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What you need to know about particle physics

Wed, 08/06/2014 - 8:02am
Mike Collins

Just before World War II, Earnest Lawrence, a physicist at Cal-Tech, found out that German physicists had split an atom of uranium using a neutron to form two smaller nuclei and release the nuclear strong force. Lawrence then built a more advanced version of an accelerator called a cyclotron to split a uranium atom into 2 new elements with atomic numbers 93 & 94. He called them neptunium and plutonium.

Lawrence then decided to help build the atomic bomb by constructing a larger accelerator called a calutron. The government funded the construction of 15 calutrons in Oak Ridge to produce fissionable uranium 235 from U238. His other discovered element, plutonium, was used for a second type of bomb at Hanford, Washington.

After the war, scientists used larger accelerators with more power to smash the nucleus and look for new particles. This led to the discovery of a cornucopia of new particles such as muons, leptons, gluons, deltas, lambda, and quarks. The discovery of all of these particles eventually led to a quantum field theory called the Standard Model. Most physicists all agree with the Standard Model but many think it is an incomplete description of nature.

The largest and most powerful of all accelerators is the Large Hadron Collider (LHC) constructed by CERN or the European Organization for Nuclear Research. The LHCHC is a circular tunnel on the Franco/Swiss border 27 kilometers (17 miles) in circumference. It was started up in 2008 but will not reach maximum power until late 2014. It cost approximately $9 billion.

The LHC is designed to accelerate particles up to .999 the speed of light at a maximum power of seven TEV, which is seven teraelectronvolts (or 14 trillion electronvolts). The particles accelerate on two different beams going in opposite directions. When the particles reach their energy levels, the beams are switched to cause a “head-on” particle collision.

The parallel pipes that carry these beams are housed in a 27 KM concrete tunnel that is 12 feet in diameter. To keep the opposing beams on their circular path requires 1,232 magnets and 392 quadrapole magnets to keep it focused. It takes 96 tons of liquid helium to keep the magnets at their operating temperature of -271.25o C.  

So What! Do I really need to know this?

When you look at the big questions that science hopes to answer with the LHC, it must be baffling to the average citizen. But, I think it may be easier to understand particle physics as a three stage process that takes years or even decades. In the first stage the research begins with the theoretical physicists trying to answer fundamental questions in science such as how many sub-particles make up a neutron. In the second stage their experiments then lead to many new technologies. In the final stage (which may take decades) these technologies define practical new products.

Stage One: The Big Physics Questions

Unified Field Theory – The four fundamental forces in nature are the strong nuclear force, the weak force, electromagnetism and gravity. After his theory of relativity, Einstein spent the remainder of his life trying to develop a theory that would unify all four forces. If such a theory can be developed, it is thought that it would be the “holy grail of physics” - A Theory of Everything. Physicists have managed to unify the strong and weak forces with electromagnetism, but they cannot find a way to incorporate gravity.

What is dark matter and dark energy? When the Hubble telescope began to operate, scientists found evidence that the universe was not only expanding – it was accelerating. They also decided that for this to happen, there had to be more to the universe than visible matter. When they worked out the mathematics, they found that the visible matter is only 5% of the universe – 70% of the universe is dark energy and 25% is dark matter. Since both dark energy and matter are invisible, but science thinks that dark matter is a particle they call weak interacting massive particle or WIMP. Recently they did an experiment by installing very sensitive equipment in an old coal mine and actually found two wimps on their germanium disk and proved that they do exist. But nobody has any idea what dark energy might be. What they need is data and that data might be discovered in the LHC.

Do energy strings exist? String theory is a mathematical theory based on a model of one-dimensional energy strings (think tiny rubber bands billions of times smaller than an atom). In other words, the fundamental building blocks that are the basic units of particles are tiny energy strings as small as 10-35.   Physicists say that string theory will explain questions that cannot be explained in the Standard Model. The hope is that proving string theory will reconcile the differences between quantum physics and relativity and eventually lead to the “Theory of Everything” or a unified field theory.

Are there other dimensions? String theory predicts that there are more than four dimensions. In fact, one version of string theory predicts 10 to 11 dimensions. These extra dimensions may become detectable at very high energies such as those created in the LHC.

Does the Higgs Boson exist? The Higgs Boson is a particle that is supposed to give other particles mass. It was theorized by Peter Higgs in the 1960s. He hypothesized that the universe has a Higgs Field (some kind of electromagnetic field) that affects other particles that move through it. Scientists know that when an electron passes through a crystal lattice of atoms, that it’s mass can increase as much as 40 times. They theorize that the same thing might happen in a Higgs Field.

The Standard Model of Physics does not explain how particles get mass. To complete the Standard Model and explain how particles get mass requires the discovery of a missing particle – The Higgs Boson. On July 2012 CERN announced the detection of the Higgs boson. Until the LHC was built, no other accelerator had enough power to smash particles down to the Higgs level. Finding the Higgs Boson will explain how particles originally gained their mass during the Big Bang and explain why different particles have different mass and reveal a new physical symmetry called super symmetry.

Nanotechnology – This is the science of manipulating materials at the subatomic level to create new materials with new advantages like strength, corrosion resistance, conductivity, etc. Using the LHC to find even smaller particles than are now known could produce a whole new level of nanotechnology.

New Forces and Energy – Science has known about the four basic forces for hundreds of years. But perhaps we will discover a new force with almost invisible characteristics such as dark energy. Finding a new force or finding out more about the four forces could lead to new sources of energy. Or perhaps LHC research might prove to offer insight into fusion that would alter the construction of a commercial fusion reactor.

Stage 2: Technology & Applications

Medicine – Particle accelerators and detectors first developed for particle physics are now used by every major medical center in the nation to treat and diagnose millions of patients.

Smaller linear accelerators are now being used to attack cancer tumors. It is possible to send a beam of protons into a body without damage. However, by tuning the accelerator they can make the protons all stop inside of a tumor. All of the damage is done at the point where the protons stop, thus killing cancer cells

Intense light for research – Particle physicists have developed cutting-edge tools; such as circular particle accelerators to bend the paths of speeding electrons, causing the electrons to emit light. This synchrotron light is a powerful research tool with many applications.

Dedicated synchrotron accelerators allow scientists to control the intensity and wavelength of light for research that’s led to better batteries, greener energy, new high-performance materials, more effective drug treatments and a deeper understanding of nature.

Homeland security – The same advanced detector technology (using high energy x-rays) that physicists use to analyze particles has also been used for practical scanning applications and security.

More than two billion tons of cargo passes through ports and waterways annually in the United States. Many ports are now turning to high-energy x-rays generated by particle accelerators to identify contraband and keep ports safe. These x-rays penetrate deeper and give screeners more detail about the nature of the cargo.

MRI – Key aspects of Magnetic Resonance Imaging (MRI) emerged from particle physics research. MRIs are now common in most hospitals to make detailed images of soft tissue in the body. Unlike x-rays, MRIs can distinguish gray matter from white matter in the brain, cancerous tissue from noncancerous tissue, and muscles from organs, as well as reveal blood flow and signs of stroke.

Grid computing – To deal with the computing demands of the LHC experiments, particle physicists have created the world's largest grid computing system, spanning more than 100 institutions in 36 countries and pushing the boundaries of global networking and distributed computing.

Particle physicists developed the cutting-edge computing technology in this giant computer grid to record and analyze the unprecedented volumes of data generated in particle collisions, making key contributions to solutions at the frontiers of computer science.

Stage 3: New Products

Advances in particle physics, especially understanding of electromagnetism, eventually led directly to new products such as television, computers, domestic appliances, radio, x-rays, CT scans, MRI, cell phones, GPS systems, and the internet. All of these technologies began as basic physics research. Particle physics has also led to:

  • Sturdy, heat-shrinkable film that wrap Butterball turkeys, as well as fruits and vegetables, baked goods, board games and DVDs.
  • The superabsorbent polymer material used in all modern-day diapers.
  • Using beams of electrons from particle accelerators to make scratch- and stain-resistant furniture.
  • The design of a new material bombarded with silver ions from a particle accelerator to make artificial heart valves (the treated surface of the material keeps the body from identifying the valve as an invader.)

I think the LHC will allow science to enter a new era of physics and discovery. In the next decade many of the big physics (Stage 1) questions might be answered and will lead to another list of new technologies. How many of these new technologies will lead to new products is as hard to predict today as it was in the 1930s when the first accelerators were built.

In this time of deficit paranoia many government programs that can’t guarantee immediate results will be cut. So it really takes an understanding of how Stage 1 experiments in the Large Hadron Collider can lead to Stage 3 technologies and products that will eventually be invented. These might be technologies that your son or grandson will use in their manufacturing process and products – so stay tuned.

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