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Neutrino Working Group Kevin T. Lesko

Neutrino Working Group Kevin T. Lesko. - q 12 Neutrino Mixing - Next Generation Solar Neutrino Experiments - National Underground Scientific Laboratory. After WMAP?. – S m n ≤0.7 eV: WMAP. Where are we with Neutrinos after SNO & KamLAND-I ?.

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Neutrino Working Group Kevin T. Lesko

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  1. Neutrino Working GroupKevin T. Lesko - q12 Neutrino Mixing - Next Generation Solar Neutrino Experiments - National Underground Scientific Laboratory

  2. After WMAP? –Smn ≤0.7 eV: WMAP Where are we with Neutrinos after SNO & KamLAND-I? • Reduced ne MSW space by 7 orders of magnitude • No dark side ne (tan2q<1) • Most likely LMA (confirmed by KamLAND! assuming CPT) • Support of MSW affects • Massive neutrinos (small Dm2) • Large mixing angles

  3. Neutrino Mixing Parameter q12 • SNO + KamLAND • Now • SNO + KamLAND • Next year (guess)

  4. Flux measurement limited to 7 -10% How can we do better? How much better can we do? KamLAND II (7Be) Flux measurement down to 1-3% Low Energy pp Experiment

  5. Neutrino Mixing Parameter q12 • Fundamental neutrino parameter, neutrino properties • The angles are large and at least q12 is non-maximal • Is the MNS matrix unitary? • Input to CP violation experiment analysis • Synergisms with other fundamental measurements

  6. Physics using the sun: 7Be and pp neutrinos • Oscillation Parameter q12 7Be - confirm q12 from SNO with ~7 to 10% pp yields factor 2-3 improvement in q12 ~1 to 3% unitarity of the MNS mixing matrix mixing angles are large but not maximal-why? input into ultimate CP studies • Sterile Neutrinos currently SNO yields ~30% limit solar neutrinos absolute intensity good ~ 1% • Magnetic Moments looking down to ~50 keV ~ 10-11mB ds/dy • Solar Physics SSM -pp flux,7Be flux CNO - ~1.2 to 1.7 MeV, 50% uncertainty FCNO~0.1 to 0.2 x 7Be and 20x 8B Surprises to Conventional Wisdom

  7. 7Be upgrade to KamLAND Upgrade a coincidence experiment to a singles, low energy experiment: Backgrounds will be a dominate concern. Dominantbackgrounds: • 85Kr • 210Pb • 210Bi (from Rn)

  8. Backgrounds: Spallation, Long-lived radioactivity Adding solar n signals 7Be window

  9. Requirements for reactor e detection 238U232Th~ 10-14 g/g 40K~ 10-15 g/g Top of the chains look encouraging, But radon is leaking in, lots of Kr 7Be

  10. 7Be Neutrino Experiment at KamLAND U, Th chains look pretty good, wrt supported chains Radon and 85Kr require ~ 1:106 reduction 210Pb needs large reduction in the bulk liquid Scintillator Collaboration (US and Japanese) now gearing up to address these issues. Japan has received some funding already (site improvements and some purification upgrades). US proposal for a KamLAND upgrade is now being considered by the US collaboration. Proposal might include items such as improved purification techniques, fixing lots of piping leaks, fresh air ducting, cave linings, etc.

  11. Next Generation Solar Neutrino Experiment: pp n • Long Term R&D Investment • Not a quick & dirty experiment • R&D applicable to several experimental fronts • Low energy solar neutrino experiments • Double beta decay • Other experiments • Experiments are challenging • For ultimate physics requires both CC and NC measurements • Requires NUSEL; a deep site

  12. Issues for Low Energy Solar Neutrino Experiment Backgrounds Internal External Detector Performance Detector Efficiency Detector Resolution Robust Signal Stability Environmental Considerations Count Rate

  13. Neutrino Elastic Scattering ne,m,t + e -=>ne,m,t + e – • Measure RATE & RECOIL SPECTRA of pp ( 7Be, CNO) ≤ 50 keV Threshold • ne& nm,tCross Sections Accurately Known. • High Statistics for Moderate Detector Mass ( > 90 % of f(solar) ; 3000 – 6000 events per 10 tonne-yr ) • f(pp) Theoretical Prediction (SSM) ~ ±1% • (more precisely predicted than reactors ~2% Bugey potential Standard Candle) • Not affected by power companies or Atomic Energy Commission reporting of Power Levels

  14. Preliminary Design of a Low Energy Solar Neutrino Detector Space Infrastructure Construction Safety Kajiyama Lanou Lesko Poon Seidel LBNL Brown U.

  15. Low Energy Solar Neutrino Experiment LDRD • Why Superfluid Helium? • High Rate ES (~ 2 events/tonne/day detected) • Intrinsically pure • Potentially good signal/bckgrd discrimination • Significant R&D invested already • scintillation yields, Rayleigh scattering, redundant signals, signal processing, background discrimination, etc. • Why Berkeley Lab? • Backgrounds (shielding & induced), Calibration and Calculations • Detector Development, signal processing (scintillation light) • Detector Design & Construction • Connections to UCB Physics • History with Neutrinos • Excellent Connection to LRP & NUSL Plan Backgrounds Develop Detection Techniques Develop Prototype

  16. Participation of Berkeley Lab in NUSEL Science Driven Positions Berkeley Lab with LRP priority Major Roles in New Laboratory • Science Experiments • Low Energy Solar Neutrino Experiment R&D • Monte Carlo Simulations & Backgrounds • Detector R&D • Prototype Detectors • Ultralow Background Counting Facility • Monte Carlo Simulations • Detector Designs • Engineering Design and Conceptual Design • Earth Sciences Division • Nuclear Astrophysics - under discussion • Double Beta Decay - under active discussion

  17. Why should LBL Participate in NUSEL? • Connections to existing experiments, upgrades, and future experiments. • SNO • KamLAND • Astrophysics • Double Beta Decay • Cuore & Majorana • • Low Background Counting • • Engineering, Design, Management • • Major Priority for Nuclear Physics Community • • Long baseline experiments, CP violation, proton decay in the future.

  18. What is the status of NUSEL? What is Berkeley’s role in NUSEL? • Workshops 2000-2002 • Long Range Planning Process • (NSAC, SNOWMASS) • National Priority • NSF Proposal submitted • Panel and Paper Reviews • NeSS Workshop • Awaiting NSF Board Action • NSF Proposal being refined • Defining LBL Role in Proposal • Still no action from NSF • Homestake not flooded • Proposal being refined and improved • NSF Management urges patience • Recently:OSTP discussing Major Initiative in Particle/Astrophysics highlighting NUSEL Lesko: NUSEL Executive Committee Poon, Heeger: members of working groups

  19. NUSEL - recent news • Barrick just (10 April) announced plans to flood the Homestake mine beginning on 14 April. A major set back for Homestake proposal from the University of Washington. - Could just be posturing by Barrick to obtain operating expenses or attention. - If real it would open the door to consideration of the full range of siting options: San Jacinto, Nevada, Henderson mine, Eastern California, etc. • OSTP considering a major initiative in Astro-particle physics, NUSEL is a major focus of this initiative.

  20. q12 Low Energy Solar Neutrino Expt National Underground Laboratory Summary • Multiple excellent science objectives • Long term mission • Synergism with other fields and n physics • Capitalizes on lab expertise and experience • Positions lab with community priorities

  21. Status of HERON: • Substantial R&D already done with prototypes: • Absolute measure of scintillation yield: >30,000 photons/MeV; Rayleigh scattering • Demonstrated two-channel detection of low energy b’s & a’s:photons & phonons • Developed calorimeter wafers magnetic readout.6 eV FWHM on 6 keV x-ray • Full simulation of coded aperture on backgnd & signal photons. • current version 3x10-3 backgnd reject; almost good enough for no electroforming • In progress: • New prototype & expts. on scintillation & drifted charge ( “e-bubbles”). • Experiments for single 16eV photon sensitivity on larger calorimeters. • Testing different versions of coded aperture in full simulation. • Decision on constructing sizeable prototype (1-1.5 yr.?) • When could there be a full HERON?: a) When & where will there be an underground lab? b) Fabricate & construct underground. c) Infrastructure for doing so? d) 2-3 yrs. From a) & c). e) Cost: $30-40 M (FY2001 $) detector, shields & aux. equip.

  22. Low Energy Neutrino Experiment Challenges • Requires VERY LOW THRESHOLD < 50 keV • FORMIDABLE BACKGROUNDS target, container, environment, muon spallation • SIGNAL: SINGLE ELECTRON RECOIL • NEEDS PRECISION high statistics, need to pin systematics on FV, dE/E, etc. • s(nm,t)/s(ne) = 1/6 “appearance” but lower sensitivity to NC • COMPLEMENTARY CC EXPTS VERY LARGE low event rate/ton; cross-sections less well known

  23. How does HERON address these challenges? • A cryogenic scintillation-”plus” detector. • Use Superfluid helium as target superfluid free of any other substance • Helium is strong scintillator at 16 eV. >30,000 photons/MeV; l(Rayleigh) > 200 m • Redundant detection channels. Scintillation, Phonons & “e-bubble”. • No PMT’s. Scintillation, phonons, electron all detected on same sapphire wafer calorimeters, looking into additional detection devices • Depth >4500 mwe and immunity of Helium to muon spallation/ capture • External shield from hall rock activity, • BUT: Helium not good self-shield from any activity in container: * Capitalize on different signature of background. gs  Multiple Comptons * Good measurement of event positions & topology. utilize coded aperture wafer array point vs. distributed source * Possible electroforming of interior cryostat.

  24. Preliminary Design of a Low Energy Solar Neutrino Detector Superfluid Helium (HERON) type detector Mass Backgrounds Shielding Construction Kajiyama Lanou Lesko Poon Seidel

  25. Log-Likelihood Coded Aperture

  26. 20 tonnes total Helium. • Variable fiducial.

  27. From Aspen 2002 Log(Dm2) SNO+Cl +Ga Standard SNO+Cl+Ga (5%+ 2% theory) Log(tan2q) Log(Dm2) SNO+Cl+Ga (1%+2% theory) Barger 0204253 Log(tan2q)

  28. Where will we be in 3-5 years? Neutrino Oscillations - fundamental issues • LMA, Dm2 < 1 x 10-4 ev2 KamLAND can observe oscillation signature, if Dm2 > 1 x 10-4 ev2 need new experiments • Low masses ] Need better Q12 => SNO, Low E Solar, KamLAND II • High Masses, still need oscillation signature and need better Q12 => HLMA experiments for Dm2 SNO, Low E Solar, KamLAND II also will seek oscillation signatures • LSND confirmed or refuted (miniBOONE) if confirmed => Sterile n • Sterile Neutrinos => BOONE • Sterile Neutrinos => Low E Solar • (If) Neutrino Oscillations: • Full MNS matrix needs to be filled out - Mixing Parameters => SNO, Low E Solar, KamLAND, LBL, 7Be expts., Minos, miniBOONE, JParc, Off-axis expts, q13 reactor experiments Neutrino Nature • Majorana or Dirac? (DbD, Cuore, Majorana) Mass Scale • Absolute mass scale? (Katrin tritium bD, DBD) • Less likely (harder) after WMAP SNO NC

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