  Laser-induced processes in ultra-dense deuterium D(0) layers eject multi-MeV
u-1 particles using ns laser pulse energies of <200 mJ. Such particles have
been observed previously as mA currents to time-of-flight (TOF) collectors at
up to 1 m distance. The signal current is mainly due to the ejection of
secondary electrons by impinging MeV particles on the collectors. Improved
two-collector time-of-flight measurements now show that the energy of the
particles is in the range 1-50 MeV u-1. Their distributions are almost thermal
at up to 13 MeV u-1 or are sharper than thermal. The fastest sharp peak may
indicate shock-wave acceleration by many-body energy transfer. A magnetic field
of 0.4 T deflects only a small part of the multi-MeV particle flux which thus
mainly consists of neutral particles. By combining the TOF method with magnetic
deflection, it is ascertained that the multi-MeV particles are studied and not
any slower particle emission from the target. The neutral multi-MeV particles
are concluded to be fragments of ultra-dense hydrogen HN(0) as observed in
other experiments.
