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Nuclear Physics Seminar

Spring 2020
The seminars are held in Nielsen Room 304 at 2:20 PM on Monday.
With classes online through April 3, the Nuclear Physics Seminar will be avilable via Zoom. Please contact Dr. Christine Nattrass if you would like to join:
Date Speaker Title
January 13

Kevin Siegl

Beta-Delayed Neutron Studies using Trapped Ions from CARIBU
January 20

NO SEMINAR/Martin Luther King, Jr., Holiday

January 27 Vincente Guiseppe The LEGEND Program: A Search for Neutrinoless Double-Beta Decay in Ge-76
February 3 Joe Osborn Hadronization and Jet Substructure at RHIC and the LHC
February 10 Ben Kay Exploring Uncharted Regions of the Nuclear Landscape using Solenoidal Spectrometers
February 17 Jon Engle  
February 24 Kyle Leach The Quest for the New Standard Model: Searching for BSM Physics with Rare-Isotopes
March 2 Becca Toomey Neutron Spectroscopy for Nuclear Physics Applications
March 9 Cheuk-yin Wong (ORNL) Quark-antiquark QED Bound State Description of X17 and Dark Matter
March 23 CANCELLED  
March 30 Mitch Allmond: CANCELLED  
April 6 Julie Ezold  
April 13 Andrea Delgato   
April 20 Friederike Bock  

January 13

Kevin Siegl

Beta-Delayed Neutron Studies using Trapped Ions from CARIBU

Beta-delayed neutron (BDN) emission, the emission of a neutron following the beta-decay of the precursor nuclide, is a decay mode for all radioactive nuclei sufficiently neutron-rich. Confining radioactive ions in a radio-frequency quadrupole ion trap allows indirect measurements of beta-delayed single neutron emission. This is accomplished by determining the energy of the recoiling ion which can be significantly larger after neutron emission than from beta decay alone. This method avoids most of the systematic errors associated with direct neutron detection but introduces dependencies on specifics of the decay and interactions of the ion with the RF fields. The decays of seven BDN precursors were studied using the Beta-decay Paul Trap (BPT) to confine fission fragments from the Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The analysis of this technique, and results for the measurement will be presented.

January 27

Vincente Guiseppe

The LEGEND Program: A Search for Neutrinoless Double-Beta Decay in Ge-76

Neutrinoless double-beta decay searches have the potential to discover the existence of a lepton-number violating process and the particle-antiparticle nature of neutrinos, which form the basis of theories explaining the matter-antimatter asymmetry in the universe. The Majorana Collaboration is operating its Demonstrator array of high-purity Ge detectors at the Sanford Underground Research Facility in South Dakota to search for neutrinoless double-beta decay in Ge-76. Along with the GERDA experiment in Italy, Ge-based experiments have achieved the lowest backgrounds and a superior energy resolution at the neutrinoless double-beta decay region of interest illustrating that Ge-76 is an ideal isotope for a large, next-generation experiment. Building on the successes of our experiments, the LEGEND collaboration has been formed to develop a phased, Ge-based double-beta decay experimental program with discovery potential at a half-life beyond 10^28 years. Our program relies on advances in detector design and a thorough understanding of existing and potentially new backgrounds. This talk will present the status and latest results from the Majorana Demonstrator experiment, studies of problematic background sources, and the plan for the LEGEND experiment.

February 3

Joe Osborn

Hadronization and jet substructure at RHIC and the LHC

In high energy proton-proton collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), conical sprays of particles, called jets, are one of the most copiously produced final states. Jets form when quarks and gluons scatter from one another, and due to confinement, these quarks and gluons nonperturbatively form collimated distributions of hadrons. While jets are one of the most frequently used objects in physics analyses at RHIC and the LHC, it was only recently realized that jet substructure can probe a wide variety of high energy and nuclear physics at collider facilities. In this talk I will discuss my recent work at the LHCb experiment on hadronization, the process by which scattered quarks and gluons form nonperturbative bound state hadrons, as well as several forthcoming opportunities for hadronization research.

February 10

Ben Kay

Exploring uncharted regions of the nuclear landscape using solenoidal spectrometers

In the anticipation of a new generation of rare isotope beam facilities, Argonne pioneered a new class of charged-particle spectrometer for reactions studies based on a large-bore superconducting solenoid of the type used for magnetic resonance imaging in hospitals. Reaction studies with rare isotope beams are by necessity carried out in so-called inverse kinematics which can lead to poor resolution due to kinematic compression. Transporting the charged particles through a solenoidal field can remove this problem allowing for studies with good resolution. The technique has proven quite powerful for nuclear structure and nuclear astrophysics studies. Inspired by HELIOS at Argonne, the ISOLDE Solenoidal Spectrometer at CERN has recently been developed. In its first campaign, it was used to explore a previously uncharted region of the nuclear landscape beyond the the closed neutron shell of N = 126. Improving our understanding of nuclear structure in this region can inform and improve our understanding of the astrophysical rapid neutron capture (r-) process, responsible for the synthesis of heavy elements in the universe. There are future plans for such a device at the Facility for Rare Isotope Beams. I will given of overview of these types of spectrometers and recent science highlights.

March 2

Becca Toomey

Neutron Spectroscopy for Nuclear Physics Applications

Neutron detection is an essential tool in many different aspects of nuclear physics. However, unlike charged particles, neutrons do not directly ionize the material through which they travel making detection a challenge. Typically, moderated 3He tubes or time-of-flight (ToF) methods are used, but are limited by the loss of neutron spectroscopic information or loss of detection efficiency for sufficient energy resolution, respectively. However, the spectrum unfolding method allows for the extraction of neutron spectroscopic information without loss of detection efficiency or en- ergy resolution. To fully utilize this method, ODeSA—the ORNL Deuterated Spectroscopic Array—was designed and built in-house at ORNL. An array of these detectors was recently deployed at the Nuclear Science Laboratory at the University of Notre Dame to measure the 18O(α,n)21Ne reaction cross section in the range Eα = 2 − 8 MeV. Constraining this re- action would have impact on numerous fields of nuclear physics, such as nuclear astrophysics and nuclear security. Neutron detection development at ORNL, including the spectrum unfolding technique, will be discussed, and preliminary results from the measurement of 18O(α,n)21Ne will be shown.

March 9

Cheuk-yin Wong (ORNL)

Quark-antiquark QED Bound State Description of X17 and Dark Matter

A quark and an antiquark interact not only with the quantum chromodynamical (QCD) interaction but also with the quantum electrodynamical (QED) interaction. As a consequence, a quark-antiquark pair can form QED bound states that are analogous to the QCD meson states in quantum chromodynamics [1]. The predicted mass of the isoscalar quark-antiquark QED bound state [1] is close to the mass of the X17 particle of about 17 MeV, leading to the suggestion that the X17 particle may be the quark-antiquark isocalar QED bound state arising from the quantum electrodynamical interaction between a quark and an antiquark [2]. The implication of the possible existence of such states on the X17 particle, the occurrence of anomalous soft photons in high-energy hadron production, the dark matter, and the production of the primordial dark matter during the quark-gluon plasma phase transition at the early history of the universe will be discussed.

[1] C. Y. Wong, {Anomalous soft photons in hadron production}, Phys. Rev. C81, 064903 (2010), arXiv:1001.1691.
[2] C. Y. Wong, {QED2 boson description of the X17 particle and dark matter}, arxiv:2001.04864 (2020).

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