LHC Towards higher intensities - CERN Bulletin

Towards higher intensities - CERN Bulletin

Over the past 2 weeks, commissioning of the machine protection system has advanced significantly, opening up the possibility of higher intensity collisions at 3.5 TeV. The intensity has been increased from 2 bunches of 1010 protons to 6 bunches of 2x1010 protons. Luminosities of 6x1028 cm-2s-1 have been achieved at the start of fills, a factor of 60 higher than those provided for the first collisions on 30 March.

The recent increase in LHC luminosity as recorded by the experiments.

(Graph courtesy of the experiments and M. Ferro-Luzzi)

To increase the luminosity further, the commissioning crews are now trying to push up the intensity of the individual proton bunches.

After the successful injection of nominal intensity bunches containing 1.1x1011 protons, collisions were subsequently achieved at 450 GeV with these intensities.

However, half-way through the first ramping of these nominal intensity bunches to 3.5 TeV on 15 May, a beam instability was observed, leading to partial beam loss.

Work is now under way to understand, control and cure this instability by using longer bunches and by powering the special correction magnets (octupoles).

LHC: Large Hadron Collider shut down until February 2010

Scientists have switched the world's most powerful atom-smasher to standby for two and a half months, the European Organisation for Nuclear Research (CERN) said on Friday.

The Large Hadron Collider (LHC) ended the year "in style", CERN said, achieving more than a million particle collisions in the last two weeks and accelerating proton beams to energy levels never reached before.

CERN said the LHC would be restarted in February after a short technical stop to prepare it for collisions at even higher energy levels.

"Commissioning work for higher energies will be carried out in January, along with necessary adaptations to the hardware and software of the protections systems," CERN said in a statement.

The 3.9 billion-euro (5.6 billion dollar) collider was relaunched in November after 14 months out of action because of an electrical fault.

Scientists hope to use the collider -- inside a 27-kilometre (16.8-mile) tunnel straddling the Franco-Swiss border -- to understand the origins of the universe by recreating the conditions that followed the Big Bang.

So far, the LHC has achieved collisions at an energy level of 2.36 teraelectronvolts (TeV), and CERN wants to reach 7.0 TeV to try to recreate the conditions of the Big Bang.

Before the LHC experiment, no particle accelerator had exceeded 0.98 TeV. One TeV is the equivalent to the energy of a flying mosquito.

The LHC aims to resolve physics problems including "dark matter" and "dark energy", thought to account for 96 percent of the cosmos.

The scientists' Holy Grail is to find a theorised component called the Higgs Boson, which would explain how particles acquire mass.

Physics finally benefits from LHC - Large UK contributions

Protons were collided in the LHC, for the first time, on Monday 23rd November at relatively low energies. High energy collisions are expected early next year when physicists hope to discover new secrets about the nature of matter and the early universe.

Professor Keith Mason, CEO of the Science and Technology Facilities Council (STFC), said, "This is great news. The LHC is now fully on track and gearing up to some unique and possibly world changing science. We're very proud of the huge contribution of our skilled scientists here in the UK."

The UK is one of the biggest contributors to the LHC project. Through the Science and Technology Facilities Council (STFC), which funds the UK nuclear and particle physics program, including the CERN subscription, the UK has contributed vital hardware, computing and scientific knowledge and has around 150 UK scientists currently involved in the project.

(LHC) Large Hadron Collider Restarts, at half speed

(Image: CERN)

A technician inspects the site of a faulty electrical connection that damaged the LHC in September 2008

The world's most powerful particle smasher will restart in November at just half the energy the machine was designed to reach. But even at this level, the Large Hadron Collider has the potential to uncover exotic new physics, such as signs of hidden extra dimensions, physicists say.

CERN Lab

The LHC is a new particle accelerator at the CERN laboratory near Geneva, Switzerland, designed to answer fundamental questions, such as what gives elementary particles their mass, by colliding particles at higher energies than ever achieved in a laboratory before.

The First Attempt

The first attempt to turn on the LHC failed in September 2008 when a joint connecting a pair of superconducting wires overheated, causing an explosive release of helium used as a coolant. Scientists have been making repairs and checking the strength of other electrical connections since then to pave the way for a second start attempt.

Restart November

Now, CERN has announced that the LHC's first data collecting run, to begin in November, will collide protons at only half the energy the accelerator was designed to achieve. The run will initially smash protons together at 7 trillion electron volts (7 TeV), compared to the design goal of 14 TeV, according to a CERN statement on 6 August. (Protons in each of the two opposing beams will have 3.5 TeV of energy, producing collisions at 7 TeV.)

Even 7 TeV is much higher than physicists have ever probed in the laboratory before. The Tevatron accelerator at Fermilab in Batavia, Illinois, is the current record holder, with collisions at 2 TeV.