my working experience
DESCRIPTION
My working experience. Marco Villa Tue, 2 nd Dec 2008. The LHCb detector at CERN. The LHCb PID system. RICH1 -> low momentum particles (1 – 60 GeV/c) RICH2 -> high momentum particles (up to 150 GeV/c). The HPDs. - PowerPoint PPT PresentationTRANSCRIPT
My working experience
Marco Villa
Tue, 2nd Dec 2008
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The LHCb detector at CERN
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The LHCb PID system• RICH1 -> low momentum particles (1 – 60 GeV/c)
• RICH2 -> high momentum particles (up to 150 GeV/c)
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The HPDs
The HPDs are extremely sensitive to external magnetic
fields and they need to be shielded
The residual anodic image distortion is parameterized and
corrected offline
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The pattern alignment system
The selected light sources are two commercial DLP LED beamers, which have been located inside the RICH2
vessel and are remotely controlled via PC’s
3 PMTs per detector side are used as absolute reference points
The pattern is moved via software on the PC connected to the beamer until a
maximum in the PMTs anodic signal is reached
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About the DLP technology
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DLP again…
The general timing properties are defined by the beamer properties and
the video refresh frequency
The photon bunch length is proportional to the color luminosity
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Purpose of the DAQ system
• The PMTs are used to accurately align the magnetic distortion test pattern• They will constitute a helpful tool during the HPDs quantum efficiency
monitoring
• Six independent readout electronics channels are needed, each of them being asked to give an output signal proportional to the anodic charge
released per unit time by the corresponding PMT↓
• Every channel has to work as an integrator
• It is of primary importance to consider what is the expected shape of the anodic signals
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Shaping times calibration
The two shaping times have been chosen following:
• analytic study of the S/N ratio, where the noise is
considered as white + strong 50 Hz component
• statistical considerations on the discrete origin of the signal
• timing properties of the beamer light
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The DAQ HW
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Shaped signal
• After system optimization, the shaper amplifiers show a good
behaviour
• The spikes are linked to the way the DLP chip has been programmed and it
is not possible to eliminate them
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The DAQ SW
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The LHCb muon system
• 5 muon stations, named M1 – M52-layers or 4-layers MWPCs and triple GEMs
• 4 muon filters, of which the first one is constituted by the calo system. The remaining 3 are named MF1 – MF3
Iron walls 2000 tons in weight
It is necessary to implement a system that is able to:• control the stations and filters movements
• monitor the detector position• stop the movement in case of danger
• give useful information during the detector alignment
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M2 – M5 system overview
1,2 – control boxes & emergency switches
3,4 – safety switches
5,6,7,8,9 – end switches
10,11 – quadrature encoders
12 – inclinmeter
13 – main electrical cupboard & electrical motor
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Control boxes & emergency switches
Each automation system is controlled by 2 human
operators
One operator on the top of the muon detector
The other operator on the bottom of the mon
detector
Each operator has to actively push a button in order to send his enable
signal to the software
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Safety switches & end switchesThe safety switches are mechanical
devices that are used to stop the movement in case the software goes
out of control
The end switches are position encoders that give information about the position of the stations when the system is fully closed or fully opened
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Quadrature encoders & inclinometer
The encoders used in the automation system are incremental encoders
They are not used to measure the system position, but to monitor the
overall tilt of the muon system
The inclinometer is used to monitor the local tilt of the system in a specific
position
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The automation SW• acquires data from all the selected devices
• processes the data• displays the results
• sends the activation signals to the motor relays
For safety reasons, the SW commands have lower priority than the
HW ones
All the safety & emergency switches have an hard-wired
implementation