DIANA an underground nuclear astrophysics experiment

Alberto Lemut


Non-resonant nuclear reactions induced by charged particles take place inside a star in a narrow energy window, the Gamow peak , which lies far below the Coulomb barrier. At such low energies, the non resonant reaction cross-section sigma(E) drops down almost exponentially with decreasing energy E, because of the tunneling probability through the Coulomb barrier. Experimental studies of nuclear reaction of astrophysical interest are hampered by the exponential drop of the cross-section. The extremely low values of sigma(E) within the Gamow peak prevents its measurement in a laboratory at the earth surface. The signal to noise ratio would be too small, even with the highest beam intensities presently available from industrial accelerators, because of the cosmic ray interactions with the detectors. An excellent solution has been proved to install an accelerator facility deep underground where the cosmic rays background into detectors is strongly suppressed. The DIANA project (Dakota Ion Accelerators for Nuclear Astrophysics) is a collaboration between the University of Notre Dame, Colorado School of Mines, University of North Carolina, Western Michigan University, and Lawrence Berkeley National Laboratory, to build a nuclear astrophysics accelerator facility 1.4 km below ground. DIANA is a part of the US proposal DUSEL (Deep Underground Science and Engineering Laboratory) to establish a inter-disciplinary underground laboratory in the former gold mine of Homestake in South Dakota, USA.