Saturday, 29 April 2017

Who switches on the LHC?

The LHC has restarted for its 2017 run

Final tests were performed in the LHC at the end of April, ready for the restart this weekend (Image: Maximilien Brice/ CERN)

Today, the LHC once again began circulating beams of protons, for the first time this year. This follows a 17-week-long extended technical stop.

Over the past month, after the completion of the maintenance work that began in December 2016, each of the machines in the accelerator chain have, in turn, been switched on and checked until this weekend when the LHC, the final machine in the chain, could be restarted by the Operations team.

“It’s like an orchestra, everything has to be timed and working very nicely together. Once each of the parts is working properly, that’s when the beam goes in, in phases from one machine to the next all the way up to the LHC,” explains Rende Steerenberg, who leads the operations group responsible for the whole accelerator complex, including the LHC.

Each year, the machines shut down over the winter break to enable technicians and engineers to perform essential repairs and upgrades, but this year the stop was scheduled to run longer, allowing more complex work to take place. This year included the replacement of a superconducting magnet in the LHC, the installation of a new beam dump in the Super Proton Synchrotron and a massive cable removal campaign.

Among other things, these upgrades will allow the collider to reach a higher integrated luminosity – the higher the luminosity, the more data the experiments can gather to allow them to observe rare processes.

“Our aim for 2017 is to reach an integrated luminosity of 45 fb-1 [they reached 40 fb-1 last year] and preferably go beyond. The big challenge is that, while you can increase luminosity in different ways – you can put more bunches in the machine, you can increase the intensity per bunch and you can also increase the density of the beam – the main factor is actually the amount of time you stay in stable beams,” explains Steerenberg.

In 2016, the machine was able to run with stable beams – beams from which the researchers can collect data – for around 49 per cent of the time, compared to just 35 per cent the previous year. The challenge the team faces this year is to maintain this or (preferably) increase it further.

The team will also be using the 2017 run to test new optics settings – which provide the potential for even higher luminosity and more collisions.

“We’re changing how we squeeze the beam to its small size in the experiments, initially to the same value as last year, but with the possibility to go to even smaller sizes later, which means we can push the limits of the machine further. With the new SPS beam dump and the improvements to the LHC injector kickers, we can inject more particles per bunch and more bunches, hence more collisions,” he concludes.

For the first few weeks only, a few bunches of particles will be circulating in the LHC to debug and validate the machine. Bunches will gradually increase over the coming weeks until there are enough particles in the machine to begin collisions and to start collecting physics data. 


Learn more about the restart:

Who switches on the LHC?

Everything you ever wanted to know about the LHC

via CERN: Updates for the general public

Solar System Grand Tour space tourism advert Shower Curtain

Solar System Grand Tour space tourism advert Shower Curtain
A wonderful, retro-style vacation advert. It urges you to take the same grand tour of the solar system taken by NASA's Voyager mission. Visit Jupiter, Saturn, Uranus and…

Fast, non-destructive test for two-dimensional materials

more »
A fast, nondestructive optical method for analyzing defects in two-dimensional materials has been developed, with applications in electronics, sensing, early cancer diagnosis and water desalination.
via Science Daily

Arches of Spring

more »
Two luminous arches stretched across the dome of the sky on this northern spring night. After sunset on March 29, the mountain view panorama was captured in 57 exposures from Chopok peak in central Slovakia at an altitude of about 2,000 meters. The arc of the northern Milky Way is visible toward the right, but only after it reaches above the terrestrial lights from the mountain top perspective. Though dusk has passed, a bright patch of celestial light still hovers near the horizon and fades into a second luminous arch of Zodiacal Light, crossing near the center of the Milky Way. Dust in the ecliptic plane reflects sunlight to create the Zodiacal glow, typically prominent after sunset in clear, dark, skies of the northern spring. Almost opposite the Sun, Jupiter shines brightly near the horizon toward the left. Since Jupiter lies near the ecliptic, it appears within the slight brightening of the Zodiacal band also opposite the Sun called the Gegenschein.

Zazzle Space Gifts for young and old