First things seen by ALICE
First LHC created particles.
First LHC Circulating beam.
First ALICE beam-gas event..
First particles created by the LHC as seen in ALICE
at 18:15 Sunday June 15

On June 15 ALICE was in its standard mode of taking data from cosmic rays. At this same time the CERN LHC was conduction a high intensity injection test sending 4 bunches of 4E10 protons (spaced by 500ns) through the TI2 injection line into the TED (beam dump) just upstream of ALICE. All of these protons where stopped and many of them interacted with the beam stop. Still a number of muons where produced and traveled through the beam stop and were detected by the ALICE ITS-SPD detector (the two inner most layers of the ITS). The signals generated by these muons are shown in the plot above. Since these muons are traveling nearly parallel with the surface of these detectors, there are many more signals produced then muons.
First beam circulating LHC as seen by ALICE
10:26 CEST September 10 2008

Here is plotted the signal, Integrated charge, from the ALICE V0 detector as a function of time. On September 10 2008 at 10:15 CEST The LHC injected into the LHC ring a bunch of 1 billion protons. They continued doing this about every 48 seconds until at 10:26 when the first bunch of 1 billion protons had made all they way around the LHC and a second bunch of protons were added to this first bunch. This is shown in the above plot as the bunch at 10:26 being twice as large as the preceding bunches. The second bunch to go around was similarly added two and also appears as a spike twice as tall as the others. This is proof that the first two bunches of protons went all they way around the LHC machine, for the first time.

Details:
How can ALICE "see" these bunches of protons? Because the LHC machine group have placed a detector (TI2 screen) in the beam, to measure the beam size and position, just up stream of ALICE (from beam 1 the clock wise circulating beam which first pass though ALICE), a very few protons interact with it and create many particle which are seen by the ALICE V0 detector. This V0 detector is designed to measure the time of and the total ionization produce by charged particle passing though it for particle which travel close the the beam pipe. This signal is what is plotted, as a function of time, above. This plot has been taken by the ALICE V0 subgroup from their on-line event display. Many thinks to the ALICE V0 group for their hard work.
One of the first proton beam gas events seen by ALICE ITS
September 12 2008
Shown below is one of the first cases where one of the protons, from a bunch in ring 2 (the counter clockwise beam), just happens to hit one of the very few atoms remaining the the vacuum of the ALICE beam pipe. Shown are the location of the signals and reconstructed track from the particles produced by this collision in the ALICE ITS.



The "+" symbols in the above plots indicate where, in 3 space, a signal was detected. These points are then used to determine the different lines draw in these plots. In the first three plots, the three different detector types of the ALICE ITS are shown as translucent volumes. The inner most red volume contains the two inner most ITS layer using silicon pixel detector technology (there are 240 such wafers). The central green volume contains the two central layers using silicon drift detector technology (there are 260 such wafers). The outer blue volume contains the double sided silicone micro-strip detector technologies (there are some 1698 such wafers). In the last three plots, each silicone wafer is displayed as a small wire frame box. The ALICE magnets are off during this data taking and so the line are all straight. You can see that most of the lines are traveling in the same direction. This is because the atom which the proton hit is nearly at rest (in the lab frame) and the proton is traveling with a large momentum. By momentum conservation, this requires most of the produced particles to travel in the same direction as the original proton.