What is the CNI experiment The CNI experiment studies pion elastic scattering off fixed hydrogen target in the Coulomb Nuclear Interference region We bombard an hydrogen target (that means, for us, a proton target) with pion projectiles in the kinetic energy range from 15 to 70 MeV. We detect scattered particles in the whole reaction plane, except an hole of around 5 degrees around the beam direction. In particular, we are concerned with particles scattered at small angles ,say, below 30 degrees. This kinematic region is called the Coulomb Interference Region because both the e.m. and the hadronic component of the pion-proton interaction are strong enough to give a substantial interference contribution. 15 < T < 70 MeV 5º <   < 30º

Who performs CNI CHAOS collaboration: (,2 ), p, DCX Canadian High Acceptance Orbital Spectrometer Detects charge particles within 360º in-plane 7º out-of-plane

Where is CNI performed M13 low energy pion channel TRIUMF, Vancouver

Why CNI

Vertex reconstruction Empty target Hydrogen target

Experimental layout Drift wire chambers Beam counter MWPCs Hydrogen target E telescope / telescope Magnet yoke

Momentum reconstruction