Measurement of low-mass e_s16 e- pair production in 1-A-GeV and 2-A-GeV C-C collision with HADES

Abstract

HADES is a secondary generation experiment operated at GSI Darmstadt with the main goal to study dielectron production in proton, pion and heavy ion induced reactions. The first part of the HADES mission is to reinvestigate the puzzling pair excess measured by the DLS collaboration in C_s13_s178201_s19_s16_s13_s178201_s19C and Ca_s13_s178201_s19_s16_s13_s178201_s19Ca collisions at 1_s13_s178201_s19A GeV. For this purpose dedicated measurements with the C_s13_s178201_s19_s16_s13_s178201_s19C system at 1 and 2_s13_s178201_s19A GeV were performed. The pair excess above a cocktail of free hadronic decays has been extracted and compared to the one measured by DLS. Furthermore, the excess is confronted with predictions of various model calculations.