  Metal atoms in solid and liquid helium-4 have attracted some interest either
as a way to keep the atoms in a weakly perturbing matrix, or using them as a
probe for the helium host medium. Laser sputtering with nanosecond pulsed
lasers is the most often used method for atom production, resulting however in
a substantial perturbation of the matrix. We show that a much weaker
perturbation can be obtained by using femtosecond laser pulses with energy as
low as 10 $\mu$J. As an unexpected benefit, the atomic density produced is much
higher.
