Bari Osmanov, University of Florida. OscSNS - proposal for neutrino experiment at ORNL SNS facility

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1 , University of Florida OscSNS - proposal for neutrino experiment at ORNL SNS facility 1 of 19

2 Outline ORNL SNS facility Neutrino production at SNS Neutrino detection at SNS Event reconstruction and particle IDs Event rates and sensitivity Conclusion 2 of 19

3 Spallation Neutron Source 1 GeV proton beam on Hg target production of spallation neutrons 3 of 19

4 Neutrino production at SNS 11.6% p produce π + π + + +ν ( 100% π decay e +ν e +ν ) 99.3% DAR 0.7% DIF + ( ~100% DAR) 4 of 19

5 Timing structure With a simple beam-on timing cut one can obtain a fairly pure ν sample (14% contamination of ν and ν e each) 5 of 19

6 Total neutrino flux - Well-known neutrino spectra ν with E = 29.8 MeV - Mono-energetic - ν, ν e end-point E = 52.8 MeV 6 of 19

7 Neutrino detection MiniBooNE-type detector - 60 m upstream from the Hg target; - 12-m diameter sphere (fiducial = 10 m); - filled with 800 t of mineral oil CH2( fiducial = 450 t) + ~30 kg of butyl-pbd scintillator; phototubes: 3262 in detector (25% coverage) and 240 in veto region; - buried under 10 ft of dirt to suppress cosmic rays and beam-induced neutrons. 7 of 19

8 Geant4 beam simulation proton beamline interaction tracks world volume detector target hall 8 of 19

9 Neutrino flux in the detector (50 M POT) ν ν e ν ν e 9 of 19

10 lifetime in various materials Material Be Fe Hg Lifetime, ns (experiment) ± ± ± 1.5 Lifetime, ns (QGSPBERT) of 19

11 Geant4 detector simulation 40 MeV positron Done: - preliminary simplified geometry (tank, veto, PMTs, oil); - optical model parameters (refractive index, absorption length, etc) taken from other experiments (MiniBooNE) - Cherenkov and scintillation (slow and fast components) light propagation (LSND) Needs to be done: - simulate the phototube and electronic response - add more event types 10 of 19

12 Event reconstruction and particle IDs Maximum likelihood algorithm (charge and time info from PMTs) Particle topology Electron (fuzzy ring) Muon (sharp ring) through-going stopping 11 of 19

13 Cross-section measurements 800 ton detector (6 m radius) 5m fiducial volume 50% detector efficiency 1 year run time 1) ν C ν C 2) ν * e C e N 3) ν e e ν ee measured by KARMEN experiment but with only 86 events and 20% error OscSNS expects ~1,300 events Main channel for sterile neutrinos <5% error can be used to normalize total neutrino flux OscSNS expects ~4,600 events measured by LSND experiment OscSNS expects but with only 191 events and 17% error ~1,300 events 100,000 events from Super-K (unknown flux) 12 of 19

14 Event rates per year 800 ton detector (6 m radius), 5m fiducial volume, 50% detector efficiency, 10% flux uncertainty, 1 year run time 13 of 19

15 Background suppression Short pulsed beam: cosmic-ray background rejection 60 Hz, 695 ns pulse-width (500 ns pulse-width was achieved) 6% p produce π π +ν e +ν ν ν (0.5% π decay + ν e (24.6% decay e 100% DIF) < % DAR) reduction as ( expect MC becomes more advanced) 14 of 19

16 More background suppression DIF negative mesons are boosted in forward direction, so neutrinos are mostly emitted in forward direction Time spectrum of ν e Slow decay of Fast decay of Time-cut at 1000 ns can eliminate ν e in low-z materials(be,al); in high-z materials(hg,pb,fe); from decay in Hg,Pb of 19

17 Appearance sensitivity Confidence level curves forν ν e oscillations 16 of 19

18 Disappearance sensitivity Confidence level curves for ν ν s oscillations 17 of 19

19 Conclusion Neutrino environment at SNS facility offers a unique opportunity for both oscillation- and cross-section type of experiments: - background suppression - well-known neutrino flux - free source of neutrinos 18 of 19

20 OscSNS collaboration Current: - U Alabama - U Florida - LANL - Purdue U Calumet - U South Carolina - ORNL / U Tennessee Submitted white-paper to DoE(nuclear and high-energy) and NSF more information: 19 of 19

21 Danke Grazie Σε ευχαριστώ Thank you Tak Спасибо Merci धन व द Gracias Obrigado