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The Large Hadron Collider has summed up the results of 2017. New improvements made to the design made it possible to increase one of the most important parameters settings - luminosity. Now it is twice the design size. Plans for the year for integral luminosity were also exceeded. By the end of the year there will be two installations technical inclusions, after which new improvements will be made.
The world's first charged particle accelerator project was developed by a Norwegian schoolboy. In 1923, Rolf Wideroe invented a device that accelerates particles using an electric field. However, it was not possible to implement the project “in hardware” due to effects that were not taken into account by the young researcher.
The first operational accelerators appeared in the early 1930s. The race for energies has begun. Scientists wanted to accelerate particles as much as possible and force them to collide first with stationary targets, and then with each other. In these collisions new particles, not yet known to science, were born. This is how modern physics was forged.
The engineering genius, driven by an insatiable thirst for knowledge, created bizarre technical giants. For example, for an accelerator at the Institute of Nuclear Physics in Gatchina, a permanent magnet with a pole diameter of 6.5 meters was cast!
There are currently about a dozen large accelerators operating in the world. They exist, for example, at the Institute of High Energy Physics in Protvino and at the Joint Institute for Nuclear Research in Dubna, where the periodic table is constantly updated. But, of course, nothing compares to the king of kings - the Large Hadron Collider.
Protons, accelerated by an electromagnetic field, rush towards each other in a 27-kilometer-long tunnel. The energy of the particles reaches 13 teraelectronvolts. There have never been such accelerators in the history of physics. It was this energy that made it possible to discover the famous field quantum, which gives mass to elementary particles.
The accelerator is responsible for particles consisting of five quarks, and not three, like a proton or a neutron. Not to mention such little things as ever achieved in an experiment, and other side records.
But, in addition to proton energy, other parameters are also important to researchers. After all, it wouldn't be much fun if the carefully accelerated protons all flew past each other without colliding.
By the way, most protons do just that. Only a very small part of the dispersed particles meets a “partner” in order to collide with it head-on, and, having generated new particles, please scientists with interesting physics.
To make collisions occur more often, the diameter of the beam must be reduced. And in the past year, the LHC was introduced for this purpose new system. The results, as they say, are obvious: as reported in the release, in 2016, experimenters received 40 collisions per 100 billion particles, and in 2017 – 60.
Number of particle collisions per second per square centimeter cross section tunnel is called the accelerator luminosity. This year it was possible to raise it to 2.06 x 10 34 cm -2 s -1, which is twice the design value.
If you multiply the luminosity by the operating time of the accelerator, you get the so-called integral luminosity. You can calculate it for a year, for one experiment, or for the entire life of the installation.
This is a very convenient value for summing up. It takes into account everything: how many experiments were carried out per year, and what luminosity was observed in each of them. The question, according to the Hamburg account, is simple: has the planned integral luminosity for 2017 been achieved? As is clear from the graph, it has been achieved and even exceeded. Hooray.
The graph shows the increase in the integral luminosity of the collider in 2017. It can be seen that it reached 50 reverse femtobarns, that is, in total, for every square centimeter of the tunnel cross-section this year there were 5 x 10 40 collisions.
Why is this quantity so important? Because the most interesting events are those that happen rarely. How unlikely they are can be conveniently judged by a parameter that experts call the event cross-section. For example, the production of the Higgs boson has a cross section of 2 x 10 35 cm 2 . Dividing the integral luminosity by this number, we find that the particle, which was discovered in 2013, was born 250 thousand times in 2017.
And insatiable physicists have plans for another improvement of the installation. After a small upgrade at the end of this year, the collider will operate until mid-2018, and then stop for a year and a half. During this time, the energy of the particles is planned to be raised to 14 teraelectronvolts, and the luminosity will be doubled compared to the design value.
But this is not the limit. Starts in 2022 new project– HL-LHC. Over two years of work, it is planned to increase the luminosity by 5–7, and possibly 10 times, compared to the nominal one. And then very rare events will no longer be so rare.
What discoveries will the updated collider give us? May be, ? Or, which several generations of theorists have been dreaming about? No one knows. Humanity is waiting for news.
Today in Dubna, near Moscow, at the Joint Institute for Nuclear Research, they are launching a new scientific megaproject - the first stone will be laid in the construction of the NICA superconducting collider. The President of the Russian Academy of Sciences Vladimir Fortov, Assistant to the President of Russia Andrei Fursenko, Governor of the Moscow Region Andrei Vorobyov, foreign ambassadors and Nobel laureates are expected at the symbolic ceremony.
As the director of the Joint Institute for Nuclear Research, Academician of the Russian Academy of Sciences Viktor Matveev said yesterday, the NICA collider (Nuclotron-based Ion Collider fAcility) will be created on the basis of the Nuclotron superconducting accelerator already existing at JINR. On new installation, which belongs to mega-science projects, will study the transition of nuclear matter under extreme conditions into a new state called quark-gluon matter.
Belarus, Bulgaria, Germany, Kazakhstan and Ukraine have already expressed their intention to participate in the creation of the collider. And the culminating event of this week was preceded by a long process of scientific research, design development and organizational approvals. The moment is also symbolic because just these days the JINR team celebrates the 60th anniversary of its birth in the “thaw” March of 1956. The official status today is an international intergovernmental research organization. As permanent members, it is supported and delegated to Dubna for the work of their scientists and specialists by 18 states, including Russia. Cooperation agreements have been signed with six more countries at the governmental level.
The emerging NICA complex consists of three large blocks: accelerator, research, and innovation. The accelerator block includes already functioning nuclear sources: a linear accelerator and the Nuclotron ring accelerator. Moreover, the Nuclotron is based on cryogenic technologies of the 21st century, developed in Dubna, and is the second superconducting accelerator in Europe after the Large Hadron Collider (LHC). It is also important to note that when creating the accelerator and detector elements of the NICA complex, the experience gained in preparing experiments at the Large Hadron Collider at CERN and in research laboratories in the USA and Europe is used.
The launch of the NICA collider is scheduled for 2017, and scientists are going to get the first results from it at the end of 2019 - beginning of 2020.
One of the first collisions of 2017 at the ATLAS detector
On May 23, the first proton collisions of 2017 took place at the Large Hadron Collider. scientific program collider. The calibration of detectors and thousands of subsystems of the largest accelerator in the world has been completed after a winter break. Over the next six months, the collider is expected to double its collision statistics at 13 teraelectronvolts. This is reported in a CERN press release.
Every winter, the collider interrupts its operation to update and repair the accelerator and detector systems. It takes engineers several weeks to launch the LHC. So, this year, the first proton beams appeared in the accelerator on April 29 - engineers checked the performance of radio frequency resonators responsible for accelerating particles and gradually raised the kinetic energy of particles to the required 6.5 teraelectronvolts (6.5 thousand times more than the rest energy of a proton) . Physicists set up magnets and collimators that correct the shape and trajectory of the beam and ensure collisions between colliding beams.
On May 10, collisions began at the intersection points of the beams - the main detectors of the LHC: ATLAS, LHCb, CMS and ALICE. the main task preliminary collisions - checking the controllability of beams and testing detector systems, in particular, adjusting the position of the point at which the beams collide. During preliminary collisions, beams consisting of a small number of bunches (about ten versus more than two thousand) and much fewer protons are used than during scientific data collection.
Now the intensity of the beams is also low. Gradually, physicists will increase the number of protons in the bunches and make the bunches denser - this will speed up the rate of proton collisions and statistics collection. In 2016, scientists achieved an integral luminosity of about 40 inverse femtobarns - this value, according to the organization's press release, corresponds to 6.5 million billion proton collisions. According to the plan for 2017, the integrated luminosity of the installation is expected to be at least 45 inverse femtobarns. For comparison, in 2015 the collider provided an integral luminosity of about 4.2 inverse femtobarns, and in 2012 Run 1 - 23 inverse femtobarns.
One of the first collisions in the CMS detector
Unlike 2015 and 2016, at the end of the new accelerator operating season there will be no collision session with lead ions to generate quark-gluon plasma. This is a state of matter that simulates the first minutes of the life of the Universe. Instead, the ALICE detector will continue to process past data and collect information about proton-proton collisions. Recently, physicists discovered that despite the small mass of protons, quark-gluon plasma can also be formed in their collisions.
CMS and ATLAS will continue research into the properties of the Higgs boson, discovered in 2012. The experiments will determine the parameters of the particle's birth and decay channels, as well as how it interacts with other particles. In addition, together with the LHCb experiment (you can read our interview with the leaders of the collaboration), physicists will continue to analyze rare and exotic processes in search of traces of New Physics.
By increasing the volume of statistics, scientists will be able to learn the nature of unusual peaks in high-energy events, which may indicate new, not yet discovered particles. For example, ATLAS recently reported on the excess production of Higgs boson-weak interaction boson pairs with a total energy of three teraelectronvolts. The statistical significance of the event is small - it does not exceed 3.3 sigma, but if its source turns out to be a real particle, then its mass will be tens of times greater than that of any known elementary particle.
Vladimir Korolev
Physicists expect a delay in the launch of the modernized Large Hadron Collider - HL-LHC (High-Luminosity LHC). The third session of work in its current form can be extended for the entire 2024, the subsequent pause for six months, so that the launch of the updated installation will take place only in 2028, and not in 2026, as was originally planned. This is stated in the presentation of a participant in one of the experiments; an official message from CERN should appear later.
The Large Hadron Collider (LHC) is the most powerful particle accelerator. It was created to study collisions of proton beams at high energies, the interaction of which produces a large number of new particles. The main achievement of this installation was the discovery of the Higgs boson. It was also expected that the LHC would be able to find new particles beyond the predictions of the Standard Model, but these hopes were not realized.
The operation plan of the LHC involves three working sessions lasting several years, during which scientific data is collected. Between them, the installation is turned off, and its elements are replaced with newer ones, which makes it possible to increase the collision energy, luminosity and other parameters. IN this moment The second period of a long shutdown for re-equipment is underway. The third working session will begin in 2021. According to the original plans, it was supposed to last until the end of 2023, then another stop for 2.5 years, and from the end of 2026 - work in high luminosity mode.
However, these plans are shifting, says Gustaaf Brooijmans of Columbia University in slides. The third session will be extended for a year until the end of 2024, and the next stop for six months - until the second half of 2027. In this case, full operation of the updated collider will begin only in 2028, with a delay of about a year and a half relative to the initial plans.
An upgrade to HL-LHC should increase one of the facility's key parameters, luminosity, by about ten times. This value characterizes the intensity of particle collisions and actually determines the rate of data collection. This will require changes to be made to 1.2 kilometers of the main ring of 27. In particular, new superconducting magnets will be installed there, generating a field of 11–12 Tesla, which will reduce the beam diameter around the two main detectors - ATLAS and CMS. The cost of the work is estimated at 1.3 billion euros.
Physics World notes that the delay is primarily due to a funding shortfall of approximately £100 million. The publication writes that these funds should have come from one of the countries that are not members of the organization collaborating with CERN.
Previously it was reported that CERN from Microsoft products and will begin a systematic transition to open software, and the Large Hadron Collider houses excess heat. We also talk in detail about the conclusion of a new agreement on scientific and technical cooperation between Russia and CERN.
Timur Keshelava
