Recent vs from IceCube Page: 4 of 8
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Configuration Year Run CR p v Rate Trigger
(# Strings) Length Rate Rate
1 2005 - - 2 (total) -
IC-9 2006 137 d 80 Hz 1.5/d 150 Hz
IC-22 2007 319 d 550 Hz 20/d 670 Hz
IC-40 2008 1 y 1000 Hz - 1400 Hz
IC-80 2011 10 y 1650 Hz 200/d TBD
Table 1. The datasets collected with IceCube at different stages of construction.
3. IceCube Construction
The holes for the IceCube strings are drilled using a hot-water drill. A 5 MW heating system
produces 760 liters/minute of 880 C water. This water is propelled through a 1.8 cm diameter
nozzle at 200 pounds/square inch, melting a hole through the ice. It takes about 40 hours to
drill each 2500 m deep, 60 cm diameter hole. Once the hole is drilled, it takes about 12 hours
to lower the string of DOMs into the hole.
Because of the Antarctic weather, the construction season is short, from November to mid-
February. Logistics is a key concern. All of the personnel and hardware must be flown in
on ski-equipped LC-130 transport planes. The right panel of Fig. 1 shows how construction
has progressed since the first string was deployed in early 2005. By the end of the 2007/8
construction season, 40 strings were deployed.
4. Triggers and Data Collection
IceCube has several triggers, all implemented in software. These triggers use the times for the
hits on all DOMs. A multiplicity trigger selects time windows when 8 DOMs fired within 5
ps. In 2008, this was supplemented with a string trigger which produced a trigger if 5 out of
7 adjacent DOMs fired within 1.5 ps; this increases our sensitivity to low energy neutrinos. A
topological trigger is also under consideration; this would be optimized for low energy, roughly
horizontal neutrinos. When a trigger condition is satisfied, the DAQ system records all hits
within a 10 ps time window. When time windows from multiple triggers overlap, they are
combined into a single window.
Events selected by the triggers are fed to a set of software filters, which perform a variety
of simple reconstructions. Filters look for upward going muons, cascades (ve, vT and neutral
current interactions), contained events of any sort, extremely high energy events, events where
a track starts or stops in the detector, and air showers. Another filter selects events that come
from near the position of the moon, to look for the moon shadow. Currently, about 6% of the
events (80 Hz) pass at least one of these criteria. These events are transferred to the Northern
hemisphere over a satellite link, allowing for rapid analysis. The satellite bandwidth is about 32
Gbytes/day. All of the data are stored on tape [3].
Table 1 shows the different IceCube datasets. The neutrino rate rises from about 1.5 v/day
with 9 strings to a projected 200 v/day with 80 strings. The rate increases faster than the
detector size because of edge effects.
5. Reconstruction and Performance
IceCube is designed to identify and reconstruct all three flavors of neutrinos: v/, ve and vT.
Figure 2 shows examples of these three topologies; the muon event is data, but the cascade and
tau are simulations. IceCube events are reconstructed using algorithms designed to select these
events based on their different topologies: long tracks from muons, blob-like cascade events, T
double-bang events, etc.
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Collaboration, IceCube & Klein, Spencer R. Recent vs from IceCube, article, October 3, 2008; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc897925/m1/4/: accessed May 8, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.