DOUBLE PHOTOIONISATION OF HELIUM : THE TDCS AT 80 eV EXCESS ENERGY 
L.  Avaldi2, G. Battera  2, R.Camilloni2, M. Coreno3, M.DeSimone1, 
K.C. Prince5, G. Turri3, M. Zitnik4 
and G. Stefani1
1 INFM Unita' di Roma 3 and Dipartimento di Fisica"E. Amaldi". 
Univers ita' di Roma Tre, via della Vasca Navale 84, I-00146 Roma 
2 CNR Istituto di Metodologie AvanzateInorganiche, Area della Ricerca 
di Roma ,CP -10, 00016 Monterortondo 
3 INFM TASC, Padriciano 99, I-34012 Trieste 
4 Jozef Stefan Institute,P.O.B. 3000, SI-1001 Ljubljana, Slovenia 
5 Sincrotrone Trieste, I-34012Trieste 
The differential cross section (TDCS) of the direct 
doublephotionisation (DPI) of He has been measured up to an excess 
energy of 80eV above threshold, with equal sharing o fthe kinetic 
energy between
the emitted electrons.  The TDCS at 40 and 20eV have been measured as 
well.  The experiments have been performed at the Gas Phase beam line 
at ELETTRA by a novel multicoincidence spectrometer that measures
 20 angular conditions at the same time.