Analysis and study of the problems on the wires used in the MEG CDCH and the construction of the new drift chamber

In the MEG II detector, measurement of momentum charged particle is performed by a high transparency single volume, full stereo cylindrical Drift Chamber (CDCH). It composed 9 concentric layers, each consisting 192 drift cells. The cell approximately squared, with 20 μm gold plate tungsten sense wire surrounded 40 μm/50 silver plated aluminum field wires in ratio 5:1. During construction first CDCH, we observed breaking about hundred cathode wires: 97 these were wires, while 10 50 wires. Since number broken cathodes less than 1% total, one can expect influence on track reconstruction efficiency to be not so dramatic. We verified means simulations that loss does change electric appreciably. Here present results analysis effects mechanical stress and chemical corrosion Finally, show studies carried out new overcome weaknesses found process will used for chamber (CDCH2). built same modular technique, as previous one, use wiring robot optimized improve some weaker step procedure, adopted 25% thicker diameter, which has very little resolution detector. Furthermore are made manufacturing different from previously.