The Large Hadron Collider is a huge ring through which protons dispersed by the magnetic field of accelerators are flying along opposite trajectories. Faced with, protons decay with the formation of other fundamental particles; Sensitive BAC detectors record everything that happens during collisions, and scientists process the data of detectors and learn about how the subatomic “zoo” of muons, gluons, quarks and other particles behaves. The more collisions occur, the more data, so CERN specialists are constantly working to tighten the particles in bunches and increase the probability of their collisions.
The potential number of collisions in the cross section of the collider per unit time is called luminosity. The higher the luminosity, the more collisions occur in the collider – and the more interesting it is for physicists to work. To increase luminosity, over the past year CERN engineers have introduced a new method for separating and compressing proton clusters; Now the diameter of each bunch is 40% smaller than last year, with the same number of particles. This means that the protons in the bunch are closer to each other, and the probability of collisions is greater. The luminosity of the collider also increased with the condensation of the collider: on June 28 it amounted to 1.58×1034 collisions per second on one square centimeter of the cross section, which is 10% more than the previous luminosity record, delivered last year, and 58% more than the calculated index. Details are reported by the press release of CERN.
The graph of the growth of the integrated luminosity of the LHC, by year2016 (the pink curve) was a record, but the schedule for 2017 is growing so fast that physicists expect this year to a new record in the number of collisions? Registered for the year
A record luminosity was achieved due to an increase in the density of individual proton clusters. Until 2016, the diameter of the clot was 3.5 μm (millionth of a meter); This year the clots were able to squeeze up to 2.5 μm with the same number of particles in each. In addition, engineers increased the frequency of particles entering the ring – from 1,225 to 200 nanoseconds between clots.
The only limitation that could not be circumvented was the limit on the number of bunches that single-handedly emerge from the SPS (proton supersynchrotron) – one of four accelerators, accelerating the particles before they hit the ring where collisions occur. If there are more than 144 proton clusters of reduced diameter (or 288 projected diameter bunches) at the output of the SPS, their total energy will be so great that in the event of loss of control over the clot, it can damage the equipment.
Now in each bundle – for 2556 clots, in each bunch – 115 billion protons with an energy of 6.5 TeV. The total energy of each beam thus turned out to be 300 megajoules – roughly equal to the total kinetic energy of a million bullets fired from Makarov pistols.
If we multiply the luminosity of the collider by the time it works, we get the number of collisions at a certain cross-sectional area during the lifetime of the beam, or its integral luminosity – the main indicator of the “yield” of the collider. Last Wednesday the LHC succeeded in reaching an integral luminosity of 0.7 reverse femtobars per day; While the first launch of the collider this year managed to gain 5.3 fb-1.