Friday, August 22, 2008

LHC Start-up To Shut-down 2008

After the Olympics, the next big thing is the international Large Hadron Collider. There's a lot of excitement at CERN. The first injections, and without a hitch, of low energy protons shot through an eighth of the 27 km LHC ring. Back to back for this weekend they're doing it again at 0.45 TeV with the anticlockwise beam. It's an important preliminary test, kicking the protons from the pre-accelerator loops, into the unknown. At this point CERN is confident there is nothing to worry about. The energy is only half of the currently most powerful collider, Fermilab's Tevatron, in Batavia, Ill. So, CERN's probably right, this time. Higher energies will be the real test.

Now for the news, major media aren't covering, from the current Strings 2008, a CERN conference, and not only on String theory. It's another window on CERN that is fascinating.

Even at 1% of design energies, as Lyn Evans, Project Director, said August 18th in his talk, on LHC Machine Status, we'll be in new territory. He also confirmed that the first beam right around the main ring is still set for September 10th, as announced last week.

There's one problem Evans said quickly, a turbine needs replacing in Sector 6-7, but it won't delay operations. Once another test is done for the other beam later in September, CERN plans to go ahead with 5 TeV runs before the standard winter shutdown. A Russian scientist, Alexander Vodopyanov of the Joint Institute for Nuclear Research (Dubna), said recently in RIA Novosti World, that he's heard that the LHC will be inaugurated October 21st, which supposes that the collider, will by that time have had one test run at least. Though beam collisions at 10 TeV, probably will start later. CERN is in a hurry though, having cancelled earlier plans for a gradual ramping up of beam energies. Going from a known quantity, suddenly into the unknown is a risk, and totally unnecessary. The big rush is due to three years of delays, construction and equipment problems.

Seems they would even have skipped 5 TeV and gone straight to 7 TeV beams this fall, as Evans said the collider wasn't ready for the design energies, as some magnets had been lying around for two years, and were found to require retraining for higher energies, though they were previously trained, this batch from some other supplier. Those will be retrained during the winter shutdown, so they can all go skiing. Mount Blanc is only a proton away. That's not official though. Ski report widgets and desktop ski weather icons and live webcam links to the best ski resorts are all over CERN desktops and laptops. Ski weekend emails fly like alarm routines.

Magnets have to sit up, bark and rollover, as they say at Fermilab. Twelve hundred 15 meter ones at about a million dollars a pop, thousands of smaller ones. But Evans added they were proceeding with care, with some magnets not fully trained, not pushing them beyond 5 TeV, as there are always some protons lost from the beams, and that can cause magnet quenches. As we know from the Tevatron, quenches can crash down the entire collider. Sometimes beams are lost, potentially a dangerous situation.

So September 10th, 21 days to go, is not the BBC's "Big Bang Day", as they're calling it, on their live Radio Four broadcast, starting at 0:8:30 BST. No need to panic yet. Try again later this October. For all you fans of micro black holes, you'll have to wait for them too. CERN's not convinced they'll show up during proton collisions. If they do, Dr O. Buchmüller, speaking on The Search for New Physics at the LHC, said at Strings 2008, after the Evans presentation, that if they show up they would be within SUSY parameters, and their signature would be clearly obvious. Keep your fingers crossed so they aren't too obvious.

Make a date to watch the September 10th LHC Sparks and Quarks, starting 0:8:30 BST, firing of the First Beam an hour later, like on BBC Radio Four, either on Eurovision, if you have a feed or can buy an Internet pass for this one. Or if you're broke after blowing $10 billion on the LHC, watch it for free on CERN's tiny TV Live Webcast, better in Flash if you have internet lite, but a fast machine.

The just-ended Strings 2008, the best in arcane viewing, even if you're a physics fanatic, was a live webcast on the same CERN url daily this week. Earlier talks from Strings 2008, you might have missed, including the must see Evans and Buchmüller talks, should be available as videos a few days late on this same CERN url, see below.


CERN Strings 2008, conference program,

CERN Webcasts, live or pre-recorded video, for Strings 2008, First Beam September 10th, or other CERN events,

CERN First Beam, news on LHC start-up, countdown to September 10th,

CERN Press Release, CERN announces start-up date for LHC, August 7, 2008,

RIA Novosti World, "Large Hadron Collider to be launched October 21 -- Russian Scientist", August 5, 2008,

Gillis, Alan, The Science of Conundrums, "Daily Battles At The Tevatron",

Gillis, Alan, The Science of Conundrums, "Major Failures At The Tevatron",

Gillis, Alan, The Science of Conundrums, "It's All About Energy At The LHC",

From First Test To First Beam To First Collisions

CERN's image (above) of last weekend's first proton bunch injection, raises some questions for those who aren't particle physicists. If you read the CERN descriptions of the particle beam and bunches of protons, they look nothing like this.

Ordinarily at design energies, CERN states there will be 3,000 bunches of protons in the beam, and numbering overall anywhere from 100 billion to the trillions of protons, depending on how much luminosity the physicists at the LHC would like for each experiment. The pictured bunch according to SciAM is 5 million protons, a far smaller number than would be usual, which would be at least 100 million protons per bunch. And CERN always describes their beams as less than the thickness of a human hair, and each bunch about 5 cm long. What we're seeing with this first bunch is a hot ball of protons, with a big halo and tail, at about 7.5 mm on the Y-axis, and with the halo included, about 11 mm overall, more like the width of your baby finger.

There's nothing wrong here, as this is typically what you get from the low energy 0.45 TeV SPS pre-accelerator that feeds the LHC. Further focusing of the beam will occur later, to produce needle-like bunches, through collimators throughout the main ring. But the halo is worth looking at. It's well understood this is mostly an electron cloud, generated through interactions of these accelerated protons and extremely high magnetic fields from the superconducting di-pole magnets.

But in the LHC the initial halos, that are cleansed later and focused, show some foreign matter in the beam cryostats which is burning, and this in the best vacuum that CERN can produce for the beam lines, a greater vacuum than is found on the Moon.

Recently, Katherine McAlpine, a science writer working for CERN, put it this way. ". . . with that first beam, they're going to be getting so much more data coming out from those protons running into things that are in the beam pipe than they're getting from cosmic rays coming in from outer space right now that the detector people will have a lot more information to work with calibrating."

Of late she's become well known as AlpineKat through her rap video, "Large Hadron Rap", with CERN back-up.

Besides some collider debris, electron cloud production at the Proton Synchrotron and the Super Proton Synchrotron has been an unresolved problem, especially the proton scattering which comes with an unfocused beam. Other pre-accelerators have the same problem.

Looking back to what Lyn Evans said at Strings 2008, there's an interesting effect that might be seen on September 10th, during the First Beam right around the collider ring.

As some magnets are not properly trained, they won't be ideal superconductors like the other magnets, that will be at 8.33 Teslas. Their magnetic fields will be somewhat weaker and so the First Beam of protons will pass through various field strengths around the collider. This also affects the Superfluid Heliums that circulate through the magnets and cool them and the cryostats. As Superfluid Helium is considered to be a Bose-Einstein Condensate, it has been demonstrated in another BEC that an abrupt change in magnetic fields starts the Bosenova implosion/explosion.

No CERN experimental studies or theoretical analysis has ever been produced on this safety issue by CERN. The recent LSAG safety report by CERN ignores this possible risk that might destroy the collider.

There should be some news this weekend on another test. The counter-rotating beam, like last weekend's test will be injected this weekend, probably with similar success. The next thing to watch is the September 10th First Beam, where there is more risk of failures in engineering and equipment. Look for a follow-up article here on what CERN might discover, when it's too late.

Katherine McAlpine also said, in line with earlier reports from CERN, " . . . on September 10th they're really only going to have one beam going around, so they're not going to have collisions until they project about two months later after startup."

So around November 10th for the first particle collisions at 10 TeV.

CERN Confirms Big Bash

If there's no big crash, CERN says the Collider Inauguration will be October 21st, as Vodopyanov said. 10 TeV Collisions are scheduled before winter shutdown, CERN says again, confirming what McAlpine said. And I was right about the second kicker magnet test. No problems. There was a bit more action from one of the smaller forward detectors, the VELO, part of the giant LHCb detector. The protons knocked through part of the VELO array, and CERN captured the first particle tracks in a series of images, showing at least that this bit works. A relief, these card modules are supercomplex. See the preliminary data and beam schedule on this CERN summary page.

(This article originally appeared in the Alan Gillis Column, Big Science Gambles, ScientificBlogging, in two parts, August 19 and 22, 2008, Big Bash update August 26, 2008,


Gillis, Alan. ScientificBlogging, "Superfluids, BECs and Bosenovas: The Ultimate Experiment", July 2, 2008,

McAlpine, Katherine (AlpineKat). Youtube, "Large Hadron Rap", July 28, 2008,

Turner, James. O'Reilly News, "Rapping the Higgs Boson: Katherine McAlpine . . .", August 19, 2008,

1 comment:

Chus said...

This is what I think: LHC News