A joint Fermilab/SLAC publication

LHC sees first low-energy collisions

05/05/15

The Large Hadron Collider is back in the business of colliding particles.

Image of First collision ATLAS
ATLAS collaboration

Today low-energy protons met in the hearts of the four Large Hadron Collider experiments. These test collisions will help the ALICE, ATLAS, CMS and LHCb collaborations calibrate their detectors in preparation for the high-energy collisions scheduled for early June.

“Our detectors need to be able to distinguish between two particles separated by about the width of a human hair,” says Fermi National Accelerator Laboratory researcher Greg Rakness, run coordinator for the CMS experiment. “We need these low-energy collisions to precisely calibrate our instruments.”

Prior to this, the LHC had been shut down for two years to undergo upgrades and repairs. It circulated its first protons of its second run on April 5.

To generate the test collisions, engineers at CERN first accelerated proton beams inside the Super Proton Synchrotron and then diverted them into the LHC. Once inside the LHC, the two beams rotated at their injection energy of 450 giga-electronvolts before colliding in the centers of the four detectors. Engineers plan to run the two colliding beams for six continuous hours before diverting the leftover protons out of the machine and into a thick column of graphite.

CERN engineers plan to circulate proton beams around the LHC with about 14 times more energy this summer.

The teams responsible for getting the LHC up and running are about halfway through the eight-week period scheduled for commissioning. Over the next few weeks, they will continue to prepare the LHC for standard operation.

Standard operation requires that the LHC can safety and continuously collide hundreds of billions of high-energy protons every 25 nanoseconds for eight to 12 hours a day, almost every day, says LHC lead engineer Giulia Papotti.

“Turning on a particle accelerator that is 27 kilometers long is very different than booting up your computer,” Papotti says. “It takes time, and we still have a number of safety systems we need to set up to protect the machine and the experiments from the high-energy beams of particles that will continuously course through the machine once we start routine operation.”

The experiments are using these last few weeks to finish calibrating their detectors and prepare for the huge influx of new data that will inundate their servers once the high-energy collisions start.

“We are very excited to see LHC collisions for the first time again in more than two years,” says deputy head of the ATLAS experiment Beate Heinemann, a scientist at Lawrence Berkeley National Laboratory and the University of California, Berkeley. “These collisions are an important step towards being fully ready for the high-energy collisions expected for June.”

Image of First collision CMS
CMS collaboration

 

LHC restart timeline

February 2015
LHC Magnets Cooled

The Large Hadron Collider is now cooled to nearly its operational temperature.

Info-Graphic by Sandbox Studio, Chicago
 

LHC filled with liquid helium

The Large Hadron Collider is now cooled to nearly its operational temperature.
Read more…
LHC Magnets Powered

A first set of superconducting magnets has passed the test and is ready for the Large Hadron Collider to restart in spring.

Info-Graphic by Sandbox Studio, Chicago
 

First LHC magnets prepped for restart

A first set of superconducting magnets has passed the test and is ready for the Large Hadron Collider to restart in spring. Read more…
LHC Experiments Ready

Engineers and technicians have begun to close experiments in preparation for the next run.

Info-Graphic by Sandbox Studio, Chicago
 

LHC experiments prep for restart

Engineers and technicians have begun to close experiments in preparation for the next run.
Read more…
March 2015
LHC accelerator ready

The Large Hadron Collider has overcome a technical hurdle and could restart as early as next week.

Info-Graphic by Sandbox Studio, Chicago
 

LHC restart back on track

The Large Hadron Collider has overcome a technical hurdle and could restart as early as next week. Read more…
April 2015
First beam seen at LHC

The Large Hadron Collider has circulated the first protons, ending a two-year shutdown.

Info-Graphic by Sandbox Studio, Chicago
 

LHC sees first beams

The Large Hadron Collider has circulated the first protons, ending a two-year shutdown. Read more…
energy record broken at LHC

The Large Hadron Collider accelerated protons to the fastest speed ever attained on Earth.

Info-Graphic by Sandbox Studio, Chicago
 

LHC breaks energy record

The Large Hadron Collider accelerated protons to the fastest speed ever attained on Earth.
Read more…
May 2015
Low-Energy Collisions seen at the LHC

LHC sees first low-energy collisions

Info-Graphic by Sandbox Studio, Chicago
 

LHC sees first low-energy collisions

The Large Hadron Collider is back in the business of colliding particles.
Read more…
record-energy collisions achieved at the LHC

The Large Hadron Collider broke its own record again in 13-trillion-electronvolt test collisions.

Info-Graphic by Sandbox Studio, Chicago
 

LHC achieves record-energy collisions

The Large Hadron Collider broke its own record again in 13-trillion-electronvolt test collisions.
Read more…
June 2015
LHC Collisions for Physics

Data collection has officially begun at the Large Hadron Collider.

Info-Graphic by Sandbox Studio, Chicago
 

LHC arrives at the next energy frontier

Data collection has officially begun at the Large Hadron Collider.
Read more…

 

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