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CMS e-commentary for 2009 LHC Beams |
CMS e-commentator
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CMS e-commentary for 2009 LHC Beams |
CMS e-commentator
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Splashes were provided to CMS for most of the night before they took a well deserved rest for a while.
A new day but still as foggy outside as yesterday. Fortunately compensated by the enthusiasm of the early-birds at CMS!
Lots of news coverage on the web, tv, radio etc. For example the potentially iconic photo below.
LHC now planning the rest of the weekend.....we'll keep you posted. Dave (standing in temporarily for Darin)
After the switch to beam 1, the LHC will provide beam splashes at Points 1, 8, and again at 5.
This commentator needs a rest. Good night! Well done LHC control!
We requested a short extension of the beam shot period. LHC plans after this are to return to Beam 1
This is a side view of the CMS experiment.
Display of a splash event just seen online. Usual transverse and longitudinal views on the bottom. An interesting view of the calorimeter energy deposits on top (calorimeter is unrolled onto a plane, phi vs. eta). Note the energy deposits measured in the 100s of TeV!
CMS requested 40 minutes of splashes. They have started arriving according to the beam monitoring.
The control centres in Cessy, Meyrin, DESY, and Fermilab were all well connected during the LHC startup. This photo is from 2 hours ago.
See the right plots which show the trajectory of the particle traveling from one endcap to the other.
LHC operators are preparing for beam splash events at ATLAS for 40 minutes. After that switching to CMS.
For the beam splash and early capture attempts, the muon systems were at reduced voltage for safety. Once the CSCs raised the voltages, the halo muons (particles created when some protons scrape the sides of the beam pipe) were easily observed.
Two beams circulated, and twins expected! (Andre and Delia)
Displays of a halo muon crossing through the CMS experiment. Hits in the RPC muon system are in yellow, hits in CSCs magenta.
Beam 2 was caught for a few seconds.
CERN reports that RF cavities are ready to capture beam 2.
Note the two spots on the right screen.
Going for a complete orbit of beam 2.
A beam onto collimator event from 23:20.
We got a "splash" event - beam onto collimator. Now moving past to P3.
Although there has been a shift change, I am still here. Finally also the beam! It's at Point 6, one arc away. Apparently also the BBC just arrived as well.
Beam 2 is now at the "TDI".
LHC operators report that beam 1 circulated for several minutes! Now they will switch to Beam 2 (anti-clockwise).
We just took 50,000 events in one attempt, as recorded by the data logging. That's a lot of orbits! Beam circulated for about 30 sec.
Injections starting again, spike in rate received by CMS.
Actually, plan changed. They will try to capture the beam with the RF system, and store the beam! (and so far they had ~500 turns!)
There is a pause, but we are next expecting beam to come anti-clockwise to CMS (beam 2). Perhaps in 20 minutes.
The signal from the RF beam pickup is showing many turns, perhaps 10-100. We see this on the trigegr signals from this system (left plot), where there is now higher rate. Since these are not collimator shots, there is only a low rate of associated halo particles coming along with the beam. But the CSC muon system does see halo signals in coincidence with the beam pickup (right plot).
The beam monitors picked up 3 turns. It's a 100 micro-seconds (us) per division, and one orbit is 89 us. See the yellow trace above.
Going to "Beam 1 inject and Dump"
Looks to be 2 turns.
Beam made it past Points 7 and 8, and is going next to Point 1 (where the ATLAS experiment is located).
LHC declares beam is going to Point 7 next, past CMS.
Beam monitors picked up the beam again!
The above are event displays of the beam splash events, 3D, longitudinal, and transverse. ECAL energy deposits are in red, HCAL are in blue (light blue for HF and HO, forward and outer calorimeters), RPC muon hits are in yellow, and CSC muon hits are in magenta.
The LHC operators are recovering the quenched magnet. We should expect beam 1 to return onto the collimators again.
Jacobo Konigsberg (center), spokesperson of the CDF experiment at the Tevatron proton-antiproton collider in the U.S., visits the CMS control room. CMS spokesperson Tejinder Virdee is on the right, and spokesperson-elect Guido Tonelli is on the left.
An LHC magnet has quenched in sector 5-6, which is the arc just past CMS.
Scope trace from the RF beam pickup on left, and beam scintillation counters (which detect halo particles) on the right.
Austin Ball, technical coordinator of CMS, investigating the beam pickup plots.
CSC muon detector triggers plotted vs. time on the left. RPC triggers in -z endcap on the right.
It was a beam shot onto the collimator! Didn't fly by after all, hit collimators.
It made it! Beam monitors picked it up, but it flew right by!
Beam 1 trying to make it to CMS. Seems to be lost in the French countryside.
Beam has made it to Point 3.
Tejinder Virdee, spokesperson of CMS, and the DAQ team getting ready.
(photos courtesy T.Camporesi)
We're waiting for the start of beam into LHC. Hopefully soon, and bound to go fast.
Expectation from the LHC operators is beam injection to start about 18:00
The skies have cleared. (well briefly, looks like the fog rolled back in). LHC cryogenics were reestablished at 15:00. Currently checking circuits. Beams have been brought to the TEDs, which are at the entrances to the LHC ring. CMS has removed the inhibit on beam injection, and is waiting for beam!
The plan from the LHC control room is to start first with a clockwise beam (from above), denoted "beam 1". They plan to go for a "fast track" approach to achieving a single orbit turn, not waiting too long at each IP for beam-collimator shots ("beam splash" events). After achieving beam 1 circulation, next is beam 2 (anti-clockwise). Once a full orbit is achieved, then the program would go to dedicated beam splashes at each IP. The overall goal this weekend is to have the radio-frequency (RF) system capture the beam for more than millions of orbits.
CMS prepares for "beam splash" mode by 15:00. LHC beams possible starting 17:00.
The coffee is stocked and the parking lot is full at point 5, the location around the LHC ring where CMS is located. Evidence that LHC beams are expected this afternoon/evening! A little difficult to drive in this morning with soupy fog, however. Let's hope for clear skies and smooth operations.
An exciting weekend is in store, as the LHC restarts tomorrow and aims for first beam circulation. To be followed by the first LHC collisions ever sometime in the coming week or so!
The story of the beam shots two weeks ago.
The story of last year's start-up.