrimination and event characterization. A two-stage trigger system enhances events containing electrons. The physics program is focused on the investigation of hadron properties in nuclei and in the hot and dense hadronic matter. The detector system is characterized by an 85 % azimuthal coverage over a polar angle interval from 18• to 85• , a single electron efficiency of 50 % and a vector meson mass resolution of 2.5 %. Identification of pions, kaons and protons is achieved combining time-of-flight and energy loss measurements over a large momentum range. This paper describes the main features and the performance of the detector system.

Pion and eta production in elementary and heavy-ion collisions at SIS energies

“…The setup comprises a Ring Imaging Cerenkov Detector (RICH) in the field-free region around the target, a low-mass tracking system, a superconducting toroidal magnet, and additional detectors for particle identification. A detailed description of the setup can be found in [1]. As of now, HADES has measured rare and penetrating probes in C+C, Ar+KCl, p+p, d+p, p+Nb, and Au+Au collisions.…”

pK+Λ final state: Towards the extraction of the ppK−Fabbietti1, Agakishiev2, Behnke3 et al. 2013Nuclear Physics ASelf Cite390110View full textAdd to dashboardCite

“…The experiment was performed with the High Acceptance Di-Electron Spectrometer (HADES) [9] at the heavy-ion synchrotron SIS18 at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. A proton beam of ∼ 10 7 particles/s with 3.5 GeV kinetic energy was incident on a liquid hydrogen target of 50 mm thickness corresponding to 0.7 % interaction length.…”

Inclusive dielectron production in proton-proton collisions at 2.2 GeV beam energy

“…Technical aspects of the detector are described in Ref. [14]. Its main component providing electron and positron selection is a hadron-blind ring-imaging Cherenkov detector (RICH).…”

“…[11,14]: (1) leptons were identified based on various detector observables, (2) an efficiency correction was applied, (3) oppositesign leptons were combined into pairs, (4) the background of uncorrelated (and partially correlated) pairs representing the combinatorial background (CB) was subtracted using the same-event geometric mean of like-sign pairs, (5) the correction for the LVL1 trigger bias was applied, and finally (6) the resulting inclusive e + e − distributions were normalized to the reconstructed yield of elastically scattered protons into the HADES geometric acceptance (see Ref. [16] for details).…”