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Megaton Water Cherenkov Detectors and Astrophysical Neutrinos

Megaton Water Cherenkov Detectors and Astrophysical Neutrinos. Maury Goodman, Argonne National Lab. Megaton Water Detectors. 1 Megaton = 1000 milli-Megaton UNO (650 milli-Megaton) US Collaboration, focusing on Henderson Mine Frejus/CERN initiative Hyper-Kamiokande (1000 milli-Megaton).

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Megaton Water Cherenkov Detectors and Astrophysical Neutrinos

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  1. Megaton Water Cherenkov Detectors and Astrophysical Neutrinos Maury Goodman, Argonne National Lab

  2. Megaton Water Detectors 1 Megaton = 1000 milli-Megaton • UNO (650 milli-Megaton) • US Collaboration, focusing on Henderson Mine • Frejus/CERN initiative • Hyper-Kamiokande (1000 milli-Megaton) Now 2004; Maury Goodman

  3. Outline • AGN n’s • “A Search for AGN n’s in Soudan 2” [Astroparticle Physics 20 (2004) 533-547] • A taste of UNO & astrophysics • Sources • Supernova Relic n’s • Shopping list of other possible sources of astrophysical n’s • Status of Thousand-Milli-Megaton Water Cherenkov projects Now 2004; Maury Goodman

  4. Search for AGN n’s in Soudan 2 Now 2004; Maury Goodman

  5. Soudan 2 • M = 1 milli-Megaton • Very fine-grained iron calorimeter drift chamber built to study proton decay • Use horizontal muons to identify neutrino induced sample • Use energy loss to search for AGN n’s Now 2004; Maury Goodman

  6. Horizontal muons are neutrino induced. • Qz > 82 o • Must take topography into account • Slant depth > 14kmwe • Multiple scattering cut Now 2004; Maury Goodman

  7. n induced m Acceptance is 1.77 sr or 14% of 4p Now 2004; Maury Goodman

  8. N = 65; t = 2 108 s live; e = .56; Aeff=87m2 • F (nm) = 4.01  0.50  0.30 10-13 cm-2s-1sr-1 • ( Em > 1.8 GeV) • The 65 events are presumably all atmospheric neutrinos. AGN neutrinos would presumably have added energy loss along the tracks Now 2004; Maury Goodman

  9. Muon Energy Lossabove 1 TeV Example of a horizontal muon in a 20m x 3m fine grained detector 1 TeV Now 2004; Maury Goodman

  10. Expected energy loss in Soudan 2 • No event had any visible catastrophic energy loss • Efficiency was calculated using a predetermined cut of 5 GeV Now 2004; Maury Goodman

  11. Soudan 2 limits Now 2004; Maury Goodman

  12. Search for AGN n’s in Water Detectors Now 2004; Maury Goodman

  13. Up-m’s in Super-K • For “SK-I” • 4/96 to 7/01 • 1680 live-days • More than other SK analyses, this is insensitive to poor detector conditions • For >7m path (>1.6 GeV): • 1901 thru-m • 354 are showering • 468 stop-m • <1.4o tracking res. Now 2004; Maury Goodman

  14. UNO and UHE n • Area matters for detecting up-going m • Take Super-K as baseline (50 milli MT) • Effective area ~1200m2 for entering events • UNO is 13x SK’s volume (650 milli MT) • Only 5.5x the area, ~6600m2 • Low background sensitivity will increase by 5.5 • Large background sensitivity will increase by 2.3 • km3 detectors will be ~1,000,000m2 • and are already under construction • UNO won’t compete for anything triggered by km3 Now 2004; Maury Goodman

  15. Lower Energies? • But long-string PMT detectors such as AMANDA, Antares, Baikal, etc. have very high Energy thresholds • UNO will have a ~5 MeV or ~10 MeV depending on final PMT density • Strategy would be similar to Soudan 2 Now 2004; Maury Goodman

  16. n Astro Issues (The next several slides courtesy Alec Habig) • In searching for sources, previous experiments have taken a hodge podge approach • Experience says: you look at noise in enough different ways, you will see surprising things! Needed- • A priori tests!! • Blind analyses? (Avoids some penalties for trials.) Now 2004; Maury Goodman

  17. Backgrounds • Our background for source searches (and most all our data) are atmospheric nm • Two approaches : • Bootstrap • Monte Carlo Now 2004; Maury Goodman

  18. Bootstrap • Take the observed events • Randomly re-assign directions and live times • Pros: • Easily generates background which matches angular and live time distribution of real data • Any astrophysical n will be scrambled in RA and disappear from the background sample • Cons: • For low statistics samples backgrounds are too granular, introducing non-Poissonian effects • Trying to smear space or time to combat granularity introduces different non-Poissonian effects Now 2004; Maury Goodman

  19. Monte Carlo • Use the experiment’s atmospheric n Monte Carlo events, assigned times from the experimental live time distribution • Pros: • Guaranteed to contain no point sources • Directly simulates your background • Cons: • Only as good as your MC • More work to make, especially the live-time distribution (given n rates << clock ticks, need to save down-going CR distribution) Now 2004; Maury Goodman

  20. All-sky survey • Do we see anything anywhere sticking out over background? • break the data into spatial bins on the sky, sizes chosen for good S/N (not obvious) • Calculate the expected atm. n background in bins • Apply Poisson statistics, discover things or set limits Now 2004; Maury Goodman

  21. Bins • Being a spherical sky, an igloo pixelization works better than the alternatives • Problem: a source on a bin boundary would be unnoticed • Doing multiple offset surveys solves this but kills sensitivity with trials factors Now 2004; Maury Goodman

  22. Cones • Another approach: overlapping cones • Any point in the sky is near center of at least one cone • Fewer bin-edge problems, but must deal with odd oversampling effects Now 2004; Maury Goodman

  23. Unbinned Searches • How about avoiding bin edges entirely? • Try 2-point correlation function • Used for galactic large-scale structure searches • Problem – best for large scale structure, not so sensitive to small clusters • Protheroe statistic • … Now 2004; Maury Goodman

  24. Pick a Source, Any Source • Haven’t seen any sources in an all-sky survey, so limits can be set on any given potential point source • To test your favorite model of n production at some high energy astrophysical source: • Up-m near sources counted, 4o ½ angle cone shown here • Expected count from atm.n background calculated • Compute flux limits for modelers to play with • SGR’s/Magnetars of current interest Now 2004; Maury Goodman

  25. Supernova Remnant Neutrinos Now 2004; Maury Goodman

  26. SN Relic n • Look for the sum of all SNe long long ago in galaxies far far away • Supernovae Relic Neutrinos (SRN) • Provides a direct test of various early star-formation models by integrating over all stars and the whole universe • Expected signal ! Now 2004; Maury Goodman 1Lucas, G., 1975

  27. SN Relic n S/N 8B n flux hep n flux SRN window! atm. ne flux Now 2004; Maury Goodman

  28. Flux limit < 1.2 cm-2 s-1 above 18 MeV Super Kamiokande Collaboration Phys.Rev.Lett. 90 (2003) 061101 Super-K SNR limit Data Total bg 90%cl SRN Michel e atm. ne Now 2004; Maury Goodman

  29. Recent estimates Now 2004; Maury Goodman

  30. SNR an expected UNO signal • With 450 kton fiducial volume, expect 20-60 events per year • This is a background limited search • Deeper underground – better sensitivity • One sigma “hint” expected in 0.5 to 6 years. Now 2004; Maury Goodman

  31. Other searches in large water detectors Now 2004; Maury Goodman

  32. WIMP Detection • WIMPs could be seen indirectly via their annihilation products (eventually nm) if they are captured and settle into the center of a gravitational well • WIMPs of larger mass would produce a tighter n beam • Differently sized angular windows allow searches to be optimized for different mass WIMPs SK Paper submitted to PRD Now 2004; Maury Goodman

  33. WIMPs in the Earth Unosc atm n MC Data Osc atm n MC • WIMPs could only get trapped in the Earth by interacting in a spin-independent way • All those even heavy nuclei in the Earth with no net spin • nm from WIMP annihilation would come from the nadir • No excess seen in any sized angular cone (compared to background of oscillated atmospheric n Monte Carlo) Now 2004; Maury Goodman

  34. Earth WIMP-induced Up-m Limits • Resulting upper limits on the WIMP-induced up-m from the center of the Earth vs. WIMP mass • Varies as a function of possible WIMP mass • Lower limits for higher masses are due to the better S/N in smaller angular search windows • Lowest masses ruled out anyway by accelerator searches Now 2004; Maury Goodman

  35. Earth WIMP-induced Up-m Limits • Resulting upper limits on the WIMP-induced up-m from the center of the Earth vs. WIMP mass • Varies as a function of possible WIMP mass • Lower limits for higher masses are due to the better S/N in smaller angular search windows • Lowest masses ruled out anyway by accelerator searches UNO Now 2004; Maury Goodman

  36. Sun WIMP-induced Up-m Limits • Resulting upper limits on the WIMP-induced up-m from the Sun vs. WIMP mass • Same features as from Earth • But probes different WIMP interactions • Unfortunately hard for South Pole detectors to see the Sun (it’s always near the horizon) Now 2004; Maury Goodman

  37. Other searches • WIMP’s from the galactic core • Galactic “Atmospheric” n’s • Diffuse AGN Search • Coincidence with Gamma Ray Bursts • Coincidence with xxx Now 2004; Maury Goodman

  38. Status of Megaton Water Cherenkov proposals Now 2004; Maury Goodman

  39. Reminder, the main goal is proton decay UNO goal Now 2004; Maury Goodman

  40. UNO sensitivity(t) Super-K 91.6 ktyr 5.7x1033 yr Now 2004; Maury Goodman

  41. UNO Conceptual Design Now 2004; Maury Goodman

  42. FREJUS Now 2004; Maury Goodman

  43. Frejus Now 2004; Maury Goodman

  44. US sites Henderson Now 2004; Maury Goodman

  45. Henderson Mine Overview Mine is owned by: Climax Molybdenum Company, a subsidiary of Phelps Dodge Corporation Mine product: Molybdenum ore (Moly) Mining method: Panel Caving (Block Caving) Production rate: 21,000 tons per day Mine life: About another 20 years Henderson is the 6th or 7th largest underground hard rock mine in the world. A 28 ft diameter shaft from surface (10,500 ft) to 7500 level capable of hauling up to 200 people at a time. Trip down takes about 5 minutes. Now 2004; Maury Goodman

  46. Henderson Mine Overview Ap, 2004 UNO Collaboration Meeting Now 2004; Maury Goodman

  47. Underground Lab layout Two access tunnels. 20 by 18 ft. 2*3600 ft @ 10% grade. Estimated access costs $11 million Estimated UNO ex. cost $81 million Total excavation cost $120 million (30% cont.) Ap, 2004 UNO Collaboration Meeting Now 2004; Maury Goodman

  48. Tochibora Now 2004; Maury Goodman

  49. Rock Properties at Proposed Sites for Hyper-KAMIOKANDE Cavern Now 2004; Maury Goodman

  50. Twin Detector Hyper-Kamiokande 2 detectors×48m × 50m ×250m, Total mass = 1 Mton Now 2004; Maury Goodman

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