Abstract: The object of the invention relates to a neutron absorbing concrete wall (10), which concrete wall (10) has an internal delimiting surface (11a), and an external delimiting surface (11b) on an opposite side to the internal delimiting surface (11a), the essence of which is that it contains a first concrete layer (13a) on the side of the internal delimiting surface (11a), and a second concrete layer (13b) on the side of the external delimiting surface (11b), which first concrete layer (13a) contains at least 0.05 mass % boron-10 isotope (10B), and the second concrete layer (13b) is formed as heavyweight concrete. The object of the invention also relates to a method for creating a neutron radiation absorbing concrete wall (10) that has an internal delimiting surface (11a), and an external delimiting surface (11b) on an opposite side to the internal delimiting surface (11a), the essence of which is a first concrete layer (13a) containing at least 0.

Abstract: The object of the invention relates to a neutron source, which contains a proton accelerator for producing a proton beam, and a target arranged in the trajectory of the proton beam exiting the proton accelerator for producing a neutron beam, to which the proton beam arrives in long, typically 0.5 ms-3 ms impulses, and contains a moderator-reflector system arranged in the vicinity of the target and serving for producing a moderated neutron beam, which has at least one moderator, and a reflector surrounding the moderator and the target, characterized by that at least one statistical neutron chopper is arranged to protrude into the at least one moderated neutron beam exiting channel that modulates at least one neutron beam intensity according to a random or pseudo-random sample as a function of time with its neutron transmittance ability varying according to such pattern.