The electronics

The analysis of the phoswich events, i.e. the recognition of the good events, is in charge of the Pulse Shape Analyzer (PSA), whose programmable thresholds determine the events' selection conditions (fig. ).

In addition to the PSA, also the AC shields contribute to the rejection of bad events: whenever the signal produced in one of the shields exceeds a programmable threshold (AC), a veto signal is generated by the PDS Analog Processor (AP).

The AP, including all the analog electronics, analog-to-digital converters (ADCs), AC logics and programmable thresholds, filters all the events detected by the PDS. All events qualified as good by the AP, are time tagged and sent to a Digital Processor (DP), which filters and formats them ready to be sent to the satellite On-Board Data Handling (OBDH). The two processors, AP and DP, constitute the Instrument Controller (IC).

Table: PDS main characteristics

Energy range	15-300 keV
NaI(Tl) phoswich thickness	3 mm
CsI(Na) phoswich thickness	50 mm
Total area through collimator	640 cm$^2$
Effective area	600 cm$^{2}$@20 keV
	500 cm$^{2}$@60 keV
	500 cm$^{2}$@100 keV
	140 cm$^{2}$@200 keV
Field of view (FWHM)	1.3$^\circ$hexagonal
Energy resolution at 60 keV	$\leq$15% (on the average)
Maximum time resolution	16 $\mu$s
Gain control accuracy	0.25%
In-flight calibration accuracy	0.1%
Energy spectra	512 channels
Minimum channel width of energy spectra	0.3 keV
Maximum throughput	4000 events s$^{-1}$