Marco Malabarba M.Sc.
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Marco Malabarba M.Sc.
Contact:
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Education
- 2021-2023, M.Sc. in Physics
Università degli studi di Milano, Italy
Master Thesis: Impact of the liquid scintillator optical properties on the JUNO detector response for the neutrino mass ordering determination - 2017-2020, B.Sc. in Physics
Università degli studi di Milano, Italy
Bachelor Thesis: Sensitivities studies of the JUNO detector to low energy solar neutrinos
Research Activity
JUNO (present)
JUNO, a multipurpose neutrino physics experiment currently under construction in China, is expected to be completed at the end of 2023. Its target will consist of 20 kton of liquid scillator. JUNO main goal is to determine the correct scenario of neutrino mass ordering within approximately 6 years of data-taking. However, thanks to its huge active volume and to an unprecedented energy resolution, JUNO will be able to detect and study solar, geo, atmosperic snd supernovae neutrinos as well. Furthermore JUNO will be the perfect candidate to perform exotic searches, such as proton decays or indirect dark matter detection.
During my master thesis I have evaluated, through Monte Carlo simulations, the impact of the liquid scintillator optical properties on the detector response. In particular, I focused on their impact on the JUNO energy resolution: this quantity is crucial to determine the correct neutrino mass ordering scenario with a good sensitivity.
I am have performed Monte Carlo studies of JUNO sensitivity to Be7, pep and CNO solar neutrinos: the experiment has the potentiality to measure their flux with an unprecedented precision through the combination of a spectral and a directional analysis. The former relies on the different spectral shapes of the solar neutrino species and backgrounds. The latter relies on the directionality of the fast, sub-dominant Cherenkov light: the PMT hits caused by Cherenkov photons exhibit a correlation with the Sun’s position only for solar neutrino events.
In particular, I worked together with the Beijing group to develop a solar neutrino generator for the JUNO official software suitable for both spectral and directional analyses. The generator also allows to perform day-night asymmetries studies and multi-channel simulation of solar neutrinos interactions . Finally, I also performed thorough checks of the JUNO official software to test it could properly simulate solar neutrino-like events and I had the leading role in the Monte Carlo simulations necessaty for the CID analysis. Finally, I came up with the strategy for aligning the physical hits of the events and hence for producting the directional PDFs.
During the filling stage of JUNO, I have studied the commissioning data in order to monitor the evolution and the quality of the detector. In particular, I have evaluated on the Dark Count Rate of the PMTs through periodic triggers. The quantity is important to have an early warning in case of issues (light leak, flashing/unstable PMTs etc). Furthermore, a precise knowledge of the Dark Count Rate of each PMT is needed to have a precise energy reconstruction of the events.
In the commissioning period I have also followed the evolution of the energy spectra of CD single events with different fiducial volume cuts. Understanding the features of the singles spectra is a necessary first step for performing any coincidence analysis (such as the IBD).
After the filling, my focus shifted on evaluating the Detector Response of JUNO. In any real detector, the reconstructed energy of an event does not coincide with its deposited energy mainly due to the non-linearity (caused both from instrinsic light production phenomena and instrumental effects), the energy resolution, and the detector non-uniformities. Hence, to succeed in any of its goals, a precise determination of these effects is needed. In particular, I focused on analyzing the calibration runs in JUNO. In fact, thanks to its vast and recurrent calibration campaigns (sources of Cs137, Mn54, Ge68, K40, Co60 and AmC are periodically deployed in several positions of the detector) the Detector Response could be thoroughly studied. Finally, low energy calibration sources (Cs137 and Mn54) showed some clear pile-ups between source events and C14 decays, allowing for a first estimation of C14 concentration in the detector.
SHELDON (May 2022 - June 2023)
The SHELDON project (Separation of CHerenkov Light for Directionality Of Neutrinos), born in the Milano working group of JUNO, has the goal to measure the experimental properties of the JUNO liquid scintillator, like its fluorescence times, emission spectrum, absorbance, refractive index and group velocity. In fact, a good knowledge of the liquid scintillator properties is crucial to perform accurate Monte Carlo simulations of JUNO.
During my master thesis I have participated in the production of the liquid scintillator and in the laboratory measurements of the fluorescence times, absorbance and refractive index.
Selected Talks:
Parallel Talk: "JUNO detector response determination through calibration data"
Seminar talk: "First results from the JUNO experiment"
Invited Parallel Talk: "JUNO potential for SN, solar, and atmospheric neutrinos"
Parallel Talk: "Directional solar neutrino analysis in JUNO "
Seminar talk: "Impact of the liquid scintillator optical properties on the JUNO detector response for the neutrino mass ordering determination"
Parallel Talk: "JUNO sensitivity studies to solar neutrinos"