The present invention relates to a detection device (6) for detecting photons emitted by a radiation source (2) and capable of adjusting ballistic deficit. The detection device (6) comprises a pre-amplifying unit (11) (such as, e.g., a charge-sensitive amplifier), a shaping unit (60) comprising a feedback discharge unit (13, I) (such as, e.g., a feedback resistor or a feedback current source), and a feedback discharge control unit (50) coupled to the feedback discharge unit (13, I). The feedback discharge control unit (50) is adapted to, e.g., adjust a resistance of a feedback resistor (and / or to adjust the current value of the feedback current source) if an electrical pulse generated by the shaping unit (60) does not exceed at least one energy comparison value (X1, X2, . . . , XN). The feedback discharge control unit (50) is adapted to not adjust the parameter of the feedback discharge unit (13, I) if the electrical pulse exceeds the at least one energy comparison value (X1, X2, . . . , XN). By tuning the feedback resistor operating point (or the feedback current source operating point), the ballistic deficit can be adjusted to a predefined expected value.