TI2 extraction test to TED, September 25th-28th, 2009

LHC-ALICE accelerator complex 

The first beam to TED appeared shortly after 18:00 on Friday Sept 25th (see following pictures). The bunch intensities and corresponding multiplicities were very similar to what we have observed during the previous TED campaigns (0.5-0.7 muons/cm^2). We saw 2105 proton bunches of the average intensity 0.5e10 proton/bunch. On Sunday evening there was a about 1 h period with 12 bunches trains. On Monday we got 485 heavy ion (Pb) bunches. Observed multiplicities were very similar to what we have observed during p-injection.

Buch intensities delivered beam

Data taking

CTP L0 timing, September 25th, p-bunches

During this TI2 test we saw for the first time TOF (0OID) and EMCAL (0OEID) signals. Enclosed are plots showing L0 signals arrival to CTP L0 board with respect the orbit signal (issued by LHC every orbit). CTP delays are ignored so this distribution corresponds to the actual arrival time without CTP alignment.

CTP L0 timing, September 27th, p-bunches

On Sunday Sep 27th the EMCAL improved the timing - no jittering observed. ACORDE provides also better signals. Below are the distribution before (upper plot) and after (lower plot) CTP alignment. 

From these distributions and from the correlation plots we derived  "real" time arrival (no CTP delays) of various L0 signals to CTP. Extrapolated interaction bunch-xsing BC0 is calculated as Dist_to_orbit-Measured_latency/25.

 * data from July 11th TED dump see plot below

** 810ns from the interaction to CTP patch panel + 50ns to CTP input 

Assuming that the SPD measured L0 latency 800 ns is correct, then the interaction bunch crossing BC0=312. With this assumption one can evaluate the latencies for all other detectors (last column of above table).