J. Wotschack 1

ATLAS micromegas

Progress report17 March 2011

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J. Wotschack 2

Large chamber with resistive strips Dimensions: 1.2 x 0.6 m2 (half of Large

CSC), 2048 strips with 0.5 mm pitch Production of first chamber with

resistive strips suffered a number of production problems Mesh not well stretched (waves) High-ohmig connection b/w mesh and

detector ground (insufficient development of support pillars)

Production of second chamber prototype started beginning of March

Several provisions to avoid the problems encountered in 1st try

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Chamber after pillar development but before curing

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Large resistive MM (CR2) ... cont'd

Chamber assembled a few days ago (Monday)

Connected to gas on Monday afternoon and applied HV a few hours later: no currents

First cosmic tracks seen on Tuesday morning

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J. Wotschack 4

The very first events with CR2 Connected one strip group to two

APV25 hybrid cards = 2 x 128 ch Trigger on cosmics with scintillators Data are clean; zero suppression as

on small chambers (not optimized) Correct mapping between electronics

channels and strips not yet done for these events (done now)

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MM test in ATLAS cavern In February the infrastructure for the MM installation was installed in the

ATLAS cavern (thanks to the help and support of ATLAS Technical Coord. and Operation) Location on HO (side A) 6th floor, close to beam HV and ethernet cables were pulled from from HO to USA15 Gas pipe from GSX1 to location close to rack Small standard rack installed and connected to safety system (missing: rack

connection to cooling water) Identified a location in USA15 for HV mainframe and PC

Setup with four small MMs being prepared in Lab 2 MMs for triggering (standalone trigger) 2 MMs with 2D readout with 250 µm strip pitch DAQ system for 1440 channels, including DCS and readout

Installation: hope to be ready for next access (end March?) or for sure for the one after that ...

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MM project time lineFollowing the request of the Muon Upgrade Management, here a preliminary time line for the MM project 2011: Summer/Fall: Proposal

Construction of CSC-size chamber with several layers and xy readout (to be installed in ATLAS); fully equipped with first version of new VMM1 chip (BNL)

2012: Technology choice (?) Detector long-term tests and ageing studies (material choice) Construction of full-size module-0 chamber with two multilayers and xy readout,

compatible with new Small Wheel design; fully equipped with VMM1 chip; commissioning of readout and trigger system

2012/13: Design optimization & industrialization of production; setup of production, assembly, and test sites; MoUs

2014-16: Construction and commissioning of 128 chambers 2016/17: Installation on Small Wheel & commissioning

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Plans for 2011

March/April: install small MMs in ATLAS cavern March/April: 2nd plane for large chamber (mirror

symmetric) to have a double layer module back-to-back

May: test large chamber in neutron beam (?) Test beam July: test double-layer chamber + 2D Summer/fall: construction of full-size module with

several active layers October: 2nd test period to test full-size chamber and

first version of new BNL chipAM Upgrade mtg 17/03/2011

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Joerg Dubert’s Questions• as you all aware we currently do not yet know how the final mechanical

design of the new Small Wheel will look like. Nevertheless, in the end the available space for detectors will be quite similar:

- in the x-y plane the maximum size will be approximately that of the current CSCs or MDT chambers. Of course, in the radial direction the new chambers could be smaller and their number increased. In the phi-direction the size is more or less fixed as we want to keep the arrangemnt in 16 sectors.

- in the z-direction the space will be about 25-40 cm, depending whether we can profit from an additional wall of neutron shielding.

• If possible we still envision the new Small Wheel to use only one single type of chamber (which could of course consist of a mechanically integrated sandwich of technologies if needed), i.e. we want to avoid regions with different technologies like the current CSC and MDT/TGCs.

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Mmegas-based Strawman Detector

Toy Detector just to get a rough idea what could be possible and approximate channel countTwo basic criteria: 1. At least one dimension of the chamber must be <= 1100 mm 2. Channels/plane give a sensible chip count with strip width ~0.5 mm

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The resulting “Parameter Table”

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Total width easily within 40 cmGenerate track at a given angle

Track crosses a strip at a random position

Generate primary ionization clusters Poisson distributed

Generate number of electrons for each cluster

Take strip with earliest time and charge over a certain threshold as the track’s coordinate

Strip pitch = 0.5 mm

Reconstruct track and compare slope with the generated oneNo transverse diffusion considered but effect is negligible for the first arriving cluster

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Services

• Power needed 22 kW (Have 18 kW presently for CSC)– 2 M channels with <10 mW/ch front-end chip ≈ 20 kW– 1 GBTx (optical fibre) link/chamber adds 1-2 mW/channel

• Existing cooling more than adequate (only use ~15 l/min/loop, 4 loops)

• Existing MDT Gas Infrastructure adequate• Optical fibers assuming 1 link/Chamber 128-256

(depending on max size) Already have 320 for CSCs • HV needs further studies to devise a distribution strategy