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4 September, 2019
The first definitive component of the High-Luminosity LHC, an absorber designed to protect the machine, has been installed in the LHC
Image above: The TANB absorber was installed in the LHC tunnel to protect the accelerator components from particles produced by collisions occurring in the LHCb experiment. (Image: Maximilien Brice/CERN).
The component concerned, known as a TANB, is the first definitive component of the High-Luminosity LHC to be installed in the Large Hadron Collider tunnel. An inauguration ceremony on Friday, 30 August, marked the arrival of this piece of equipment for the future collider.
The High-Luminosity LHC, which will be commissioned in 2026, will boost the performance of the current accelerator by substantially increasing the number of collisions in the experiments. Luminosity, which corresponds to the number of potential collisions per second per surface unit, is a crucial indicator of an accelerator’s performance. The higher the luminosity, the higher the probability of new discoveries.
Increasing the number of collisions, and therefore the number of particles in circulation, requires the protection of the LHC’s equipment to be reinforced, as particles that diverge from the trajectory can collide with sensitive components such as superconducting magnets and interfere with their operation. Protection is particularly important near the experiments. The billions of collisions occurring every second inside the detectors create the particles that are studied by the physicists. While almost all of these particles shoot off into the detector that surrounds the collision point, a miniscule number of them are emitted towards the tube where the beam circulates and can therefore reach the accelerator equipment.
The aim of the TANB absorber is thus to protect the accelerator equipment by stopping the particles near the LHCb experiment. During the current second long technical shutdown that will continue until 2021, the LHCb experiment will undergo major upgrades to enable it to record five times as many collisions from 2021 onwards. This collision rate will be kept at the same level for the LHCb when the High-Luminosity LHC comes into service.
“Two of the same type of absorbers are already used on either side of the ATLAS and CMS experiments,” explains project leader Francisco Sanchez Galan. “However, we had to come up with a new design for LHCb, notably owing to a lack of space inside the accelerator.” Space is at a premium in the LHC, especially around the experiments. Therefore, it was necessary to design the simplest and most compact absorber possible.
Large Hadron Collider (LHC). Animation Credit: CERN
Simplifying things can sometimes turn out to be very complicated. After a detailed design study and numerous simulations, engineers proved that it was possible to design an absorber that was more compact yet just as effective by positioning the equipment further away. Several models were proposed and the optimal absorber was finalised on paper before being manufactured in Germany. It measures only 65 centimetres in depth, as opposed to 5 metres for previous models.
An innovative positioning table was developed at the same time. “All its actuators are positioned on the side with easy access. We had to develop this model because the lack of space makes difficult the adjustment of traditional tables on all four sides, and in addition we needed to limit intervention time,” says Francisco.
Finally, the TANB’s integration was complicated by the lack of space. “Moving components and modifying the beam line allowed us to proceed millimetre by millimetre,” underlines Francisco. Mission accomplished, “thanks to the collaboration between numerous teams”, he smiles. Two TANB models have now been installed on both sides of the LHCb, ready for the next collision run and high luminosity.
Note:
CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.
The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.
Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 23 Member States.
Related link:
High-Luminosity LHC (HL-LHC): https://home.cern/science/accelerators/high-luminosity-lhc
Large Hadron Collider (LHC): https://home.web.cern.ch/topics/large-hadron-collider
For more information about European Organization for Nuclear Research (CERN), Visit: https://home.cern/
Image (mentioned), Animation (mentioned), Text, Credits: CERN/Corinne Pralavorio.
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