1. The new set of MWPCs for CB CB@MAMI Collaboration Meeting Glasgow March 2006 A. Braghieri, P.Pedroni

2. Time Schedule Aug Sep Oct Nov Dec Gen ‘06 Not a realistic schedule ! (June 05) today we are more or less here ….

3. Why ? Very limited availability of our electronic workshop Problems in PCB design (signal distributions to connectors) due to the limited space (all signals are on the same side) new PCB test underway using new miniconnectors from AVX (additional problems to connect signals to the existing electronic setup) Electronic workshop is giving more support to our group I can not give at the moment any realistic estimate (mwpcs ready not before october)

4. Possible ways out until the new mwpc set is ready: Use CB without mwpcs and PID Use CB with old PID only (PMTs on the upstream side) Use old mwpcs and old PID (downstream dead region)

5. CAD Layout (mwpcs)

6. Beam axis CAD Layout Wire planesCathode planes Distance between wire planes: 20 mm (old mwpcs:32 mm)   resolution will be worse (x 1.6) still acceptable (if ADCs performances will improve) 1 2

7. new Cerenkov detector (needed for the GDH measurement): Dr.T. Rostomyan (PhD from Gent Univ.) 1+1 year Post-Doc contract at INFN- Pavia (start: feb.06) his main task is to build this detector with the technical help of RUG-Gent (D.Ryckbosch)

9. Technical Design Two coaxial Multi-wire Proportion Chamber Mechanics and assembling Diameter definitions CB Frame, PID2, new target Gap between the two chambers and number of channels Tracking resolution Upstream Cathode and Anode readout Connectors Critical Parameters  205 mm: Outer diameter  132 mm: Inner diameter  2 mm: wire spacing (Electric field)  4 mm: strip width (charge collection) } MAGIC NUMBERS

10. Improvements in the mwpc setup  Flash ADC problem (see Schumann’s talk) needs to be solved  Now all signals are at the upstream mwpc end; strip preamplifier/ADC crates need to be moved and space has to be found for them; probably new (longer) cables p.a.  ADC need to be made  Are there new p.a.-discriminators cards available for wires ? (COMPASS has built similar cards …)  Are there new p.a.(single channel hybr. chips) available for strips ? (NOT commercially available, this would need a dedicated project)