The interaction/target region and the outer tracker are assembled on to the Detector Support Frame, whose shape resembling a sand-clock attributed it the Clepsydra nickname. The Clepsydra provides endplates between which the straw tubes are mounted and strung to tension. The drift chambers are slid in rails made in the axial links connecting the Clepsydra radial spokes, while the interaction/target region and the beampipe with two pairs of permanent compensating quadrupoles are sustained by the two inner cylinders connecting the radial spokes on the lateral surface of the structure. The detectors will be installed in the Clepsydra independently of the magnet, connected to the readout electronics and tested with cosmic rays in an assembly laboratory. When ready in the FINUDA experimental pit, the magnet will receive the instrumented Clepsydra via the sequence shown in fig.4, and finally the beampipe section with the compensating quadrupoles.
Figure 4: Sequence to slide the Clepsydra (equipped with interaction/target
region and outer tracker) inside the FINUDA magnet. The beam pipe section
complete with compensator quadrupoles is inserted, finally the spectrometer
is moved in the 
ring.
Figure 5:
(a) Raw reconstructed momentum distribution of the prompt 270 MeV/c 
;
(b) only forward pions, i.e. not crossing back the interaction/target
region;
(c) only forward pions, after correction for the energy loss in the target
based on the 
stopping point as determined by ISIM and OSIM.