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Reference : UMR7638-BENQUI-001
Workplace : PALAISEAU
Date of publication : Friday, April 30, 2021
Scientific Responsible name : Benjamin Quilain
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
The supernovae are one of the most dramatic event in our universe. When a supernova explosion occurs, 99% of its energy is carried out by neutrinos. Therefore, the latter represents an ideal probe to characterize the supernovae explosion mechanism.
However, the galatic or near-galactic supernovae explosions are fairly rare (3 every century), reducing the possibility for neutrinos to bring significant constraints to the supernovae model since the last near-galatic explosion in 1987 (which led to a Nobel Prize for the Kamiokande experiment).
To overcome this limitation, the Super-Kamiokande experiment aims to detect the Diffuse Neutrino Supernovae Background (DSNB). It corresponds to the neutrino background coming from all the supernovae explosion since the beginning of the Universe. Its detection would open an unprecedented window on cosmology, the history of star formation, nucleosynthesis, and stellar evolution.
However, due to its relatively small flux, the DSNB remains undetected. In order to measure it for the first time, the Super-Kamiokande collaboration finished adding Gadolinium (Gd) to the 50 ktons of water of its tank in 2020, which will significantly improve the signal detection efficiency. Without any doubt, we are entering an era of extraordinary research with the next generation of this detector.
This thesis project proposes to actively contribute to the first detection of the DSNB. The student will be able to determine the reconstruction and selection of the DSNB events in Super-K Gadolinium, as well as studying possible ways to mitigate the background coming from radioactive nuclei or spallation. She/he will then be able to produce the fist measurement of the DNSB using the very first Super-Kamiokande Gd data taken from August 2020. Using these measurements, students interested in phenomenology may study the impact on the supernovae explosion or cosmic history models.
Finally, the student may study the prospects and perspectives of DSNB in the gigantic future Hyper-Kamiokande, the next generation of neutrino observatory to be built in Japan until 2027.
The neutrino group in LLR has been created in 2006 by Michel Gonin, as the first historical group in France to work on the world-leading neutrino experiments in Japan. Since then, the group has joint the unique T2K experiment, which has first discovered the neutrino appearance, as well as provided the very first hints of violation of the leptonic CP symetry. Since 2016, the group has also joined the Super-Kamiokande experiment, and have built a strong leadership inside regarding the DSNB neutrino detection and phenomenology.
The group is composed of 6 permanent researchers, 2 postdoctoral researchers and 3 PhD students, who has unique expertize in both high energy (CP violation, mass-hierarchy issue etc.) and low energy neutrinos (Supernovae, solar or reactor neutrinos).
The student will be able to travel to Japan to contribute to the Super-K data taking, actively work on the Super-K detector and collaborate with our colleagues from the University of Tokyo.
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