Thursday, July 9, 2015
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Preschool and beginner swim lesson registration due July 13

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Press Release

Fermilab's flagship accelerator sets world record

Fermilab's Main Injector accelerator, one of the most powerful particle accelerators in the world, has just achieved a world record for high-energy beams for neutrino experiments. Photo: Reidar Hahn

A key element in a particle-accelerator-based neutrino experiment is the power of the beam that gives birth to neutrinos: The more particles you can pack into that beam, the better your chance to see neutrinos interact in your detector. [Wednesday] scientists announced that Fermilab has set a world record for the most powerful high-energy particle beam for neutrino experiments.

Scientists, engineers and technicians at the U.S. Department of Energy's Fermi National Accelerator Laboratory have achieved for high-energy neutrino experiments a world record: a sustained 521-kilowatt beam generated by the Main Injector particle accelerator. More than 1,000 physicists from around the world will use this high-intensity beam to more closely study neutrinos and fleeting particles called muons, both fundamental building blocks of our universe.

The record beam power surpasses that of the 400-plus-kilowatt beam sent to neutrino experiments from particle accelerators at CERN.

Setting this world record is an initial step for the Fermilab accelerator complex as it will gradually increase beam power over the coming years. The next goal for the laboratory's two-mile-around Main Injector accelerator — the final and most powerful in Fermilab's accelerator chain — is to deliver 700-kilowatt beams to the laboratory's various experiments. Ultimately, Fermilab plans to make additional upgrades to its accelerator complex over the next decade, achieving beam power in excess of 1,000 kilowatts, also referred to as 1 megawatt.

"We have the world's highest-power beam for neutrinos, and we're only going up from here," said Ioanis Kourbanis, head of the Main Injector Department at Fermilab.

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In Brief

Comment period for DUNE environmental assessment document ends July 10

The Department of Energy is seeking input from interested citizens, including employees, to review and comment on the possible environmental effects of building and operating the Long-Baseline Neutrino Facility and the associated Deep Underground Neutrino Experiment.

The comment period on the DOE's Draft Environmental Assessment, which has been publicly released, lasts through Friday, July 10.

You can comment by:

  • U.S. mail: LBNF/DUNE Comments, U.S. Department of Energy (STS), Fermi Site Office, PO Box 2000, Batavia IL 60510;
  • Email; and
  • Online.

All comments, both oral and written, received during this period will be given equal consideration. Read the press release for more information.

In Brief

Exterior window washing at Wilson Hall - July 13-16

Clorica Management workers will wash the exterior windows of Wilson Hall from July 13-16. Employees should take care when walking outside of Wilson Hall during these work days.

In the News

These deep-space snapshots could help retrace the evolution of the universe

From Chicago magazine, July 7, 2015

You could be looking right at the secret to the universe when you gaze skyward this summer. Now, if only your eyes were as powerful as a 570-megapixel camera. In April, scientists with the Dark Energy Survey, led by Josh Frieman at Fermi National Accelerator Laboratory in Batavia, released their first major results, two years into the ongoing five-year project aimed at unraveling the evolution of the cosmos. They're using a supersized camera — the world's most powerful — to snap photos from Earth of deep space. We're talking eight-billion-light-years-away-deep.

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Physics in a Nutshell

Accelerator tunes

This diagram shows the so-called tune space for an accelerated particle beam. The colored lines indicate resonances in tune space to be avoided. The dot represents a possible stable area where neither horizontal nor vertical tunes are near a line.

In my last column, we concluded that circular accelerators that pass charged particles through a set of accelerating cavities many times is an effective strategy for achieving high energies. However, maintaining a beam while it makes many passes around the accelerator is not as simple as it may seem.

The first problem arises because the beam has a tendency to spread and will do so very quickly, becoming too large for the vacuum chamber unless we employ a mechanism to focus it. To solve the problem, quadrupole magnets, which focus the beam, are inserted at regularly spaced intervals between the bending magnets in the accelerator. Two quadrupole magnets at each location are required to focus the beam simultaneously in the horizontal and vertical planes. The result is a beam that oscillates in height and width as it circumnavigates the accelerator ring.

The number of oscillations the beam makes on each pass around the accelerator is called the tune. If we could make perfect magnets, our job would be done. However, the outstanding staff in Technical Division simply cannot make a perfect magnet.

To illustrate the problem caused by an imperfect magnet, imagine a particle going around the machine many times and passing through the magnets in the same position each time. Suppose it experiences a tiny error in the field on each pass that causes a horizontal displacement error in the beam of one millimeter. Imagine the particle is in the Main Injector, where each beam particle makes almost 100,000 trips around the accelerator each second. The additive one-millimeter error would result in a net displacement for the beam particle of almost 100 meters in one second, which means the particle would be lost in much less than a second.

To keep the beam in the accelerator, we must make certain that the particle does not see the same error each time it passes around the machine. We can do this by adjusting the tune so that the number of oscillations each particle makes per orbit is not an integer. The result is that the particle takes a different path each time around.

However, this adjustment is still not good enough. Taking the same path every other time or every fourth time (and so on) is also a problem. Problem tunes such as these are called resonances, and they must be avoided as much as possible to achieve stable beam. The tune space available for stable running is remarkably small.

Nevertheless, resonances are not all bad. They can be used to slowly extract beam from an accelerator by gradually moving the tune toward a resonance using a focusing magnet tied to a feedback system. Changing the tune in this manner causes the beam to stream smoothly toward an exit channel, where an electric field deflects it, allowing it to be extracted to a beamline.

Now you know the tunes that the accelerator operators play. They are catchy.

Roger Dixon

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Photo of the Day

Lunch on the ledge

A red-tailed hawk lunches on a snake on the sixth-floor ledge of Wilson Hall. Photo: Rick Hersemann, DOE
In the News

Reproducibility: Don't cry wolf

From Nature, July 1, 2015

The past few years have seen a slew of announcements of major discoveries in particle astrophysics and cosmology. The list includes faster-than-light neutrinos; dark-matter particles producing γ-rays; X-rays scattering off nuclei underground; and even evidence in the cosmic microwave background for gravitational waves caused by the rapid inflation of the early Universe. Most of these turned out to be false alarms; and in my view, that is the probable fate of the rest.

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