Astroparticle physics

Source: Wikipedia, the free encyclopedia.
For the scientific journal, see Astroparticle Physics (journal).

Astroparticle physics, also called particle astrophysics, is a branch of

solid state physics, and cosmology. Partly motivated by the discovery of neutrino oscillation, the field has undergone rapid development, both theoretically and experimentally, since the early 2000s.[1]

History

The field of astroparticle physics is evolved out of optical astronomy. With the growth of detector technology came the more mature astrophysics, which involved multiple physics subtopics, such as

plasma physics, nuclear physics, relativity, and particle physics. Particle physicists found astrophysics necessary due to difficulty in producing particles with comparable energy to those found in space. For example, the cosmic ray spectrum contains particles with energies as high as 1020 eV, where a proton–proton collision at the Large Hadron Collider
occurs at an energy of ~1012 eV.

The field can be said to have begun in 1910, when a German physicist named Theodor Wulf measured the ionization in the air, an indicator of gamma radiation, at the bottom and top of the Eiffel Tower. He found that there was far more ionization at the top than what was expected if only terrestrial sources were attributed for this radiation.[2]

The Austrian physicist

cosmic rays'.[3]

Many physicists knowledgeable about the origins of the field of astroparticle physics prefer to attribute this 'discovery' of cosmic rays by Hess as the starting point for the field.[4]

Topics of research

While it may be difficult to decide on a standard 'textbook' description of the field of astroparticle physics, the field can be characterized by the topics of research that are actively being pursued. The journal Astroparticle Physics accepts papers that are focused on new developments in the following areas:[5]

Open questions

One main task for the future of the field is simply to thoroughly define itself beyond working definitions and clearly differentiate itself from astrophysics and other related topics.[4]

Current unsolved problems for the field of astroparticle physics include characterization of dark matter and dark energy. Observations of the orbital velocities of stars in the Milky Way and other galaxies starting with Walter Baade and Fritz Zwicky in the 1930s, along with observed velocities of galaxies in galactic clusters, found motion far exceeding the energy density of the visible matter needed to account for their dynamics. Since the early nineties some candidates have been found to partially explain some of the missing dark matter, but they are nowhere near sufficient to offer a full explanation. The finding of an accelerating universe suggests that a large part of the missing dark matter is stored as dark energy in a dynamical vacuum.[6]

Another question for astroparticle physicists is why is there so much more matter than antimatter in the universe today. Baryogenesis is the term for the hypothetical processes that produced the unequal numbers of baryons and antibaryons in the early universe, which is why the universe is made of matter today, and not antimatter.[6]

Experimental facilities

The rapid development of this field has led to the design of new types of infrastructure. In underground laboratories or with specially designed telescopes, antennas and satellite experiments, astroparticle physicists employ new detection methods to observe a wide range of cosmic particles including neutrinos, gamma rays and cosmic rays at the highest energies. They are also searching for

gravitational waves
. Experimental particle physicists are limited by the technology of their terrestrial accelerators, which are only able to produce a small fraction of the energies found in nature.

Facilities, experiments and laboratories involved in astroparticle physics include:

  • IceCube (Antarctica). The longest particle detector in the world, was completed in December 2010. The purpose of the detector is to investigate high energy neutrinos, search for dark matter, observe supernovae explosions, and search for exotic particles such as magnetic monopoles.[7]
  • ANTARES (telescope). (Toulon, France). A Neutrino detector 2.5 km under the Mediterranean Sea off the coast of Toulon, France. Designed to locate and observe neutrino flux in the direction of the southern hemisphere.
  • XENONnT, the upgrade of
    XENON1T
    , is a dark matter direct search experiment located at the Gran Sasso National Laboratories and will be sensitive to WIMPs with SI cross section of 10−48 cm2.
  • BOREXINO, a real-time detector, installed at Laboratori Nazionali del Gran Sasso, designed to detect neutrinos from the Sun with an organic liquid scintillator target.[8]
  • Pierre Auger Observatory (Malargüe, Argentina). Detects and investigates high energy cosmic rays using two techniques. One is to study the particles interactions with water placed in surface detector tanks. The other technique is to track the development of air showers through observation of ultraviolet light emitted high in the Earth's atmosphere.[9]
  • CERN Axion Solar Telescope (CERN, Switzerland). Searches for axions originating from the Sun.
  • NESTOR Project (Pylos, Greece). The target of the international collaboration is the deployment of a neutrino telescope on the sea floor off of Pylos, Greece.
  • Kamioka Observatory is a neutrino and gravitational waves laboratory located underground in the Mozumi Mine near the Kamioka section of the city of Hida in Gifu Prefecture, Japan.
  • Gran Sasso mountain, near L'Aquila
    (Italy). Its experimental halls are covered by 1400 m of rock, which protects experiments from cosmic rays.
  • SNOLAB
  • Aspera European Astroparticle network Started in July 2006 and is responsible for coordinating and funding national research efforts in Astroparticle Physics.
  • Telescope Array Project (Delta, Utah) An experiment for the detection of ultra high energy cosmic rays (UHECRs) using a ground array and fluorescence techniques in the desert of west Utah.

See also

  • Astroparticle Physics
     (journal)
  • Urca process
  • Unsolved problems in physics

References

  1. ISBN 978-3-319-78181-5
    .
  2. ISBN 978-0-521-23513-6
    .
  3. ^ "April 17, 1912: Victor Hess's balloon flight during total eclipse to measure cosmic rays". Retrieved 2013-09-18.
  4. ^
    PMID 28179823
    . Retrieved 23 January 2013.
  5. ^ Astroparticle Physics. Retrieved 2013-09-18.
  6. ^
    ISBN 978-3-540-25312-9
    .
  7. ^ "IceCube - Deutsches Elektronen-Synchrotron DESY". Archived from the original on 2013-01-23. Retrieved 2013-01-24.
  8. ^ http://borex.lngs.infn.it Archived 2012-07-23 at the Wayback Machine
  9. ^ "Home". Archived from the original on 2013-05-06. Retrieved 2013-04-29.

External links

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