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Results from the Antarctic Muon and Neutrino Detector Array (AMANDA)

This presentation discusses the recent results from the Antarctic Muon and Neutrino Detector Array (AMANDA). It covers new analyses of older and newer data, the challenges and discoveries made by the AMANDA collaboration, and the potential for future discoveries. The presentation also highlights the construction and functioning of the AMANDA detector, as well as the sensitivity to up-going muons and cascades.

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Results from the Antarctic Muon and Neutrino Detector Array (AMANDA)

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  1. Results from the Antarctic Muon and Neutrino Detector Array (AMANDA) Allan Hallgren** Uppsala University Allan.Hallgren@tsl.uu.se • For the most excellent marriage of • particle physics and astronomy: • Something old • Recap of recent results • Something new • New analyses of older data • New analyses of newer data • Something borrowed • Extreme Cold Weather Clothing • Something blue • Lips, fingertips, noses,… The South Pole **Talk prepared largely by: Doug CowenPennsylvania State University, cowen@phys.psu.edu Results from AMANDA/Allan Hallgren, Uppsala

  2. The AMANDA Collaboration 7 US and 9 European institutions, about 110 current members: • Bartol Research Institute, University of Delaware, Newark, USA • BUGH Wuppertal, Germany • Universite Libre de Bruxelles, Brussels, Belgium • DESY-Zeuthen, Zeuthen, Germany • Dept. of Technology, Kalmar University, Kalmar, Sweden • Lawrence Berkeley National Laboratory, Berkeley, USA • Dept. of Physics, UC Berkeley, USA • Institute of Physics, University of Mainz, Mainz, Germany • University of Mons-Hainaut, Mons, Belgium • University of California, Irvine, CA • Dept. of Physics, Pennsylvania State University, University Park, USA • Dept. of Physics, Simon Bolivar University, Caracas, Venezuela • Physics Department, University of Wisconsin, River Falls, USA • Physics Department, University of Wisconsin, Madison, USA • Division of High Energy Physics, Uppsala University, Uppsala, Sweden • Fysikum, Stockholm University, Stockholm, Sweden • Vrije Universiteit Brussel, Brussel, Belgium Results from AMANDA/Allan Hallgren, Uppsala

  3. Discovery Potential! Results from AMANDA/Allan Hallgren, Uppsala

  4. The Site: 5 cm of Powder, 3 km of Base, Never Rains, and Lots of Non-stop Sunshine Skiway (for planes!) AMANDA South Pole Dome Aerial view of South Pole 1 km Results from AMANDA/Allan Hallgren, Uppsala

  5. The AMANDA Detector • Hot-water-drill 2km-deep holes & insert strings of PMTs in pressure vessels. • AMANDA-B10: 302 PMTs, completed in 1997 • Old & new A-B10 results presented • AMANDA-II: 677 PMTs, completed in 2000 • Prelimin. results presented • AMANDA challenges: • Natural medium! • Blame Mother Nature • Remote location! • Blame Scott & Amundsen who made it look too hard to get there • Unfettered bkgd. source! • We’d all like to know exactly who to blame… • Prototype detector! • Can you blame us for trying to improve things? AMANDA-II Results from AMANDA/Allan Hallgren, Uppsala

  6. Building AMANDA:Drilling Holes with Hot Water Results from AMANDA/Allan Hallgren, Uppsala

  7. Building AMANDA: The Optical Module (OM) and the String Results from AMANDA/Allan Hallgren, Uppsala

  8. AMANDA Event Signatures:Muons CC muon neutrino interactions  Muon tracks nm + N  m + X Results from AMANDA/Allan Hallgren, Uppsala

  9. AMANDA Event Signatures: “Cascades” • CC electron and tau neutrino interactions: n(e,t) + N  (e,t) + X • NC neutrino interactions: nx + N  nx + X Cascades Results from AMANDA/Allan Hallgren, Uppsala

  10. Sensitivity to up-going muons demonstrated with CC atm. nm interactions: Sensitivity to cascades demonstrated with in-situ sources (see figs.) & down-going muon brems. AMANDA Is Working Well Data MC 290 atm. nm candidates (2000 data) Simulated light source In-situ light source Horizontal Up-going Zenith • AMANDA also works well with SPASE: • Calibrate AMANDA angular response • Do cosmic ray composition studies. Results from AMANDA/Allan Hallgren, Uppsala

  11. AMANDA Results Results from AMANDA/Allan Hallgren, Uppsala

  12. Reconstruction Handles Results from AMANDA/Allan Hallgren, Uppsala

  13. “Something Old”: 1997 Data1. Atmospheric n’s, Our Test Beam The only known high energy n source is also the hardest to work with: low E with no temporal or directional handle. • 204 events • esig= 4% • edata= 2•10-5 % • MC normalized to data • Roughly 10% background • (MC, visual scan) 204 needles in a really big haystack EASIER WITH AMANDA-II! 1997 Data: Final Zenith Angle Distribution Results from AMANDA/Allan Hallgren, Uppsala

  14. 2. EM & Hadronic Showers: “Cascades” • Motivations for searching for cascades: • Oscillations: nmne,t • Better En measurement • Less cosmic-ray background • Easier to calibrate • Glashow resonance source nm nt ne UHE n fluxes are equal at earth due to oscillations At E > 100 TeV, onlynt can penetrate earth* det. Hard to use downgoing nm due to cosmic ray background, but can have 4p sensitivity to lower energy ne, all energy nt Cosmic rays another source *Halzen & Saltzberg Results from AMANDA/Allan Hallgren, Uppsala

  15. Response to Cascades: Simulated vs. Actual In-Ice Laser Data Dz (m) Dx (m) Good agreement! Disagreements: Understood in light of known systematic uncertainties. vLINE Likelihood Results from AMANDA/Allan Hallgren, Uppsala

  16. Response to Cascades: Cosmic Ray Muon Brems, Simulated vs. Measured • Discrepancy due to • uncertainties in: • ice optical properties • OM sensitivity • cosmic-ray spectrum • rate of m energy losses • Agreement restored by • shifting energy scale by • 0.2 in log10E. Taken into • account as systematic. Results from AMANDA/Allan Hallgren, Uppsala

  17. New Result,1997 Data: Cascade Search • Unique result: • Limit on all nflavors and • First to use full reconstruction of cascade • Analysis gets easier and more competitive with muons as detector grows in size, especially at higher energies Results from AMANDA/Allan Hallgren, Uppsala

  18. Preliminary Limit 3. EHE (E1016eV) Event Search EHE events very bright; many PMTs detect multiple photons • Main background: muon “bundles” • Comparable NPMT but smaller Ng • Calibrate with in-situ N2 laser • Still evaluating systematic uncertainties vertical lm10 km Note: At EHE energies, expect only ~horizontal events* *Klein & Mann, 1999 Results from AMANDA/Allan Hallgren, Uppsala

  19. 4. WIMP Search Limit on Fm from WIMP annihilation WIMP annihilation at Earth’s center, use directional handle: Earth nm (Area approximate) AMANDA m MSSM/ DarkSUSY astro-ph/0202370, submitted to PRD Results from AMANDA/Allan Hallgren, Uppsala

  20. Comparison to random distribution Results: 5. Point Source Search Point Sources: In each 12ox12o angular bin, look for more up-going m’s than expected from statistical fluctuations of a random distribution Muon flux limit (E-2 spectrum assumed) Sky plot Em>1-2 GeV Em>10GeV Neutrino flux limit (E-2 spectrum assumed) Results from AMANDA/Allan Hallgren, Uppsala

  21. 6. Bonus Physics: Cosmic-ray Composition Technique: Parameterize light distribution from muon bundle: “K70” • Cosmic-ray composition (especially at the “knee” around 1016 eV) may help us understand: • Acceleration mechanism • Intervening matter • Age of cosmic rays • Use SPASE-AMANDA coincidences • SPASE: air shower array located on surface above AMANDA • Unique capability to measure simultaneously: • Electrons at surface with SPASE • Muons at depth with AMANDA • Such a measurement can tell us about composition of primary surface ice Results from AMANDA/Allan Hallgren, Uppsala

  22. Iron Proton AMANDA (number of muons) log(E/GeV) Spase (number of electrons) Separation: Protons vs. Iron From Rawlins, Thesis, UW-Madison 2001 Results from AMANDA/Allan Hallgren, Uppsala

  23. “Something New”: Preliminary Results from AMANDA-II • A-II is much larger than AMANDA-B10 • Higher expected event rates • Improved angular acceptance near horizon • More efficient reconstruction of muons and cascades • As of 2002, initial reconstruction is done in real time • Preliminary results: • Atmospheric neutrinos • the “test beam” for muons • see ~5 clean n/day with very simple set of selection criteria • Diffuse cascade search • Diffuse nm source search • Point source search • GRB search Results from AMANDA/Allan Hallgren, Uppsala

  24. 2002 Data: Real Time Analysis Passing rate (%) Weds. 15 May, 2002 Passing rate (%) tracks cascades Results from AMANDA/Allan Hallgren, Uppsala

  25. “Something New”: 2000 Data1. Atmospheric n’s, Still Our Test Beam • Selection Criteria: • Nhit < 50 • Zenith > 110o • High fit quality • Uniform light deposition along track • Excellent shape agreement! • Less work to obtain than with A-B10! Results from AMANDA/Allan Hallgren, Uppsala

  26. 2. Cascade Search A-B10 (1997) • Larger detector size • Improves angular acceptance to 4p  • Easier to reject backgrounds • Increases reach in energy by 3x to ~1PeV • Will enable us to push limit down by about an order of magnitude—or to see something! • Current analysis based on 20% subsample of the 2000 data in accordance with our blind analysis procedures • At the current limit of F10-6 from AMANDA (muon analysis) expect about one signal event in 20% sub-sample Up-going Down-going A-II (2000) Up-going Down-going Results from AMANDA/Allan Hallgren, Uppsala

  27. Preliminary Cascade Limit (20% of 2000 Data) 20% AII limit Expected signal MPR[1.5] W&B  Results from AMANDA/Allan Hallgren, Uppsala

  28. 3. Diffuse nm Search • Analysis: • Look for good muon tracks with channel density rch > 3 • Normalize background to Nhit < 50 data • Preliminary results using 20% of 2000 data • No systematics incorporated! • Sensitivity*: ~810-7 • PreliminaryLimit: •  ~10-6 GeV cm-2s-1sr-1 • ~same as full 1997 6 Data events 6.6 MC E-2n 5.0 MC Atm n keep *Average limit from ensemble of experiments w/no signal Hit channels/10m tracklength Results from AMANDA/Allan Hallgren, Uppsala

  29. 4.Point Source Search Effective Area (MC; E-2) Expected BG (from Data) Results from AMANDA/Allan Hallgren, Uppsala

  30. Sky Plot (Preliminary) 4. nm Point Source Search ~2350 events • Improved coverage near horizon • In 6x6o bin, for E-2 spectrum,10-8 cm-2s-1 flux: • ~ 2 signal events • ~ 1 background event • Sensitivities calculated using background levels predicted from off-source data N.B.: Event times scrambled for blind analysis purposes. 60% of 2000 dataset shown. Sensitivities (Preliminary) Preliminary Results from AMANDA/Allan Hallgren, Uppsala

  31. 5. GRB nm Search m GRB (W-B) • Look for n’s in 10-100 TeV range, coincident with a GRB • Use off-source & off-time data—ideal for maintaining blindness • 2000 data very stable • Virtually background-free analysis • only need BG rejection factor of 10-4 (orders of magnitude less than other analyses) • Anticipate having ~500 GRBs to look at with 1997—2000 dataset • Waxman-Bahcall limit still out of reach, but we’re getting there! Em Average event count/10s(some cuts applied) Gradual cuttightening in atime window aroundaparticular GRB(10-3–10-4bkgd. rejectionattainable). Results from AMANDA/Allan Hallgren, Uppsala

  32. Grand Summary & Mediterranean Results from AMANDA/Allan Hallgren, Uppsala

  33. Conclusions • AMANDA-B10 • Continues to produce results, many of which are competitive or better than existing measurements, & challenge existing models • Additional B10 data from 98 & 99 is being analyzed • AMANDA-II • As expected, detector works much better than B10 alone • Larger instrumented volume • More mature experiment • Preliminary results based on 20% subsamples of 2000 data are already comparable to B10 results from full 1997 dataset • 2001, 2002 data ready to be processed and analyzed • Detector upgrade: Adding full pulse digitization capability to extend physics reach • Will integrate A-II into… • IceCube: The Second Honeymoon…….. Results from AMANDA/Allan Hallgren, Uppsala

  34. THE END Results from AMANDA/Allan Hallgren, Uppsala

  35. World’s Longest Reconstructed Muon Track: 1.1 km! Results from AMANDA/Allan Hallgren, Uppsala

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