Search for sterile neutrino with sources NuFACT 2015 Centro - PowerPoint PPT Presentation

Search for sterile neutrino with sources NuFACT 2015 Centro Brasileiro de Pesquisas Física Chiara Ghiano Universita di Genova (Italy) and INFN

Talk content Science Neutrinos: a golden field for astroparticle physics Neutrino anomalies The global picture Source experiments Sterile neutrino searches with sources Ideas and papers SOX experiment The BOREXINO experiment Ce144 production, extraction purification CeANG Geometry Disappearence and Waves High precision calorimetry Ce144 SOX-CE sensitivity Conclusions 2 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

Neutrinos: a golden field for astro-particle physics Over the last several years, neutrinos have been the origin of many important discoveries Masses are non-zero Oscillations are analogous to the CKM quark mixing Oscillations due to matter exist Important discoveries may be ahead: CP violation in the lepton sector (CPT ?) ν ν β ν Majorana or Dirac ’s; -less -decay, -masses Sterile neutrinos Right handed neutrinos and see-saw mechanisms The astronomical importance of neutrinos from space is immense, so is their role in the cosmic evolution. 3 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

Anomalies: experimental hints for sterile neutrinos Some experiments show anomalies at small L/E which may be interpreted as mixing of one or more sterile neutrinos with known states LSND Collaboration,A.Aguilar (1)Accellerator anomaly (3.8 σ ) et al. LSND LSND/MiniBoone P( ν µ → ν e ) and P( ν µ → ν e ) Collaboration Phys.Rev.D 64 112007 (2001) ( recently narrowed by Icarus/Opera/Minos down to a small region of MiniBooNE Collaboration ∼ 2 ) mass 1eV A.Aguilar et al. (MiniBooNE Collaboration) Phys.Rev.Lett. (2)Gallium anomaly (2.8 σ ) 110 161801 (2013) Calibration runs with radioactive sources at solar C. Giunti and M. Laveder, radiochemical experiments Gallex/SAGE. Phys.Rev. C83, 065504 (2011), Deficit observed in neutrinos coming from 51 Cr and 37 Ar sources arXiv:1006.3244 [hep-ph]. (3)Reactor antineutrino anomaly (2.5 σ ) New calculations of reactor anti-neutrino spectra A.Mueller et al. Phys.Rev.C → increased the flux by about 3% 83, 054615 (2011) G.Mention et al, effect of 6% on rate: R = 0.943+-0.023 Phys.Rev.D83, 073006 (2011) , *** Error on flux prediction ? (Reactor: unknown nuclear effects in reactor: e.g. 5 MeV anomaly) ***Missing new physics (oscillations to one or more sterile) (4)Some analysis of cosmological data 5 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

Combining all indications and exclusions The global picture The measured anomalies could be explained by a 4 th (& 5 th ?) sterile neutrino Δ 2 new ~ eV 2 with m Further running and new experiments are being planned to address this possibility → Establishing the existence of sterile neutrinos would be a major result! J.Kopp et al.,arXiv:1303.3011 6 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

Sterile neutrino searches with sources To be sensitive to ∆ 2 ~ 1eV 2 m → Need a source with E ~ 1-10 MeV → Located at a distance L ~ 1-10 m Neutrino source Detecting reaction ν → ν − + e − + e (1) Look for disappearance of ν e → radioactive background not possible to put the emitted by the source source inside the (2) Look for oscillation waves within the detector Monocromatic detector volume (oscillometry) low energy Anti-neutrino source ● Advantages of using nuclear decays: Detecting reaction ν + p n + e → + → ν e (or anti- ν e ) beam Intrinsicly pure → very little background → Neutrino spectrum known very precisely feasible to put the → Neutrino cross-sections in the ~MeV source inside the region known more precisely than at ~GeV detector → Neutrino flux known with high precision Continuum spectrum higher energy (~1.5 % level) 7 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

Several papers and ideas Technique Detector Sources Reaction Activity Reference 51 Cr JHEP08(2013)038, ν → ν + e + e 10MCi SOX Phys. Rev. Lett. (Borexino) 144 Ce- 144 Pr 107, ν + p e → + + n 100 kCi 201801 8.2 x 10 14 arXiV:1205.4419, 8 Li(ISODAR) arXiv:1312.0896 ν ν + p e → + + n /sec ArXiV:1310.3857 KamLAND 144 Ce(CeLAND) (2011) ν + p e → Large Liquid + + n 100 kCi scintillator arXiV:1109.6036 detectors 144 Ce- 144 Pr ν + p e → + + n Daya-Bay 500 kCi Phys.Rev.D75 51 Cr 093006(2007) ν → + 115 In e - + 115 Sn * LENS 10MCi 8.2 x 10 14 arXiV:1310.3857 8 Li(ISODAR) ν ν + p e → /sec + + n JUNO arXiV:1204.5379 51 Cr ν → + 70 Ga e - + 71 Ge Radiochemical BEST 3MCi Phys. Rev. D85, 37 Ar 013009, (2012) ν → ν + N + N Bolometers Richochet 5MCi 8 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

Source physical parameters 9 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

SOX: Short Distance Oscillation with the BoreXino experiment ● The idea of making a neutrino or anti-neutrino source experiment with BoreXino dates back to the birth of the project (1991) N.G. Basov, V. B. Rozanov, JETP 42 (1985) Borexino proposal, 1991 (Sr90) J.N.Bahcall,P.I.Krastev,E.Lisi, Phys.Lett.B348:121-123,1995 N.Ferrari,G.Fiorentini,B.Ricci, Phys. Lett B 387, 1996 (Cr51) I.R.Barabanov et al., Astrop. Phys. 8 (1997) Gallex coll. PL B 420 (1998) 114 Done (Cr51) A.Ianni,D.Montanino, Astrop. Phys. 10, 1999 (Cr51 and Sr90) A.Ianni,D.Montanino,G.Scioscia, Eur. Phys. J C8, 1999 (Cr51 and Sr90) SAGE coll. PRC 59 (1999) 2246 Done (Cr51 and Ar37) SAGE coll. PRC 73 (2006) 045805 C.Grieb,J.Link,R.S.Raghavan, Phys.Rev.D75:093006,2007 V.N.Gravrin et al., arXiv: nucl-ex:1006.2103 C.Giunti,M.Laveder, Phys.Rev.D82:113009,2010 C.Giunti,M.Laveder, arXiv:1012.4356 SOX Proposal European Research Council 320873 - Feb. 2012 - APPROVED and FINANCED Original SOX proposal: 51 Cr neutrino source OR 144 Ce anti-neutrino source Jan. 2014: agreement between CEA and INFN and Borexino Collaboration to merge the CELAND proposal with SOX SOX-Ce using the 144 Ce source proposed and developed by the CEA group 10 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

The BOREXINO experiment Mainly a solar neutrino experiment: ν e + e - → ν e + e - in an organic liquid scintillator Ultra-low radioactive background obtained via selection, shielding, and purifications Low energy threshold, good energy resolution, spatial recontruction, and pulse shape identif. Detection of ~ 500 pe/MeV Energy resolution σ E /E ~ 5% (@ 1MeV) Position resolution σ x ~ 10 cm (@ 1MeV) But also anti-neutrinos (Geo, Reactors, SN) Sub-MeV neutrino detection capability proved by the 7 Be, pep, pp solar neutrino detection down to few cpd/100 ton Anti-neutrino detection capability proved by geo-neutrino detection down to a few background events per Year in 300 t 11 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

The BOREXINO detector 2212 8” ETL 9351 PMTs mounted inside the SSS Water Tank Two Nylon balloons 150 µm (d=18 m, V = 2400 m 3 ) γ thick Shielding from and n. Inner Vessel Water Cerenkov detector (8.5 m, V = 340 m 3 ) (Muon Veto) 208 PMTs Filled with 278 tons of scintillator (PC @ 1.5 g/l of PPO) Inner Buffer (11.5 m) filled with PC + DMP Stainless Steel Sphere (d= 13.7 m, Volume = 1340 m 3 ) 12 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

Borexino detection capabilities Neutrinos Compton-like on electrons : ν → ν − + e − + e Mono-energetic ν e produce characteristic shoulder Main background: 7 Be solar ν e ∼ 45 cpd 100 t target Electron anti-neutrinos n Standard Reines-Cowan delayed β Delayed coincidence technique ( inverse p ~250 µsec decay on p ) ν e γ (2.2MeV) ~70 cm Extremely small background - 4 geo-neutrinos ev/y in 300 t Prompt - 9 reactor ~1 ns, ~1 cm - 0.4 random coincidence γ (511 KeV) γ (511 KeV) e + 13 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

Location of the source 14 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN

Technology and logistics To make a 100 kCi 144 Ce anti neutrinO generator (CeANG) → both technical and burocratic challenge Essentially a unique vendor (Mayak, Russia) Many paper work for authorizations: transportation, handling, storage.. (in Russia, France, Italy) Many technical problems to be solved for: CeANG production CeANG transportation and biological shielding requirements Usage and insertion beneath Borexino β High precision measurement of the activity and of the neutrino flux Synergy between CEA and Borexino Collaboration CEA : source production and transportation INFN : site preparation and Borexino detector preparation CEA/INFN/TUM : High precision calorimetry Borexino Collaboration : high precision MC, data analysis, calibrations 15 NuFACT 2015, Centro Brasileiro de Pesquisas Físicas Chiara Ghiano, University of Genova - INFN