First Observation of Coherent Elastic Neutrino-Nucleus Scattering

Abstract

Rise-time distributions of OFF events passing all optimized data cuts. .. .. 9.19 Rise-time distributions of ON events passing all optimized data cuts. .. .. . 9.20 Residual rise-time distributions of ON events passing all optimized data cuts. .

Coherent elastic neutrino-nucleus scattering at the European Spallation Source

“…As shown by COHERENT [2] an opportunity exists at the SNS to (partially) isolate prompt from delayed neutrino components via timing, but only for detectors sited in a small area of the "neutrino alley" [2], of roughly 10×1 m 2 . This limitation is due to a large gradient in prompt neutron background measured along the length of the alley (five orders of magnitude over 25 m [5,56,57]), and safety restrictions on corridor width encumbrance. The end of the SNS alley farthest from target (28 m) offers additional space for detectors requiring ancillary equipment such as cryogenic and purifier stages for liquid noble targets.…”

“…7 shows that an increase by a factor of eight in CEνNS signal rate per unit CsI mass can be obtained from this alternative cryogenic approach. The steady-state background adopted in Table I is that achieved for CsI[Na] at the SNS [2,5], with the estimated Cherenkov contribution subtracted. The presently envisioned design of a ESS cryogenic CsI detector is a small array of four crystals of individual dimensions 5 × 5 × 50 cm 3 , each read out by two 25 cm 2 LAAPDs, for a total mass of 22.5 kg.…”

“…In what respects the expected backgrounds, they can be divided into three classes: (i ) steady-state backgrounds (dominated by cosmic ray interactions or by their by-products inside or in the surroundings of a radioclean detector); (ii ) beam-related backgrounds, produced by neutrons escaping the target and reaching the detector; and (iii ) neutrino-induced neutrons. While the latter is irreducible, it has been shown that its contribution to the total event rate at the SNS is very small [2,5], and therefore will be neglected here. Beam-related backgrounds have also been neglected (awaiting confirmation from ESS neutron background studies), assuming that similar levels to those in [2] or shown in Fig.…”

“…Therefore, we deem a 10% representative of the cumulative uncertainties in QF, neutrino flux, nuclear form factor, and signal acceptance by the time data taking starts. While the steady-state background is in principle subject to sizable systematic uncertainties, it will be efficiently measured using beam-off data, as demonstrated at CO-HERENT [2,5]. Therefore, this systematic uncertainty is set to 1% in our calculations for all detectors under consideration.…”

Flavor-dependent radiative corrections in coherent elastic neutrino-nucleus scattering

“…Loops with charged leptons depend on the mass of the lepton resulting in flavor-dependent corrections (see figure 1). These effects are reasonably well appreciated in the CEνNS literature at a qualitative level [110,[121][122][123][124][125]. According to [126,127], neutrino-photon interactions are induced via loops of charged particles.…”