Séminaire doctorant

vendredi 9 juil. 2021, 14:00 → 16:00 Europe/Paris

Anthony Downes (LAPP - IN2P3), Paul Lagabbe (LAPP)

14:00 → 14:20 Calibration of Advanced Virgo and verification of the reconstructed gravitational wave signal with a photon calibrator

Virgo is a power-recycled Michelson interferometer with two arms of 3 km length, designed to detect gravitational waves (GWs) in a frequency range from 10 Hz to 10 kHz.
One needs to calibrate the interferometer (ITF), and to recontruct the de- tector strain signal h(t), from which GW signals are detected. The photon calibrator (PCal) is a particular mirror actuator which uses the radiation pres- sure of an auxiliary laser to drive the motion of the ITF mirror. Since the LIGO-Virgo Observing run O3 (2019/2020), the PCal is used as reference to calibrate the Virgo detector and to validate h(t).
The PCal setup is being modified to further reduce its calibration uncertain- ties for the LIGO-Virgo-KAGRA run O4 to be started mid 2022. During O3, the PCal calibration uncertainty was 1.73% and contributed for about half of the final h(t) uncertainty.
The goal for O4 is to reduce this uncertainty under 1%. To do so, we are:
• Modifying the optical setup to reduce power calibration variation cor- related with humidity as seen during O3. It has been shown that this correlation mainly came from the beam splitters used on the setup.
• Using InGaAs photodiodes instead of silicon photodiodes, in order to re- duce the photodiode sensing noise thanks to a more powerful pickoff and new electronics, and to reduce correlation between photodiode response and temperature.
• Using an integrating sphere on the PCal reflection bench to measure the reflected power directly, without additional optical elements on the beam path.
• Reducing laser power noise, which creates mirror movement noise.

Orateur: Paul Lagabbe (LAPP)

Presentation_seminaire.pdf

14:20 → 14:40 Analyse des données cosmiques du prototype double phase ProtoDUNE pour l'expérience de physique des neutrinos DUNE

ProtoDUNE double phase est un prototype de Chambre à Projection Temporelle à Argon Liquide avec une phase liquide dans laquelle vont dériver les électrons et une phase gazeuse servant à l'amplification du signal. Les données prises par ce détecteur au CERN en 2019 et 2020 avec des rayons cosmiques permettront de le caractériser et d'évaluer les performances de cette technologie. Il est notamment possible d'évaluer la pureté dans l'Argon liquide, le gain des amplificateurs de charges (LEMs), de caractériser la dépendance du gain aux différents paramètres de fonctionnement du détecteur et des effets dus aux non-uniformités du champs du dérive. Je présenterai les études en cours et les premiers résultats que j'ai obtenus sur ces différents sujets.

Orateur: Pablo KUNZE

Presentation_second_year_vfinal.pdf