LHCb Summer Student ProjectsLHCb Summer Student Projects

Relevant Technologies:Field Programmable Gate Arrays – FPGACockcroft Walton Voltage Converters – CW bases

Detector Section: LHCb event filter farm Project Title: Acquisition of rack cooling equipment fans with ELMB and PVSS Student: Jonás Arroyo

Outline:Acquisition of rack cooling fans, from the LHCb event filter. Design the signal acquisition using the ELMB and linked to the control system and the PVSS scada.

Main Challenges:• Acquire the 64 fan signals and capture them with the 4 differential 16 channels ADC (each with 16 bits) in the ELMB.• Configure the CANopen OPC Server in the PC to connect the ELMB with the PCIcan-Q card.• Test the server and the capture signals using LabView.• Connect the CANopen OPC Server in the PC to the Control System and the PVSS scada.

Relevant Technologies :• Embedded Local Monitor Board - ELMB128.• Controller Area Network bus - CAN bus.• LabView.• Frequency to Voltage Converter.• PVSS SCADA – PVSS Supervisory Control And Data Acquisition.

Detector Section: RICH 2Project Title: Mirror AlignmentStudent: Janneke Blokland

Outline:The RICH2 is designed to give a positive kaon identification for particles with momentum between 15 and 100 GeV/c.To achieve this the mirrors which focus and guide the Cherenkov light have to be aligned with high accuracy.

Main Challenges:•Alignment of the spherical mirrors.•Monitoring the alignment and analyse the data.

Picture of the sphericalmirror in the flat mirrors

Data of the position of the left spherical mirror taken with laser and CCD-camera.

Left mirror positions

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Installation scaffoldingand flat panels

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Error ± 10 μrad

Day/night cycle

Target

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The light of the source is reflected bythe spherical mirror. The position of the light with respect to the target is a measure for the position of the mirror.

Picture of the lightspot taken withthe CCD-camera.

Detector Section: LHCb Trigger SystemsLHCb Data Acquisition (DAQ)Project Title: GigaEthernet AnalysisStudent: Cedric Walravens

Outline:Analyse LHCb’s currently available commodity server farm, in order to locate both software and hardware bottlenecks.

Main Challenges:• Conceive test schemes to make relevant measurements• Provide solid understanding of the various factors at play on a commodity platform.• If possible, make adjustments to the current setup to improve network performance

Results:• A profound analysis to provide a basis upon which acquisition decisions can be taken with regard to the configuration of hardware and software for the LHCb farm. • Improved characterisation of used components.• Predictions of final performance for the complete setup.

Detector Section: Electromagnetic CalorimeterProject Title:Quality Control of the Electromagnetic Calorimeter (ECAL) Calibration Fibres Student: Abigail Kaboth

Purpose:To measure and analyse the light yield from the phototube calibration fibres to ensure their functionality.

Method:•Each of the 5952 fibres is measured individually using a pin diode•The fibres are of varying length and so must be normalized for analysis•After the fibres are normalized to a mean of 2.5 (in arbitrary units), any fibre under 1.25 (50% of the mean) is considered “bad” and investigated to find the cause

Causes of “Bad” Fibres:•Fibre itself is damaged•Connection to ECAL is bad•Fibre inside ECAL is damaged•Misaligned optics in the ECAL module•Missing optics in the ECAL module

Results:•Less than 1% of fibres have some sort of problem•For 90% of these fibres, the problem is fixable•As of 28 July, measurement and troubleshooting 67% (or 3994 fibres) completed.

The data, with cutoff marked

The Calorimeter

Project Title: Analysis of LHCb trigger via visual inspectionStudent: Jamie Tattersall

Outline:Develop a system that will trigger on as many b-quark events as possible whilst reducing the recorded event rate from ~ 10MHz to ~ 2KHz.

HLT Trigger (software):• Inclusive selections for calibration and systematic errors.• Exclusive selections of important channels.• Full reconstruction of event.• Reduces event rate to ~ 2kHz.• Processing time of ~ 10ms.

L0 Trigger (hardware):• Selects events that contain high pT

particles.• Reduces the event rate from 10MHz to 1Mhz.• Processing time of 4µs.

L1 Trigger (software):• Partially reconstructs events using VELO (VErtex LOcater), TT (Trigger Tracker) and L0 information.• Selects tracks that have a high IP and pT.• Reduces event rate to 40kHz.• Processing time of ~ 1ms.

Challenge:• The trigger has to quickly and efficiently select interesting b-quark events.• Calibration events are needed to resolve the biases caused by the trigger algorithms.• The trigger has to have a small calculation time, ~ 10ms because of limited computational facilities.

A LHCb reconstructed MC event in VELO with two collision vertices.

SummerStudents2005

A LHCb reconstructed MC event viewed in Panoramix.

Results:•39 point baseline characterisation of ideal CW base performance•Fault identification in 50 defective CW bases•>45 repaired CW bases successfully passed test bench, ready for installation•Synthesisable single HV channel implementation for FPGA

Detector Section: Hadron CalorimeterProject Title: Power Supply ControlStudent: James Devine

Outline:Develop firmware for the control of power supplies to calorimeter detectors using a radiation hard FPGA chip.

Main Challenges:•Implementation of sequentialset-up for 200 independent power supplychannels, using 12-bit Digital-to-Analogue converters.•Test bench construction to evaluate the effectiveness of hardware implementation.•Repair and testing of defective High Voltage supply modules.

Test Point Comparison(Control Voltage 0.19V)

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