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SUMMARY:CE$\\nu$AS processes in He-II: Beyond the model of ideal BEC
DTSTART;VALUE=DATE-TIME:20261029T144500Z
DTEND;VALUE=DATE-TIME:20261029T150000Z
DTSTAMP;VALUE=DATE-TIME:20261030T002914Z
UID:indico-contribution-6245@cern.ch
DESCRIPTION:Speakers: Konstantin Kouzakov (Lomonosov Moscow State Universi
 ty)\nSuperfluid helium-4 (He-II) is being considered as a detector materia
 l for light dark matter searches [1\,2] and the observation of coherent el
 astic neutrino-atom scattering (CE$\\nu$AS) [3]. It has extreme intrinsic 
 radiopurity\, high impedance to external vibration noise\, and a unique qu
 antum evaporation signal channel enabling the detection of phonon- and rot
 onlike modes via liberation of He-4 atoms into a vacuum. Detecting the lib
 erated atoms using atomic adsorption onto a calorimeter suspended in vacuu
 m above the free surface of the target He-II\, in principle\, can make it 
 possible to measure unprecedentedly low recoil energies (on a meV scale). 
 \n\nIn this contribution we address the issue of the He-II response to low
 -energy elastic neutrino-atom scattering. Specifically\, we focus on how t
 he effects of the real medium alter the atomic recoil spectra calculated i
 n the simplified model of ideal Bose-Einstein condensate (BEC) for He-II. 
 We present calculations for scattering of tritium electron antineutrinos o
 n atoms in He-II\, which case is relevant to the SArov Tritium-Ultra-Rich 
 Neutrino Experiment (SATURNE) [4] that aims at the first ever observation 
 of CE$\\nu$AS and the search of neutrino magnetic moment with a world-lead
 ing sensitivity. We show that taking into account the realistic atomic mom
 entum distribution in He-II [5] leads to quantitative and qualitative diff
 erences with respect to the ideal BEC model. We outline the risks to misin
 terpret the future SATURNE data as a signal of new physics\, in particular
 \, such as the neutrino magnetic moment\, if ignoring the effects of the r
 eal He-II medium.\n \n[1] S. A. Hertel\, A. Biekert\, J. Lin\, V. Velan\, 
 and D. N. McKinsey\, Phys. Rev. D **100**\, 092007 (2019)\n\n[2] B. von Kr
 osigk et al.\, SciPost Phys. Proc. **12**\, 016 (2023)\n\n[3] M. Cadeddu\,
  F. Dordei\, C. Giunti\, K. A. Kouzakov\, E. Picciau\, and A. I. Studeniki
 n\, Phys. Rev. D **100**\, 073014 (2019)\n\n[4] K. A. Kouzakov\, I. S. Ste
 pantsov\, and A. I. Studenikin\, Phys. Atom. Nucl. **88**\, 275 (2025)\n\n
 [5] P.E. Sokol and W.M. Snow\, in *Excitations in Two-Dimensional and Thre
 e-Dimensional Quantum Fluids*\, ed. by A.G.F. Wyatt and H.J. Lauter (Plenu
 m Press\, New York\, 1991)\, p. 47\n\nhttps://indico.particle.mephi.ru/eve
 nt/626/contributions/6245/
LOCATION: Conference Hall 1
URL:https://indico.particle.mephi.ru/event/626/contributions/6245/
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