From The DOE’s Fermi National Accelerator Laboratory : “First demonstration of a new particle beam technology at Fermilab” 

FNAL Art Image
FNAL Art Image by Angela Gonzales

From The DOE’s Fermi National Accelerator Laboratory , an enduring source of strength for the US contribution to scientific research worldwide.

Tracy Marc

Physicists love to smash particles together and study the resulting chaos. Therein lies the discovery of new particles and strange physics, generated for tiny fractions of a second and recreating conditions often not seen in our universe for billions of years. But for the magic to happen, two beams of particles must first collide.

Researchers at the U.S. Department of Energy’s Fermi National Accelerator Laboratory have announced the first successful demonstration of a new technique that improves particle beams. Future particle accelerators could potentially use the method to create better, denser particle beams, increasing the number of collisions and giving researchers a better chance to explore rare physics phenomena that help us understand our universe. The team published its findings in a recent edition of Nature [below].

The beam particles each emit ultrafast light pulses as they pass through a special magnet called a pickup undulator (bottom right). Information about each particle’s energy or trajectory error is encoded in its light pulse. The light pulses are captured, focused and tuned by various light optics. The particles then interact with their own pulses inside an identical kicker undulator (center). The interaction can be used to cool the particles or even control them depending on the configuration of the system. Image: Jonathan Jarvis, Fermilab.

Particle beams are made of billions of particles traveling together in groups called bunches. Condensing the particles in each beam so they are packed closely together makes it more likely that particles in colliding bunches will interact—the same way multiple people trying to get through a doorway at the same time are more likely to jostle one another than when walking through a wide-open room.

Packing particles together in a beam requires something similar to what happens when you put an inflated balloon in a freezer. Cooling the gas in the balloon reduces the random motion of the molecules and causes the balloon to shrink. “Cooling” a beam reduces the random motion of the particles and makes the beam narrower and denser.

Scientists at Fermilab used the lab’s newest storage ring, the Integrable Optics Test Accelerator, known as “IOTA”, to demonstrate and explore a new kind of beam cooling technology with the potential to dramatically speed up that cooling process.

“IOTA was built as a flexible machine for research and development in accelerator science and technology,” said Jonathan Jarvis, a scientist at Fermilab. “That flexibility lets us quickly reconfigure the storage ring to focus on different high-impact opportunities. That’s exactly what we’ve done with this new cooling technique.”

The new technique is called “optical stochastic cooling”. It was first proposed in the early 1990s, and while significant theoretical progress was made, an experimental demonstration of the technique remained elusive until now.

This kind of cooling system measures how particles in a beam move away from their ideal course and then uses a special configuration of magnets, lenses and other optics to give corrective nudges. It works because of a particular feature of charged particles like electrons and protons: As the particles move along a curved path, they radiate energy in the form of light pulses, giving information about the position and velocity of each particle in the bunch. The beam-cooling system can collect this information and use a device called a kicker magnet to bump them back in line.

Conventional stochastic cooling, which earned its inventor, Simon van der Meer, a share of the 1984 Nobel Prize, works by using light in the microwave range with wavelengths of several centimeters. In contrast, optical stochastic cooling uses visible and infrared light, which have wavelengths around a millionth of a meter. The shorter wavelength means scientists can sense the particles’ activity more precisely and make more accurate corrections.

To prepare a particle beam for experiments, accelerator operators send it on several passes through the cooling system. The improved resolution of optical stochastic cooling provides more exact kicks to smaller groups of particles, so fewer laps around the storage ring are needed. With the beam cooled more quickly, researchers can spend more time using those particles to produce experimental data.

The cooling also helps preserve beams by continually reigning in the particles as they bounce off one another. In principle, optical stochastic cooling could advance the state-of-the-art cooling rate by up to a factor of 10,000.

This first demonstration at IOTA used a medium-energy electron beam and a configuration called “passive cooling,” which doesn’t amplify the light pulses from the particles. The team successfully observed the effect and achieved about a tenfold increase in cooling rate compared to the natural “radiation damping” that the beam experiences in IOTA. They were also able to control whether the beam cools in one, two or all three dimensions. Finally, in addition to cooling beams with millions of particles, scientists also ran experiments studying the cooling of a single electron stored in the accelerator.

“It’s exciting because this is the first cooling technique demonstrated in the optical regime, and this experiment let us study the most the essential physics of the cooling process,” Jarvis said. “We’ve already learned a lot, and now we can add another layer to the experiment that brings us significantly closer to real applications.”

With the initial experiment completed, the team is developing an improved system at IOTA that will be the key to advancing the technology. It will use an optical amplifier to strengthen the light from each particle by about a factor of 1,000 and apply machine learning to add flexibility to the system.

“Ultimately, we’ll explore a variety of ways to apply this new technique in particle colliders and beyond,” Jarvis said. “We think it’s very cool.”

Science paper:

See the full article here .


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The DOE’s Fermi National Accelerator Laboratory, located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operated by the Fermi Research Alliance, a joint venture of the University of Chicago, and the Universities Research Association (URA). Fermilab is a part of the Illinois Technology and Research Corridor.

Fermilab’s Tevatron was a landmark particle accelerator; until the startup in 2008 of the Large Hadron Collider(CH) near Geneva, Switzerland, it was the most powerful particle accelerator in the world, accelerating antiprotons to energies of 500 GeV, and producing proton-proton collisions with energies of up to 1.6 TeV, the first accelerator to reach one “tera-electron-volt” energy. At 3.9 miles (6.3 km), it was the world’s fourth-largest particle accelerator in circumference. One of its most important achievements was the 1995 discovery of the top quark, announced by research teams using the Tevatron’s CDF and DØ detectors. It was shut down in 2011.

[Earlier than the LHC at CERN, The DOE’s Fermi National Accelerator Laboratory had sought the Higgs with the Tevatron Accelerator.

But the Tevatron could barely muster 2 TeV [Terraelecton volts], not enough energy to find the Higgs. CERN’s LHC is capable of 13 TeV.

Another possible attempt in the U.S. would have been the Super Conducting Supercollider.

Fermilab has gone on to become a world powerhouse in neutrino research with the LBNF/DUNE project which will send neutrinos 800 miles to SURF-The Sanford Underground Research Facility in in Lead, South Dakota.

FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota


In addition to high-energy collider physics, Fermilab hosts fixed-target and neutrino experiments, such as MicroBooNE (Micro Booster Neutrino Experiment), NOνA (NuMI Off-Axis νe Appearance) and SeaQuest. Completed neutrino experiments include MINOS (Main Injector Neutrino Oscillation Search), MINOS+, MiniBooNE and SciBooNE (SciBar Booster Neutrino Experiment). The MiniBooNE detector was a 40-foot (12 m) diameter sphere containing 800 tons of mineral oil lined with 1,520 phototube detectors. An estimated 1 million neutrino events were recorded each year. SciBooNE sat in the same neutrino beam as MiniBooNE but had fine-grained tracking capabilities. The NOνA experiment uses, and the MINOS experiment used, Fermilab’s NuMI (Neutrinos at the Main Injector) beam, which is an intense beam of neutrinos that travels 455 miles (732 km) through the Earth to the Soudan Mine in Minnesota and the Ash River, Minnesota, site of the NOνA far detector. In 2017, the ICARUS neutrino experiment was moved from CERN to Fermilab.
In the public realm, Fermilab is home to a native prairie ecosystem restoration project and hosts many cultural events: public science lectures and symposia, classical and contemporary music concerts, folk dancing and arts galleries. The site is open from dawn to dusk to visitors who present valid photo identification.

Asteroid 11998 Fermilab is named in honor of the laboratory.

Weston, Illinois, was a community next to Batavia voted out of existence by its village board in 1966 to provide a site for Fermilab.

The laboratory was founded in 1969 as the National Accelerator Laboratory; it was renamed in honor of Enrico Fermi in 1974. The laboratory’s first director was Robert Rathbun Wilson, under whom the laboratory opened ahead of time and under budget. Many of the sculptures on the site are of his creation. He is the namesake of the site’s high-rise laboratory building, whose unique shape has become the symbol for Fermilab and which is the center of activity on the campus.

After Wilson stepped down in 1978 to protest the lack of funding for the lab, Leon M. Lederman took on the job. It was under his guidance that the original accelerator was replaced with the Tevatron, an accelerator capable of colliding protons and antiprotons at a combined energy of 1.96 TeV. Lederman stepped down in 1989. The science education center at the site was named in his honor.

The later directors include:

John Peoples, 1989 to 1996
Michael S. Witherell, July 1999 to June 2005
Piermaria Oddone, July 2005 to July 2013
Nigel Lockyer, September 2013 to the present

Fermilab continues to participate in the work at the Large Hadron Collider (LHC); it serves as a Tier 1 site in the Worldwide LHC Computing Grid.