  Interaction of a frequency-chirped laser pulse with single protons and a
hydrogen plasma cell is studied analytically and by means of particle-in-cell
simulations, respectively. Feasibility of generating ultra-intense (10^7
particles per bunch) and phase-space collimated beams of protons (energy spread
of about 1 %) is demonstrated. Phase synchronization of the protons and the
laser field, guaranteed by the appropriate chirping of the laser pulse, allows
the particles to gain sufficient kinetic energy (around 250 MeV) required for
such applications as hadron cancer therapy, from state-of-the-art laser systems
of intensities of the order of 10^21 W/cm^2.
