PSI-21-january-2004MEG Drift chambers1 1)Hardware Foils Hood Inner cathode Prints and preamps 2)Calibration Malte‘s Garfield isochronal Lines and drift.

PSI-21-january-2004 MEG Drift chambers 1

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

PSI-21-january-2004 MEG Drift chambers 2

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

PSI-21-january-2004 MEG Drift chambers 3

-2

-1.5

-1

-0.5

0

0.5

1

-800 -600 -400 -200 0 200 400 600Reihe1

Reihe2

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

PSI-21-january-2004 MEG Drift chambers 4

hood frame

PSI-21-january-2004 MEG Drift chambers 5

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 !!

PSI-21-january-2004 MEG Drift chambers 6

Garfield calculation and calibration of drifttime

PSI-21-january-2004 MEG Drift chambers 7

a) Practically identical in both directions

b) Small effect of magnetic field

c) Garfield OK to a few %

PSI-21-january-2004 MEG Drift chambers 8

Wire 1

Wire 2

Plan 1 Plan 4

x 1.10 x 1.05 x 1.00

PSI-21-january-2004 MEG Drift chambers 9

Norm_cath1= ( x1 + y1*sin())*(1 + p1*sin() ) (1)

Norm_cath2= ( x2 - y2*sin())*(1 + p2*sin()) (2)

Norm_cath3= (x3 + y3*cos())*(1 + p3*cos()) (3)

Norm_cath4= (x4 - y4*cos() )*(1 + p4*(cos()) (4)

p1,p2,p3,p4 correction for the trackside

For each event and each wire:

Si : sin(from equation i Ci : cos(from equation i

1 = atan2(S1,C3) 2 = atan2(S2,C4) 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_cathj-measj ) )

PSI-21-january-2004 MEG Drift chambers 10

• 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

PSI-21-january-2004 MEG Drift chambers 11

Plan 1 2 3 4

wires

12

Choose the correct combination of and with the

Maximum of cos(1) + cos(2)

Selection and classification of events

PSI-21-january-2004 MEG Drift chambers 12

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

PSI-21-january-2004 MEG Drift chambers 13

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