Role in ATLAS New Muon Spectrometer LIA FORMENTI SUPERVISORS: - - PowerPoint PPT Presentation

Zooming into Canada’s Role in ATLAS’ New Muon Spectrometer

LIA FORMENTI SUPERVISORS: BRIGITTE VACHON AND YAN BENHAMMOU WORKING WITH MCGILL’S ATLAS STGC GROUP SUPPORTED BY INSTITUTE OF PARTICLE PHYSICS (CANADA) AND NSERC

Outline

• The future of LHC and ATLAS
• Why the muon small wheel needs replacing
• Small strip thin gap chamber testing
• My role
• Project progress

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LHC and ATLAS

100 m 27 km around

• LHC: Large Hadron

Collider – world’s largest accelerator

• Four experiments,

including ATLAS

https://www.swissinfo.ch/eng/sci-tech/the-big-bang- machine-is-back_what-s-next-for-cern-s-large- hadron-collider-/41337172

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http://hilumilhc.web.cern.ch/about/hl-lhc-project 4

http://hilumilhc.web.cern.ch/about/hl-lhc-project 5

http://hilumilhc.web.cern.ch/about/hl-lhc-project 6

NOW

http://hilumilhc.web.cern.ch/about/hl-lhc-project 7

Collision point Small Wheel Big Wheel Outer wheel

ALTAS’ Muon Reconstruction

• Muons pass through all

inner layers

• Three wheels make up

endcap muon detection system

• Feeds into level 1 trigger

– do we record data from this event?

• Position and momentum

reconstruction

https://www.eurekalert.org/multimedia/pub/88092.php

~40 m ~20 m

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https://mediastream.cern.ch/MediaArchive/Photo/Public/2007/0709002/0709002 _01/0709002_01-A4-at-144-dpi.jpg

Old Small Wheel Problems:

• Increased number of collisions

will degrade efficiency and position resolution

• Muon system only uses middle

wheel for triggering

• 90 % of triggers are fake [1]

New Small Wheel Solutions:

• New small wheel data will also

be used for triggering

• New detectors designed to

handle increased trigger rate

• Precise muon track

reconstruction

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https://mediastream.cern.ch/MediaArchive/Photo/Public/2007/0709002/0709002 _01/0709002_01-A4-at-144-dpi.jpg

New Small Wheel Construction

[1]

• Make wedges of

detectors to fill wheel

• Sandwich sTGCs and

MicroMegas

• MicroMegas are the

primary tracker

• sTGCs are the primary

triggers

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Small Strip Thin Gap Chambers (sTGC’s)

• Muon ionizes gas in gap
• Ionization products

induce current on wires, pads and strips

• Pads provide region of

interest and coarse tracking

• Strips and wires provide

finer position resolution

• Four sTGCs stacked to

make quadruplet

[2]13

sTGC Production and Testing in Canada

TRIUMF, Vancouver BC: Raw material preparation Carleton University, Ottawa ON: Chamber construction McGill University, Montreal QC: Chamber testing with cosmic muons

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Testing with Cosmic Muons at McGill

• Muon flux: ~ 1 muon /

cm2 / min

• Use scintillators to

trigger detector readout

• Use tests to get noise

level, efficiency map, and position resolution

[3] 15

McGill’s sTGC Laboratory

Gas system Slow control system Test bench

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Electronics and Temperature Control

Thermal image of Analog 1.2 V FEAST during operation, ~ 35 ⁰C

• All wires’, strips’ and pads’ signals are readout by electronic boards
• DC – DC voltage converter (FEAST) dissipates so much heat it requires cooling
• Tested various heat sinks, helped build temperature monitoring infrastructure

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Temperature Monitoring Infrastructure

Prepared RTDs and cables for temperature monitoring Added RTDs to central DAQ: National Instruments compact DAQ Wrote program and designed interface for temperature monitoring18

Transport

First production quadruplet from Carleton to McGill First production quadruplet arrives at CERN!

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Testing at CERN

Beam Secondary detector

• Can use beam from pre

– accelerator to test chambers with a higher rate than cosmic muons

• Goals:
• Does the quadruplet

work?

• Characterize chamber

and electronics

• Best settings for

electronics

• Use a secondary

detector to confirm the presence of muons to calculate efficiency

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Efficiency Measurements

• When secondary detector fires, record data

from sTGC using oscilloscope

• The number of pulses recorded compared to

the number of triggers gives the efficiency

• Prototype sTGC wedge over 97 % efficient

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Current Tests: High Background in Gamma Irradiation Facility

• Last week, craned over the quadruplet

into GIF++

• Activity: 13.6 TBq (367 Ci)
• Testing to see if the detector performs

well in a radiation background similar to in ATLAS

• Also have muon beam to continue

testing and characterizing electronics and chamber response

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Conclusion

• Muon New Small Wheel needs replacing so that ATLAS can continue

to run effectively

• Multinational project with Canada being one of five countries

involved in sTGC production

• First production quadruplet is at CERN, with more predicted to arrive

in the next months

• Testing at CERN to learn how to best use these detectors in ATLAS

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Acknowledgements

• Brigitte Vachon
• Steven Robertson
• Yan Benhammou
• Gerardo Vasquez
• Tony Kwan
• Kathrin Brunner
• AlamToro Salas
• Rimsky Rojas Caballero
• Paris Franz
• Nicolas Viaux Maira
• Charlie Chen
• Evan Carlson

Contact me at lforment@uoguelph.ca 24

References

[1]

• B. Stelzer, Nuclear and Particle Physics Proceedings 273–275, 1160 (2016).

[2]

• E. Perez Codina, Nuclear Instruments and Methods in Physics Research

Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 824, 559 (2016). [3] Leger, Felix, Studies of Cosmic Ray Events in ATLAS STGC Muon Chamber Prototypes, McGill University, 2017.

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Landau Distribution of Pulse Heights

• Energy deposited by muons fits a Landau distribution
• Mostly, a certain fraction of their energy is deposited, but as they slow down lots
• f energy can be transferred per interaction

Energy, arbitrary units 26

Different Configurations

27 Without source With source

• Lower gain

Normalized Counts

Different Configurations

28 Without source With source

• Higher gain

Normalized Counts

Countries Involved in sTGC Production: Canada, Chile, China, Israel, Russia

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Temperature Monitoring and Cooling

• Monitor temperature with surface mount RTDs
• Use fans, Gap Pad and heat sinks for cooling

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