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Development on beam phase monitoring. G. Anders (CERN/Heidelberg), C. Gabaldon, T. Pauly (CERN) L1Calo Joint Meeting 17 th September 2010. LHC Timing S ignal D istribution. Timing signals from the LHC: Bunch clock 40.079 MHz ORBIT signal, every 88.9 μs. LHCb. 3.8 km. ATLAS. CCC.
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Development on beam phase monitoring G. Anders (CERN/Heidelberg), C. Gabaldon, T. Pauly (CERN) L1Calo Joint Meeting 17th September 2010
LHC Timing Signal Distribution • Timing signals from the LHC: • Bunch clock 40.079 MHz • ORBIT signal, every 88.9 μs LHCb 3.8 km ATLAS CCC 9.5 km CMS Independent RF system per beam Picture of the clock and the ORBIT signal ALICE G.Anders, C. Gabaldon, T. Pauly P4 (RF)
The ATLAS BPTX System The ATLAS BPTX stations are comprised of electrostatic button pick-up detectors, located about 200 m away along the beam pipe on both sides of ATLAS. 4 buttons Oscilloscope 8 bit ADC 5 GS/s (200 ps) 600 MHz bandwidth 200 m cable • A passing bunch gives bipolar signal (low frequency cut-off) • Time measurement of a single bunch: • Zero-crossing of signal G.Anders, C. Gabaldon, T. Pauly
Clock distribution through ATLAS RF2TTC NEW VME Board ~10 ps delay BC1 LHC BCmain RFRX ATLAS CTP RF Fanout DELAY25 QPLL optical 0.5 ns AFG BCM BC1 QPLL RF Fanout DELAY25 BC1 • Measure the clock phase with the BPTX: • Precision for BPTX ~50 ps being improved (G. Anders) • New VME Board with ~10 ps step in design (P. Farthouat) ORBIT1 BPTX2 BPTX1 G.Anders, C. Gabaldon, T. Pauly
Beam phase monitoring (C. Gabaldon) BeamEnergy: - Beam energy LumiBlock: - run, LB, startTime RF2TTC: - BC1/BC main delay setting BPTX: - BPTX 1/2 delay setting, bunch info, phase ½, Δphase POLL from IS IS object: initial/LHC/RFPhase Information for LumiBlock Offline: comparison with other sub-detectors and LHC OH histograms Write to COOL • Based on the BPTX: Correct the phase seen by ATLAS using RF2TTC Delay25 (0.5 ns step): • Now manually • Next step automatic process G.Anders, C. Gabaldon, T. Pauly
Phase drift seen by ATLAS • Using the BPTX measurement to extract the phase seen by ATLAS. • Good agreement between BPTX and Tile • LAr and TRT show similar trend Comparison with other sub-detectors measurements Run 158801 2 ns RF2TTC G.Anders, C. Gabaldon, T. Pauly
Clock drift seen by LHC • Using the BPTX measurement to extract the phase seen by LHC. • The beam phase drift is due to the optical fiber Comparison with optical fiber measurements by S. Baron G.Anders, C. Gabaldon, T. Pauly
Conclusions • We are monitoring the phase with the BPTX • We correct any drift (mainly clock drift) with the RF2TTC “fine” delay • We plan to store into COOL • Future improvements: • the BPTX precision • the fine delay with a new VME board (~10 ps) G.Anders, C. Gabaldon, T. Pauly
