21-04-23

Building and Operating a Gas Quality Measurement System for

LHCb Muon

Maarten van DijkLHCb Summer Student

Men love to wonder and that is the seed of science -Emerson

2LHCb Muon Gas Quality Measurement

Maarten van Dijk – LHCb Muon

Personal Information

• Master project (12 sept 2009 – 05 jul 2010) @ Nikhef

• Summer Student (15 jun 2010 – 10 sept 2010) @ CERN

• LHCb Muon

• Supervisors: • Burkhard Schmidt• Alessandro Cardini

3LHCb Muon Gas Quality Measurement

Maarten van Dijk – LHCb Muon

Project Description

Continuous gas gain measurement for the Triple-

GEM Detectors

(…)

This is achieved by a test chamber flushed with

gas from the supply and return line of the Muon

Detector, comparing the gain of the supply and

return lines by means of a radioactive source.

(…)

It is necessary to monitor the short-term gas

density and its effects on the gas gain (due to

atmospheric temperature / pressure variations)

4LHCb Muon Gas Quality Measurement

Maarten van Dijk – LHCb Muon

GEM Detectors

• Insulating foil

• Copper on top and bottom

• Holes in foil

• Strong field in gap

Working principle

• Electron multiplication in holes

5LHCb Muon Gas Quality Measurement

Maarten van Dijk – LHCb Muon

Triple GEM chamber

• Triple GEM chamber

• Rack PC

• High voltage supply

• Ampere meter

• Low voltage supply (supplies HV)

• Pressure and temperature from WCS

6LHCb Muon Gas Quality Measurement

Maarten van Dijk – LHCb Muon

GEM data

• Current through cathode and ground

• Gas from premixed bottle

• Source used: Sr-90• 40 MBq β 0.546 MeV

• Gain dependent on location

• GEM not uniform: to be studied

Current (nA) vs. time (s)

7LHCb Muon Gas Quality Measurement

Maarten van Dijk – LHCb Muon

Pressure corrections

• Gain varies strongly with pressure

• Analysis of pressure correction ongoing

• Precise pressure measurement is essential

Local vs central pressure

8LHCb Muon Gas Quality Measurement

Maarten van Dijk – LHCb Muon

To do

• Implement pressure measurement adjustment into labview

• Study GEM uniformity

• Try to stabilize ground

• Take measurements with return and supply lines

9LHCb Muon Gas Quality Measurement

Maarten van Dijk – LHCb Muon

That’s all folks!

Questions?

Thank you for listening!