IceCube: First Light Doug Cowen IceCube Collaboration Pennsylvania State University cowen(at)phys.psu.edu

Transcription

1 IceCube: First Light Doug Cowen IceCube Collaboration Pennsylvania State University cowen(at)phys.psu.edu KITP May 2005 IceCube/Doug Cowen/Penn State 1

2 Photons (attenuation) (magnetic bending) Protons Sun, SNe Neutrinos TeV PeV EeV ZeV Log 10 (Energy) [ev] Note: every time we open a new window on the heavens, we discover something interesting. KITP May 2005 IceCube/Doug Cowen/Penn State 2

3 Neutrino Detection KITP May 2005 IceCube/Doug Cowen/Penn State 3

4 Detecting UHE Neutrinos Pathologically antisocial particles Good: They can emerge from ultra-dense regions of space, conveying information to us that no other astronomical messenger can provide Bad: They are fiendishly difficult to detect Not So Ugly: Can use the earth as a filter to block backgrounds KITP May 2005 IceCube/Doug Cowen/Penn State 4

5 Detecting UHE Neutrinos On the rare occasion that a UHE neutrino crashes into normal matter, its enormous energy is imparted to many charged particles These charged particles will move faster than light in the interaction medium (v > c/n, where n is the refractive index). They will emit Cherenkov light. Cherenkov light can be detected by photomultiplier tubes (PMTs) N.B.: Must have thorough knowledge of propagation medium for event reconstruction to work KITP May 2005 IceCube/Doug Cowen/Penn State 5

6 Reconstructing Neutrino Events J. Ahrens et al., Nucl. Inst. & Meth. A524, 169 (2004). Relative PMT-to-PMT timing w/ns accuracy is absolutely vital. KITP May 2005 IceCube/Doug Cowen/Penn State 6

7 Cherenkov Light in Ice: Ice Properties Matter! Perfect Cherenkov cone With scattering (dust, acid, crystal boundaries) KITP May 2005 IceCube/Doug Cowen/Penn State 7

8 Optical Properties of South Pole Ice 110 m absorption length! 20 m scattering length KITP May 2005 IceCube/Doug Cowen/Penn State 8

9 The Dustlogger: Are We Glaciologist Wannabes?

10 Detecting UHE Neutrinos To detect UHE neutrinos, therefore, we need: Large instrumented volume but to keep costs reasonable, detector has to barely work (F. Halzen), i.e., should function with low pixelization density Clear, well-understood medium Lots of scientists willing to travel to a remote location for years on end with no guarantee of discovering anything KITP May 2005 IceCube/Doug Cowen/Penn State 10

11 The AMANDA and IceCube Collaborations: >100-fold Proof that There s a Sucker Born Every Minute! Bartol Bartol Research Research Institute, Institute, Delaware, Delaware, USA USA Univ. Univ. of of Alabama, Alabama, USA USA Pennsylvania Pennsylvania State State University, University, USA USA UC UC Berkeley, Berkeley, USA USA UC UC Irvine, Irvine, USA USA Clark-Atlanta Clark-Atlanta University, University, USA USA Univ. Univ. of of Maryland, Maryland, USA USA USA USA (13) (13) IAS, IAS, Princeton, Princeton, USA USA University University of of Wisconsin-Madison, Wisconsin-Madison, USA USA University University of of Wisconsin-River Wisconsin-River Falls, Falls, USA USA LBNL, LBNL, Berkeley, Berkeley, USA USA University University of of Kansas, Kansas, USA USA Southern Southern Univ. Univ. and and A&M A&M College, College, Baton Baton Rouge Rouge Europe Europe (11) (11) Japan Japan Chiba Chiba University, University, Japan Japan University University of of Canterbury, Canterbury, Christchurch, Christchurch, NZ NZ Universite UniversiteLibre Librede de Bruxelles, Bruxelles, Belgium Belgium Vrije Vrije Universiteit Universiteit Brussel, Brussel, Belgium Belgium Université Universitéde de Mons-Hainaut, Mons-Hainaut, Belgium Belgium Universität UniversitätMainz, Germany Germany DESY-Zeuthen, DESY-Zeuthen, Germany Germany Universität UniversitätWuppertal, Germany Germany Uppsala Uppsala University, University, Sweden Sweden Stockholm Stockholm university, university, Sweden Sweden Imperial Imperial College, College, London, London, UK UK University University of of Oxford, Oxford, UK UK NIKHEF, NIKHEF, Utrecht, Utrecht, Netherlands Netherlands New New Zealand Zealand KITP May 2005 IceCube/Doug Cowen/Penn State 11

12 The IceCube Detector 1 km 3 instrumented volume: 1 Gton of ice 4800 digital optical modules (DOMs) on 80 strings. AMANDA will be enclosed within the array. An IceTop air shower station at the top of each string. IceCube IceTop South Pole AMANDA 1400 m 2400 m KITP May 2005 IceCube/Doug Cowen/Penn State 12

13 50 m Volume = ~100 PSU Beaver Stadii or, about 10 6 UCSB Gauchos Stadii Size perspective KITP May 2005 IceCube/Doug Cowen/Penn State 13

14 IceTop Surface Array One station (two tanks, four DOMs) above each IceCube string Used for calibration, veto, and cosmic ray composition studies Sensitive to showers above ~3 x ev KITP May 2005 IceCube/Doug Cowen/Penn State 14 05

15 Building IceCube KITP May 2005 IceCube/Doug Cowen/Penn State 15

16 Getting There: Almost as Much of an Adventure as Being There KITP May 2005 IceCube/Doug Cowen/Penn State 16

17 Flying First Class with the Air National Guard KITP May 2005 IceCube/Doug Cowen/Penn State 17

18 Flying Economy Class: Fewer Windows! KITP May 2005 IceCube/Doug Cowen/Penn State 18

19 Antarctic Airways NPX Airport Terminal KITP May 2005 IceCube/Doug Cowen/Penn State 19

20 In 2003, We Built the Drill Winch! Big 2.5km Hose goes here Sled runners EHWD Hose Reel Engineering model-isometric View KITP May 2005 IceCube/Doug Cowen/Penn State 20

21 The Sled You Wanted as a Child KITP May 2005 IceCube/Doug Cowen/Penn State 21

22 21Jan04 at the Pole KITP May 2005 IceCube/Doug Cowen/Penn State 22

23 Non-Fragile Cargo Arrives at Pole: Nov 04 KITP May 2005 IceCube/Doug Cowen/Penn State 23

24 The Counting House December 04: Sunnier! November 04: not very sunny yet KITP May 2005 IceCube/Doug Cowen/Penn State 24

25 Melting the First IceCube Hole Tower Return Pump Drill Cable Reel Drill Return Hose Reel Drill Supply Hose Reel Drill Head with Short Weight Stack and Nozzle KITP May 2005 IceCube/Doug Cowen/Penn State 25

26 KITP May 2005 IceCube/Doug Cowen/Penn State 26

27 Melting the First IceCube Hole KITP May 2005 IceCube/Doug Cowen/Penn State 27

28 Building IceCube: Drilling Holes with Hot Water KITP May 2005 IceCube/Doug Cowen/Penn State 28

29 Drill Upgrades for Next Season Firn drill with better heat transfer--design is nearly complete, out for bids Stronger weight stack with insulation--design is nearly complete, out for bids Simpler and larger crescent--have concept, working on details Working on hose strain relief concept--could work with present drum and crescent Sheaves for TOS (Tower Operating Structure) designed Designing brakes for reels that do not have any--replacing solenoid valves on some others Combo cable for RW and RWS--design complete out for bids Adding accelerometer and internal pressure gauge for drill head, design of daughter board complete Heated hoses designed and ordered Replacement motors for submersible pumps ordered--adding better cooling Design of MECC unit (for workshop, DNF, breaks, etc) complete KITP May 2005 IceCube/Doug Cowen/Penn State 29

30 Deployment Cycle KITP May 2005 IceCube/Doug Cowen/Penn State 30

31 The Surface Array Sub-detector: IceTop Serap Tilav, Bartol/U.Delaware (First Turkish Pole in the history of the world) KITP May 2005 IceCube/Doug Cowen/Penn State 31

32 IceCube Drill Hole 25 m Junction box Two DOMs : 10 PMT One high -gain; one low -gain in each tank IceTop Design LG HG HG LG Ice Cherenkov Tank 10 m 0.9 m clear ice Diffusely reflecting liner 2 m KITP May 2005 IceCube/Doug Cowen/Penn State 32

33 Freeze control unit under ~75cm clear ice 2 DOMs in liquid water in IceTop Tank

34 IceCube string anchored between IceTop tanks KITP May 2005 IceCube/Doug Cowen/Penn State 34

35 What We Did Over Winter Vacation 4 IceTop Stations deployed in December st IceCube string deployed on Jan KITP May 2005 IceCube/Doug Cowen/Penn State 35

36 The Digital Optical Module (DOM): The Heart of IceCube KITP May 2005 IceCube/Doug Cowen/Penn State 36

37 Digital Optical Modules (DOMs) 10 Hamamatsu PMT Glass pressure sphere Time resolution: < 5 ns Dynamic range: 200 photoelectrons / 15 ns 2000 PE integrated / 5 µs Digitization rate: 300 MHz for first 300 ns 40 MHz for 6.4 µs Noise rate in situ < 1 khz Deadtime < 1% On-board electronics PMT Glass pressure vessel LED flashers (calibration) Mu metal shield All waveforms captured by on-board digitizers Full digitized amplitude series transmitted for complex waveforms Summary info extracted from simple waveforms KITP May 2005 IceCube/Doug Cowen/Penn State 37

38 DOM Mainboard Almost-invisible hand 2 four-channel ATWDs Analog Analog Transient Waveform Digitizers low-power ASICs ASICs recording at at MHz MHz over over first first 0.5µs 0.5µs signal signal complexity at at the the start start of of event event 2xATWD HV Board Interface fast ADC recording at 40 MHz over 5 µs event duration in ice Dead time < 1% Memories FPGA Dynamic range p.e./15 ns p.e./5 µs energy measurement (TeV PeV) CPLD oscillator (Corning Frequency Ctl) running at 20 MHz maintains δf/f < 2x10-10 FPGA FPGA (Excalibur/Altera) (Excalibur/Altera) reads reads out out the the ATWD ATWD handles handles communications communications time time stamps stamps events events system system time time stamp stamp resolution resolution 7 ns ns wrt wrt master master clock clock KITP May 2005 IceCube/Doug Cowen/Penn State 38

39 Buried Array Works (Known dust -2km) Plot of the <z> of the DOMs participating in a triggered event. Not terribly meaningful -2450m -1450m Until you are told that someone in senior management created Dr. G. Marx it! KITP May 2005 IceCube/Doug Cowen/Penn State 39

40 Surface Array Works KITP May 2005 IceCube/Doug Cowen/Penn State 40

41 Run 872 Event 5945 KITP May 2005 IceCube/Doug Cowen/Penn State 41

42 Monitoring Page from Yesterday KITP May 2005 IceCube/Doug Cowen/Penn State 42

43 It All IceTop (on surface) Works! Please hold your applause: it is only run-of-the-mill cosmic-ray muon. Possibly the longest one ever reconstructed, though Still, to be able to do this only a few weeks after deployment is (if we do say so ourselves) VERY impressive! IceCube array (buried) KITP May 2005 IceCube/Doug Cowen/Penn State 43

44 Anticipated IceCube Performance 1. versus topic 2. versus time 3. versus flavor KITP May 2005 IceCube/Doug Cowen/Penn State 44

45 IceCube Physics Topics Neutrino point sources (AGN, microquasars, magnetars, SNRs, ) Neutrinos from GRBs (afterglow, precursors, collapsars, supranovæ) Diffuse extraterrestrial neutrino fluxes Ultrahigh energy cosmogenic neutrinos (GZK interactions) Supersymmetry and Dark Matter (WIMPs, sleptons, ) Atmospheric neutrino spectrum & oscillations(?) Cosmic ray composition above the knee Sources of ultrahigh energy cosmic rays Galactic supernovæ (SNEWS) Ultralong baseline neutrino oscillations Tests of Lorentz invariance, weak equivalence principle Exotic massive particles (topological defects, relic particles) TeV-scale extra dimensions, electroweak instantons, Magnetic monopoles, nuclearites, Q-balls, KITP May 2005 IceCube/Doug Cowen/Penn State 45

46 Planned Deployment Schedule IceCube AMANDA SPASE-II Counting House PY5: ~16 PY4: ~10 PY6: ~18 Runway 125 m PY7: ~18 PY3: 1 PY8: Balance South Pole KITP May 2005 IceCube/Doug Cowen/Penn State 46

47 Physics Reach vs. Time Date New Strings Accumulated total accumulated total accumulated diffuse UHE diffuse UHE added string-yrs/yr string-yrs km3-yrs Feb Feb Feb Feb Feb Feb Point sources Diffuse sources Note: Conservative estimates, AMANDA efficiencies assumed Average flux upper limit (cm -2 s -1 ) Calculated for pure ν µ +anti-ν µ E -2 spectrum integrated above 1 TeV ~1 Crab

48 awesome IceCube Neutrino Sensitivity vs. Energy vs. Flavor & up/down ok atmosphere nope cosmic-ray background Log(E/GeV) earth absorption KITP May 2005 IceCube/Doug Cowen/Penn State 48

49 Electron Cascades Electron cascades over ~10 m: pointlike ν e at 375 TeV Roughly spherical distribution of light 500 m diameter at 1 PeV 100 m per decade of energy Energy resolution currently 10% in log(e) Angular resolution currently 27 KITP May 2005 IceCube/Doug Cowen/Penn State 49

50 Simulated ev neutrino event in AMANDA in IceCube Bigger = Better for high energies! KITP May 2005 IceCube/Doug Cowen/Penn State 50

51 AMANDA Cascade Response Achilles Thetis River Styx KITP May 2005 IceCube/Doug Cowen/Penn State 51

52 IceCube Muon Response A eff / km 2 cos θ cos θ Results with simulated AMANDA hardware, software Big improvements possible waveforms, more hits, better noise reduction, reconstruction techniques KITP May 2005 IceCube/Doug Cowen/Penn State 52

53 IceCube Muon Field of View TeV: look down to avoid atmos. muons PeV: Earth opaque, look horizontally EeV: Can look above horizon atmospherics are at lower energy IceCube angular range for ν µ detection Cascades: 4π, except for absorption at high energies (with muons vetoed!) KITP May 2005 IceCube/Doug Cowen/Penn State 53

54 IceCube Muon Energy Response Long tracks: Better resolution, flavor identification Lower limit on E estimated Thetis from brightness Achilles River Styx AMANDA KITP May 2005 IceCube/Doug Cowen/Penn State 54

55 Tau Events Two cascades νn interaction vertex τ lepton decay Double Bang (Learned & Pakvasa 1995) Dim lepton track connects the vertices ~50 m/pev Suppressed by (m τ / m µ ) 2 E» PeV: Lollipop Dim track ending in a spectacular vertex AMANDA KITP May 2005 IceCube/Doug Cowen/Penn State 55

56 Tau Identification: Digitization is Good KITP May 2005 IceCube/Doug Cowen/Penn State 56

57 IceCube Tau Neutrino Response Energy: ~same as for ν e cascades when double bang is contained Directionality: double bangs: connect the vertices! 100s of meters separation each vertex position known to several meters find φ < ~1 o lollipops sub-degree muon pointing accuracy from tau track plus anchor point from single shower almost certainly better than 0.5 o KITP May 2005 IceCube/Doug Cowen/Penn State 57

58 Emoticonic Summary of IceCube Response vs. Flavor Directional resolution Energy Resolution Effective volume or area Background susceptibility Acceptance E: lo hi lo hi lo hi lo hi lo hi ν e 4π 2π( ) ν µ 2π( ) 2π( ) ν τ 4π 4π KITP May 2005 IceCube/Doug Cowen/Penn State 58

59 Neutrino Flavor Separation KITP May 2005 IceCube/Doug Cowen/Penn State 59

60 IceCube All-Flavor Neutrino Detection E µ =10 TeV ν e e E = 375 TeV ν τ τ+"cascade" KITP May 2005 IceCube/Doug Cowen/Penn State 60

61 Neutrino Sensitivity Neutrino flavor Conservative: current techniques ντ νe νµ ν e (supernovæ) full flavor ID showers vs. tracks Sensitive to all flavors of neutrinos Log(ENERGY/eV) Solid areas show best reconstruction: flavor, direction, energy Hatched areas show triggers, more difficult reconstruction. KITP May 2005 IceCube/Doug Cowen/Penn State 61

62 IceCube Signal Sensitivities KITP May 2005 IceCube/Doug Cowen/Penn State 62

63 Atmospheric Neutrino Oscillations(?) 100,000 atmospheric neutrinos/yr with full IceCube Can we profit from the facts that Although have unfavorable δm 2 at these energies, limiting ν µ ν τ oscillations, At high energies, atmospheric ν e suppressed relative to ν µ Note: electron and tau neutrinos look the same at sufficiently low energies Conceivably, the small number of extra ν τ due to ν µ ν τ oscillations may be comparable to those from atmospheric ν e and measurable! See Stanev astro-ph/ KITP May 2005 IceCube/Doug Cowen/Penn State 63

64 Diffuse Neutrino Fluxes Per flavor (mixed ν µ + 1:1:1) ν µ muons (B10) cascades unfolded atm opaque to neutrons UHE (B10) neutrons can escape MPR WB IceCube 3yr (exp.) KITP May 2005 IceCube/Doug Cowen/Penn State 64

65 Steady & Transient Pt. Sources Steady Sources: Search cone 1 opening half-angle + soft energy cut (< 1 TeV) Sensitivity point sources (1 y): E -2 (cm -2 s -1 GeV) Transient Sources (e.g., GRB): Essentially background-free search energy, spatial and temporal correlation with independent observation For ~1000 GRB s observed/year expect (looking in Northern sky only) signal: 12 ν background (atm ν): 0.1 Sensitivity GRB (1 y): ~0.2 φ WB Excellent prospects for detection of GRB ν s within 1-2 km 3 -years KITP May 2005 IceCube/Doug Cowen/Penn State 65

66 WIMPs from the Sun + x disfavored by direct searches near direct search sensitivity inaccessible to direct searches Complementary to direct searches Best for high WIMP masses Depends on low energy muon response KITP May 2005 IceCube/Doug Cowen/Penn State 66

67 Cosmic Ray Composition Iron Proton log(e/gev) AMANDA (number of muons) ln(a) SPASEII (number of electrons) KITP May 2005 IceCube/Doug Cowen/Penn State 67

68 Supernova Detection Detect MeV supernova neutrinos through overall increase in tube noise rates AMANDA B10 AMANDA-II Count rates IceCube sec LMC KITP May 2005 IceCube/Doug Cowen/Penn State 68

69 Magnetic Monopoles Relativistic monopoles: Cherenkov emission enhanced by (g/e) compared to muons May be able to look for slow monopoles through nucleon decay Can also look for nuclearites, Q-balls, and for stuff dimmer than muons, like staus upper limit (cm -2 s -1 sr -1 ) Soudan KGF MACRO Orito δ electrons IceCube β = v/c 0.75 Amanda Baikal 1.00 KITP May 2005 IceCube/Doug Cowen/Penn State 69

70 A Note on Nearby GRBs Gamma-rays create nitrous oxide (laughing gas) in atmosphere We all die, but we all die laughing What if neutrinos arrive first, by a significant time margin? May have enough time to write a paper before we die! Also known as publish and perish KITP May 2005 IceCube/Doug Cowen/Penn State 70

71 Endnote: In case you were wondering, there are no penguins at the South Pole. So this, for example, does not happen there: KITP May 2005 IceCube/Doug Cowen/Penn State 71

72 THE END I lied, but only about the penguin. Thanks to Peter and Eli for organizing this excellent workshop! KITP May 2005 IceCube/Doug Cowen/Penn State 72