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Beam conditions monitoring motivation: protecting sensitive detectors in HEP experiments

Commissioning of the Beam Conditions Monitor of the LHCb Experiment at CERN Ch. Ilgner, October 23, 2008 on behalf of the LHCb BCM group at TU Dortmund: M. Domke, S. Köstner (CERN), M. Lieng, M. Nedos, J. Sauerbrey, S. Schleich, B. Spaan, K. Warda. Beam conditions monitoring

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Beam conditions monitoring motivation: protecting sensitive detectors in HEP experiments

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  1. Commissioning of theBeam Conditions Monitor of theLHCb Experiment at CERNCh. Ilgner, October 23, 2008on behalf of the LHCb BCM group at TU Dortmund: M. Domke, S. Köstner (CERN), M. Lieng, M. Nedos, J. Sauerbrey, S. Schleich, B. Spaan, K. Warda • Beam conditions monitoring • motivation: protecting sensitive detectors • in HEP experiments • readout concept and integration into LHCb The LHCb BCM project at TU Dortmund is supported by: Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

  2. Implementation in LHCb Sensitive devices, such as the Vertex Locator („VeLo“), need protection from adverse beam conditions. BCM-U BCM-D The VeLo, Courtesy of LHCb VeLo group -2131mm +2765mm Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

  3. D1 magnet failure: fastest generic beam-loss scenario, timescale: 5 turns ~ 500 μs → defines the response time scale (beam dump becomes effective after 270 μs (max., depending on the position of the abort gap) (anything faster than that could help in LHC commissioning) Accident Scenarios – Time Scales after V. Kain, R. Schmidt, R. Assmann, EPAC 2002 Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

  4. Radiation Levels in the Vertex Locator and the BCM What VeLo sees (in last Si plane) if it gets hit by one 7 TeV proton: X-check: VeLo signal BCM-D signal What BCM-D sees (energy deposition (sum over all 8 diamond sensors) if VeLo gets hit by one 7 TeV proton: Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

  5. Simulated Energy Deposition in the Vertex Locator Energy deposition of 40μs of minimum-bias events in the Vertex Locator (VeLo): • Normal LHC running • conditions over 107s • (15MHz event rate): • 13.3 kGy for • „upstream“ BCM • sensors • 3.4 kGy for • „downstream“ BCM • Sensors • 10.6 kGy for VeLo • Si paddles • (Simulations: M. Lieng) Failure scenario: MCBX.1L8 magnet with reversed field at full strength. BCM-D signals as multiples of nominal signal Energy deposition of 40μs of minimum-bias events in the Vertex Locator (VeLo): Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

  6. BCM-D Station tested at ELBE Facility (FZD) Exposure to 71fA to 225pA electron beam current (20MeV) in order to calibrate diamond sensors and analogue frontend electronics. Beam currents through sensors: 5.62 pA, 39.6 pA, 805 pA, 2.59nA, 17.8 nA. Sensor currents: 1nA-3 μA. The support by FZD staff (P. Michel, U. Lehnert et al.) is greatly appreciated. Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

  7. LHC-Experiments Data Exchange Courtesy of R. Jacobsson LHCb Experiment Control System (ECS) VeLo Interlocks Beam Dump System Beam Dump (BIS) Injection Inhibit, Status & Flags BCM ok General Machine Timing (GMT) Safe Beam Flags, Post-Mortem Trigger Beam Conditions Monitor LHC Injection Injection Inhibit Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

  8. FPGA features three parallel algorithms to trigger an LHC beam dump Beam-Abort Logics Sampling period: 40 μs 32 (1280 μs) 2 1 Coincidence conditions provide protection against erratic dark currents (commonly known for pCVD diamond detectors)‏ Fast abort: 80μs 3 adjacent sensors consecutively over threshold Slow abort:1280μs discarding min. and 2 max. values, summing over the other values Single bunch mode: 80μs 3 adjacent sensors in one CFC frame Only during injection OR Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008 Beam abort (effective after <270ms)

  9. First LHC beams as seen by the BCM Threshold excesses during exposure of TDI at small particle fluxes: threshold 22.08.2008, 20:36h: Max(BCM-D): 500nA (20% of threshold)‏ Max(BCM-U): 50nA (0.5% of threshold)  Dump logics have been successfully tested. Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

  10. Conclustion LHCb BCM measures ... ... CCC operator confirms three turns. The LHCb Beam Conditions Monitor has been successfully calibrated, integrated into the LHCb control structure and proven to monitor reliably the particle flux at startup of CERN‘s Large Hadron Collider. A careful but realistic test has shown that the dump logics work reliably. Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

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