If you go to a hospital and undergo any diagnostic procedure involving technology, chances are that most of them started out as a physics experiment.
Although quarks and neutrinos are subatomic particles that you’ll never see – unless you’re a physicist – diagnostic technology such as the MRI (magnetic resonance imaging) device is derived from equipment that was originally created to study these fundamental particles of matter.
The U.S. Department of Energy has renewed the New Mexico State University physics department’s $1.26 million grant to continue research on these subatomic particles – quarks and neutrinos.
The three-year DOE grant will fund NMSU physics faculty, students and post-doctoral researchers for three projects: SeaQuest, MicroBooNE and PHENIX.
NMSU’s newest experiment at the U.S. Department of Energy’s Fermi National Accelerator Laboratory near Chicago is called SeaQuest. The goal of this experiment is to explore the contribution of anti-up and anti-down quarks to the spin of the proton. These quarks are collectively called "sea quarks," temporary particles that wink in and out of existence.
“We call them sea quarks because there’s an ocean of them inside a proton and we distinguish them from the three quarks that are there all the time,” said Stephen Pate, physics professor who, along with physics associate professor Vassiliou Papavassiliou, leads the NMSU High-Energy Nuclear Physics team in the College of Arts and Sciences. “Sea quarks flitter in and out of existence, but on average there’s always a few of them there and they do contribute to the structure of the proton. We don’t know much about them, so on both the MicroBooNE and SeaQuest experiments, we’ll focus on exploring the activities of these sea quarks.”
NMSU’s physics department has been conducting experiments at Fermilab since 1985. The MicroBooNE, short for “Micro Booster Neutrino Experiment,” is the latest in a series of “BooNE” experiments. This one uses a large tank the size of a school bus filled with liquid argon to detect neutrinos.
The MicroBooNE scientific collaboration consists of nearly 200 physicists from 31 institutions in the U.S., U.K., Switzerland, Turkey and Israel. The MicroBooNE physicists presented their first collection of science results earlier this month at the international Neutrino 2018 conference in Heidelberg, Germany. The measurements are of various quantities that describe neutrino interactions with argon atoms, which make up the 170 tons of total target material used for neutrino collisions inside the MicroBooNE detector.
Neutrinos are so small that a hundred billion of these ghostly subatomic particles pass unnoticed through the tip of your finger every second.
“There’s a dual purpose in the MicroBooNE experiment,” said Papavasilliou. “One of them is to study the properties of the neutrinos themselves. The second goal is to study the nucleus of an atom. Our interest is to use the neutrino as a probe of the interior of the proton. Our group is mostly concerned with the second goal. We hope that within a year we can produce results and start publishing.”
In the MicroBooNE experiment, Ph.D. student Samantha Sword-Fehlberg is using one of the most sophisticated processing programs ever designed for a neutrino experiment. She is teaching the computer to sift through the thousands of interactions that occur every day and create 3-D images of the most interesting ones.
“The protons and neutrons inside the argon nucleus do a dance. So we can use neutrinos to probe this dance and to understand the properties within the nucleus itself,” said Sword-Fehlberg. “Since we’re running all the time, we produce a ton of data so somebody has to look at that data to find all the interesting things that are happening.
“In the volume of a school bus, the events are about the size of your pinky. Instead of caffeinating a bunch of grad students and hoping they catch everything, I work on convolutional neural networks. My research is focused on this really advanced detection algorithm. What we do is take a set of pictures and we teach these networks what is in the images and we train them like a human being.”
This research is progressing well, she said. The team has a neural network that is up to 79 percent accurate. Within the next year or so, Sword-Fehlberg expects that accuracy to go up and they’ll be able to train the networks on actual data. With that, she hopes to earn her Ph.D. within about two years.
While the MicroBooNE experiment is well underway and the SeaQuest experiment is just beginning, the third project at the Brookhaven National Laboratory in New York has wrapped up. PHENIX (Pioneering High-Energy Nuclear-Interaction eXperiment), involving 400-plus scientists from more than a dozen countries is completed and researchers currently are writing up their findings. Graduate students Jeongsu Bok and Chen Xu are working together with post-doctoral researcher Haiwang Yu to publish their work on unusual interactions seen when polarized protons collide with gold nuclei at very high energies.
NMSU’s DOE funding supports two physics faculty members, Pate and Papavassiliou, along with two post-doctoral researchers, Lu Ren at Fermilab and Haiwang Yu at Brookhaven. The grant also funds research activity for three to five graduate students: currently, Katherine Woodruff, Samantha Sword-Fehlberg, Jeongsu Bok, Chen Xu, and Forhad Hossain.
“The contribution of the sea quarks is relatively unknown,” said Hossain, a Ph.D. student who will work on the SeaQuest project. “The experiment will have a proton beam and a proton target, but the protons in the target will be polarized so each proton acts like a tiny magnet. The purpose of the experiment is to explore how those quarks and anti-quarks are created and destroyed spontaneously, and how they contribute to the actual structure of the proton.”
In addition to expected and unexpected results physicists discover while researching the tiniest building blocks of the universe, Pate says an important outcome of the research they conduct is the number of well-equipped physicists who contribute to the U.S. economy in industries as varied as technology, health and finance.
“It’s been about 25 years I’ve been exploring the proton,” Pate said. “Like medical diagnostic tools, a lot of the applications are not things we thought of ahead of time. What we do is explore the fundamental nature of the universe and its parts and share that knowledge. We also train really smart people and that has an impact on the rest of the economy. There are lots of people out there who got their degrees in nuclear physics or particle physics who go out into the economy and bring their problem-solving skills to integrate information and find solutions in all kinds of jobs.”
Information from NMSU