Ideas and Plans on Tracker Module Mechanics Developments

Ideas and Plans on Tracker Module Mechanics

Developments

FNAL CMS Upgrade Workshop, Nov 2011 Antti Onnela, CERN

Module types

Module mechanics common topics

with reference examples from the present

Tracker

Planning

• The Phase II module mechanics depend strongly on the tracker layout and module types/functions. – Tracker’s trigger function (or not) is very decisive, upgrade tracker design hinges

on it.

• Several module types have been proposed:A. “Vertically integrated 3D”B. “2 Strip PT”

C. “Pixel + Strip PT”

D. “Stereo Strip”

Module types


B. C. D.

A.

Module mechanics, common topics

• Build them light!• Make sure they are properly cooled• Make them to a really needed precision• Build modules robust enough, for their full life-cycle

– A late patch reinforcement added to TOB modules to prevent wire bond damage during transport

• Limit number of module variants– Reduces design and prototyping work– Simplifies and reduces costs in production, logistics and spares– Particularly relevant for an end-cap design

• Present studies assume use of barrel type rectangular modules, no wedge shapes 2 types of modules instead of ~ 10 types.


Next slides

Mass• Supports are significant in the today tracker

• Modules are significant in the present tracker. • The upgrade tracker will have ~ same amount of modules

again.FNAL CMS Upgrade Workshop, Nov 2011 Antti Onnela, CERN

X/X0

Careful with this plot:It contains all TK supports, including the outermost parts (cylinders, end disks) which are much less harmful than those closer to the beam.

• Inner cylinder + disks ~75 kg• End-flange services 125 kg (two ends)

– Cooling 66– Cables 15– Other electronics and connectors 44

• Total rods 626 kg– Modules 260 (31% of total TOB)– Cooling 66– Electronics 206– Mechanics 91

• Total: 826 kg

Mass example from the present TK: TOB


Module frames: 8% of total TOB.

Module mass


Pixellated and 3D twin-detectors:Spacers, interposers, heat spreaders particularly important.

We (CMS Tracker) need to gain know-how and experience with these !

Room for plenty of further work:• Material choice• Geometry/dimension

optimisation• Connections (mechanical,

electrical)• Prototyping, testing

The future does not seem easier than the past !

Module cooling

• Different variants of module cooling were applied in the present TK– So, we have now a wider experience than if everything would have been

common...


Module cooling: Present TK


Support

Module cooling

• Uncertainities in calculation inputs (composites, glues, joints) measurements are necessary, though not fully obvious either (e.g. inputting of power load, availability of correct materials/components)

• For the present tracker calculations and tests done mostly in 2000-2002


• Coolant temperature: 5 - 6 ºC.• Module power loads:

– FE-power ~ 0.45 W / APV– Silicon self-heating ~ 0.014W / module @ 5 fb-1,

0.4W / module expected @ 500 fb-1 (10y LHC)

• Silicon mean temp: 13 – 14 ºC• ΔT (silicon - coolant) = 7 – 9 ºC

– Will grow to ~ 10 ºC due self-heating increase

Module cooling (TOB)


Plots by Christian Barth

DS modules P = 3.6W

SS6 modules P = 2.7 W

SS4 modules P = 1.8 W

Cooling segment #44TOB 1.3.1 (132 modules) off

Module cooling

• Estimated power load in a Pixel – Strip module: 5.6 W (TOB: 1.8 – 4.4 W)

• Following calculations (A. Mussgiller, S. Kyre) and present TK experience ΔT (silicon – coolant) of 10 ºC seems reachable, but not automatic!– In present TK no active electronics placed directly on the silicon sensors.– In 3 of 4 proposed upgrade modules there are active read-out components on

silicon.

• Good quality dry cooling contact is sufficient– No need for thermal pastes. Avoid them, they are ‘dirty’– But requires good planarity of the module and support contacts (no gaps,

minimal stresses)– Even a small contact area is enough with these low powers, if the contact is

good.

Room for plenty of further work:– Choice of module frame materials (CFRP, TPG, PGS, …?)

• In TOB alu heat spreaders. Could we do without those?– Frame dimension and geometry optimisation– Assembly glues and methods, ensure thermal contacts within the module– Prototyping and testing are essential !


Module positioning

• Like with the module cooling, in the present TK there is no common module positioning method– So, we have now a wider experience...


Module positioning: TOB


Module positioning: TEC


TIB and TID? Like TEC?

And the net result with TK precision?


Already after first cosmic runs the residuals with Track Based Alignment are at ~50um rms, and improve within 2008 to ~30um.Much better than what the mechanics can (reasonably) do!

Module positioning

• Sufficient precision can be reached with the TEC method– Smaller and lighter than the TOB method

• Maybe a sufficient precision can be reached even without positioning pins?!– Precision screw + hole / slot ?– Counter sunk screw + 2 holes or 1 hole and 1 slot ?– Use module edge as guide reference ?– What is the material on the module side, are inserts needed?

• Room for plenty of further work:– Analyse the present TK results and set precision requirements for the upgrade

TK.• This is very important, impacts the mechanics design from modules up to complete

TK, as well as what needs to be done in terms of pre-alignment and measurements.– Design and prototyping of module positioning materials and methods

• Aim for simplicity, reliability and low mass.


Planning• Upgrade TK installation in ~2021, not much time left anymore for

R&D!– “R&D over” by Technical Proposal in 2014 ?

• During 2012-2013 acquire as much as possible all needed ‘building blocks’ for making the final tracker design.– The more this is successful, the easier it is to use common, tested

solutions throughout the TK. This part must be done better than in the present TK!

• For mechanics the focal point now is on the modules, including their connections to cooling and other services.– In 2012: Continue calculations, consolidate our data base of materials and their

use. Proceed to making test modules, support/cooling contacts.– CO2 cooling test equipment available (Pixel phase 1). Rods recently (this

morning!) tested to hold >400 bar pressure and can be used as module test platforms with CO2.

• 3D modelling on local and larger structures should advance as well, to make sure we have the needed concepts matching the proposed TK layouts.

• We need to see that all essential topics are covered, who contributes where in 2012. Discussions during this workshop, and after.


Spares


Module and layout variants


From Stefano Mersi. More in his talk.

Long barrel geometry


End-cap: Minimise the module frames


Nick Lumb / Lyon

End-cap: Curved rod


Nick Lumb / Lyon

End-cap: Twin-disk


Nick Lumb / Lyon

Module frame mass

• Is a closed frame needed, can the silicon sensors take the loads– And what are all the loads...?


Documents

Ideas and Plans on Tracker Module Mechanics Developments