Neutrino Detector Sizes are Measured in Cubic Kilometers

The IceCube Neutrino Observatory is a neutrino observatory constructed at the Amundsen–Scott South Pole Station in Antarctica. Its thousands of sensors are located under the Antarctic ice, distributed over a cubic kilometer.

IceCube consists of spherical optical sensors called Digital Optical Modules (DOMs), each with a photomultiplier tube (PMT) and a single-board data acquisition computer which sends digital data to the counting house on the surface above the array. IceCube was completed on 18 December 2010.

DOMs are deployed on strings of 60 modules each at depths between 1,450 to 2,450 meters into holes melted in the ice using a hot water drill. IceCube is designed to look for point sources of neutrinos in the TeV range to explore the highest-energy astrophysical processes.

In November 2013 it was announced that IceCube had detected 28 neutrinos that likely originated outside the Solar System.

The IceCube Neutrino Observatory is composed of several sub-detectors in addition to the main in-ice array.

* AMANDA, the Antarctic Muon And Neutrino Detector Array, was the first part built, and it served as a proof-of-concept for IceCube. AMANDA was turned off in May 2009.
* The IceTop array is a series of Cherenkov detectors on the surface of the glacier, with two detectors approximately above each IceCube string. IceTop is used as a cosmic ray shower detector, for cosmic ray composition studies and coincident event tests: if a muon is observed going through IceTop, it cannot be from a neutrino interacting in the ice.
* The Deep Core Low-Energy Extension is a densely instrumented region of the IceCube array which extends the observable energies below 100 GeV. The Deep Core strings are deployed at the center (in the surface plane) of the larger array, deep in the clearest ice at the bottom of the array (between 1760 and 2450 m deep). There are no Deep Core DOMs between 1850 m and 2107 m depth, as the ice is not as clear in those layers.

PINGU (Precision IceCube Next Generation Upgrade) is a proposed extension that will allow detection of low energy neutrinos (GeV energy scale), with uses including determining the neutrino mass hierarchy, precision measurement of atmospheric neutrino oscillation (both tau neutrino appearance and muon neutrino disappearance), and searching for WIMP annihilation in the Sun.

PINGU, proposed as a low-energy infill extension to the IceCube observatory, will feature the world’s largest effective volume for neutrinos at an energy threshold of a few GeV, enabling it to reach its chief goal of determining the neutrino mass hierarchy (NMH) quickly and at modest cost.

PINGU will deploy 40 new strings at the center of IceCube.

A vision has been presented for a larger observatory called IceCube-Gen2.

IceCube measured 10 to 100 GeV atmospheric muon neutrino disappearance in 2014 using 3 years of data from 2011 to 2014.

In July 2018, the IceCube Neutrino Observatory announced that they have traced an extremely-high-energy neutrino that hit their detector in September 2017 back to its point of origin 3.7 billion light-years away in the direction of the constellation Orion. This was the first time that a neutrino detector had been used to locate an object in space. A source of cosmic rays was identified.

Ten Cubic Kilometer Generation 2 Detector

An in-depth exploration of the neutrino universe requires a next-generation IceCube detector. Named IceCube-Gen2 and based upon the robust design of the current detector, the goal for the new observatory is to deliver statistically significant samples of very high energy astrophysical neutrinos, in the PeV to EeV range, and yield hundreds of neutrinos across all flavors at energies above 100 TeV. This will enable detailed spectral studies, significant point source detections, and new discoveries.

Members of the recently formed IceCube-Gen2 Collaboration are working to develop a detailed proposal that will also include the PINGU sub-array. PINGU, the Precision IceCube Next Generation Upgrade, targets precision measurements of the atmospheric oscillation parameters and the determination of the neutrino mass hierarchy as well as the search for dark matter.

The facility’s reach will be further enhanced by exploiting the air-shower measurement and vetoing capabilities of an extended surface array. A radio array, the proposed Askaryan Radio Array (ARA) experiment, will also help achieve improved sensitivity to neutrinos in the 10^16-10^19 eV energy range.

The unique properties of the Antarctic glacier, revealed by the construction and operation of IceCube, allow the spacing between light sensors to exceed 250 meters, instead of the current 125 meters in IceCube. The deployment of sensors in strings with larger spacings will enable the IceCube-Gen2 instrumented volume to rapidly grow at modest costs.

IceCube-Gen2 will benefit from the successful designs of the hot water drill systems and the digital optical modules in the original IceCube project. Minimal modifications will target improvements focused on modernization, efficiency, and cost savings. Because of its digital architecture, the next generation facility can be operated without a significant increase in costs.

By roughly doubling the instrumentation already deployed, the telescope will achieve a tenfold increase in volume to about 10 cubic kilometers, aiming at an order of magnitude increase in neutrino detection rates. The instrument will provide an unprecedented view of the high-energy universe, taking neutrino astronomy to new levels of discovery.

Antares Detector

ANTARES is the name of a neutrino detector residing 2.5 km under the Mediterranean Sea off the coast of Toulon, France. It is designed to be used as a directional neutrino telescope to locate and observe neutrino flux from cosmic origins in the direction of the Southern Hemisphere of the Earth, a complement to the South Pole neutrino detector IceCube that detects neutrinos from both hemispheres.

KM3NeT the next generation neutrino telescopes

The full KM3NeT neutrino telescope will contain on the order of 12000 pressure-resistant glass spheres attached to about 600 strings. The strings hold 18 sensor spheres each, anchored to the sea floor and supported by floats. Each sphere, called a “digital optical module” (DOM), is about 17 inches (43 cm) in diameter, contains 31 3-inch (7.6 cm) photomultiplier tubes with supporting electronics, and is connected to shore via a high-bandwidth optical network.

The KM3NeT-It site, at a depth of 3400 m, hosts the ARCA (Astroparticle Research with Cosmics in the Abyss) detector, with more widely spaced DOMs optimised for detecting high-energy cosmic neutrinos in the TeV–PeV range. Its strings are 650 m long, spaced 90 m apart.

The KM3NeT-Fr site, at a depth of 2475 m, hosts the ORCA (Oscillation Research with Cosmics in the Abyss) detector, a more compact array with more closely spaced sensors optimised for atmospheric neutrinos in the GeV range. This will consist of 115 strings in a 20 m triangular grid, with a 9 m spacing between the DOMs in a string. Overall, the array is about 210 m in diameter, and the strings are 200 m long.

KM3NeT is a research infrastructure housing the next generation neutrino telescopes. Once completed, the telescopes will have detector volumes between megaton and several cubic kilometers of clear sea water. Located in the deepest seas of the Mediterranean, KM3NeT will open a new window on our Universe, but also contribute to the research of the properties of the elusive neutrino particles. With the ARCA telescope, KM3NeT scientists will search for neutrinos from distant astrophysical sources such as supernovae, gamma ray bursters or colliding stars. The ORCA telescope is the instrument for KM3NeT scientists studying neutrino properties exploiting neutrinos generated in the Earth’s atmosphere. Arrays of thousands of optical sensors will detect the faint light in the deep sea from charged particles originating from collisions of the neutrinos and the Earth. The facility will also house instrumentation for Earth and Sea sciences for long-term and on-line monitoring of the deep sea environment and the sea bottom at depth of several kilometers.