Research Experimental High-Energy Physics and Astrophysics
Research Experimental High-Energy Physics and Astrophysics
The MACRO Experiment: (Monopole Astrophysics and Cosmic Ray Observatory) --
E. Kearns, J. Stone, L. Sulak
The deep underground MACRO detector is currently operating at the Laboratori Nazionali del Gran Sasso in Abruzzo, Italy. MACRO has a geometrical acceptance of 10,000 square meters at an average depth of 3.8 kilometers of water equivalent under the mountainous overburden of the Gran Sasso d'Italia. The MACRO detector is used to research several topics.
The specialty of MACRO is the search for
magnetic monopoles: particles with bare north or south magnetic
charge. These particles are a natural consequence of Grand
Unified Theories, which also predict that the monopole will be
very massive, perhaps 1016 GeV. Such particles can
only be produced by the intense energies available during the big
bang. MACRO operates like a giant Time-Of-Flight counter to
detect the unique signature of a slow moving but penetrating
massive particle. It is equipped with tanks of liquid
scintillator, planes of streamer tubes and plates of track etch
material in the hopes of recording a convincing signature from a
single candidate event.
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MACRO's high-resolution tracking and timing are also used to perform high statistics measurements of cosmic ray muons; in particular, the scintillator timing is used to distinguish upward going muons produced by neutrino interactions in the rock. This is an opportunity to investigate the possible flavor oscillation of massive neutrinos as suggested by the atmospheric neutrino puzzle, as well as possible astrophysical point sources of neutrinos. The large area and fine grain of the tracking affords unique measurements of large multiplicity muon showers. From these showers, we hope to infer information about the nature of the primary particles in the high-energy range of the cosmic ray spectrum. The large mass of liquid scintillator (~600 tons) is also instrumented to identify a burst of low energy pulses as might be caused by the flux of neutrinos from a supernova within our galaxy. |
| The MACRO Project: Photo of the MACRO project at Laboratori Nazionali del Gran Sasso in Abruzzo, Italy. |