In
this work, we present our magnetron sputtering based methodology
to produce amorphous silicon coatings with closed porosity, as a strategy
to fabricate solid helium targets, in the form of supported or self-supported
thin films, for nuclear reactions. We show how by changing the He
working pressure it is possible to obtain highly porous homogeneous
structures incorporating different He amounts. These porous coatings
(a-Si:He) are very reproducible from run to run, and the high He amount
incorporated makes them excellent candidates for solid He targets.
The possibility of producing self-supported films is illustrated here,
and its potential use in inverse kinematics experiments with radioactive
beams is shown through the dispersion in forward geometry of a stable
6
Li beam. Also the elastic scattering cross-sections for proton
from helium were determined using an a-Si:He coating. The results
agree well with the ones reported in the literature. These two examples
validate our coatings as good candidates to be used as solid He targets
in nuclear reactions. The stability of He inside the coatings, fundamental
for its use as solid He targets, was investigated, both over time
and after irradiation. The coatings proved to be very stable, and
the amount of He inside the pores remains unaltered at least 2 years
after deposition and after high irradiation fluence (5 × 10
17
particles/cm
2
; with a dose rate of 5 × 10
12
particles/(cm
2
s)).