South Pole Summer Wednesday Science Lectures January 22, 2003

1. South Pole Summer Wednesday Science Lectures January 22, 2003 8:00 PM Upper Galley Serap Tilav Bartol Research Institute University of Delaware SPASE: South Pole Air Shower Experiment What’s Cosmic Ray Air Showers got to do with growing Crystal Clear Ice at South Pole ?

2. What are Cosmic Rays? • Naturally occurring particles (protons and nuclei) having very high energies • From sources far outside the solar system • Discovered nearly a century ago • Studied with detectors on balloons and spacecraft as well as from the ground • Positron, pion, kaon were all discovered by observations of cosmic-ray interactions in the atmosphere

3. Cosmic Ray spectrum • Differential spectral index • changes at ~ 3 x1015eV • a = 2.7  a = 3.0 • Continues to 3 x 1018 eV • Expect exp{-E / Z Emax} • cutoff for each Z

4. What is an electron volt? An electron volt, or eV for short, is a measure of energy. It is quite a small amount of energy similar to the amount of energy possessed by a single photon of light. Radiation Energy Photon of lightCan be detected by your eye 1 eV Ultra Violet ray from sunEnough to burn your skin 10 eV X-RayCan pass right through your body 1000 eV = 1 keV Gamma raysdetected by ground telescopes 1012 eV = 1 TeV Cosmic Raydetected by the SPASE-2 experiment 1015 eV = 1 PeV Cosmic Raydetected by the planned Pierre Auger Observatory 1020 eV = 100 EeV Highest energy Cosmic Ray ever recorded 3x1020 eVThis is the amount of energy that you would feel if you dropped a bowling ball on your foot from a height of 1 metre! Energy Shorthand 103 eV = 1,000 eV Kev = Kilo electron volt 106 eV = 1,000,000 eV MeV = Mega electron volt 109 eV = 1,000,000,000 eV GeV =Giga electron volt 1012 eV = 1,000,000,000,000 eV TeV = Terra electron volt 1015 eV = 1,000,000,000,000,000 eV PeV = Peta electron volt 1018 eV = 1,000,000,000,000,000,000 eV EeV = Exa electron volt 1021 eV = 1,000,000,000,000,000,000,000 eV ZeV = Zeta electron volt

5. High-energy accelerators • Accelerator labs  high energy particles • Cosmic accelerators  cosmic rays • What are the sources? • How are the particles accelerated? • How do they get here? • What happens on the way?

6. Cosmic accelerators (some supernova remnants in our galaxy) SN1987A Circa 1650 (Cas-A) SN1054 SN1572

7. Really Big Cosmic accelerators: jets in active galaxies 20 TeV gamma rays observed Higher energies obscured by IR light but the universe is transparent to  VLA image of Cygnus A

8. Satellites Top of atmosphere Balloons Ground Arrays Detection Techniques of Cosmic Rays 1 2 3 1-Low energy cosmic rays by satellites --direct detection of primary cosmic rays 2- Medium energy cosmic rays by balloons --direct detection of primary cosmic rays 3- High energy cosmic rays by Extensive Air Shower Arrays on ground --indirect detection of primary cosmic rays • Ground array samples shower front • High altitudes desirable to be near the shower maximum

9. Primary Cosmic Ray Interaction with atmospheric nuclei Air Shower

10. Cosmic Ray Air Shower Array Detectors Scintillator detectors Water Cherenkov detectors

11. SPASE-1 array and the old Clean Air Bldg 1992 SPASE-1 scintillator detector Inside the SPASE-1 Shack 1995 SPASE-1 Shack 1995 SPASE-1 1988 – 1998 University of Leeds, Bartol Research Inst. Search for point sources of high energy (1014 eV) gamma rays

12. South Pole Air Shower Experiment @ 10000ft altitude 30 stations on area of 16,000 sq. meters 4 modules per station each module contains hexagonal scintillator of 0.2 m2 and a PMT 30m between stations Energy range of operation 1013 eV to 1016 eV

13. SPASE stations & signals cables

14. SPASE electronics rack SPASE counting house

15. SPASE/AMANDA Coincidence Experiment • Electronic component of • air showers detected by • SPASE • Primary CR direction • and energy • Penetrating muons detected by • AMANDA • Very good tool for • Cosmic Ray mass composition • & • AMANDA calibration SPASE Skiway

16. SPASE-2 SPASE-1 369m 885m  = 12º  = 27º 800 m 1000 m AMANDA-A 1500 m AMANDA-B 2000 m Stereo View of AMANDA-B10 by SPASE-1 & SPASE-2 in 1997

17. Calibration of angular resolution SPASE-2 SPASE-1 Distribution of space angle between SPASE/AMANDA-B10 SPASE-2 angular resolution: s63 ~1.5o Inferred B10 resolution: s63 ~ 4.7o for SPASE-1 s63 ~ 5.2o for SPASE-2

18. Absolute pointing~ 1o offset seen by SPASE-1, SPASE-2 & GASP SPASE-2 Point source Monte Carlo also sees some offset (upper panel)

19. 1997 AMANDA-B10 Survey with SPASE muons AMANDA-B10 seen from SPASE-1 AMANDA-B10 seen from SPASE-2 XXVII ICRC, 7-15 August 2001, Hamburg, Germany Poster Session HE2.01 Poster Board Number HE208

20. Muon Tomography of South Pole Ice at AMANDA depths Dust layers located by SPASE/AMANDA coincident events

21. K50 measures energy deposited by Nm simulation S30 measure particle density at 30m from the shower core

22. Cosmic Ray Composition around the Knee

24. IceTop AMANDA • 1 station on top of each IceCube string • 2 ice tanks per station • 2 DOMs in each tank • IceTop will detect Air Showers • of energies 1014 eV to 1018 eV South Pole Skiway • 4800 PMT • Instrumented volume: 1 km3 (1Gt) • 80 Strings • IceCube is designed to detect neutrinos of all flavors at energies from 107 eV to 1020 eV 1400 m IceCube 2400 m

25. IceCube Hole ~20 m IceTop Station 2 Ice Tanks per station 3.6 m2 x 1 m each Two DOMs: 10 in PMTs High Gain w/station coincidence: 1 p.e. resolution Low Gain: 1 resolution

26. IceTop R&D Tank2000 Tank2001

27. Where are the Tanks? MAPO Tank2000 10 m Tank2001 SPASE2 Shack

28. 60 cm 51 cm crack 99.1 cm Heating rod (later removed) Tank2000 • Technical details: • Deployed in December 2000 • Cylindrical Polyethylene tank • radius=60cm height= 124cm • Lined with white Tyvek inside • for diffusive,high reflectance • Black velvet on top • 2 Standard AMANDA OMs frozen • in top looking down • Heating rod in the middle • to channel excess water during freezing • Filled with station water • 36 days to freeze • Block of ice of 1.14 m2 x 0.99 m

29. Tank2001 • Technical details: • Deployed in December 2001 • Cylindrical Polyethylene tank • radius=107cm height= 124cm • Lined with white Tyvek inside • Black velvet on top • 2 Standard AMANDA OMs frozen • in top looking down • PVC pipe in the middle with heating • tapes, thermo sensors • to channel excess water during freezing • Several different color LEDs • for later calibration • Filled with station water • 28 days to freeze • Block of ice of 3.6 m2 x 0.99 m 107.32 cm 102 cm 99 cm LEDs Heating tapes Thermosensors

30. Freezing Method Developed at Bartol Top-Down Freezing • Insulated plastic barrel of d=10in h=16in • Water pump circulates water through degasser • 10 thermosensors monitor temperature • Heater at output , Chiller at input • Temps at input and output controlled via PC • Water flow controlled • Expansion water released from the pressure release' pipe

31. TopDown Method Tets in Lab

32. Commercial Methods for Making Crystal Clear Ice Method I Bottom-up freezing Metal container, metal tank Bottom at –30F Sides and top at ~30 ~34 F 51cm x 102cm x 38cm => 300lb blocks ~3.5 days freezing time Method II Bottom-up+ Sides-in Molds immersed in –10F water/alcohol bath water/alcohol bath circulated constantly Small pump on top of mold Ambient temp ~ 30 ~ 34F Pump for water circulation Pump for water circulation ice water –10F water/alcohol bath molding Freon coils @ -30F

34. Ice Occasions Ellsworth Wisconsin Moldings immersed in –10F turbo bath

35. Tests @ Port of Wilmington –DE Commercial freezer at ONLY 7F HOW to implement @ South Pole ?

36. Black painted Spole type outhouse Metal plate exposed to ~ -35F