Transcript IceCube - Ohio State University

South Pole Neutrino Observatory
Ian Brandeberry
ICECUBE
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
Digital Optical Module (DOM)
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]
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]
DOM
Diagram of the circuitry within a DOM [4]
Detectors
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/
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 muonfree showers from PeV photons [4]
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
1010 − 1021 𝑒𝑉 [4]
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
Two Downgoing Events
Source: http://icecube.wisc.edu/
Extremely high energy downgoing event
Source: http://icecube.wisc.edu/
High energy event passing through the bottom
Source: http://icecube.wisc.edu/
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.