• MARATHON measures mirror nuclei

    From ScienceDaily@1:317/3 to All on Thursday, March 31, 2022 22:30:46
    MARATHON measures mirror nuclei
    Experiment exploring mirror nuclei opens the door to new details about
    the internal structures of protons and neutrons

    Date:
    March 31, 2022
    Source:
    DOE/Thomas Jefferson National Accelerator Facility
    Summary:
    Scientists are holding up a 'mirror' to protons and neutrons to
    learn more about the particles that build our visible universe. The
    MARATHON experiment has accessed new details about these particles'
    structures by comparing the so-called mirror nuclei, helium-3
    and triton.



    FULL STORY ========================================================================== Scientists are holding up a 'mirror' to protons and neutrons to learn
    more about the particles that build our visible universe. The MARATHON experiment, carried out at the U.S. Department of Energy's Thomas
    Jefferson National Accelerator Facility, has accessed new details about
    these particles' structures by comparing the so-called mirror nuclei,
    helium-3 and triton. The results were recently published in Physical
    Review Letters.


    ==========================================================================
    The fundamental particles that form most of the matter we see in the
    universe - - quarks and gluons -- are buried deep inside the protons
    and neutrons, the nucleons that make up atomic nuclei. The existence
    of quarks and gluons was first confirmed a half-century ago in Nobel Prize-winning experiments conducted at DOE's Stanford Linear Accelerator
    Center (now known as SLAC National Accelerator Laboratory).

    These first-of-their-kind experiments introduced the era of deep inelastic scattering. This experimental method uses high-energy electrons that
    travel deep inside protons and neutrons to probe the quarks and gluons
    there.

    "When we say deep inelastic scattering, what we mean is that nuclei
    bombarded with electrons in the beam break up instantly thereby revealing
    the nucleons inside them when the scattered electrons are captured with state-of-the art particle detection systems," said Gerassimos (Makis)
    Petratos, a professor at Kent State University and the spokesperson and
    contact person for the MARATHON experiment.

    The huge particle detector systems that collect the electrons that emerge
    from these collisions measure their momenta -- a quantity that includes
    the electrons' mass and velocity.

    Since those first experiments five decades ago, deep inelastic
    scattering experiments have been performed around the world at various laboratories. These experiments have fueled nuclear physicists'
    understanding of the role of quarks and gluons in the structures of
    protons and neutrons. Today, experiments continue to fine-tune this
    process to tease out ever more detailed information.



    ==========================================================================
    In the recently completed MARATHON experiment, nuclear physicists compared
    the results of deep inelastic scattering experiments for the first time in
    two mirror nuclei to learn about their structures. The physicists chose
    to focus on the nuclei of helium-3 and tritium, which is an isotope of hydrogen. While helium-3 has two protons and one neutron, tritium has
    two neutrons and one proton. If you could 'mirror' transform helium-3
    by converting all protons into neutrons and neutrons into protons,
    the result would be tritium. This is why they are known as mirror nuclei.

    "We used the simplest mirror nuclei system that exists, tritium and
    helium-3, and that's why this system is so interesting," said David
    Meekins, a Jefferson Lab staff scientist and a co-spokesperson of the
    MARATHON experiment.

    "It turns out that if we measure the ratio of cross sections in these
    two nuclei, we can access the structure functions of protons relative
    to neutrons.

    These two quantities may be related to the distribution of up and down
    quarks inside the nuclei," Petratos said.

    First conceived in a summer workshop in 1999, the MARATHON experiment was finally carried out in 2018 in Jefferson Lab's Continuous Electron Beam Accelerator Facility, a DOE user facility. The more than 130 members of
    the MARATHON experimental collaboration overcame many hurdles to carry
    out the experiment.

    For instance, MARATHON required the high-energy electrons that were made possible by the 12 GeV CEBAF Upgrade Project that was completed in 2017,
    as well as a specialized target system for tritium.



    ==========================================================================
    "For this individual experiment, clearly the biggest challenge was
    the target.

    Tritium being a radioactive gas, we needed to ensure safety above
    everything," Meekins explained. "That's part of the mission of the
    lab: There's nothing so important that we can sacrifice safety."
    The experiment sent 10.59 GeV (billion electron-volt) electrons into
    four different targets in Experimental Hall A. The targets included
    helium-3 and three isotopes of hydrogen, including tritium. The outgoing electrons were collected and measured with the hall's left and right
    High Resolution Spectrometers.

    Once data taking was complete, the collaboration worked to carefully
    analyze the data. The final publication included the original data to
    allow other groups to use the model-free data in their own analyses. It
    also offered an analysis led by Petratos that is based on a theoretical
    model with minimal corrections.

    "The thing that we wanted to make clear is that this is the measurement
    we made, this is how we did it, this is the scientific extraction from
    the measurement and this is how we did that," Meekins explains. "We don't
    have to worry about favoring any model over another -- anyone can take
    the data and apply it." In addition to providing a precise determination
    of the ratio of the proton/ neutron structure function ratios, the data
    also include higher electron momenta measurements of these mirror nuclei
    than were available before. This high-quality data set also opens a door
    to additional detailed analyses for answering other questions in nuclear physics, such as why quarks are distributed differently inside nuclei
    as compared to free protons and neutrons (a phenomenon called the EMC
    Effect) and other studies of the structures of particles in nuclei.

    In discussing the results, the MARATHON spokespeople were quick to credit
    the hard work of collaboration members for the final results.

    "The success of this experiment is due to the outstanding group of
    people who participated in the experiment and also the support we had
    from Jefferson Lab," said Mina Katramatou, a professor at Kent State
    University and a co- spokesperson of the MARATHON experiment. "We also
    had a fantastic group of young physicists working on this experiment,
    including early career postdoctoral researchers and graduate students."
    "There were five graduate students who got their theses research from
    this data," Meekins confirmed. "And it's good data, we did a good job,
    and it was hard to do."

    ========================================================================== Story Source: Materials provided by DOE/Thomas_Jefferson_National_Accelerator_Facility. Note: Content may
    be edited for style and length.


    ========================================================================== Journal Reference:
    1. D. Abrams, H. Albataineh, B. S. Aljawrneh, S. Alsalmi,
    D. Androic,
    K. Aniol, W. Armstrong, J. Arrington, H. Atac, T. Averett,
    C. Ayerbe Gayoso, X. Bai, J. Bane, S. Barcus, A. Beck, V. Bellini,
    H. Bhatt, D.

    Bhetuwal, D. Biswas, D. Blyth, W. Boeglin, D. Bulumulla,
    J. Butler, A.

    Camsonne, M. Carmignotto, J. Castellanos, J.-P. Chen,
    E. O. Cohen, S. Covrig, K. Craycraft, R. Cruz-Torres,
    B. Dongwi, B. Duran, D. Dutta, E. Fuchey, C. Gal,
    T. N. Gautam, S. Gilad, K. Gnanvo, T. Gogami, J. Gomez,
    C. Gu, A. Habarakada, T. Hague, J.-O. Hansen, M. Hattawy, F.

    Hauenstein, D. W. Higinbotham, R. J. Holt,
    E. W.

    Hughes, C. Hyde, H. Ibrahim, S. Jian, S. Joosten, A. Karki,
    B. Karki, A. T. Katramatou, C. Keith, C. Keppel,
    M. Khachatryan, V.

    Khachatryan, A. Khanal, A. Kievsky, D. King, P. M. King, I.

    Korover, S. A. Kulagin, K. S. Kumar, T. Kutz,
    N. Lashley- Colthirst, S. Li, W. Li, H. Liu, S. Liuti, N. Liyanage,
    P. Markowitz, R. E. McClellan, D. Meekins, S. Mey-Tal Beck,
    Z.-E. Meziani, R.

    Michaels, M. Mihovilovic, V. Nelyubin, D. Nguyen, Nuruzzaman,
    M. Nycz, R.

    Obrecht, M. Olson, V. F. Owen, E. Pace, B. Pandey,
    V. Pandey, M.

    Paolone, A. Papadopoulou, S. Park, S. Paul, G. G. Petratos,
    R.

    Petti, E. Piasetzky, R. Pomatsalyuk, S. Premathilake,
    A. J. R. Puckett, V. Punjabi, R. D. Ransome,
    M. N. H. Rashad, P. E. Reimer, S. Riordan,
    J. Roche, G. Salme`, N. Santiesteban, B. Sawatzky, S. Scopetta,
    A. Schmidt, B.

    Schmookler, J. Segal, E. P. Segarra, A. Shahinyan,
    S. Sirca, N.

    Sparveris, T. Su, R. Suleiman, H. Szumila-Vance,
    A. S. Tadepalli, L. Tang, W. Tireman, F. Tortorici,
    G. M. Urciuoli, B.

    Wojtsekhowski, S. Wood, Z. H. Ye, Z. Y. Ye, J. Zhang.

    Measurement of the Nucleon F2n/F2p Structure Function Ratio by the
    Jefferson Lab MARATHON Tritium/Helium-3 Deep Inelastic Scattering
    Experiment. Physical Review Letters, 2022; 128 (13) DOI: 10.1103/
    PhysRevLett.128.132003 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220331151556.htm

    --- up 4 weeks, 3 days, 10 hours, 51 minutes
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)