Overview of the MEG * CDCH * one of the following ( MEG UP MEG2 MEG + ) Marco Grassi on behalf of the CDCH Group

Introduction Fukuoka, Oct The upgrade completion is planned for autumn 2015 The current estimates for the New Chamber production is 18 months During this Collaboration Meeting 1.the external constraints to the chamber geometry have to be checked and agreed on 2.the azimuthal coverage needs to be fixed definitely A brief report has been submitted to the collaboration as suggested during the last bi weekly meeting

Report Fukuoka, Oct

Index Fukuoka, Oct

External constraints Fukuoka, Oct mm 128mm 140 / 115mm Minimum distance between foil and bellow = 10 mm External constraints from COBRA R_Cobra_min297.0mm R_Cobra_safe3.0mm R_bellows114.0mm Bellows_Sag13.0mm Bellows_Safe30.0mm MaxLoadXxxkg Z_Cobra_max1420.0mm chamber allowed space R_ext_max294.0mm R_ext_min157.0mm Z_max1420.0mm

Bellow system Fukuoka, Oct Equal sharing of the 20 mm distance between the bellow system and the wire minimum radius

Other dimensions and weight Fukuoka, Oct Outer radius Planned measurement of the soldering ribs with respect to COBRA flange Length “natural” chamber length of 2840 mm, including “extension volumes” Weight 250 Kg, mainly flanges, electronics cooling and cables He He / iB air

Costraints on wires R_ext_max mm R_safe_fiber5.000mm Fiber_thick2mm R_wire_max mm R_ext_min mm R_safe_foil10.000mm R_wire_min mm Internal safety margins Fukuoka, Oct mm 156 mm R_safe_ext R_safe_int Tests with long prototype

endplate Fukuoka, Oct End Plate ichamR_iZ_iTh_i2*Alpha_iArc_iCt_incell_iCw_iCt/Cw mm deg mm guard field signal field signal field signal field signal field signal field signal field signal field signal field signal field signal field guard

center Fukuoka, Oct Center ichamRm_iDR_iCt_iCw_iCt/Cw mm guard field signal field signal field signal field signal field signal field signal field signal field signal field signal field signal field guard

Chamber length Fukuoka, Oct The chamber length defines the geometrical matching with the timing counter: as long as possible Long chamber has reduced longitudinal resolution: effects seen in MC at half-length=100 cm Construction concerns Measurable volume 2550x1500x1350 mm 3

Chamber length Fukuoka, Oct Construction concerns 1.Long cells have larger gravitational sag and impose more stringent constraints on wiring position: functioning long prototype with half-length=90 cmOK 2.Wiring machine needs a larger cylinder: increased inertial momentumunder study 3.Assembly under measuring machine with a total length of 2600 mm: half-length≤95 cm need double check 1900 mm 60 mm 150 mm 120 mm

Limited azimuthal coverage Fukuoka, Oct The chamber described in the upgrade proposal has an azimuthal coverage with both U and V views of ~240 deg at Z=0 ~180 deg at end plate The wire suspension at the end-plates spans 300 deg The choice was suggested only by the comparison with the present detector configuration in which the target is hung to the chamber system. The limited azimuthal coverage is possible even if not optimal for the tracker.

Limited azimuthal coverage Fukuoka, Oct The support structure limits the space available for target movement The structure is more robust and simple 1.E field is not well defined everywhere: up to 50% noise increase on 50% of the wires 2.The carbon fibre support is “straight-forward” 3.The end-plate structure is simplified 4.Kapton foil structure and tensioning is simplified

2  azimuthal coverage Fukuoka, Oct The 2  solution eliminates zones with weak E fields (only HV is needed, not FE nor DAQ) opens up extra physics channels with e- facilitates chamber construction but Impacts on the target system Is more expensive (wire PCB and HV) The design of the azimuthal limited chamber is pursued but the 2  solution is strongly preferred

Target system location Fukuoka, Oct Simple proposal Target holder Inside US extension R in 130 ÷ 155 mm Target displacement 25 cm Target Light rohacell support (or even lighter) Simulation of the background induced on the Calorimeter is in progress

Beam line interference Fukuoka, Oct cm Interference with muon beam line seems negligible

Fukuoka, Oct

Fukuoka, Oct

Electronics and cables Fukuoka, Oct Chamber FE electronics placed in 2 “extensions” maintained in 294 mm < R < 156 mm Cables through “extensions” circular covers Check of available space

He He / iB Gas volumes Fukuoka, Oct air Support structure stiff enough to rotate the chamber in vertical position Gas sealing directly on end-plates by potting Selection of potting material

He He / iB Coupling to COBRA, BTS and Bellows Fukuoka, Oct air Coupling flanges ending at 1420 mm (end og COBRA) –Stress release by mean of bellows Mechanical coupling to COBRA via cable flange

Presentations Fukuoka, Oct Construction – End plates (Miccoli) – FE electronics (Grancagnolo) – HV (Piredda) Prototypes – Long prototype (Baracchini) – cosmic telescope (Galli) Reconstruction and analysis – LXe – CDCH alignment (Kang) – Pattern recognition (Cei) – Reconstruction (Renga) – Single hit resolution (Cascella)

Summary Fukuoka, Oct The CDCH group endorses a 2  azimuthal coverage and asks the Collaboration to approve it Decision could be revised in case of sensitive increase of background on the calorimeter (ongoing study with an heavy target system) Decisions or checks on the following items are needed – gas volumes separation – constraints on external dimension – coupling to COBRA, BTS and bellow system Construction aspects are under discussion within the chamber group – chamber length – electronic location and service – end plates structure

End

Timing summary Fukuoka, Oct TaskStartcompletion Geometry01/201306/2013 Assembly procedure01/201306/2013 End plate design05/201310/2013 Support struct. design05/201312/2013 Material procurement10/201306/2014 Mounting tool10/201306/2014 Wiring tool10/201306/2014 Assembly06/201402/2015 Laboratory test03/201504/2015 Integration at PSI05/201506/2015 Contingency06/201509/2015

Wires Fukuoka, Oct Wire types 20 um W gold plated 40 um Al silver plated 50 um Al silver plated Pre production for long prototypes was expected by September 7 th Not delivered yet Solicited twice by and phone call … Producer California Fine Wires Already funded for the full production (84 kEu) waiting for delivery and acceptance test.

Revision of baseline geometry Fukuoka, Oct Option 3 presently used in Geant4 simulation 10 layer fixed sector width  = 60 deg planar EndPlate at  = 900 mm Equal number of cells per sector (power of 2) nC_i = {32, 32, 32, 32, 32, 32, 32, 32, 32, 32,} Cell Width C W from nC_i Cell Thickness C T equal to C W Radial position R from C T Stereo angle  fixed by R Total  coverage = 240 deg at Z=0

End plates Fukuoka, Oct History Two end-plate prototypes have been designed Last week the two option were reviewed Status Delays with the prototype production of the baseline solution (Lecce) In production the alternative solution (Pisa)

End Plate Fukuoka, Oct

End plates Fukuoka, Oct Agreed strategy Fully test the alternative solution If ok -> { end} If fail -> { Combine mechanical design of the alternative solution with the PCB stacking up method of the baseline solution } In both cases PCB similar to the one shown