A detector for detecting signals derived from charged particles (1) incident thereon, the charged particles consisting of at least one of protons, deuterons, tritons, and α-particles, and for distinguishing signals caused from the charged particles interacting with the detector from background radiation containing neutron and gamma particles, the detector comprising: a silicon wafer (4) having an entrance opening etched through a low-resistivity layer of silicon; a sensitive layer of high-resistivity silicon (3) for converting the radiation particles into detectable charges; a passivation layer (6) between the low-resistivity layer and the sensitive layer of high-resistivity silicon; a plurality of electrodes (2) built in the form of vertical channels for collecting the charges etched into the sensitive layer of high-resistivity silicon; and read-out electronics for generating signals from the collected charges, wherein the detector is constructed to take in the charged particles to be detected directly through the passivation layer and wherein the thickness of the sensitive layer of high-resistivity silicon has been selected as a function of the mean free path of the charged particles to be detected.