IceCube

1. South Pole Neutrino Observatory Ian Brandeberry IceCube

2. The Goal • IceCube was designed with the goal of looking at several sources of neutrinos: • Solar neutrinos and neutrino oscillations – can detect different flavors of neutrinos because of the size of the array • Gamma ray bursts • Supernovae • Weakly interacting massive particles (WIMPs) from dark matter – as of yet, still undetected, but IceCube has improved the limits from the cross sections of these particles [4] • These extremely high energy neutrinos will occasionally interact with the nuclei in the ice and produce muons and other secondary electromagnetic and hadronic particle showers • These charged particles radiate Cherenkov light • The ice has an effective absorption length of 100m or more, depending on the depth of the particle in the ice

3. Digital Optical Module (DOM)

4. Digital Optical Module • Roughly the size of a basketball • Equipped with LEDs to measure the optical properties of the surrounding ice [3] • Muons from muon-neutrinos have ranges from kilometers at TeV energy to tens of kilometers at EeV energy – they generate showers along their path via pair production, bremsstrahlung, and photonuclear interactions [4] • Each DOM is autonomous from the other and receives power and calibration signals from the surface [4]

5. DOM Hardware • Timing resolution of less than 5 ns • Capable of working in temperatures of -55 C • Draws less than 5W of power – fuel must be flown in, so energy requirements are quite stringent • Uses field-programmable gate array (FPGA) • Common triggering setup – selects for the event when 8 DOMs (that are near each other) fire within 5 µs [4]

6. DOM Diagram of the circuitry within a DOM [4]

7. Detectors

8. Layers of Observation • IceTop - detects particles in cosmic showers, such as the muon • IceCube Array – forms the bulk of the IceCube observatory • DeepCore – designed to detect lower energy neutrinos and used as an additional veto module Source: http://icecube.wisc.edu/

9. IceTop • Consists of ice-filled tanks with DOMs – located above the Antarctic ice • Used to detect cosmic ray showers – upper limit of about 300 TeV [4] • Used as a coincidence module – can be used to veto high energy events in IceCube, or rule out low energy events and screen for muon-free showers from PeV photons [4]

10. IceCube Array • 5,160 DOMs in place on 86 strings • Forms the bulk of the IceCube detector • Lowest detectable energy is roughly 100 GeV • Combined with the IceCube Deep Core, the IceCube array can detect energy ranges of [4]

11. The Deep Core • Designed to detect lower energy neutrinos, potentially as low as 10 GeV [4] • Has a greater sensitivity to weakly interacting massive particles (WIMPs) [1] • Has a higher density of DOMs and takes advantage of the purer ice at depths of 2100m and lower [1] • The DOMs used in the Deep Core are more sensitive than the DOMs in the rest of IceCube • Functions as an additional veto module for cosmic showers

12. Two Downgoing Events Source: http://icecube.wisc.edu/

13. Extremely high energy downgoing event Source: http://icecube.wisc.edu/

14. High energy event passing through the bottom Source: http://icecube.wisc.edu/

15. Sources • [1] Abbasi R., et al., “The design and performance of IceCube DeepCore,” Astroparticle Physics, Volume 35, Issue 10, May 2012, Pages 615-624. • [2] “Science.” IceCube South Pole Neutrino Observatory. University of Wisconsin-Madison, 2012. Web. 05 May 2012. • [3] Abbasi, R., et al., “Calibration and characterization of the IceCube photomultiplier tube,” Nuclear Instruments and Methods in Physics Research A , Volume A618, Issues 1-3, Pages 139-152, June 2012. • [4] Halzen, F. and Klein, S., “IceCube: An instrument for neutrino astronomy,” Rev. SCi.Instrum,. Volume 81, Issue 8, Article 081101, August 2010.