High quality STJs of type Nb/Al/AlxOy/Al/Nb and Nb/Al/AlxOy/Nb/NbN, in
which Al and Nb act as quasiparticle traps, were realized and tested
under 6 KeV X ray radiation. The experimental results show an enhancem
ent of the collected charge with respect-to basic Nb/Nb configuration.
An energy resolution of 300 eV was achieved for a 50x50 mu m(2) NbN-b
ased STJ.