LHCb Summer Student Projects

1. LHCb Summer Student Projects LHCb Summer Student Projects Detector Section: Hadron Calorimeter Project Title: Power Supply Control Student: James Devine Project Title: Analysis of LHCb trigger via visual inspection Student: Jamie Tattersall Outline: Develop firmware for the control of power supplies to calorimeter detectors using a radiation hard FPGA chip. Detector Section: LHCb event filter farm Project Title: Acquisition of rack cooling equipment fans with ELMB and PVSS Student: Jonás Arroyo • 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. 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. 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: • Implementation of sequential • set-up for 200 independent power supply • channels, 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. A LHCb reconstructed MC event viewed in Panoramix. • 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. • 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. • L0 Trigger (hardware): • Selects events that contain high pT particles. • Reduces the event rate from 10MHz to 1Mhz. • Processing time of 4µs. Relevant Technologies: Field Programmable Gate Arrays – FPGA Cockcroft Walton Voltage Converters – CW bases • 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 • 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. • 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. A LHCb reconstructed MC event in VELO with two collision vertices. Detector Section: Electromagnetic Calorimeter Project Title: Quality Control of the Electromagnetic Calorimeter (ECAL) Calibration Fibres Student: Abigail Kaboth Detector Section: RICH 2 Project Title: Mirror Alignment Student: 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. 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 Summer Students 2005 • Main Challenges: • Alignment of the spherical mirrors. • Monitoring the alignment and analyse the data. Picture of the spherical mirror in the flat mirrors Source The light of the source is reflected by the spherical mirror. The position of the light with respect to the target is a measure for the position of the mirror. The Calorimeter Mirror • 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 Detector Section: LHCb Trigger Systems LHCb Data Acquisition (DAQ) Project Title: GigaEthernet Analysis Student: Cedric Walravens Target • 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 Installation scaffolding and flat panels Outline: Analyse LHCb’s currently available commodity server farm, in order to locate both software and hardware bottlenecks. Error ± 10 μrad Picture of the light spot taken with the CCD-camera. The data, with cutoff marked • Results: • A profound analysis to provide a basis upon whichacquisition 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. • 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. 1 week Day/night cycle Data of the position of the left spherical mirror taken with laser and CCD-camera.