Electromagnetic Calorimeter for HADES

TL;DR

The paper details the design, simulation, and testing of an electromagnetic calorimeter for HADES, enhancing meson and photon detection in nucleus-nucleus collisions to improve dilepton data interpretation.

Contribution

It introduces a new calorimeter with specific layout, performance metrics, and capabilities for the HADES spectrometer, including detailed simulation and test results.

Findings

Photon and electron energy resolution of 5-6%/sqrt(E[GeV])

Reconstruction of eta mesons with S/B ratio of 0.4%

Lepton identification purity over 80% at >500 MeV/c

Abstract

We propose to build the Electromagnetic calorimeter for the HADES di-lepton spectrometer. It will enable to measure the data on neutral meson production from nucleus-nucleus collisions, which are essential for interpretation of dilepton data, but are unknown in the energy range of planned experiments (2-10 GeV per nucleon). The calorimeter will improve the electron-hadron separation, and will be used for detection of photons from strange resonances in elementary and HI reactions. Detailed description of the detector layout, the support structure, the electronic readout and its performance studied via Monte Carlo simulations and series of dedicated test experiments is presented. The device will cover the total area of about 8 m^2 at polar angles between 12 and 45 degrees with almost full azimuthal coverage. The photon and electron energy resolution achieved in test experiments amounts to 5-6%/sqrt(E[GeV]) which is sufficient for the eta meson reconstruction with S/B ratio of 0.4% in Ni+Ni collisions at 8 AGeV. A purity of the identified leptons after the hadron rejection, resulting from simulations based on the test measurements, is better than 80% at momenta above 500 MeV/c, where time-of-flight cannot be used.