In addition it includes an axle counting sensing arrangement (18).

The photon counting detector elements may also use dynamic thresholds to define energy windows.

The coins slotted into a coin slotting unit (101) are counted based on the sensing output from a counting sensor (104).

Typically, the photon-counting detector is a Geiger- mode avalanche photodiode (APD) that emits brief pulses every time it detects a photon.

The method includes providing single photon counting detector modules (40), each of the modules being configured to receive photons from a respective direction and to generate a signal in response thereto.

Preferentially, the at least one second region (15) is an inner region and the at least first region (14) is an outer region of the detection device (6) and in the at least one second region (15) photon-counting detector elements are present.