MACRO

Home page of the Experiment: http://www.lngs.infn.it/site/exppro/macro/macro.html

`MACRO is a large area multipurpose underground detector designed to search for rare events in the cosmic radiation. It has been optimized to look for the supermassive magnetic monopoles predicted by Grand Unified Theories (GUT) of the electroweak and strong interactions; it can also perform measurements in areas of astrophysics, nuclear, particle and cosmic ray physics. These include the study of atmospheric neutrinos and neutrino oscillations, high energy (E` `n``` `>~` `1 GeV) neutrino astronomy, indirect searches for WIMPs, search for low energy (E` `n``` `>~` `7 MeV) stellar collapse neutrinos, studies of various aspects of the high energy underground muon flux (which is an indirect tool to study the primary cosmic ray composition, origin and interactions), searches for fractionally charged particles and other rare particles that may exist in the cosmic radiation. The mean rock depth of the overburden is` `~``3700 m.w.e., while the minimum is 3150 m.w.e. This defines the minimum muon energy at the surface at` `~``1.3 TeV in order to reach MACRO. The average residual energy and the muon flux at the MACRO depth are` `~``310 GeV and` `~``1 m``-2``h``-1``, respectively. The detector has been built and equipped with electronics during the years 1988 - 1995. It was completed in August 1995 and the data taking terminated in December 2000 .`

`The MACRO detector has a modular structure: it is divided into six sections referred to as supermodules. Each active part of one supermodule has a size of 12.6 x 12.6 x 9.3 m``3``and comes with separate mechanical structure and electronics readout. The full detector has global dimensions of 76.5 x 12.6 x 9.3 m``3` `and provides a total acceptance to an isotropic flux of particles of``~``10. 000 m``2``sr. The total mass is` `~``5300 t.`

`The detector is composed of three sub-detectors: liquid scintillation counters, limited streamer tubes and nuclear track detectors. Each one of them can be used in "standalone" and in "combined" mode.`

`Redundancy and complementarity have been the primary goals in designing the experiment. For example, since no more than few magnetic monopoles can be expected, multiple signatures and ability to perform cross checks among various parts of the apparatus are important.`