Data collection and analysis from Monolithic Active Pixel Sensors in Heavy Ion Physics at ALICE/CERN and proton CT prototype at Haukeland Universitetssykehus/Bergen

Project summary

Heavy Ion collisions produced at the CERN LHC collider produce unprecedented amounts of data, and will increase following the ongoing hardware upgrade projects to be installed by the end of 2020. The ALICE innter tracking system will be replaced by a full pixel-based detector using 7 planes of monolithic active pixels (MAPS), constructed from the custom designed ALPIDE (ALICE Pixel Detector) chip, containing 1024x512 in each chip.

The ALPIDE chips will also for m the basis for the Forward Calorimeter (FoCAL) to be build for the ALICE Long Shutdown 3 (2024). The proton CT prototype to be developed in collaboration with Helse Vest/Haukeland Universitetssykehus is based on the FoCAL layout. By building a calorimeter based on active pixels intertwined by absorbermaterial (Aluminium), a high track density (corresponding to short measurement time) can be detected, thus giving a precise position measurment necessary for efficient proton therapy treatment.

This project, in collaboration with UiB and other partner institutions in ALICE, makes active contributions to the development of readout electronics for the ALPIDE chips, to be used for all the detector systems described above. The readout system is required to collect data from all active sensors/pixels, and build events in real time, suppressing non-active pixels, otherwise the data volume would be prohibitive. Included in the readout system development is also readout, monitoring and slow control software. Design of the complete proton CT system also requires simulation at several levels, from system C based readout models through data occupancy simulations to complete tracking/physics simulation by GATE/Geant4.

The ALICE detector at CERN produces final data rates of several GB/s in continuous operation. Offline processing of these data requires a coordinated computing effort at a global scale. The ALICE collaboration has developed a grid middleware, AliEn (ALICE Environment), coordinating these efforts. This project is involved in the redesign and virtualisation generating a new generation jAliEn (Java AliEn) middleware, with a redesigned security algorithm based on certificate tokens with limited functional (as well as time) validity. The jAliEn system will also use container technology as a modern cloud-inspired lightweight virtualisation approach.