PoS(ICHEP2020)211 AS) a https://pos.sissa.it/ and A. I. 3 K. A. Kouzakov 2 He detectors: The coherent C. Giunti, 4 1 decay and a liquid helium target. In this scattering − V F. Dordei, 1 M. Cadeddu, ∗ 4, 5 0, [email protected], , [email protected] Speaker ∗ using electron antineutrinos from tritium process with the whole ,weak that charge has of not the been nucleus observed asthe so seen by far, nucleus the the and electron electrons the antineutrino tend electron probe. toenergies cloud screen The of produces interference the a about between sharp 9 dipcoherent meV, reducing in elastic -nucleus the sizably scattering recoil the case. spectrum number Thisthe at technique of atomic weak allows, in expected recoil mixing principle, events angle to with measure atexperiment respect could energy provide to scales a sensitive the never test reached ofstronger before. the limit neutrino than the magnetic In current moment, addition, setting, ones. potentially, such a a low-energy [email protected], , [email protected] [email protected], [email protected] We propose an experimental setup to observe coherent elastic neutrino-atom scattering (CE Dipartimento di Fisica, Università degli StudiUniversitario di di Cagliari, Monserrato and - INFN, S.P. Sezione per di Sestu Cagliari,Istituto Km Complesso Nazionale 0.700, di 09042 Fisica Monserrato Nucleare (Cagliari), (INFN), Italy Monserrato Sezione - di S.P. Cagliari, per Complesso Sestu Universitario Km di 0.700,Istituto 09042 Nazionale Monserrato di (Cagliari), Fisica Italy Nucleare (INFN), SezioneDepartment di of Torino, Nuclear Via Physics P. Giuria and 1, QuantumMoscow I–10125 Theory State Torino, of University, Italy Moscow Collisions, 119991, Faculty Russia of Physics,Department Lomonosov of Theoretical Physics, Faculty of119991, Physics, Russia Lomonosov Moscow State University, Moscow Joint Institute for Nuclear Research, Dubna 141980,E-mail: Moscow Region, Russia Copyright owned by the author(s) under the terms of the Creative Commons 4 2 0 1 3 5 © Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). elastic neutrino-atom scattering E. Picciau, New process in superfluid 40th International Conference on High EnergyJuly physics 28 - - ICHEP2020 August 6, 2020 Prague, Czech Republic (virtual meeting) Studenikin PoS(ICHEP2020)211 4 a and ) 2 AS. In @ a ( Z E. Picciau is the weak  Å, meaning , is the atomic , ) 5 2 ] . o . The detection 0 @ Å ) ( [ N ∼  meV atom where , ' atom O( )] ' 2 AS), might unlock a door NS) by COHERENT Col- . At very low momentum @ a ) a ( 2 e @ ( , where  /  ] ) Å [ , o 2 atom ' / AS events, electron with energies 4 sin a + 1 AS for a spin-zero target is proportional to the 2 keV a 2  ) + (± 2 is the radius of the target atom including the electron @ @ ( N atom ' meV (Fig. 1(a)), while the minus sign applies to all the other #  AS detection 9 a ) − 2 ' @ ' ( , where ) 1 Z  /  ) He detectors: The coherent elastic neutrino-atom scattering are the number of and in the atom, 4 , atom o NS interaction requires a neutrino scattering off a nucleus at an energy scale # a 2 @' AS are well below the thresholds of currently available detectors. However, a and a 4 sin -dependent matrix element of the vector neutral-current charge for atomic processes: / 2 − @ 1 -decay source, that is characterized by a Q-value of 18.58 keV. The small recoils V [( keV. The differential cross section of CE 1 2 are the , and electron form factors, respectively. The minus sign applies to giving rise to the destructive interference between the electron and nuclear contributions at = 20 ) 4 2 In Fig. 1(b), we propose a future experiment that would allow the observation of CE A very important breakthrough within neutrino physics has been obtained in 2017 with the ¯ a @ ( i ' Atom + e @ h  shells, the reaction cancondition be is viewed translated as into taking theradius place condition in on of angstroms. the atomthat as Choosing this a a effect whole target is [11]. of expectedof to helium, this Satisfying be process, the this important called atomic Coherent for size Elastic atomic Neutrino-Atom is recoil Scattering energies (CE of square of the and atomic recoil energies around neutrino species. Such aUnfortunately, process the could downside be arises very from suitableenergy the is for detection very the challenging. point investigation of In of the view, neutrinoissue. next since section physics. detecting we will such describe a a possible small solution to overcome this 2. Experimental setup for CE order to achieve a sufficient number ofof low-energy CE few keV needis to be tritium exploited.produced One by promising CE sourcenew producing promising such technology based low-energy on neutrinos thesubsequent evaporation of detection helium using from field aexcitations ionization cold ( is surface and and taking rotons) their place. inwith the a Nuclear threshold target of that recoils about can 1 produce meV, representing result elementary an in ideal experimental the setup evaporation to of observe neutrino-atom helium atoms, transfers, such that for the looking at weak-interaction neutrino physics at scales never reached before, of the order of mixing angle, first observation of Coherent Elastic Neutrino-Nucleus Scattering (CE New process in superfluid 1. Coherent Elastic Neutrino Atom Scattering laboration with a CsI detectorits [1] prediction [3]. and in These 2020gations observations and with opened measurements a of a liquid neutron very argon distributionsneutrino-electromagnetic promising radii detector properties window [4,8], [2], [6–8] for weak and forty interaction new physics parameters years physicsanalyses beyond [5,8], investi- after the have very Standard Model unique [9, characteristicsprocess.10]. because Indeed, of These CE the lowlow momentum enough transfer to involved guarantee in the the about coherence the of the neutrino process. probingformation Under a quantitatively this given embedded consideration, size in one the of could so-called think the form target factors depending on the momentum transfer, in-  PoS(ICHEP2020)211 E. Picciau (b) AS (dashed red line). (b) Schematic representation a 3 AS processes it is necessary to use a tritium source a CE f AS. The recoil of a helium atom after the scattering with an electron a (a) He detectors: The coherent elastic neutrino-atom scattering 4 NS (black solid line) and CE a , for CE ' ) (a) Differential number of neutrino-induced events on helium atoms as a function of the atomic The work of K.K. and A.S. was supported by the RFBR under Grant No. 20-52-53022-GFEN-a. [1] D. Akimov et al. (COHERENT), Science 357,[2] 1123 (2017). D. Akimov et al. (COHERENT Collaboration), arXiv:2003.10630 [3] D. Z. Freedman, Phys. Rev. D 9, 1389[4] (1974). M. Cadeddu, C. Giunti, Y. F. Li,[5] and Y. Y.M. Zhang, Cadeddu Phys. Rev. and Lett. F. 120, Dordei, 072501 Phys. (2018). Rev. D[6] 99, 033010C. (2019). Giunti and A. Studenikin, Rev. Mod.[7] Phys. 87, 531M. (2015). Cadeddu et al., Phys. Rev. D 98,[8] 113010 (2018). M. Cadeddu et al., Phys. Rev. D 102[9] (2020). C. Giunti, Phys. Rev. D 101 (2020) 035039. References [10] M. Cadeddu et al., arXiv:2008.05022. [11] L. M. Sehgal and M. Wanninger, Physics Letters[12] B171,107 (1986). M. Cadeddu et al., Phys. Rev. D 100, 073014 (2019) of about 60 g, a160 tank cm filled and with radius about 90unique 500 measurements cm) kg exploiting and of this liquid a process are helium data-taking better (contained period described in of in a [12]. about cylinder 5 of years. height Some of the possible and antineutrino coming from the tritium source produces phonons and rotons which cause quantum evaporation. effects. We estimated that to observe at 3 New process in superfluid Figure 1: recoil energy of the detector proposed to observe CE