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.