My working experience Marco Villa Tue, 2 nd Dec 2008

2 The LHCb detector at CERN

3 The LHCb PID system RICH1 -> low momentum particles (1 – 60 GeV/c) RICH2 -> high momentum particles (up to 150 GeV/c)

4 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

5 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

6 About the DLP technology

7 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

8 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

9 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

10 The DAQ HW

11 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

12 The DAQ SW

13 The LHCb muon system 5 muon stations, named M1 – M5 2-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

14 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

15 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

16 Safety switches & end switches The 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

17 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

18 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