Ph.D. in Physics

Eventi del Dottorato

Dottorato in Fisica

Journal Club Seminari 2021

24/03/2021 ore 15:00
in modalita' telematica
ore 15:00 Nina Burlac
(DOTTORATO IN FISICA) Towards a new approach for the Pulse Shape Discrimination in the GERDA experiment.
Abstract:
Neutrinoless double beta (0νββ) decay is a powerful tool to investigate lepton
number violation and the only practical way to assess the neutrinos nature (Dirac or
Majorana particles). It can therefore provide unique information about the physics
beyond the Standard Model (SM). Thanks to observing the neutrino oscillation
phenomenon, we know that neutrinos have mass, but the nature and the size of their
mass are still open issues in the neutrino sector beyond the SM. At present, the
only feasible experiments that have the potential to define the absolute scale of
the neutrino mass and to establish their nature are those searching for 0νββ decay.
GERDA experiment is considered among the leading experiments in the field, obtaining
the to-date best limit on the half-life of the 0νββ decay. This achievement results
from the careful selection of highly radio-pure materials and the efficient
background suppression techniques, such as pulse shape discrimination (PSD).
The initial phase of my master degree’s work concerned the investigation of the PSD
method applied to the data collected with germanium detectors in the GERDA
experiment. A new and innovative approach was subsequently implemented to improve
the PSD capabilities through a new digital filter that effectively treats the
experimental noise. The long-term goal of this thesis’s work is to apply the newly
developed technique to the forthcoming LEGEND-200 data, which will continue the
search of 0νββ decay, within the upgraded GERDA infrastructure.
The GERDA experimental setup, the pulse shape discrimination technique and the new
filtering technique with the obtained results will be summarized.

ore 15:45 Sacha Cormenier
(DOTTORATO IN FISICA) Theory of jet energy loss in the quark-gluon plasma
Abstract:
The quark-gluon plasma, the deconfined phase of Quantum ChromoDynamics (the theory
of the strong interaction) can be probed in the laboratory through ultrarelativistic
heavy-ion collision experiments, such as those at the Large Hadron Collider (LHC) at
CERN. The investigation of the medium produced in these experiments proceeds through
two complementary approaches: bulk properties (collective behavior of the many
lower-energy produced particles) and hard probes (the fewer higher-energy
particles).
Jets (collimated sprays of hadrons) are one of the key hard probes: understanding
the difference between jet development in a hot plasma, compared to development in
the vacuum or near-vacuum environment of a lower-multiplicity collision (e.g
proton-proton) is of the utmost importance for quantifying the properties of the
quark-gluon plasma. Also, this study is used in the light of the challenge posed by
the recent discovery of collective behavior in “small systems”, i.e. proton-nucleus
and high-multiplicity proton-proton collisions, unaccompanied by the modification of
jet spectra (“jet quenching”) observed in heavy-ion collisions.
Motivated by these current challenges and intense activity, the presentation will
investigate jet propagation in a hot quark-gluon plasma, concentrating on the theory
approaches to energy loss of the energetic partons composing the jet as they
traverse the medium.

Chair:

info: journal club time table

ore 15:00	Nina Burlac (DOTTORATO IN FISICA)	Towards a new approach for the Pulse Shape Discrimination in the GERDA experiment. Abstract: Neutrinoless double beta (0νββ) decay is a powerful tool to investigate lepton number violation and the only practical way to assess the neutrinos nature (Dirac or Majorana particles). It can therefore provide unique information about the physics beyond the Standard Model (SM). Thanks to observing the neutrino oscillation phenomenon, we know that neutrinos have mass, but the nature and the size of their mass are still open issues in the neutrino sector beyond the SM. At present, the only feasible experiments that have the potential to define the absolute scale of the neutrino mass and to establish their nature are those searching for 0νββ decay. GERDA experiment is considered among the leading experiments in the field, obtaining the to-date best limit on the half-life of the 0νββ decay. This achievement results from the careful selection of highly radio-pure materials and the efficient background suppression techniques, such as pulse shape discrimination (PSD). The initial phase of my master degree’s work concerned the investigation of the PSD method applied to the data collected with germanium detectors in the GERDA experiment. A new and innovative approach was subsequently implemented to improve the PSD capabilities through a new digital filter that effectively treats the experimental noise. The long-term goal of this thesis’s work is to apply the newly developed technique to the forthcoming LEGEND-200 data, which will continue the search of 0νββ decay, within the upgraded GERDA infrastructure. The GERDA experimental setup, the pulse shape discrimination technique and the new filtering technique with the obtained results will be summarized.
ore 15:45	Sacha Cormenier (DOTTORATO IN FISICA)	Theory of jet energy loss in the quark-gluon plasma Abstract: The quark-gluon plasma, the deconfined phase of Quantum ChromoDynamics (the theory of the strong interaction) can be probed in the laboratory through ultrarelativistic heavy-ion collision experiments, such as those at the Large Hadron Collider (LHC) at CERN. The investigation of the medium produced in these experiments proceeds through two complementary approaches: bulk properties (collective behavior of the many lower-energy produced particles) and hard probes (the fewer higher-energy particles). Jets (collimated sprays of hadrons) are one of the key hard probes: understanding the difference between jet development in a hot plasma, compared to development in the vacuum or near-vacuum environment of a lower-multiplicity collision (e.g proton-proton) is of the utmost importance for quantifying the properties of the quark-gluon plasma. Also, this study is used in the light of the challenge posed by the recent discovery of collective behavior in “small systems”, i.e. proton-nucleus and high-multiplicity proton-proton collisions, unaccompanied by the modification of jet spectra (“jet quenching”) observed in heavy-ion collisions. Motivated by these current challenges and intense activity, the presentation will investigate jet propagation in a hot quark-gluon plasma, concentrating on the theory approaches to energy loss of the energetic partons composing the jet as they traverse the medium.
Chair: