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Posts Tagged ‘accelerator’

This Fermilab press release came out on July 8, 2015.

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: Fermilab

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: Fermilab

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. Today 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.

Laboratory-made neutrino experiments start by accelerating a beam of particles, typically protons, and then smashing them into a target to create neutrinos. Scientists then use particle detectors to “catch” as many of those neutrinos as possible and record their interactions. Neutrinos rarely engage with matter: Only one out of every trillion emerging from the proton beam will interact in an experiment’s detector. The more particles in that beam, the more opportunities researchers will have to study these rare interactions.

The amped-up particle beam provided by the Main Injector enriches the lab’s neutrino supply, positioning Fermilab to become the primary laboratory for accelerator-based neutrino research. Neutrinos are also made in stars and in the Earth’s core, and they pass through everything — people and planets alike.

“The idea is that if you build a more intense beam, neutrino scientists from around the world will beat a path to your door,” said Fermilab Deputy Director Joe Lykken. “This is exactly what’s happening.”

Fermilab currently operates four neutrino experiments: MicroBooNE, MINERvA, MINOS+ and the laboratory’s largest-to-date neutrino experiment, NOvA, which sends particles from Fermilab’s suburban Chicago location to a far detector 500 miles away in Ash River, Minnesota. The laboratory is working with scientists from around the world on expanding its short-baseline neutrino program and would also serve as host to the proposed flagship Long-Baseline Neutrino Facility and Deep Underground Neutrino Experiment, or DUNE. Scientists aim to address basic questions about the mass and properties of each kind of neutrino as well as the role neutrinos played in the evolution of the universe.

“Reaching this milestone is a fantastic achievement for Fermilab; beam power is everything in our field,” said DUNE co-spokesperson Mark Thomson of the University of Cambridge. “The ability for Fermilab to deliver, yet again, gives the international neutrino community huge confidence in the future U.S.-hosted neutrino program.”

Fermilab is also preparing to operate two experiments for studying muons, short-lived particles that could reveal secrets about the earliest moments of the universe. The increased beam power will also benefit the Fermilab Test Beam Facility, one of the few facilities in the world that provides muons, pions and other particles that researchers can use to test their particle detectors.

Since 2011, Fermilab has made significant upgrades to its accelerators and reconfigured the complex to provide the best possible particle beams for neutrino and muon experiments. With the dedicated work of the Fermilab Accelerator Division, the Main Injector is on track to nearly double its Tevatron-era beam power by 2016.

“Fermilab’s beamline has been a tremendous driver of neutrino science for many years, and the continued improvements to the intensity mean that it will remain a driver for many years to come,” said Indiana University’s Mark Messier, co-spokesperson for the NOvA experiment.

Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC. Visit Fermilab’s website at www.fnal.gov, and follow us on Twitter at @Fermilab.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

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Physics + wine = plasma + fun

Wednesday, February 4th, 2015

Ever fancied making your own particle accelerator? Fermilab posted a great blog entry last month (here) showing how anyone can make a particle detector for viewing cosmic rays. In this post, I will explain how particle accelerators can also be hacked so that you can make your very own cathode ray tube (CRT).

I came across this experiment when attending an accelerator school at the Australian Synchrotron last year. To read more about my adventures down under please see Accelerating Down Under and If you can’t stand the heat, get into the Synchrotron!.

What is a cathode ray tube?

Good question. It consists of a vacuum chamber containing some electrodes between which a high voltage is applied. Electrons are accelerated from the negatively charged cathode to the positively charged anode. But some electrons fly past the anode to hit a glass wall. CRTs were utilised in old television sets to form images on a fluorescent screen.

Ingredients

You will need:

  • – a clear wine bottle
  • – a vacuum pump
  • – a rubber hose
  • – epoxy resin
  • – mini chrome-plated metal doorknob
  • – a piece of steel brake line
  • – a piece of steel wire several centimetres long
Empty wine bottles at the Australian Synchrotron.

Experimental preparation at the Australian Synchrotron: GRAPE 1, 2 & 3. Image credit: Ralph Steinhagen.

Recipe

A detailed method for this experiment may be found (here) but I summarise the main steps below:

  1. Drink a bottle of wine. Wash out the wine bottle with warm soapy water and remove all labelling from the exterior.
  2. Drill a hole about 1/2 way down the wine bottle which is big enough to fit the metal wire through. This will act as the mount for the anode. If your bottle cracks, throw it away and return to step 1.
  3. Drill a hole through the metal doorknob. Use epoxy to attach the break line to the doorknob’s screw mount. This will act both as the cathode and vacuum port. Apply epoxy to the rim of the mouth of the wine bottle and attach the cathode to form an airtight seal.
  4. Bend the steel wire into a C-shape and thread it through the hole you drilled in the wall of the wine bottle. This is your anode. Orient it so that all points on it are equidistant from your cathode. Secure it with epoxy and ensure it is airtight.
  5. Attach the rubber hose to your anode and the other end to the vacuum pump. Attach the anode and cathode to a high voltage power supply. Turn on the power supply and vacuum pump and enjoy!

 

GRAPE 2

The GRAPE 2 experiment: a vacuum pump is connected to the experiment via the rubber tube to the right of the bottle. The anode and cathode, which are connected to a high voltage supply, are seen to glow. Image credit: Ralph Steinhagen.

Safety

A word of warning: using high voltages, creating vacuums and drilling holes in glass bottles are all inherently dangerous activities. If you attempt this experiment please observe all safety advice. In particular, wear protective clothing and safety glasses, don’t use cracked bottles for the experiment – you risk implosion – and apply the voltage for a maximum of 30/40 seconds.

And please leave adequate time between consuming the wine and carrying out the experiment to sober up.

Plasmatastic!

The video below shows what happened when the switch was flicked on the GRAPE 2 experiment at the Australian Synchrotron:

 

Initially there is a clear purple electric discharge between the anode and cathode. This discharge excites the atoms in the gas in the bottle causing a burst of liberated free electrons. The electrons are travelling much faster than the positive ions they leave behind and so diffuse to the cathode and bottle walls. Thus a plasma (or ionised gas) is created.

The plasma stabilises as more ionisation occurs, then begins to glow as electrons and ions recombine and emit photons. This process of ionisation and recombination is continuous. The instabilities or fluctuations observed indicate that different proportions of the remaining gas are being excited as the experiment proceeds. Can you think of why this happens? If so, please comment below.

When a magnet is placed near the bottle the plasma is visibly distorted. This phenomenon is known as magnetic deflection and is described by the Lorentz force law. The plasma’s charged particles experience a force when they travel through the magnetic field which is perpendicular both to the path they follow and to the applied magnetic field, that is the magnet causes the particles to follow a curved path. This effect is used in circular particle accelerators, such as the Large Hadron Collider, where strong dipole magnets are used to steer the particles around the machine.

A cross section of the LHC showing the dipole magnets which are used to bend the path followed by protons.

A cross section of the LHC showing the dipole magnets which are used to bend the path followed by protons. The magnets may be seen flanking the left-hand beam pipe. Image credit: James Doherty

What are you waiting for?

Particle physics is not a game that only elite scientists at well-funded institutions can play. With a little effort, determination and ingenuity, it is possible to make your own particle accelerator or detector. So what are you waiting for? Give it a go and let us know how you get on in the chat box below. Good luck!

The GRAPE 2 experiment was carried out by Kaitlin Cook, Paul Bennetto and Tom Lucas under the supervision of Ralph Steinhagen at the 2014 Australian Synchrotron Accelerator School. The above photos and video are courtesy of Ralph Steinhagen.

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This article appeared in Fermilab Today on Aug. 21, 2013.

Craig Hogan

Craig Hogan

Craig Hogan, head of the Center for Particle Astrophysics, wrote this column.

Everyone knows that Fermilab builds accelerators, fabulous machines that boost elementary particles to almost the speed of light. But Fermilab accelerates more than just particles: It propels the advancement of our nation, and our technical civilization, into the future.

Fermilab’s basic mission is to understand the nature of matter, energy, space and time. Since everything is made of matter moving in space-time, startling inventions often spring from innovations in physics. Surprising technologies emerge all the time from newly invented ways of measuring and manipulating matter, forces and data.

The sooner we get the knowledge, the sooner we get the inventions. The faster we learn new physics, the faster humanity advances. That’s acceleration: It moves everything faster.

The most direct acceleration happens when physicists take their techniques out into the world and build all kinds of new things, not just physics experiments. Around the lab, we see this happening all the time in the careers of our close colleagues.

A couple of years ago I stood on a festively flower-festooned Stockholm stage, dressed in an elegant Swedish tuxedo, with an experimental team that celebrated the award of the Nobel prize in physics to two of our team members, Adam Riess and Brian Schmidt. The team had worked together in the 1990s to discover a unique kind of acceleration: the speeding up of the cosmic expansion, sometimes called “dark energy.” Our two youngest team members had been physics graduate students at the time of the discovery; at our Nobel reunion feast 13 years later, they talked with excitement about their jobs at a Seattle biotech company, where they apply techniques they learned in experimental astrophysics to develop machines that study close details of living systems.

Last year, a brilliant postdoc from MIT who had helped us create Fermilab’s Holometer experiment surprised everyone on that team when he chose not to become a physics professor at the University of Chicago but decided instead to join Elon Musk’s SpaceX company and develop new ways of going to space. He’s already developed a ranging system that the Dragon space capsule uses to dock with the International Space Station.

And just this summer, a senior Fermilab physicist, James Volk, left the lab and our Holometer team, not to retire, but to join a private biomedical company. He now develops magnets for accelerator beams—not for physics research, but for new kinds of cancer treatment.

These close-up stories show the substantial contributions that our colleagues make beyond basic physics research. They create things that did not exist before and make them happen better and sooner because of their physics training, experience and creative insight—just one of many ways that Fermilab accelerates our nation.

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This article appeared in Fermilab Today on Aug. 8, 2013.

Bill Dymond (foreground) and Paul Schild, AD, work on one of the new 53-MHz cavities for the Recycler upgrade. Photo: Denton Morris, AD

Bill Dymond (foreground) and Paul Schild, AD, work on one of the new 53-MHz cavities for the Recycler upgrade. Photo: Denton Morris, Fermilab Accelerator Division

A beam of protons whizzed through the Main Injector for the first time in over a year on July 30, representing a major milestone in the year-long process of overhauling the Fermilab accelerator complex. The upgrade will eventually culminate in an accelerator with double the power it had previously.

“The shutdown has been challenging, and we all look forward to returning to beam operations and providing beam to the experiments,” said Dave Capista, an engineering physicist in the Accelerator Division. “It is exciting for us to see the results of our hard work.”

The upgraded accelerator complex will push the laboratory’s Intensity Frontier program forward, ultimately delivering high-intensity beams efficiently to the many current experiments that use it and to the future Muon g-2 and Mu2e experiments.

Upgrading the complex requires an elaborate choreography of four main pieces: the Linac, the Booster, the Recycler and the Main Injector. Prior to the 2012 shutdown, the Main Injector and Recycler operated mostly independently. The primary change in the new system is the ability to move beam manipulation functions out of the Main Injector and into the Recycler, allowing the two to coordinate operations to deliver more beam in less time, resulting in more powerful beams.

Now that the Main Injector has seen beam, the laboratory will begin gradually ramping up accelerator operations.

With the Main Injector now operational, it can send low-intensity beam to the NuMI target and the Switchyard so experiments such as NOvA and SeaQuest can begin to commission their equipment. Within a few weeks, the Accelerator Division hopes to begin running beam through the Recycler so commissioning can begin there as well.

“Once you have all the equipment functioning and doing its job, then it’s a case of sitting down and doing the tuning and understanding how the machine behaves,” said Phil Adamson, a scientist in the Main Injector Department. “It’ll be a fun period. There are a lot of systems, so there are a lot of things to do. It will take time.”

Although the Recycler isn’t operational yet, in the coming months the Accelerator Division will begin running beam through it and hope to have the Recycler and Main Injector working together by the end of the year. Ultimately, the Fermilab accelerator will deliver beams of up to 700 kilowatts, instead of the current maximum of 350.

“It’s simply about trying to deliver as much as we can to all the customers that we have,” said Duane Newhart, deputy department head of the Operations Department. “We have a lot. And we hope to have more.”

As the beam is ramped up to greater intensities, the Accelerator Division will monitor how the machines handle it and make adjustments as it goes along.

“When you get to the highest intensities, that’s where you find all the edges,” Adamson said. “At the lower intensities everything works fairly easily, but when you start pushing intensity as high as you can go, all the interesting features start to show up.”

Fermilab will celebrate the restart of the accelerator complex in the fall.

Laura Dattaro

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This is a follow-up from our last post where Paul Schaffer, Head of the Nuclear Medicine Division at TRIUMF, was talking about his experience of being in the media spotlight. In this post, Paul talks more in-depth about the science of medical isotopes.

It all started 19 months ago. A grant that would forever change my perspective of science geared specifically toward innovating a solution for a critical unmet need—in this situation, it was the global isotope crisis. In 2010, not too long out of the private sector, I was already working on an effort funded by NSERC and CIHR through the BC Cancer Agency to establish the feasibility of producing Tc-99m—the world’s most common medical isotope—on a common medical cyclotron. The idea: produce this isotope where it’s needed, on demand, every day, if and when needed. Sounds good, right? The problem is that the world had come to accept what would have seemed impossible just 50 years ago.

The current Tc-99m production cycle, which uses nuclear reactors. Image courtesy of Nordion.

We are currently using a centralized production model for this isotope with just a six hour half-life. This model involves just a handful of dedicated, government-funded research reactors, producing molybdenum-99 from highly enriched uranium (which is another issue for another time). Moly, as we’ve come to affectionately call it, decays via beta emission to technetium, and when packaged into alumina columns, is sterilized, and encased in a hundred pounds of lead. It is then shipped by the thousands to hospitals around the world. The result: the world has come to accept Tc-99m, which is used in 85% of the 20 to 40 million patient scans every year as an isotope available from a small, 100 pound cylinder that was replaced every week or so, without question, without worry. Moly and her daughter were always there…but in 2007 and again in 2009, suddenly they weren’t. The world had come to realize that something must be done.

In the middle of our NSERC/CIHR effort, we were presented with an opportunity to write a proof-of-concept grant based on the proof-of-feasibility we were actively pursuing. Luckily, the team had come far enough to believe we were on the right track. We believed that large scale curie-level production of Tc-99m using existing cyclotron technology was indeed possible. The ensuing effort was—in contrast to the current way of doing things—ridiculous.

With extensive, continuous input from several top scientists from around the country, I stitched together a document 200 pages long. It was a grant that was supposed to redefine how the most important isotope in nuclear medicine was produced. 200 pages, well 199 to be exact, describing a process—THE process—we were hopefully going to be working on for the next 18 months. We waited…success! And we began.

The effort started the same way as the document – with nothing more than a blank piece of paper. Blank in the sense that we knew what we had to do, we just had not defined exactly how we were going to achieve our goal. But what happened next was a truly remarkable thing; with that blank sheet, I witnessed first-hand a team of people imagine a solution, roll up their sleeves and turn those notions into reality.

If you would like to read the PET report, click here

 

 

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Paul Schaffer is the head of the Nuclear Medicine Division at TRIUMF. For the past 18 months, he and his team have been devising a method for Canada and the world to have an alternative way to produce medical isotopes. Currently, these isotopes are created on aging nuclear reactors, which are beginning to show signs of wear by needing emergency repairs. These repairs stop the flow of isotopes, affecting hundreds of thousands of people around the world. This is an inside perspective of what it means to work on the front line, and be in the media spotlight.

I’m going to start this post with the day I had the privilege of standing in front of a group of reporters along with a few of my esteemed colleagues to announce that we had, in fact, delivered on a promise we had made just over a year ago; the promise of making medical isotopes with existing hospital cyclotrons. We had set out to prove that it was possible to produce Tc-99m on a small medical cyclotron and at quantities sufficient to supply a large urban centre. The solution to Tc-99m shortages is to decentralize production. It was an example of Canadian innovation at its best – by taking a group of existing machines in existing facilities already tasked at making various other medical isotopes and extending the functionality of those facilities to produce another isotope.

Paul presenting his team's findings

The response from the press was remarkable to witness. The interest was swift, broad, and far reaching. The 24-hour news cycle had begun and with it came a deluge of requests for radio, TV, and print interviews. In the ensuing days I read a number of wonderful reports from capable reporters, often writing about a topic well outside of their background or familiarity. For that, I admire the work that they collectively pulled together in the short amount of time involved.

Something else happened, though; something I didn’t anticipate – the ensuing media blitz ended up becoming a very personal social experiment, an intense self-examination. On the way to my first-ever national television interview, I can distinctly remember reality sinking in—for most of my life, I’ve dealt with significant hearing loss. In my ever-quiet world, acutely and perpetually punctuated by tinnitus, verbal communication can be a consuming task.

It is a fact that I comprehend only 33% of the words spoken to me and that my brain fills the gaps using whatever facts it can absorb from my surroundings—expressions, moving lips, and other non-verbal cues. In that car on the way to the interview, I couldn’t help but to continuously wonder about how I would handle verbal questions on camera? What do you say on live TV when you can’t for the life of you figure out what your conversational counterpart is saying? My wingman kept reassuring me, giving background from experience and many, many reassuring comments; but deep down I had to wonder, was this the moment when the whole situation would finally come undone? My charade of being able to hear the world around me would finally end. Worse still, had the moment come to sell the team’s amazing accomplishments on national TV, with a significant number of people literally watching; and all I kept wondering was: will it fall apart simply over an unheard or misinterpreted question? Good thing most communication is non-verbal.

The interview ended up being remote, with the reporters in Ontario and a conspicuous 5 second ‘safety’ delay between what I thought I heard and what showed up on the TV monitor facing me. Five seconds was long enough for them to cut out a fleeting wardrobe malfunction, should I become a bit too passionate during my scientific descriptions, but not nearly long enough to spare a poor soul a repeat question. So, seated in a large, empty, and thankfully quiet studio it began with a single chair, bright lights, and an audio test – ‘please count to 5’ came in over the ear piece…this out of context and no non-verbal queue jolted my fear into reality. I couldn’t understand the question. Out of the corner of my eye, I could see my wingman turn a shade lighter. Worry was setting in. The in-studio producer was almost dumbstruck – this ‘expert’ couldn’t count to five.  45 seconds to ‘go’ and he repeated the question. I got it, counted to five….30 seconds….15, an ambulance was coming, getting louder, I couldn’t hear the commercial any longer…..10, the ambulance was on the street directly below. I had to look away from the TV screen, as the delay was overwhelmingly distracting. 5 seconds. The sirens were starting to recede and before you knew it, I was live.

Paul on CTV News

At first I didn’t want to watch the interview, but family, friends and colleagues from across Canada starting chiming in and eventually convinced me to watch. I felt satisfied with the results, relieved that I had heard every question, answered everything without wandering or forgetting what the question was, covering the topics I wanted to cover. However, I was definitely watching an objective projection of somebody I wasn’t familiar with. I won’t get into the details of what I saw – it’d be different for everyone, but the experience has been life altering, as has this project. That said, I’m proud of the team that has worked so well and so hard together for the past 18 months. It’s been a remarkable project on all fronts. Whether our results continue to keep their momentum and become a permanent solution to the isotope issues that plagued us for two years remains to be seen. I do know success when I see it, and this team of Canadian scientists, engineers, and medical professionals should all be immensely proud of what they have done. They are Canadian innovation at its best.

The team of TRIUMF scientists Paul collaborated with on the groundbreaking project

 

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CDF (red) and DZero (yellow) recorded the Colorado earthquake. Image courtesy of Todd Johnson, AD

On Tuesday, Aug. 23, the Tevatron accelerator knew something none of the people operating it knew. It felt what employees didn’t, and it reported the news faster than the media could upload it to the Internet.

A 5.9-magnitude earthquake had struck the East Coast, and the super-sensitive Tevatron felt it as it happened about 600 miles away. It had also registered a similar quake in Colorado the night before.

The quakes were recorded by sensors on large underground focusing magnets that compress particle beams from the four-mile Tevatron ring into precision collisions at the CDF and DZero detectors. The sensors keep these areas most sensitive to misalignment under constant surveillance. Quakes can jiggle small numbers of particles – less than one percent of the beam – out of alignment and force the shutdown of parts of the three-story detectors to avoid damage. Tevatron operators compare the sensor recordings with updates from the U.S. Geological Survey to rule out natural causes before having to spend time diagnosing machine trouble that caused beam movement.

Typically, two quakes occurring in this short a timeframe would cause headaches for those who run the Tevatron, but fortunately the machine didn’t have beam in the tunnels at the time.

CDF (red) and DZero (yellow) recorded the East Coast earthquake. Image courtesy of Todd Johnson, AD

The Tevatron has recorded more than 20 earthquakes from all over the globe, as well as the deadly tsunamis in Sumatra in 2005 and in Japan in March.

—Tona Kunz

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The CERN Accelerator Complex

Sunday, April 24th, 2011

With all the buzz this past week regarding the breaking of the world instantaneous luminosity record, I thought it might be interesting for our readers to get an idea of how we as physicists achieved this goal.

Namely, how do we accelerate particles?

(This may be a review for some of our veteran readers due to this older post by Regina)

 

The Physics of Acceleration

Firstly, physicists rely on a principle many of us learn in our introductory physics courses, the Lorentz Force Law.  This result, from classical electromagnetism, states that a charged particle in the presence of external electric and/or magnetic fields will experience a force.  The direction and magnitude (how strong) of the force depends on the sign of the particle’s electric charge and its velocity (or direction its moving, and with what speed).

So how does this relate to accelerators?  Accelerators use radio frequency cavities to accelerate particles.  A cavity has several conductors that are hooked up to an alternating current source.  Between conductors there is empty space, but this space is spanned by a uniform electric field.  This field will accelerate a particle in a specific direction (again, depending on the sign of the particle’s electric charge).  The trick is to flip this current source such that as a charged particle goes through a succession of cavities it continues to accelerate, rather than be slowed down at various points.

A cool Java Applet that will help you visualize this acceleration process via radio frequency cavities can be found here, courtesy of CERN.

Now that’s the electric field portion of the Lorentz Force Law, what about the magnetic?  Well, magnetic fields are closed circular loops, as you get farther and farther away from their source the radii of these loops continually increases.  Whereas electric fields are straight lines that extend out to infinity (and never intersect) in all directions from their source.  This makes the physics of magnetic fields very different from that of electric fields.  We can use magnetic fields to bend the track (or path) of charged particles.  A nice demonstration of this can be found here (or any of the other thousands of hits I got for Googling “Cathode Ray Tube + YouTube”).

Imagine, if you will, a beam of light; you can focus the beam (make it smaller) by using a glass lens, you can also change the direction of the beam using a simple mirror.  Now, the LHC ring uses what are called dipole and quadropole magnets to steer and focus the beam.  If you combine the effects of these magnets you can make what is called a magnetic lens, or more broadly termed “Magnetic Optics.”  In fact, the LHC’s magnetic optics currently focus the beam to a diameter of ~90 micro-meters  (the diameter of a human hair is ~100 micro-meters, although it varies from person to person, and where on the body the hair is taken from).  However, the magnetic optics system was designed to focus the beam to a diameter of ~33 micro-meters.

In fact, the LHC uses 1232 dipole magnets, and 506 quadrupole magnets.  These magnets have  a peak magnetic field of 8.3 Tesla, or 100,000 times stronger than Earth’s magnetic field.  An example of the typical magnetic field emitted by the dipole magnets of the LHC ring is shown here [1]:

Image courtesy of CERN

 

The colored portions of the diagram indicate the magnetic flux, or the amount of magnetic field passing through a given area.  Whereas the arrows indicate the direction of the magnetic field.  The two circles (in blue) in the center of the diagram indicate the beam pipes for beams one and two.  Notice how the arrows (direction of the magnetic field) point in opposite directions!  This allows CERN Accelerator physicists to control two counter-rotating beams of protons in the same beam pipe (Excellent Question John Wells)!

Thus, accelerator physicists at CERN use electric fields to accelerate the LHC proton/lead-ion beams and the magnetic fields to steer and squeeze these beams (Also, these “magnetic optics” systems are responsible for “Lumi Leveling” discussed by Anna Phan earlier this week).

However, this isn’t the complete story, things like length contraction, and synchrotron radiation affect the acceleration process, and design of our accelerators.  But these are stories best left for another time.

 

The Accelerator Complex

But where does this process start?  Well, to answer this let’s start off with the schematic of this system:

Image courtesy of CERN

One of our readers (thanks GP!) has given us this helpful link that visualizes the acceleration process at the LHC (however, when this video was made, the LHC was going to be operating at design specifications…but more on that later).

A proton’s journey starts in a tank of research grade hydrogen gas (impurities are measured in parts per million, or parts per billion).  We first take molecular hydrogen (a diatomic molecule for those of you keeping track) and break it down into atomic hydrogen (individual atoms).  Next, we strip hydrogen’s lone electron from the atom (0:00 in the video linked above).  We are now left with a sample of pure protons.  These protons are then passed into the LINear ACcelerator 2 (LINAC2, 0:50 in the video linked above), which is the tiny purple line in the bottom middle of the above figure.

The LINAC 2 then accelerates these protons to an energy of 50 MeV, or to a 31.4% percent of the speed of light [2].  The “M” stands for mega-, or times one million.  The “eV” stands for electron-volts, which is the conventional unit of high energy physics.  But what is an electron-volt, and how does it relate to everyday life?  Well, for that answer, Christine Nattrass has done such a good job comparing the electron-volt to a chocolate bar, that any description I could give pales in comparison to hers.

Moving right along, now thanks to special relativity, we know that as objects approach the speed of light, they “gain mass.”  This is because energy and mass are equivalent currencies in physics.  An object at rest has a specific mass, and a specific energy.  But when the object is in motion, it has a kinetic energy associated with it.  The faster the object is moving, the more kinetic energy, and thus the more mass it has.  At 31.4% the speed of light, a proton’s mass is ~1.05 times its rest mass (or the proton’s mass when it is not moving).

So this is a cruel fact of nature.  As objects increase in speed, it becomes increasingly more difficult to accelerate them further!  This is a direct result of Newton’s Second Law.  If a force is applied to a light object (one with little mass) it will accelerate very rapidly; however, the same force applied to a massive object will cause a very small acceleration.

Now at an energy of 50 MeV, travelling at 31.4% the speed of light, and with a mass of 1.05 times its rest mass, the protons are injected into the Proton Synchrotron (PS) Booster (1:07 in the video).  This is the ellipse, labeled BOOSTER, in the diagram above.  The PS Booster then accelerates the protons to an energy of 1.4 GeV (where  the “G” stands for giga- or a billion times!), and a velocity that is 91.6% the speed of light [2].  The proton’s mass is now ~2.49 times its rest mass.

The PS Booster then feeds into the Proton Synchrotron (labeled as PS above, see 2:03 in video), which was CERN’s first synchrotron (and was brought online in November of 1959).  The PS then further accelerates the protons to an energy of 25 GeV, and a velocity that is 99.93% the speed of light [2].  The proton’s mass is now ~26.73 times its rest mass!  Wait, WHAT!?

At 31.4% the speed of light, the proton’s mass has barely changed from its rest mass.  Then at 91.6% the speed of light (roughly three times the previous speed), the proton’s mass was only two and a half times its rest mass.  Now, we increased speed by barely 8%, and the proton’s mass was increase by a factor of 10!?

This comes back to the statement earlier, objects become increasingly more difficult to accelerate the faster they are moving.  But this is clearly a non-linear affect.  To get an idea of what this looks like mathematically, take a look at this link here [3].  In this plot, the Y-axis is in multiples of rest mass (or Energy), and the x-axis is velocity, in multiples of the speed of light, c.  The red line is this relativistic effect that we are seeing, as we go from ~91% to 99% the speed of light, the mass increases gigantically!

But back to the proton’s journey, the PS injects the protons into the Super Proton Synchrotron (names in high energy physics are either very generic, and bland, or very outlandish, e.g. matter can be charming).  The Super Proton Synchrotron (SPS, also labeled as such in above diagram, 3:10 in video above) came online in 1976, and it was in 1983 that the W and Z bosons (mediators of the weak nuclear force) were discovered when the SPS was colliding protons with anti-protons.  In today’s world however, the SPS accelerates protons to an energy of 450 GeV, with a velocity of 99.9998% the speed of light [2].  The mass of the proton is now ~500 times its rest mass.

The SPS then injects the proton beams directly into the Large Hadron Collider.  This occurs at 3:35 in video linked above, however, when this video was recorded the LHC was operating at design energy, with each proton having an energy of 7 TeV (“T” for tera-, a million million times).  However, presently the LHC accelerates the proton to half of the design energy, and a velocity of 99.9999964% the speed of light.  The protons are then made to collide in the heart of the detectors.  At this point the protons have a mass that is ~3730 times their rest mass!

 

 

So, the breaking of the world instantaneous luminosity record was not the result of one single instrument, but the combined might of CERN’s full accelerator complex, and in no small part by the magnetic optics systems in these accelerators (I realize I haven’t gone into much detail regarding this, my goal was simply to introduce you to the acceleration process that our beams undergo before collisions).

 

Until next time,

-Brian

 

 

 

References:

[1] CERN, “LHC Design Report,” https://ab-div.web.cern.ch/ab-div/Publications/LHC-DesignReport.html

[2] CERN, “CERN faq: The LHC Guide,” http://cdsweb.cern.ch/record/1165534/files/CERN-Brochure-2009-003-Eng.pdf

[3]  School of Physics, University of Southern Wales, Sydney Australia, http://www.phys.unsw.edu.au/einsteinlight/jw/module5_equations.htm

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