Antineutrino Energy [MeV] 0 10 20 30 40 50 0 0.5 1 1.5 ] -1 MeV -3 ) [10 e ν → ) µ ( µ ν ( osc P × φ 0.03 0.04 0.05 0.06 Oscillation Probability e ν → ) π ( µ ν (cp) = 0 δ /2 π (cp) = δ π (cp) = δ /2 π (cp) = 3 δ ν / ν CP-Violation Framework Exploiting π Decay at Rest F. Pessina* [PUC (Rio de Janeiro BR)], M. Grassi** [APC/CNRS (Paris FR)] A. Cabrera [APC/CNRS (Paris FR) & LNCA (Chooz FR)], S. Dusini [INFN (Padova IT)], H. Nunokawa [PUC (Rio de Janeiro BR)], F. Suekane [Tohoku U. (Sendai JP)] (Anti)Neutrino Energy [MeV] 0 10 20 30 40 50 ] -1 dN/dE [MeV 0 5 10 15 20 25 30 35 40 3 − 10 × Neutrino energy (MeV) 10 20 30 40 50 60 70 80 90 100 Cross section (10–38 cm2) 10–7 10–6 10–5 10–4 10–3 10–2 10–1 1 10 102 cohNC-p IBD νe-e νx-e νe-e νx-e NC-12C νe-12C νe-12C NC-16O νe-16O νe-16O cohNC-40Ar νe-40Ar νe-40Ar NC-ν-208Pb NC-ν-208Pb νe-208Pb Neutrino Detection Neutrino Interaction Neutrino Production & Oscillation Open Questions in Neutrino Physics Why yet another neutrino CP violation experiment ? Analysis Methods Results: Sensitivity to CP Violation Loading Fraction ) η Number of Interactions at 30 MeV ( 0 0.2 0.4 0.6 0.8 1 osc P × σ × targets N = n Neutrino Antineutrino Loading [g(Pb)/kg(LS)] 10 0.01 20 0.02 50 0.05 100 0.10 200 0.20 500 0.50 Exploit Charged-Current Quasi-Elastic interactions yielding positrons and electrons in the ﬁnal state Antineutrino: Inverse beta decay (IBD) on liquid scintillator H Neutrino: element with cross-section larger than IBD to be loaded into liquid scintillator. Eg Lead Sensitivity via χ2 analysis Main external uncertainty: sin2(θ23) = 0.5 ± 0.04 [3] ✤Implemented via pull parameter Different exposures studied through a scale factor B ✤Detector efﬁciency (assumed 100%) scanned via B Near Detector foreseen to investigate ✤Beam-on backgrounds (intrinsic neutrino contamination) ✤Flux normalization through 12C(v,v)12C* reaction ✤Cross-section of the element X loaded into liquid scintillator, normalized to IBD: σ(ν Χ)/σ(v p) ✤If σ(ν Χ) was suppressed (eg. Pb), use 12C charged-current interactions to bridge X and IBD Expected to be leading systematic uncertainty ✤Accounted for through parameter η ✤Scan both η central value and uncertainty References & Acknowledgments Past proposals to investigate CP violation in the neutrino sector aimed at exploiting oscillation-induced distortions in the ve appearance spectrum at multiple baselines, with either a decay-in- ﬂight (HH) [5] or a decay-at-rest [6] neutrino source. The left plot shows how our approach yields better sensitivity in the case of a single-baseline detector, and the expected improvement in the case of a multiple-baseline conﬁguration. Beyond CP Violation Pb allows to tag neutral current interactions thanks to neutron emission ▶︎ Use CC & NC to constrain non-standard v interactions. In case of Supernova burst, clear detection of ve, ve, vx [1] Bolozdynya at al, Arxiv 1211.5199 [2] Scholberg, Annu. Rev. Nucl. Part. Sci. 62 (2012), 81 [3] Capozzi et al, PRD D 95 (2017), 096014 [4] https://europeanspallationsource.se/technology [5] Minakata, Nunokawa PLB 413 (1997), 369 [6] Conrad et al, PRL 104 (2010), 141802 MG acknowledges support by the Marie Curie Research Grants Scheme, grant 707918. FP supported by CnPq and CAPES. *frcs.pessina@aluno.puc-rio.br,**marco.grassi@apc.in2p3.fr ⇡+ ! µ+ + ⌫(⇡) µ µ+ ! e+ + ⌫(µ) e + ¯⌫(µ) µ ⇡−! µ−+ ¯⌫(⇡) µ µ−! e−+ ¯⌫(µ) e + ⌫(µ) µ Accelerated protons hitting target produce pions. Pion decay (τ~28ns) results in mono energetic neutrino emission. Subsequent muon decay (2.2 μs) results in neutrino spectra characterized by 52.8 MeV endpoint. Distance source-detector L=16km (ﬁrst maximum) Look for appearance of electron (anti)neutrinos from π+ decay chain: %CRVWTGF D[VCTIGV Neutrino: counting analysis (“rate” analysis) Antineutrino: rate & shape analysis v OSCILLATION + ⌫(⇡) µ ¯⌫(µ) µ ⌫(µ) e FLAVOR SOURCE ⌫(⇡) µ ! ⌫e ¯⌫(µ) µ ! ¯⌫e Loading fraction in terms of η = ¯⌫e + p ! e+ + n 208Bi⇤! 208−YBi + Xγ + Yn ⌫e +208Pb ! 208