1. PSI-21-january-2004MEG Drift chambers1 1)Hardware Foils Hood Inner cathode Prints and preamps 2)Calibration Malte‘s Garfield isochronal Lines and drift time calibration Calibration of cathode to anode ratio‘s,.... 3)2004 MEG Drift chambers

2. PSI-21-january-2004MEG Drift chambers2 New foil sample (.25  m Al), ~ 5 x 5 cm good quality 36 kCHF for 40 foils  final design 1.Shape of the frame 2.Deformation by mechanical pre-tension Precise measurements (.1 mm) Flexibility in the procedure to digest differences between old and new foil

3. PSI-21-january-2004MEG Drift chambers3 Tension of the foil must give the same torque as the forces used to pre-tension the frame : minimal final displacements Constant during manipulation Inner cathode frame New tool to ‚transport‘ the frame, groove with O-ring around the edge to pump Measurements and simulations (FSE) number of „pre-tension“ points optimal frame shape

4. PSI-21-january-2004MEG Drift chambers4 hood frame

5. PSI-21-january-2004MEG Drift chambers5 Same information as for the inner cathode modify design of frame, f. ex. He „bag“ at the same pressure as chambers, bubbler,.... !! tool is very efficient !!

6. PSI-21-january-2004MEG Drift chambers6 Garfield calculation and calibration of drifttime

7. PSI-21-january-2004MEG Drift chambers7 a)Practically identical in both directions b)Small effect of magnetic field c)Garfield OK to a few %

8. PSI-21-january-2004MEG Drift chambers8 Wire 1 Wire 2 Plan 1 Plan 4 x 1.10 x 1.05 x 1.00

9. PSI-21-january-2004MEG Drift chambers9 Norm_cath 1 = ( x1 + y1*sin(  ))*(1 + p1*sin(  ) ) (1) Norm_cath 2 = ( x2 - y2*sin(  ))*(1 + p2*sin(  )) (2) Norm_cath 3 = (x3 + y3*cos(  ))*(1 + p3*cos(  )) (3) Norm_cath 4 = (x4 - y4*cos(  ) )*(1 + p4*(cos(  )) (4) p1,p2,p3,p4 correction for the trackside For each event and each wire: S i : sin(  from equation i Ci : cos(  from equation i  1 = atan2(S 1,C 3 )  2 = atan2(S 2,C 4 )  m =.5*(  1+  2) Calibration : Only ratio‘s are important,right-left,anodes-cathode Minimize   event( abs( S1-sin(  m) ) + abs( S2-sin(  m) ) + abs( C3-cos(  m) ) + abs( C4-cos(  m) ) +  cath (abs(Norm_cath j -meas j ) )

10. PSI-21-january-2004MEG Drift chambers10 more on minimalisation function Quality of the procedure seen only after fit of trajectories (particularly effects of p‘s) Procedure works with defined p1,p2,p3,p4

11. PSI-21-january-2004MEG Drift chambers11 Plan 1 2 3 4 wires 11 22 Choose the correct combination of and with the Maximum of cos(  1) + cos(  2) Selection and classification of events

12. PSI-21-january-2004MEG Drift chambers12 2004 Design of Prototyp Optimise construction procedure and get all informations for foils and frames access MC (Hajime) to look for alternative solutions „final“ design test run in summer construction, assembling

13. PSI-21-january-2004MEG Drift chambers13 Non magnetic preamp and cable Anode print test chamber (1:1) {no cathode strip } Print, non magnetic preamp and cable,...sampling chip Mount cathodes Wire positioning tool