Seminars CSI : Mael Martin and Ward Amar

vendredi 18 sept. 2026, 14:00 → 16:00 Europe/Paris

Auditorium Marcel Vivargent (LAPP)

Francesco Costanza (LAPP), Luis Manzanillas (Manzanillas)

CSI

14:00 → 14:25 CSI Mael Martin: Low-energy neutrinos with DUNE, data reconstruction and analysis with DUNE’s Prototypes and sensitivity to solar neutrinos

The Deep Underground Neutrino Experiment (DUNE) is a next-generation long baseline neutrino experiment. First dedicated to observe accelerator GeV-scale neutrinos, the DUNE experiment with its gigantic Liquid Argon Time Projection Chamber (LArTPC) detectors, aims to explore the MeV energy range where solar and supernovæ neutrinos can be observed.
By observing neutrinos coming from the Sun, this experiment will be able to measure the solar oscillations parameters and might be capable of detecting for the first time hep neutrinos thanks to the high cross-section of the Charge-Current channel on Argon. In the low-energy regime relevant for solar neutrinos detection, DUNE faces significant backgrounds arising from neutrons, radiogenic gamma rays and cosmogenic isotopes. The first analyses conducted during the thesis evaluated, by meaning of simulation, the backgrounds before and after application of passive shielding. Discrimination techniques were also developed by analyzing the signal and the topology of the background in order to further reduce it. These techniques have subsequently been improved, making background reduction even more effective.
To understand detector performance, DUNE has built two full-scale prototypes at CERN.
At the MeV-scale, a ProtoDUNE-HD data analysis first permitted to determine the detector response and energy resolution. With ProtoDUNE-VD data taking, further analyses were conducted. Cosmic muons have been used to characterize the field distortion and a neutron source has been deployed to investigate experimentally the background signal.

Orateur: Maël Martin

CSI_2A_Labo_MM.pdf

14:25 → 14:50 CSI Ward Amar: Low-Loss Cavities for Advanced Virgo+: From the Stable Recycling Cavities to the Output Mode Cleaner

The Advanced Virgo+ gravitational-wave detector is planning to upgrade its interferometer recycling cavities to stable recycling cavities. This upgrade aims to eliminate the degeneracy of higher-order transverse modes (HOMs) and their excitation, reducing the losses of the cavities. However, the constraints imposed by the existing Virgo infrastructure make the optical design of these stable cavities particularly challenging.

In this talk, we present the latest results of our optical simulations and the validation of the proposed stable recycling cavity design, which is expected to be implemented in the coming years.

In parallel, we study another important cavity in the interferometer: the output mode cleaner (OMC). The OMC filters out HOMs at the output of the interferometer, playing a crucial role in the detection of gravitational waves. We experimentally characterize the spare OMC at LAPP and present our latest measurements of its total optical losses. We then investigate the origin of these losses, with a particular focus on losses due to scattering. These include backscattered light propagating along the cavity beam path towards the interferometer and Rayleigh scattering in the fused-silica substrate.

At LAPP, we measure and characterize both sources of scattering. These measurements provide new insight into the mechanisms contributing to OMC losses and help identify possible strategies for mitigating them in the future.

Orateur: Ward AMAR

LAPPSeminar_Low-Loss Cavities for Advanced Virgo+.pptx