Investigating the cosmos at CSU

An example of simulated data modelled for the ...
An example of simulated data modelled for the CMS particle detector on the Large Hadron Collider (LHC) at CERN. Here, following a collision of two protons, a is produced which decays into two jets of hadrons and two electrons. The lines represent the possible paths of particles produced by the proton-proton collision in the detector while the energy these particles deposit is shown in blue. (Photo credit: Wikipedia)

In the first nanoseconds of existence, the universe exploded to the size of a grapefruit and after the initial blast, the rate of expansion slowed, reported the Harvard-Smithsonian Center for Astrophysics in March 2014.

Two months ago, or 13.8 billion years after the big bang, a detector in Antarctica called BICEP2 picked up gravitational waves from cosmic inflation in the first trillionth of a second after the birth of the universe. Cosmic inflation allowed young particles to interact with one another in the earliest moments after the big bang.

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At this point, energy was condensing into particles, but did not yet have any mass. The Higgs field, first hypothesized in 1964, was said to give mass to some of these early particles.

The detection of cosmic inflation and the Higgs field have been priorities in physics since the mid-nineties, and their discoveries have just been confirmed in the last two years.

In order to prove these theories, huge financial investments were made and teams of physicists assembled. But there are still questions about the nature of mass which these projects could not answer, and Colorado State’s physics department is well-positioned to fill in the gaps.

Robert Wilson studies neutrinos at CSU. Neutrinos are a type of subatomic particle abundant in our universe. Wilson believes that by recreating conditions of the big bang — with much less mass, but with similar energy density — neutrino study is capable of providing answers to questions, such as why matter exists in the universe.

“We will try to understand all of the forces which we think were at play in the early universe, which means trying to recreate the energy and density conditions,” Wilson said.

Wilson is co-science director of an international collaboration of scientists that includes over 500 physicists and engineers. The collaboration, known as the Long-Baseline Neutrino Experiment, will attempt to answer this question and many others over the next 30 years. Phase one of the project is projected to cost $900 million alone, and is funded by the US Department of Energy.

The LBNE team will fire neutrinos from Fermilab near Chicago to a giant underground detector in South Dakota. They are looking for something called charge parity violation, which would explain why matter exists in our universe.

“If you have CP violation it will explain why you have matter-antimatter asymmetry in the universe,” Wilson said.

Wilson explained that neutrinos, along with all other particles, are created in pairs — the particle and the antiparticle, matter and antimatter. These types of particles are created and destroyed all the time; when a particle and its anti-particle collide, they annihilate.

But, there is a problem with this theory.

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“If the early universe was all this energy, and it produced matter and antimatter, where’s all the antimatter?” Wilson asked.

Dan Cherdack is a postdoctoral fellow working at CSU with Wilson, and is co-leader of the LBNE physics group. Cherdack describes a process that favors matter over antimatter when the two are created. When they recombine and annihilate, there is residual matter left over. That process is called CP violation.

Wilson has seen CP violation before while studying quarks, a kind of particle that makes up atomic nuclei, but the process they see in quarks falls short of explaining what is observed in the universe.

“The problem is if we look at how much asymmetry there is, there isn’t nearly enough to create as much matter as we see,” Cherdack said.

The new hope is neutrinos.

Neutrinos are one of the most abundant known subatomic particles in the universe — neutrinos make up as much mass in the universe as all the stars and galaxies, according to Wilson. But neutrinos are notoriously hard to study because they do not interact with other particles the way normal matter does, according to WIlson. Neutrinos pass through planets and stars without contact. In order to study neutrinos, a sophisticated detector is required.

Norm Buchanan is an associate professor at CSU who studies neutrinos as they are produced from supernovae, the energy released from dying stars. Buchanan is a major part of the detection team at LBNE.

As neutrinos travel through the earth, they spin and oscillate and eventually reach the detector in South Dakota. The detector is composed of 34 kilotons of liquid argon in an abandoned mine buried a mile beneath the earth.

Buchanan explained that even though neutrinos rarely interact with anything, they do react with quarks. The results of that interaction are much easier to detect.

“Because neutrinos don’t interact directly, we set up a situation where a neutrino comes in and interacts with a quark inside of one nuclei (in the detector). The interaction causes a particle that can be detected,” Buchanan said.

The size of the neutrino beam, 800 miles long, is contingent on the time it takes for neutrinos to reach the appropriate state after their creation, according to Buchanan. This takes some major high-tech machinery that has never before been created.

“We’re doing technologically something that has never been done before, which is super exciting.”

If LBNE succeeds, it will be on the heels of some major work being done in high-energy physics this century. In 2012, researchers at the European Organization for Nuclear Research, known as CERN, discovered the Higgs boson. The Higgs is thought to explain why particles have mass. In March 2014, in a study that has yet to be peer-reviewed, researchers discovered evidence for cosmic inflation, detailing energy formation in the initial moments of creation.

As a graduate student at Stanford in 1980, Wilson thought he had discovered the Higgs particle, but did his calculations wrong. He was looking forward to another chance in the early 90s during construction of the Superconducting Super Collider in Texas, but Congress cut funding in 1993. Construction of the Large Hadron Collider at CERN began in 1994. Wilson does not want to miss out of the next big discovery in physics, and he says neither does the US government.

“The US has decided that this science is high-priority, and that is the focus of the main high energy lab in the US. It’s whole strategy for the future is built around LBNE,” Wilson said.

The LBNE project involves institutions in India, Italy, Japan, Brazil, the UK and the US. Wilson said these international collaborations are becoming common because the projects are so expensive, but points out that for this particular one, CSU is at the crux.

“Most people don’t realize that the things we’re involved in are at the center of high-energy physics in the US,” Wilson said.

Collegian Science Beat Reporter Remi Boudreau can be reached at news@collegian.com.