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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. - PowerPoint PPT Presentation
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Development on beam phase monitoring
G. Anders (CERN/Heidelberg), C. Gabaldon, T. Pauly (CERN)
L1Calo Joint Meeting17th September 2010
G.Anders, C. Gabaldon, T. Pauly 2
LHC Timing Signal Distribution
Friday, September 17, 2010
Picture of the clock and the ORBIT signal
CMS
LHCb
ATLAS
ALICE
P4 (RF)
Independent RF system per beam
Timing signals from the LHC:Bunch clock 40.079 MHzORBIT signal, every 88.9 μs
9.5 km
3.8 km
CCC
3
The ATLAS BPTX System
Friday, September 17, 2010 G.Anders, C. Gabaldon, T. Pauly
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.
Oscilloscope
8 bit ADC5 GS/s (200 ps)
600 MHz bandwidth
200 m cable
4 buttons
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 4
Clock distribution through ATLAS
DELAY25 QPLL
QPLL
RF2TTC
DELAY25
RF F
anout
0.5 ns
RF F
anout
RFR
X BC1LHC
optical
BCMBC1
BPTX1
BPTX2
ORBIT1
BC1
AFG
Friday, September 17, 2010
BCmain
NEW VME Board ~10 ps
delay
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)
CTP
ATLA
S
)1()(2/12/1 BCtimeBPTXtimePhase
G.Anders, C. Gabaldon, T. Pauly 5
Beam phase monitoring (C. Gabaldon)
Friday, September 17, 2010
BeamEnergy:- Beam energy
BPTX:- BPTX 1/2 delay setting, bunch info, phase ½, Δphase
RF2TTC:- BC1/BC main delay setting
POLL from IS
LumiBlock:- run, LB, startTime
Write to COOL
Offline: comparison with other sub-detectors and LHC
OH histograms
IS object: initial/LHC/RFPhase Information for LumiBlock
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 6
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
Friday, September 17, 2010
Comparison with other sub-detectors measurements
2 ns RF2TTC
Run 158801
G.Anders, C. Gabaldon, T. Pauly 7
Clock drift seen by LHC
Friday, September 17, 2010
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 8
ConclusionsWe are monitoring the phase with the BPTXWe correct any drift (mainly clock drift) with the
RF2TTC “fine” delayWe plan to store into COOLFuture improvements:
the BPTX precisionthe fine delay with a new VME board (~10 ps)
Friday, September 17, 2010
