Semiconductor drift detector, comprising a semiconductor layer comprising on a first face: - a central electrode acting as an anode (71, 81, 91); - a series of drift electrodes acting as a cathode around said central electrode; - a last electrode (73, 83, 93) of the series of drift electrodes, opposite to the anode; - one or more further guard electrodes (75, 85, 95); and further comprising on a second face, opposite the first face, a continuous junction (74, 84, 94) acting as an "entrance window" for particles to be detected and, externally to said continuous junction, one or more further guard electrodes (76, 86, 96), a first central zone or core comprising the central electrode and ending at the last electrode and a second peripheral zone comprising the guard electrodes and mechanically closing the structure, wherein between said first zone and second zone an intermediate region (77, 87, 97) is interposed in the layer, comprising on said first face one or more further "symmetrization" electrodes (78, 88, 98' and 98") acting as cathodes, and comprising on said second face an extension of said continuous junction (74, 84, 94) having a width of at least the thickness of the detector, said one or more symmetrization electrodes being adapted to create, when all electrodes are powered, an almost symmetrical shape of the electric field lines in the layer, with opposite slope, relative to the shape of the electric field lines generated by said series of drift electrodes, characterized in that said intermediate region (77, 87, 97) has a width at least equal to the thickness of the layer, and beginning at and across said last electrode (73, 83, 93). - a central electrode acting as an anode (71, 81, 91); - a series of drift electrodes acting as a cathode around said central electrode; - a last electrode (73, 83, 93) of the series of drift electrodes, opposite to the anode; - one or more further guard electrodes (75, 85, 95); and further comprising on a second face, opposite the first face, a continuous junction (74, 84, 94) acting as an "entrance window" for particles to be detected and, externally to said continuous junction, one or more further guard electrodes (76, 86, 96), a first central zone or core comprising the central electrode and ending at the last electrode and a second peripheral zone comprising the guard electrodes and mechanically closing the structure, wherein between said first zone and second zone an intermediate region (77, 87, 97) is interposed in the layer, comprising on said first face one or more further "symmetrization" electrodes (78, 88, 98' and 98") acting as cathodes, and comprising on said second face an extension of said continuous junction (74, 84, 94) having a width of at least the thickness of the detector, said one or more symmetrization electrodes being adapted to create, when all electrodes are powered, an almost symmetrical shape of the electric field lines in the layer, with opposite slope, relative to the shape of the electric field lines generated by said series of drift electrodes, characterized in that said intermediate region (77, 87, 97) has a width at least equal to the thickness of the layer, and beginning at and across said last electrode (73, 83, 93).