Outlook on Underground Science

1. Outlook on Underground Science Thomas Bowles Los Alamos National Laboratory / University of Washington American Physical Society Meeting Philadelphia April 5, 2003 Nuclear Physics

2. The Reach of Underground Science A Remarkably Wide Range of Science and Engineering Issues Can Be Addressed Underground • Neutrino Physics* • Particle Physics* • Astrophysics* • Geophysics+ • Geobiology+ • National Security* • Education and Outreach In order to fully exploit this potential requires the construction of a National Underground Science and Engineering Laboratory (NUSEL) * Requires depth to eliminate radiactive backgrounds + Requires underground environment Nuclear Physics

3. Photomultipliers Neutrino Experiments • Neutrino Physics - redefining our view of the world • Recent results from SuperKamiokande, SNO, and KamLAND demonstrate conclusively that neutrinos have mass and oscillate between different flavors (e, m, t) • These results come from large underground detectors in Japan (SuperK and KamLAND) and Canada (SNO) Nuclear Physics

4. Neutrino Properties • What We Know • Neutrinos have mass and oscillate • Oscillation parameters (Dm2 and tan2q) known to ~ 30% • Neutrino masses are small • 50 meV < mn < 2.8 eV (90% CL) • Neutrinos account for at least as much mass in the Universe • as the visible stars • What We Don’t Know • Are neutrinos their own antiparticles? (Majorana n) • What is the absolute scale for neutrino mass? • Is the mass scale normal ordered or inverted hierarchy? • Are there sterile neutrinos? • What are the elements of the MNS mixing matrix? • Is CP / CPT violated in the neutrino sector? • Why is the neutrino sector so different than the quark sector? Nuclear Physics

5. Rare Decays / Interactions • Double beta decay • Allowed 2 n decay : (A,Z)  (A, Z-2) + 2 e– + 2ne • 0 n decay : (A,Z )  (A, Z-2) + 2 e– • Requires neutrino mass • Requires lepton number violation • Requires Majorana neutrino • Current experiments have sensitivity mn < 300 meV _ • New generation of experiments now being proposed • to reach 7 - 50 meV mass range from solar/atmospheric n • Search for the source of dark matter • Dark matter may be Weakly Interacting Massive Particles (WIMPs) • Our galaxy is moving through the dark matter with a velocity of 270 km/s • WIMP interactions result in recoil nuclei with energies of few tens of keV • Many experiments are underway to search for WIMPs • New generation of experiments now being proposed • to reach into the range predicted by SUperSYmettry Nuclear Physics

6. Particle Physics • Search for baryon number violation • New generation of proton decay • experiments proposed: • LANND - 70 kton liquid argon TPC • UNO, HyperKamiokande • Water Cerenkov detectors in US, Japan • with lifetime limits on proton decay: • Decay Present Projected (UNO-15 yr) • p  e+po 5 x 1033 yr 2 x 1035 yr • p n K+ 1.6 x 1033 yr 2 x 1034 yr • Long-baseline neutrino oscillations • Brookhaven AGS to UNO at NUSEL • Atmospheric neutrinos • < 1%measurement of Dm232, sin22q23 • Sensitive to sin22q13 > 0.005 • Good sensitivity to CP violation • 60,000 events per year in UNO • Including 400 nt events per year • Provides good sensitivity to oscillation parameters Nuclear Physics

7. Astrophysics at NUSEL Improve our understanding of solar and stellar processes • Future solar neutrino experiments will provide direct measurements of the flux of solar neutrinos with En < 5 MeV • Provides test of the Standard Solar Model (p-p, 7Be, CNO n’s) • CNO n’s power initial convective stage during first 108 years • of solar burning • CNO rate tests initial core metallicity • Future supernova neutrino experiments will provide important information: • Supernova dynamics • Role of neutrino physics in nucleosynthesis • High event rates for galactic supernova (10 kpc): • ~ 1000 SNO events, 9000 SuperK events • ~ 140,000 UNO events Nuclear Physics

8. Nuclear Astrophysics at NUSEL Improve our understanding of the nuclear reactions in solar and stellar processes • Nuclear cross section measurements at a high- • intensity, underground accelerator facility • Depth is required to suppress cosmic ray • backgrounds in measurements of extremely • small cross sections of solar fusion. • Improve our understanding of nucleosynthesis • of the heavy elements in supernova Nuclear Physics

9. Geosciences at NUSEL • Need ability to instrument extensive u/g volume: • Generally working mines only allow • restricted access for limited periods of time • To make significant progress requires: • Continuous access • Access to heterogeneous structures • Access to large-scale formations • Active experiments with heating, chemical tracers, water, … • Instrumentation throughout mine • Data over very extended periods of time (decades) • Extensive diamond coring • Deep drilling starting from deepest location possible • Understand characteristics and recovery of water, energy, and mineral resources • Understand fractures in rock • Rock strength • Fluid flow • Heat flow • Chemical transport • Ore formation • Faults and earthquakes • Develop models and predictive capabilities for water movement, waste storage, … • Develop and test techniques for environmental remediation of contaminated wastewater, soil, … Nuclear Physics

10. Geosciences and Neutrino Physics • Search for geophysical antineutrinos • Primary thermal driver of the Earth comes from the radioactive decay of the U and Th chains • Geophysical data provides only indirect estimate of the total amount of U and Th in the Earth • There exist different theories of the heating of the Earth’s core, including the possibility of a nuclear reactor in a liquid nickel core • Neutrino experiments are starting to provide the first direct measurements of the total amount of U and Th in the Earth! Nuclear Physics

11. Geomicrobiology at NUSEL • Study life in extreme conditions • Microbial life exists in deep, hot rock! • 200 M yr old bacteria at WIPP shown to be viable • Deep rock may have been shelter for life at early times • Outstanding questions: • How long has life at depth been sequestered? • What are the connections between life at the surface • and life in deep rock? • Are there unknown microbes at depth? • What are the limiting conditions for life at depth? • What can life at depth teach us about extraterrestrial life? • Applications in geomicrobiology • New microbes may be of benefit to medicine • Microbes may be efficient means for environmental remediation Nuclear Physics

12. Additional Aspects of NUSEL • National security • Ultra low-level counting • Background reductions of 10-100 possible • Provides new capabilities and flexibility: • Nuclear forensics • Theatre defense applications • Industrial applications - Single Event Upsets • Improved capabilities for environmental applications • Education and Outreach: • The public has great interest in the science • that will be carried out at NUSEL. • Research will include E&O as an integral part Nuclear Physics

13. Depth Issues at NUSEL Experiment Requirements • Ultra-low level experiments • bb decay, dark matter, reactor/SN/solar n • Great depth, modest to large size • High-energy experiments • Proton decay, long-baseline, atmospheric n • Moderate depth, large size • Geophysics / Geomicrobiology • 3-D from surface to great depth • Heterogeneous, DT, H2O • National Security • Modest depth, small size • Ultra low-level counting facility • Great depth, moderate size for R&D on n experiments Nuclear Physics

14. NUSEL at Homestake Nuclear Physics

15. NUSEL at San Jacinto Nuclear Physics

16. WIPP as an Underground Laboratory Nuclear Physics

17. An Extension to SNO Nuclear Physics

18. Comparison of Underground Labs Nuclear Physics

19. The Best Site • Homestake provides the optimal site in the US • Dedicated operation of a deep u/g science laboratory • Location appropriate for long-baseline experiments • 600 km of existing drifts down to great depths (8000’) • Extremely strong rock • Ability to excavate large chambers at depth • Minimal risk in excavation (109 yrs of experience) • A tremendous amount of existing infrastructure • 15 MVA of power substations, 860,000 cfm HVAC, … • Large hoisting capabilities • Ability to take sea-containers directly u/g • Ability to excavate UNO-size cavity in 2-3 years • Complex geology throughout site • Provides ideal conditions for geoscience / geomicrobiology Nuclear Physics

20. Homestake - A Unique Opportunity Geosciences proposing Earthlab at Homestake Nuclear Physics

21. The Status of NUSEL Compelling Science Case for NUSEL Established and Vetted • Homestake planned closure on 1/1/02 announced 9/11/00 • UW Long Range Plan n workshop starts NUSL-Homestake effort Support for NUSEL: Homestake Recommended as the Best Site • Committee on Underground Scientific Laboratory • recommends Homestake as preferred site • April 2001 - NUSEL consortium formed • Homestake proposal submitted to NSF June 2001 • San Jacinto proposal submitted to NSF September 2001 • Established Interim Homestake-NUSEL Collaboration • http://int.phys.washington.edu/NUSL/ • Revised Homestake proposal being prepared: • Much improved use of lifts • Preserves prime area at 4850 for megadetector construction • No shaft extension or major drift excavations required • Proposal will be completed this summer • NSAC Long Range Plan recommends construction of a • deep u/g lab as the highest priority for near-term construction • NSAC sends support letter for Homestake to NSF and DOE • HEPAP Long Range Plan • NRC Committee on Physics of the Universe • NeSS ‘02 workshop held in September - 320 participants • Unanimous agreement of working group leaders to construct NUSEL • NRC Neutrino Facilities Assessment Committee • Strong interest in NSF Physics, Geology, Biology Divisions Nuclear Physics

22. The Status of Homestake • Mine is secure, Barrick is positive about NUSL If all goes well, we will be able to return to the site of the first oservation of solar neutrinos by Davis et al. with a major new science facility. • Continuing to carry out environmental remediation • Carrying out maintenance on hoists, replaced hoist ropes • Continues to employ ≈ 35 people on site • Continued operations to keep mine available for NUSEL • Costs Barrick ~ $200K/month with no reimbursement • Indemnification is still a major issue • Barrick working with the state of SD to reach agreement • Strong support from the SD governor, senators and • congressmen, local legislature, and neighboring states. Thar’s more gold in them thar hills than what comes out of the ground. • Indemnification needs to be resolved. • NSF and OMB need to resolve issues/priorities on funding • Proposal needs to be approved by NSF Science Board. • Funding possible in FY05 ??? Nuclear Physics