  In order to allow a good separation of isotopes in a High Resolution Mass
Spectrometer (HRMS), the transverse emittance and the energy spread of the beam
should have very low values, for this reason a Beam Cooler (BC) is planned to
be located between the ISOL target, i.e. the beam source, and the HRMS in the
new project Selective Production of Exotic Species (SPES).
  In the SPES project the spectrometer resolution must be higher than dm/m=5E-5
and thus the features of the beam at the entrance of the HRMS should be at
least emittance (95%, normalized) < 8.3E-3 pi mm mrad and sigma_E < 1.5eV.
  A new BC has been designed and realized by the Laboratoire de Physique
Corpuscolaire (LPC) at Caen, France, for the SPES facility at Laboratori
Nazionali di Legnaro (LNL), near Padova, Italy.
  BCs cool down the beam thanks to a dissipative process in which the thermal
energy passes from the beam ions to another medium whose constituent is
typically much lighter, Helium gas in our case. This process takes place inside
a confinement system that on the one hand to limit the spread of the cooling
medium, and on the other to allow the beam to continue along the required
trajectory, in the presented device it is a row of radio frequency quadrupoles
in an almost closed chamber.
  This document presents the main features of the new BC together with the
results of a preliminary study where the beam dynamic has been simulated. The
analysis embeds also the investigation of the gas distribution inside and
outside the BC.
  The beam dynamic simulations are based on the Simion code while the
estimation of the gas distribution is computed with MolFlow+.
  Simulations show that accurately setting the BC leads to a large improvement
of the emittance while the energy spread still needs to be improved. Limiting
the gas pressure in the acceleration zone seems to allow the required final
boost.
