6533b854fe1ef96bd12af318

RESEARCH PRODUCT

Zepto-Second Atomic Clock for Nuclear Contact Time Measurements

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description

Renewed interest in search for the spontaneous decay of the neutral vacuum by emission of positrons in overcritical nuclear collision systems prompted the question of how to find experimental triggers for the required long sticking times in the order of \(10^{-20}\) s in dissipative heavy ion collisions [1]. A survey of various conceivable experimental methods led to the conclusion that the most promising way may be either to search directly for the positron line [2] or to investigate the shape of \(\delta \)-electron spectra [3, 4], both as function of the total kinetic energy loss or a large mass transfer between the collision partners. The \(\delta \)-electron-spectroscopy tool has been employed in a previous experiment for the dissipative U \(+\) Au collision system at an uranium beam energy of 8.65 MeV/u [5] in which nuclear contact times in the order of only 1 zs = \(1\times 10^{-21}\) s were deduced.