Main research activity
The primary goal of my research activity was to better understand the potentiality of one among a few of silicon-based technologies that showed promising timing capabilities, to determine whether such capabilities could be further improved to meet the requirements of the ALICE 3 Time-Of-Flight (TOF) detector. Indeed, extensive research on new generations of silicon sensors, including characterization measurements, performance studies, and simulations is being carried out.
The research activity done until now has focused on the characterization and performance study of different types of silicon sensors. The main goal was to verify the possibility of improving their performance and especially their time resolution up to values close to 20 ps, which is the target for the TOF detector of the ALICE 3 experiment. I take care of the characterization, preliminary performance study in laboratory and beam tests (preparation, setup and analysis of the data) and simulations of several types of sensors:
- LGADs: thanks to their already impressive timing performance, state-of-the-art LGADs, are planned to be used in many detector upgrades, but the demanding requirements of future experiments, like ALICE 3, have motivated significant R&D efforts. A wide range of LGADs, both single channel sensors and matrices, including different thickness, area, doping and inter-pad design have been fully characterized with laboratory measurements and studied first with a laser setup and subsequently using particle beams at CERN facilities. First tests of 25 μm and 35 μm LGADs compared to 50 μm-thick sensors highlighted the potential of a thinner design for improved time resolution. This prompted further investigations into progressively thinner sensors, arriving to test the first 15 μm-thick LGADs ever produced by FBK. Additionally, the innovative double-LGAD concept was introduced to address the challenge of small input signals in the electronics. Notably, this new concept not only yields the significant benefit of an enhancement of the charge at the input of electronics which allows for reduced power consumption, but also translates into an improvement in overall time resolution. Finally, a dedicated study has been performed to determine the impact of particle incidence angles on the time resolution, a crucial aspect to be taken into account in the ALICE 3 experiment. Overall, this R&D campaign on LGAD detectors, finally resulted in sensors that meet the time resolution requirements of ALICE 3 Time-Of-Flight detector, establishing them also as strong candidates for future-generation experiments.
- Fully depleted CMOS sensors: these sensors have the potential to offer both time resolution and complete coverage in a single layer with a true 2D monolithic design, offering a simpler and cheaper assembly. Extensive R&D has already started with the goal to significantly push the time resolution of CMOS sensors well beyond current values, by considering layouts with a thin gain layer that could allow them to reach the time performance requirements while maintaining a reasonable power consumption.
- SiPMs: a TOF layer equipped with SiPMs has the advantage that it can be also used as readout for a RICH detector being such sensors able to detect both charged particles and photons. Recently it has been demonstrated that SiPMs can directly detect charged particles thanks to Cherenkov light emission occurring in the protective layer typically placed above the sensor. Ongoing R&D involves the test of SiPMs with various materials and thicknesses of the protective layer. A time resolution of around 20 ps was measured.
All the sensors were also studied when connected to an electronic chain: a test beam was done with a full electronic chain, composed by LIROC ASIC front-end or a pFEB-d board and a TDC (picoTDC developed at CERN with a time resolution of 3 ps LSB), connected to the sensors, to study both the electronics itself and the performance of the sensors connected to a discriminator and a time-to-digital converter.
Data analysis on TOF performance
I’m one of the leading people in the data analysis to measure the performance of the ALICE Time-Of-Flight system in Run 3. This is done by evaluating the detector resolution and verifying the quality of the reconstructed data. The timing resolution of the detector is measured with Run 3 data collected with pp collisions at √s = 13.6 TeV with two independent methods: the first one is a self-consistent measurement using only the data from the TOF and the second one by using the event times obtained with the TOF and the FT0 detectors, in order to have a cross-check. I'm the chair of the Paper Committee for the paper "Performance of the ALICE Time-Of-Flight detector in Run 3" currently in the last stage of IRC review.
ALICE Time-Of-Flight (TOF) detector activities
ALICE Time-Of-Flight (TOF) detector activities: during my first year of PhD, I was involved in maintenance activities of the TOF detector of the ALICE experiment, participating in the replacement of electronics modules. Currently stationed at CERN I have significantly enhanced my contributions to TOF operations on multiple levels. I've been an on-site expert for the TOF detector, providing fast resolutions to any hardware-related issues, but also actively involved in all detector maintenance operations during data-taking periods. During the LHC year-end technical stop (YETS), I helped in many maintenance and small upgrades activities. Since the 1st of July 2024, I am the System Run Coordinator (SRC) of the ALICE TOF detector, responsible for the proper working and data quality of the TOF during the ALICE data taking, and for the maintenance and development of the hardware and software components of the whole system.
Other activities
▪ Construction of a tracking telescope: we are currently developing a tracking telescope with the main purpose of providing precise reference track information of beam particles to measure the performance of ours DUTs in the next test beam campaigns. We constructed the telescope using ALTAIs sensors, we integrated the DAQ into EUDAQ2 and we configured all the programs to perform the reconstruction of the tracks with Corryvreckan framework. The whole system was then tested using cosmic data and a test beam setup to control that everything is working as expected.
▪ Teaching activities: I was the co-supervisor of several thesis, for bachelor and master students in Physics and Nuclear and Subnuclear Physics. I’m assigned supervisor of a summer student at CERN.
▪ Outreach: I collaborate in the organization of two masterclasses for high school students devised by the International Particle Physics Outreach Group and I am CERN guide for the ALICE Collaboration.
▪ Presentations: during the first year I presented the various results obtained with the different types of sensors in many national and international conferences, workshops and schools.
▪ Publications: many papers were published with the different results obtained with LGADs, SiPMs and CMOS LGADs sensors. In addition, an ALICE collaboration paper with the results coming from the data analysis on the performance of the ALICE Time-Of-Flight system in Run 3 is currently under the final stages of the review process.
