Mainz 2022 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 57: Heavy-Ion Collisions and QCD Phases XII

HK 57.6: Vortrag

Donnerstag, 31. März 2022, 15:15–15:30, HK-H2

Background studies for a soft-photon measurement with the Forward Conversion Tracker in ALICE 3 — •Tim Rogoschinski for the ALICE collaboration — IKF Frankfurt

=1 =10000 =10000 We propose to construct a Forward Conversion Tracker at the LHC to measure photons of a few MeV in transverse momentum, so called ultra-soft photons, which have the potential to resolve the long standing No-dqsoft-photon puzzleNo-dq: Several experiments have observed an excess of ultra-soft photons with respect to the expected yield from Low’s theorem, which is very fundamentally relating ultra-soft photon production from inner Bremsstrahlung and the spectrum of charged hadrons. It is proposed to include a Forward Conversion Tracker (FCT) in ALICE 3, the next-generation heavy-ion collision experiment proposed for Run 5 and 6 at the LHC, to measure ultra-soft photons. The dominant background in this measurement, decay photons and external Bremsstrahlung, has been investigated and compared to the signal expectation derived from Low’s theorem. pp collisions at 13 TeV are simulated via PYTHIA and the produced particles are propagated through the proposed ALICE 3 geometry implemented in a GEANT4 setup. Aiming at a significant measurement, several background-suppression capabilities have been explored: Major improvements were achieved by the rejection of events with an electron or positron in the η - range of the FCT and by reducing the material budget in optimising the shape of the beam pipe. In this talk the status of the simulation and the background studies for a soft-photon measurement with the FCT is presented.