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 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

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

Accident Scenarios – Time Scales Name Operation mode Loss type Loss location ΔT/turns D1 warm collision local triplet/collimator 5 damper injection arc/triplet 6 warm quadrupoles any distributed collimator 18 dump septum diluter kicker/septum 35 warm orbit corrector aollision 55 RF (?) arc/triplet/septum arg/triplet/collimators 120 D1 Cold 220 arc/triplet/collimator 250 MB quench 280 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) after V. Kain, R. Schmidt, R. Assmann, EPAC 2002 Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

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: What BCM-D sees (energy deposition (sum over all 8 diamond sensors) if VeLo gets hit by one 7 TeV proton: X-check: VeLo signal BCM-D signal Ch. Ilgner (TU Dortmund), NSS-MIC 2008, Oct. 23, 2008

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

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, 2.59 nA, 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

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

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

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

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