Dielectron production in pp and dp collisions at 1.25 GeV/u with HADES

TL;DR

This study investigates dielectron production in proton-proton and deuteron-proton collisions at 1.25 GeV/u using HADES, revealing a significant enhancement in pair yield for invariant masses above 140 MeV/c2 in deuteron-proton interactions.

Contribution

The paper provides new experimental data on dielectron emission in quasi-free neutron-proton collisions, extending the HADES setup with a Forward Wall hodoscope for spectator proton detection.

Findings

Enhanced dielectron yield for M > 140 MeV/c2 in dp compared to pp collisions.

Successful extension of HADES setup to identify quasi-free np interactions.

Quantitative data on dielectron production at 1.25 GeV/u.

Abstract

Inclusive production of e+e--pairs in pp and dp collisions at a kinetic beam energy of 1.25 GeV/u has been studied with the HADES spectrometer. In the latter case, the main goal was to obtain data on pair emission in quasi-free np collisions. To select this particular reaction channel the HADES experimental setup was extended with a Forward Wall hodoscope, which allowed to register spectator protons. Here, the measured invariant mass distributions demonstrate a strong enhancement of the pair yield for M > 140 MeV/c2 in comparison to pp data.