Facility for Rare Isotope Beams

Constraining the equation of state (EOS) of strongly interacting, dense matter is the focus of intense experimental, observational, and theoretical effort. Chiral effective field theory (ChEFT) can describe the EOS at densities up to twice nuclear saturation density (n0), while perturbative QCD (pQCD) can be applied to properties of deconfined quark matter. The uncertainty due to truncation of the perturbative series at a finite order can be quantified for both theories using a single methodology, developed by the BUQEYE collaboration, that I will explain in my talk. However, this still leaves uncertainty quantification for the EOS in the intermediate region between 2n0 and (20-40)n0 as an unsolved problem. To bridge this gap between ChEFT and pQCD, we employ Bayesian model mixing (BMM) techniques we are developing for the BAND collaboration’s cyberinfrastructure framework. Specifically, we combine Gaussian random variables that constitute the predictions from each theory for the pressure as a function of the density in symmetric nuclear matter. In this FRIB theory seminar, I will present results from our recent arXiv submission for the pressure and speed of sound squared of symmetric nuclear matter. These results were obtained from the application of two BMM approaches: a pointwise approach, and a correlated approach implemented via a Gaussian process (GP), the latter of which allows for inclusion of full covariance information from both theories to the model mixing. I will also discuss extensions of this work for future improvements and applications to neutron-rich matter.

Starting over two decades ago, the MoNA Collaboration has now established itself as a leader in the understanding of the nuclear structure from the study of neutron unbound nuclei through (primarily) nuclear breakup or particle removal reactions. This Collaboration, comprised of eleven undergraduate institutions working with Michigan State University, started at the then National Superconducting Cyclotron Laboratory and is now entering a new era at the Facility for Rare Isotope Beams. It uses the invariant mass spectroscopy technique to reconstruct the decay energy of these neutron rich nuclei from the experimentally measured four-momenta of the decay (fragments and neutrons) products. This is performed by leveraging the Modular Neutron Array and Large multi-Institutional Scintillator Array (MoNA-LISA) plastic scintillator-based neutron detectors and a large gap Sweeper magnet, the latter preceding a suite of charged detector systems. This talk will highlight two experiments utilizing the MoNA-LISA-Sweeper system: the measurement of the 26O lifetime and search for excited states in 31Ne. In addition to their primary focus, the former lead to extracting further insights into 27O, thus complementing a recent measurement of this isotope at the Japanese RIKEN facility, and the latter is providing new pathways to extract information about nuclear sizes for neutron rich nuclei. These novel analyses are opening new science opportunities for the MoNA Collaboration, including bridging a gap with a recent effort to address the neutron skin puzzle through electron scattering at intermediate energies. The aforementioned also contributed strongly to expanding the reach of FRIB to broaden representation in nuclear science furthering the impact of this facility for the U.S. nuclear science workforce.

Quantum computers offer the potential to simulate nuclear processes that are classically intractable. With the goal of understanding the necessary quantum resources, we employ state-of-the-art Hamiltonian-simulation methods, and conduct a thorough algorithmic analysis, to estimate the qubit and gate costs to simulate low-energy effective field theories (EFTs) of nuclear physics. In particular, within the framework of nuclear lattice EFT, we obtain simulation costs for the leading-order pionless and pionful EFTs. We consider both static pions represented by a one-pion-exchange potential between the nucleons, and dynamical pions represented by relativistic bosonic fields coupled to non-relativistic nucleons. We examine the resource costs for the tasks of time evolution and energy estimation for physically relevant scales. We account for model errors associated with truncating either long-range interactions in the one-pion-exchange EFT or the pionic Hilbert space in the dynamical-pion EFT, and for algorithmic errors associated with product-formula approximations and quantum phase estimation. Our results show that the pionless EFT is the least costly to simulate and the dynamical-pion theory is the costliest. We demonstrate how symmetries of the low-energy nuclear Hamiltonians can be utilized to obtain tighter error bounds on the simulation algorithm. By retaining the locality of nucleonic interactions when mapped to qubits, we achieve reduced circuit depth and substantial parallelization. This work highlights the importance of combining physics insights and algorithmic advancement in reducing quantum-simulation costs.

The STREAMLINE (SmarT Reduction and Emulation Applying Machine Learning In Nuclear Environments) collaboration aims to advance the frontiers of theoretical and computational research on the nuclear many-body problem using ML. The scientific problems we address are among the most challenging in computational nuclear many-body theory and the collaboration is aligned with the U.S. government initiative to build a broad-based, multidisciplinary, multi-agency program for a sustained national AI structure. STREAMLINE will advance large nuclear physics computations to dramatically increase predictive power and improve our understanding of nuclear structure and dynamics, dense nucleonic matter, and emergent many-body phenomena -- this includes the properties of heavy neutron-rich nuclei and related astrophysical environments at the Facility for Rare Isotope Beams (FRIB); structure and reactions of nuclei and nuclear astrophysics at the Argonne Tandem Linac Accelerator System (ATLAS); neutron distributions in nuclei and few-body systems at Thomas Jefferson National Accelerator Facility (TJNAF); properties of fission at Los Alamos Neutron Science Center (LANSCE); and nuclear structure, reactions, and astrophysics at Association for Research at University Nuclear Accelerator facilities (ARUNA).

The Nuclear Science Summer School (NS3) is a summer school that introduces undergraduate student participants to the fields of nuclear science and nuclear astrophysics. NS3 is hosted by FRIB on the campus of Michigan State University (MSU). The school will offer lectures and activities covering selected nuclear science and astrophysics topics.