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Future SK Program for n e Physics

Future SK Program for n e Physics. Atsuko Kibayashi For the Super- Kamiokande Collaboration Okayama University June 14, 2013. Motivations. Neutron Capture by Gadolinium. 100% 80% 60% 40% 20% 0%. Captures on Gd. L arge cross section of Gd for neutron capture

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Future SK Program for n e Physics

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  1. Future SK Program for ne Physics Atsuko Kibayashi For the Super-Kamiokande Collaboration Okayama University June 14, 2013 RENO５０

  2. Motivations RENO５０

  3. Neutron Capture by Gadolinium 100% 80% 60% 40% 20% 0% Captures on Gd • Large cross section of Gd for neutron capture • ~49,000 barns (0.3 barns on free proton) • Coincident signal detection to suppress background • Beacom and Vagins, Phys. Rev. Lett., 93:171101, 2004] ne n p Gd + e γ 8 MeV ΔT~20μs Vertices within 50cm • 0.1% Gd gives 90% neutron capture eff. • ~100ton of Gd2(SO4)3 in SK 0.0001% 0.001% 0.01% 0.1% 1% RENO５０ Gd in Water

  4. Physics of neby GADZOOKS!Gadolinium Antineutrino Detector Zealously Outperforming Old Kamiokande, Super! • Observation of Supernova Relic Neutrino (SRN) • SRN has not yet been observed • Supernova Burst Neutrinos • Better direction determination by enhancement of electron scattering events • Reactor Neutrinos • Precise measurements of oscillation parameters by high statistics RENO５０

  5. SRN Spectrum SRN flux calculations Horiuchist al. PRD, 79, 083013 (2009) Expected no. of SRN events 1.3-6.7 events/year/22.5kton (10-30MeV) Expected SRN Spectrum (ne fluxes) • Need: • Large target mass • Background removability RENO５０

  6. Expected SRN Signal and Background Assume : • 90 % neutron capture efficiency, • 74% Gd gamma detection efficiency, • invisible muon B.G. is 35% of the SK-IV invisible muon B.G. Expect: • 10-45 SRN events in 10-years data taking (Evis = 10-30 MeV) RENO５０

  7. Supernova Burst Direction ne+p ne+p ne+p ne+p w/o Neutron Tagging n+e n+e n+e n+e SN at 10kpc Neutrino flux and spectrum from Livermore simulation RENO５０

  8. Supernova Burst Direction ne+p ne+p ne+p ne+p w/ Neutron Tagging Removing tagged events n+e n+e n+e n+e SN at 10kpc Neutrino flux and spectrum from Livermore simulation RENO５０

  9. SN Direction Determination Precision H. Ishino Direction Determination Precision (1000MC events) Direction Determination Precision tag eff. = 1.0 振動なし No Osc. 振動あり（正階層性） Oscillated (normal hierarchy) tag eff. = 0.8 振動あり（逆階層性） Oscillated(inverted hierarchy) Number of supernovae tag eff. = 0.0 2x better precision with neutron tagging. RENO５０

  10. Questions Gd in SK? • Water transparency? • How to purify Gd water? • How to introduce/remove Gd? • Effect on SK material? • Effect on solar neutrino analysis? • In a water Cherenkov detector? EGADS RENO５０

  11. R&D EGADS RENO５０

  12. Super-Kamiokande EGADS Evaluating Gadolinium’s Action on Detector Systems EGADS hall SK water purification system To Atotsu entrance ５０ｍ Parking place Underground site map RENO５０

  13. EGADS Lab. in Kamioka Mine Transparency measuring device Gd Removing Resin 200m3SUStank Feb.16, 2011 15 m3plastic tank (for dissolving Gd) Gdpurification (resin to remove U keeping Gd) Gd-water filtration RENO５０

  14. M. Vagins Membrane filter technology Water Monovalent Multivalent Viruses Bacteria Suspended Ions Ions Solids Microfiltration 1,000 – 100,000 angstroms membrane pore size Ultrafiltration 100 – 1,000 angstroms membrane pore size Nanofiltration 10 – 100 angstroms membrane pore size Reverse Osmosis 5 – 15 angstroms membrane pore size Water Monovalent Multivalent Viruses Bacteria Suspended Ions Ions Solids Water Monovalent Multivalent Viruses Bacteria Suspended Ions Ions Solids Water Monovalent Multivalent Viruses Bacteria Suspended Ions Ions Solids small large size Gd2(SO4)3

  15. EGADS Selective Filtration System M. Vagins To Drain UF#1 Reject Line Ultrafilter #1 Ultrafilter #1 Chiller 200 ton EGADS Main Tank UV #1 0.2 m 2nd Stage Filter Repressurization Pump (>0.6 MPa, >4 ton/hr) 5 m 1st Stage Filter Intake Pump (>4 ton/hr) Membrane Degas UF#2 Reject Nanofilter #1 Nanofilter #1 0.5 ton Collection Buffer Tank Concentrated Gd NF Reject Lines Nanofilter #1 Nanofilter #1 Conveying Pump (~0.35 MPa, >4 ton/hr) Ultrafilter #2 Ultrafilter #2 Recycles RO Reject Lines UV #2 0.5 ton Buffer Tank Repressurization Pump (>0.6 MPa, >3 ton/hr) RO Permeate Lines Nanofilter #2 Nanofilter #2 Nanofilter #2 TOC Repressur-ization Pump (>0.9 MPa, >2 ton/hr) DI #2 Repressurization Pump (>0.9 MPa, >1.5 ton/hr) DI #1 RO #2 5 m Filter 5 m Filter RO #1 RENO５０

  16. EGADS (Step 1) 200 m3tank 15m3tank Gd-water filtration system w/o PMT • Circulation of pure water in200 m3 tank, to evaluate basic performance of the filtration system • March – June, 2011

  17. EGADS (Step 2) 200 m3tank 15m3tank Gd-water filtration system w/o PMT • Circulation of 0.2% Gd2(SO4)3 dissolved waterin15m3 tank through the filtration system • Measurement of Gd-dissolved water transparency • August, 2011 – December, 2012

  18. EGADS (Step 3) 200 m3tank 15m3tank Gd-water filtration system w/o PMT • Circulation of 0.2% Gd2(SO4)3 dissolved waterin 200m3 tank through the filtration system. • Study of effects on SUS tank (accelerated studies have shown no problems) • December, 2012 – June, 2013

  19. T. Yano Water Transparency MeasurementMethod RENO５０

  20. Light Remaining at 15 m in 200 ton tank M. Vagins SK-III and SK-IV Ultrapure Water = 74.7% - 82.1% @ 15 m 70 % => 85% of pure water 60 kg of Gd2(SO4)3*8H2O 52% n capture on Gd 89.4 kg of Gd2(SO4)3*8H2O 62% on Gd 149.4 kg of Gd2(SO4)3*8H2O 73% on Gd 274 kg of Gd2(SO4)3*8H2O 83% on Gd 400 kg of Gd2(SO4)3*8H2O 88% on Gd 30 kg of Gd2(SO4)3*8H2O 35% n capture on Gd RENO５０

  21. EGADS (Step 4) 200 m3tank 15m3tank Gd-water filtration system • 240 PMT mounting • July - August, 2013

  22. EGADS (last Step) 200 m3tank 15m3tank Mini-SK (w/ same SK material) Gd-water filtration system • Circulation of pure water, then 0.2% Gd2(SO4)3 dissolved water • Integrated test • Starting September, 2013

  23. for GADZOOKS! RENO５０

  24. M. Smy Effect on Solar Neutrino Analysis? • To achieve 3.5 MeV(Kin.) solar neutrino analysis in 0.2% Gd+H2O SK, the following radioactivity levels would be needed. < 2.8 x 10-11 g(238U)/g(Gd) < 8.6 x 10-11 g(232Th)/g(Gd) < 9.6 x 10-18 g(226Ra)/g(Gd) =>Corresponds to < 0.35 mBq/kg(Gd) RENO５０

  25. L. Labarga Radioactivity of Gd2(SO4)3 Radioactivity in Gd2(SO4)3batches measured in Canfranc[mBq/Kg, limits are @ 95% c.l.] Still too high preliminary => To reduce Radium, one solution is to use commercial selective resins available. RENO５０

  26. Answers Gd in SK? • Water transparency? • How to purify Gd water? • How to introduce/remove Gd? • Effect on SK material? • Effect on solar neutrino analysis? • In a water Cherenkov detector? 85% of pure water Method being established Mass removal still under study, commercial resin available Gd2(SO4)3 proven to be safe Radioactivity still too high (esp. Ra). Commercial resin will be tested. Demonstration of Cherenkov detection of Gd(n, gamma) Gd (H.Watanabe et al. Astropart. Phys., 31, 320-328 (2009) RENO５０

  27. M. Nakahata R&D Schedule RENO５０

  28. Conclusion • For SRN detection • A large target volume is needed => SK is the only one w/ that kind of volume • Addition of Gd unable us to detect SRN • For SN detection • Direction accuracycan be improved by tagging ne events Gd in water Cherenkov detector R&D project (EGADS) is in progress. Gd in SK looks more and more promising. As soon as EGADS successfully demonstrates the feasibility for GADZOOKS!, schedule for GADZOOKS! will be discussed among the SK collaboration. We hope to start GADZOOKS! in a few years. RENO５０

  29. Backups RENO５０

  30. EGADS Members • ICRR, University of Tokyo • Y. Kishimoto , M. Nakahata, H. Sekiya • Kavli, IPMU • L. Marti, M. Vagins • Kobe University • Y. Takeuchi • Okayama University • H. Ishino, A. Kibayashi, Y. Koshio, T. Mori, M. Sakuda, Y. Yamada, T. Yano, • University Autonoma Madrid • L. Labarga, P. Fernadez • University of California, Irvine • G. Carminati, J. Griskevich, B. Kropp, A. Renshaw, M. Smy, P. Weather RENO５０

  31. Concept of the water circulation system Gd2(SO4)3 (NF reject) Gd2(SO4)3and UF passed water (UF pass) Water with Gd2(SO4)3from the tank Ultrafilter Nanofilter Small size contaminants (NFpass) Reject large size contaminants (UF reject) RO pure water (RO pass) and Gd2(SO4)3 Return to tank RO reject (processed in another loop)

  32. Reactor Neutrino at GADZSOOKS! Number of events at SK per year（~３０００/year） Sensitivity of parameter measurement （10 years） w/o oscillation ９５％ＣＬ very preliminary w/ oscillation Δm2 (10-4eV) 10 years’ sensitivity With / without oscillation sin2(2θ) Current solar+KamLANDerror size MeV

  33. M. Vagins 100% 80% 60% 40% 20% 0% Thermal neutron capture cross section (barns) Gd =49700 S =0.53 H =0.33 O =0.0002 Captures on Gd 400 kg  88% 274 kg  83% 149.4 kg  73% 89.4 kg  62% 60 kg  52% 30 kg of Gd2(SO4)3 8H2Oin 200 tons 35% captureon gadolinium Gd in Water 0.0001% 0.001% 0.01% 0.1% 1% RENO５０

  34. [Yano-san] RENO５０

  35. [Yano-san] RENO５０

  36. [Yano-san] RENO５０

  37. Gd Recovery SystemR&D at UCI RENO５０

  38. M.Smy, “Low Energy Requirements for the GADZOOKS! Project”, SK meeting, Dec.3, 2006 RENO５０ Y. Takeuchi, ICRR

  39. Epoxy Testpaint on welded part of the SUS tank M20 bolts in a flange apply epoxy w/o welding. BIO-SEAL 197 BIO-DUR 560 Epoxy paints on the base of bolt. RENO５０

  40. Epoxy Test Pressure vessel Pressure test (0  5kg/cm2) was done on Oct.19, 2011. No leak and no pressure drop. Pressure cycle (0  5kg/cm2) test was done on Oct.20-27. No leak and no pressure drop. Long term stability test is running from Oct.28 for 3 months and no problem was found. The test flanges are put on both sides and give pressure to the vessel. Successful RENO５０

  41. Possibility of Acrylic Vesseladditional layer of protection Outer detector Inner detector Acrylic vessel Gd-loaded water Basic idea: extend the frame above the PMTs and put thin acrylic plates. RENO５０

  42. Test Cherenkov emission of Gd(n,g)Gd GdCl3 test vessel This apparatus deployed in the SK tank. BGO 0.2 % GdCl3 Solution 18 cm 5 cm BGO Am/Be 13 cm 18 cm BGO signal (prompt signal (large and long time pulse)) Look for Cherenkov signal (delayed signal) α+ 9Be→12C*+n 12C*→12C+ g(4.4 MeV) n+ p → …… →n +Gd→Gd+g (totally 8 MeV)

  43. Cherenkov signal of Gd gamma rays Time from prompt Energy spectrum 0 100ms Vertex position 92% within 2m Measured time, vertex and energy distributions are as expected from the MC simulation. Astropart. Phys. 31, 320-328 (2009) arXiv:0811.0735 dR [cm]

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