Development of readout electronics for the RICH detector in the HADES and CBM experiments - HADES RICH upgrade, mRICH detector construction and analysis -

This work contributes large parts to the development, installation and monitoring of the FPGA based readout of the new DiRICH board in the HADES, CBM and mCBM experiments. In addition, an analysis of data taken in the 2020 mCBM beamtime campaign is performed. The HADES and CBM experiments are fixed target heavy ion experiments at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt/Germany respectively at the upcoming Facility of Antiproton and Ion Research (FAIR). HADES is a well established experiment at the SIS18 accelerator of GSI and will be completing the future Compressed Baryonic Matter (CBM) pillar of FAIR together with the CBM experiment at SIS100. Both experiments aim for the measurement of di-electrons and their spectrum in different energy regimes. The Ring Imaging Cherenkov (RICH) detector, a subdetector in both experiments, is allowing for clean electron identification. The HADES RICH detector has been upgraded with a new photon detector based on MAPMTs. New front end electronics have been developed which will also be used for CBM at SIS100. The DiRICH FEE is based on TDC measurement of MAPMT signals in a FPGA on the DiRICH board. The presented work focusses on the upgrade of the HADES RICH with a new photodetection plane based on MAPMTs and DiRICH readout. The use of 428 MAPMTs with 856 DiRICH boards is opening up new capabilities in the electron identification for the HADES experiment and is in parallel a large scale prototype test of the CBM RICH detector electronics. The powering scheme as well as the monitoring of the RICH is upgraded to match the new electronics. The full upgraded HADES RICH performed excellently in the march 2019 Ag+Ag beamtime at 1.58 AGeV. A second prototype, based on the same DiRICH electronics as the upgraded HADES RICH, has been developed for the mCBM experiment. The mCBM experiment is a prototype experiment of the future CBM experiment for the test of the common free-streaming readout and online analysis algorithms. A dedicated mRICH prototype has been designed, constructed and commissioned with a new readout concept, based on the known TrbNet network and adapted to the free-streaming environment. The readout concept of mRICH in phase-I of mCBM is further developed towards phase-II with the first implementation of the readout concept on the final CBM hardware. The new development includes i.a. major changes in the data transport and the handling of the readout. The data from the phase-I beamtime 2020 of mCBM is analysed in terms of the readout performance as well as the synchronisation to the other sub-detectors. Excellent time- and spatial correlations between the mRICH and mTOF detectors are found and described in detail in this work. An additional analysis of the mRICH rings and the hits is performed in detail and shows the reliable behaviour of the constructed mRICH prototype detector in the free streaming environment. Finally, in a first test beam, a first version of the phase-II readout with full synchronisation to the other mCBM detectors could successfully be brought into operation

Event reconstruction of free-streaming data for the RICH detector in the CBM experiment

The Compressed Baryonic Matter (CBM) experiment is a dedicated heavy ion collision experiment at the FAIR facility. It will be one of the first HEP experiments which works in a triggerless mode: data received in the DAQ from the detectors will not be associated with events by a hardware trigger anymore. All raw data within a giventime period will be collected continuously in containers, so-called time-slices. The task of the reconstruction algorithms is to create events out of this raw data stream. In this contribution, the optimization of the reconstruction software in the RICH detector to the free-streaming data flow is presented. The implementation of ring reconstruction algorithms which use time measurements of the hits as an additional parameter is discussed

New results on light nuclei, hyperons and hypernuclei from HADES (HADES collaboration)

International audienceIn March 2019 the HADES experiment recorded 14 billion Ag+Ag collisions at √sNN = 2.55 GeV as a part of the FAIR phase-0 physics program. In this contribution, we present and investigate our capabilities to reconstruct and analyze weakly decaying strange hadrons and hypernuclei emerging from these collisions. The focus is put on measuring the mean lifetimes of these particles

Exploring time like tranistions in pp, πp and AA reactions with HADES

Radiative transition of an excited baryon to a nucleon with emission of a virtual massive photon converting to dielectron pair (Dalitz decays) provides important information about baryon-photon coupling at low q2 in timelike region. A prominent enhancement in the respective electromagnetic transition Form Factors (etFF) at q2 near vector mesons ρ/ω poles has been predicted by various calculations reflecting strong baryon-vector meson couplings. The understanding of these couplings is also of primary importance for the interpretation of the emissivity of QCD matter studied in heavy ion collisions via dilepton emission. Dedicated measurements of baryon Dalitz decays in proton-proton and pion-proton scattering with HADES detector at GSI/FAIR are presented and discussed. The relevance of these studies for the interpretation of results obtained from heavy ion reactions is elucidated on the example of the HADES results