IceCube – IceCube
Detector
IceCube, the South Pole neutrino observatory, is a cubic-kilometer particle detector manufactured from Antarctic ice and situated close to the Amundsen-Scott South Pole Station. It’s buried beneath the floor, extending to a depth of about 2,500 meters. A floor array, IceTop, and a denser inside subdetector, DeepCore, considerably improve the capabilities of the observatory, making it a multipurpose facility.
IceCube is the primary gigaton neutrino detector ever constructed and was primarily designed to look at neutrinos from essentially the most violent astrophysical sources in our universe. Neutrinos, nearly massless particles with no electrical cost, can journey from their sources to Earth with primarily no attenuation and no deflection by magnetic fields.
The in-ice part of IceCube consists of 5,160 digital optical modules (DOMs), every with a ten-inch photomultiplier tube and related electronics. The DOMs are connected to vertical “strings,” frozen into 86 boreholes, and arrayed over a cubic kilometer from 1,450 meters to 2,450 meters depth. The strings are deployed on a hexagonal grid with 125 meters spacing and maintain 60 DOMs every. The vertical separation of the DOMs is 17 meters.
Eight of those strings on the middle of the array had been deployed extra compactly, with a horizontal separation of about 70 meters and a vertical DOM spacing of seven meters. This denser configuration types the DeepCore subdetector, which lowers the neutrino vitality threshold to about 10 GeV, creating the chance to review neutrino oscillations.
IceTop consists of 81 stations situated on high of the identical variety of IceCube strings. Every station has two tanks, every outfitted with two downward dealing with DOMs. IceTop, constructed as a veto and calibration detector for IceCube, additionally detects air showers from main cosmic rays within the 300 TeV to 1 EeV vitality vary. The floor array measures the cosmic-ray arrival instructions within the Southern Hemisphere in addition to the flux and composition of cosmic rays.
Developments in neutrino astronomy have been pushed by the seek for the sources of cosmic rays, main at an early stage to the idea of a cubic-kilometer neutrino detector. Cosmic rays, which consist primarily of protons, are the very best vitality particles ever noticed, with energies over one million instances these reached by at the moment’s particle accelerators on Earth.
AMANDA, the Antarctic Muon and Neutrino Detector Array, was constructed as a proof of idea within the mid Nineties and demonstrated that the extraordinarily clear Antarctic ice was appropriate for detecting energetic neutrinos. IceCube, the one cubic-kilometer neutrino detector constructed up to now, was accomplished in December 2010, solely six years after the deployment of the primary string on the South Pole.
Neutrinos should not noticed straight, however after they occur to work together with the ice they produce electrically charged secondary particles that in flip emit Cherenkov gentle, on account of touring by way of the ice quicker than gentle travels in ice.
The IceCube sensors acquire this gentle, which is subsequently digitized and time stamped. This info is distributed to computer systems within the IceCube Lab on the floor, which converts the messages from particular person DOMs into gentle patterns that reveal the course and vitality of muons and neutrinos.
The IceCube Neutrino Observatory was constructed below a Nationwide Science Basis (NSF) Main Analysis Gear and Amenities Building grant, with help from companion funding companies world wide. The NSF Workplace of Polar Packages helps the mission with a Upkeep and Operations (M&O) grant. The College of Wisconsin–Madison is the lead establishment, coordinating data-taking and M&O actions. The worldwide IceCube Collaboration, with greater than 40 establishments worldwide, is liable for the scientific analysis program.
Building
On December 18, 2010, simply after 6 pm New Zealand time, the final of IceCube’s 86 strings was lowered into the Antarctic ice. Seven austral summers of development had come to an finish, and IceCube was accomplished a decade after the collaboration submitted the proposal.
Devoted groups melted 60-centimeter diameter holes to a depth of two,450 meters, deployed sensors, and commissioned strings from November to February annually from 2004 till 2011. Deployment specialists spent 11 hours on common to expertly join sensors to a cable and decrease them into the water-filled holes, which finally refroze. In seven seasons, 86 holes in all had been drilled and instrumented.
The drill was designed by the IceCube mission and constructed on the UW Physical Sciences Lab. The high-pressure hose and nozzle delivered sizzling water that melted by way of the ice at file speeds, about 2 meters per minute, right down to depths of two,450 meters. A separate drill was designed and deployed to advance by way of the firn layer, the highest 50 meters of compacted snow the place sizzling water drilling just isn’t environment friendly. Collectively the 2 drills had been in a position to constantly produce nearly good vertical holes prepared for deployment of instrumentation at a price of 1 gap each two days.
Since water begins to freeze instantly, IceCube sensors had been shortly deployed following drilling. As soon as the refreezing course of ended, which took a few weeks to stabilize, the failure price of the instrumentation has been extraordinarily low—fewer than 100 of the roughly 5,500 sensors are at present nonoperational.
IceCube sensors, designed with foremost contributions from Lawrence Berkeley Nationwide Laboratory, DESY-Zeuthen, and UW–Madison, had been produced and examined on the universities in Stockholm and Uppsala in Sweden, DESY-Zeuthen in Germany, and the Bodily Sciences Lab in Stoughton, Wisconsin, USA. Every string of sensors had a normal theme, with a reputation given to every of the deployed sensors as a simpler technique of identification somewhat than a numbering system.
Building IceCube was a rare engineering achievement. It was accomplished on time, on finances, and considerably exceeding efficiency specs. This can be a tribute to the perseverance and dedication of the physicists, engineers, and technicians that overcame the various challenges of making and working a detector in such an inhospitable surroundings.
The whole price of development was $279 million. The Nationwide Science Basis offered round $242 million with the remaining funds coming from funding agencies within the US and overseas.