psi-21-january-2004meg drift chambers1 1)hardware foils hood inner cathode prints and preamps...
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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
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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
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-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
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hood frame
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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 !!
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Garfield calculation and calibration of drifttime
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a) Practically identical in both directions
b) Small effect of magnetic field
c) Garfield OK to a few %
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Wire 1
Wire 2
Plan 1 Plan 4
x 1.10 x 1.05 x 1.00
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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 ) )
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• 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
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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
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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
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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