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

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