A detector (100) for detecting neutrons includes a neutron reactive material (102) adapted to interact with neutrons to be detected and release ionizing radiation reaction products in relation to the interactions with neutrons. The detector also includes a first semiconductor element (101) being coupled with the neutron reactive material (102) and adapted to interact with the ionizing radiation reaction products and provide electrical charges proportional to the energy of the ionizing radiation reaction products. In addition electrodes are arranged in connection with the first semiconductor element (101) for providing charge collecting areas (106) for collecting the electrical charges and to provide electrically readable signal proportional to the collected electrical charges. The thickness of the first semiconductor element (101) is adapted to be electrically and/or physically so thin that it is essentially/practically transparent for incident photons, such as background gamma photons.