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MEG Drift Chambers: Foils, Hardware, and Calibration

This document provides information on the MEG Drift Chambers, including details on foils, hardware, and calibration procedures. It also discusses the design, construction, and testing of the chambers. The text language is English.

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MEG Drift Chambers: Foils, Hardware, and Calibration

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  1. MEG Drift chambers • Hardware • Foils • Hood • Inner cathode • Prints and preamps • Calibration • Malte‘s Garfield isochronal Lines and drift time calibration • Calibration of cathode to anode ratio‘s,.... • 2004 MEG Drift chambers

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

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

  4. hood frame 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 !! MEG Drift chambers

  6. Garfield calculation and calibration of drifttime MEG Drift chambers

  7. Practically identical in both directions • Small effect of magnetic field • Garfield OK to a few % MEG Drift chambers

  8. x 1.10 x 1.05 x 1.00 Wire 1 Wire 2 Plan 1 Plan 4 MEG Drift chambers

  9. Calibration : Only ratio‘s are important,right-left,anodes-cathode Norm_cath1= (x1 + y1*sin(a))*(1 + p1*sin(a) ) (1) Norm_cath2= (x2 - y2*sin(a))*(1 + p2*sin(a)) (2) Norm_cath3= (x3 + y3*cos(a))*(1 + p3*cos(a)) (3) Norm_cath4= (x4 - y4*cos(a) )*(1 + p4*(cos(a)) (4) p1,p2,p3,p4 correction for the trackside For each event and each wire: Si : sin(a) from equation i Ci : cos(a) from equation i a1 = atan2(S1,C3) a2 = atan2(S2,C4) am = .5*(a1+ a2) Minimize  Sevent(abs( S1-sin(am) ) + abs( S2-sin(am) ) + abs( C3-cos(am) ) + abs( C4-cos(am) ) +Scath (abs(Norm_cathj-measj )) 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 MEG Drift chambers

  11. Plan 1 2 3 4 a1 a2 wires Selection and classification of events Choose the correct combination of and with the Maximum of cos(a1) + cos(a2) 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 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 MEG Drift chambers

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