New inelastic dispersion experiments measure two glass nuclei

MARATHON measures glass nuclei

Two state -of -the -art optical systems, the High Resolution Spectrometers in Jefferson Lab’s Experimental Hall A, assisted in collecting data in the MARATHON experiment. Available: Jefferson Lab of DOE

Scientists are holding a “light” to protons and neutrons to learn more about the parts that make up our universe. The MARATHON experiment, conducted at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility, gained new details about these building blocks by comparing a glass nuclei called, helium-3. a me triton. The results are published in Physical inspection messages.

The basic elements that make up most of what we see in the universe – quarks and gluons – are buried deep in protons and neutrons, the nucleons that make up the universe. atomic nuclei. The survival of quarks and gluons was first confirmed half a century ago in Nobel Prize -winning experiments held at DOE’s Stanford Linear Accelerator Center (known as the SLAC National Accelerator Laboratory).

These early experiments introduced the era of deep inelastic dispersion. This type of experiment uses high -energy electrons to travel deep into protons and neutrons to look for quarks and gluons there.

“We’re talking about deep inelastic scattering, which we think is the nuclei attached to the electrons in the beam that will quickly break there showing the nucleons in them when to capture the scattered electrons with state -of -the -art information systems, ”says Gerassimos. (Makis) Petratos, a professor at Kent State University and a speaker and co -founder for the MARATHON exam.

Large -particle sensing systems that collect the electrons that emerge from these compounds measure their time – an area that includes the size and speed of the electrons.

Since those first experiments five years ago, deep inelastic dispersion experiments have been performed around the world in a variety of laboratories. These experiments have strengthened the understanding by nuclear physicists of the role of quarks and gluons in the structures of protons and neutrons. Today, experiments continue to refine this process to mock more detailed information.

In the recently concluded MARATHON experiment, nuclear physicists compared the results of deep inelastic dispersion experiments for the first time into two glass nuclei to learn about their properties. Physicists chose to look at the nuclei of helium-3 and tritium, an isotope of hydrogen. While helium-3 has two protons and one neutron, tritium has two neutrons and one proton. If you could “mirror” -convert helium -3 by converting all protons into neutrons and neutrons into protons, the result would be tritium. That is why they are called glass nuclei.

“We used the simplest glass nuclei system, tritium and helium-3, which is why this system is so exciting,” said David Meekins, an associate scientist at Jefferson Lab. Language of the MARATHON test.

“It turns out that if we measure the ratio of the cross -sections in these two nuclei, we can get into the construction of protons relative to neutrons. These two magnitudes may be related to each other. the distribution of ascending and descending quarks in the nuclei, ”Petratos said.

Originally launched as a summer project in 1999, the MARATHON test was conducted in 2018 at Jefferson Lab’s Continuous Electron Beam Accelerator Facility, a DOE -operated facility. More than 130 members of the MARATHON testing team overcame many challenges in implementing the experiment.

For example, MARATHON requires the highest energy electrons that can be produced by the 12 GeV CEBAF Upgrade Project completed in 2017, as well as a special target system for tritium.

“For this one experiment, the goal is obviously very difficult. Tritium is a radioactive gas, we need to ensure safety on all surfaces,” Meekins explains. “That’s where the mission of the lab is: There’s nothing so important that we can weigh on safety.”

The experiment sent 10.59 GeV (billion electron-volt) electrons to four different targets in Experimental Hall A. The targets contained helium-3 and three isotopes of hydrogen, including tritium. The external electrons were collected and measured with the left and right High Resolution Spectrometers.

At the end of the data collection, the association undertook a thorough analysis of the data. The final release contains the source data to allow other organizations to use the sample data in their own evaluations. It also provides a review led by Petratos based on a model with minor edits.

“What we wanted to explain was the measurement that we did, that’s the way we did it, it was the scientific translation from the measurement and that’s how we did it,” he explained. Meekins. “We don’t have to worry about wanting one model over another – someone can take the data and use it.”

In addition to providing an accurate determination of the proton / neutron structure function ratios, the data also included higher electron time measurements of these glass nuclei than previously obtained. This advanced data set also opens the door to more detailed analyzes to answer other questions in nuclear physics, such as the reason for the different distribution of quarks in the nucleus when compared. with free protons and neutrons (a phenomenon called the EMC Effect) and other functions of the structures of parts in the nuclei.

Discussing the results, the MARATHON spokesperson immediately praised the hard work of the team members for the final results.

“The success of this experiment is due to the important group of people who participated in the experiment and the support we received from Jefferson Lab,” said Mina Katramatou, a physician at Kent State University and a spokesperson for the MARATHON test. “We have a very good team of young physicists working on this experiment, including former postdoctoral researchers and graduate students.”

“Five graduate students received their research theses from this data,” Meekins confirmed. “And it’s good data, we do it well, and it’s hard to do.”

The Marathon test shows the characteristics of quarks

More information:
D. Abrams et al, Measurement of the Nucleon F2n / F2p Structure Function Ratio by the Jefferson Lab MARATHON Tritium / Helium-3 Deep Inelastic Scattering Experiment, Physical inspection messages (2022). DOI: 10.1103 / PhysRevLett.128.132003

Presented by Thomas Jefferson National Accelerator Facility

Directions: New inelastic scattering experiments measuring two glass nuclei (2022, March 31) retrieved 31 March 2022 from html

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