Engineering topics

Dean, D. J.

Publications and source records attributed to Dean, D. J..

8 records

DOE OSTI2024

Strong interaction physics at the luminosity frontier with 22 GeV electrons at Jefferson Lab

Here, the purpose of this document is to outline the developing scientific case for pursuing an energy upgrade to 22 GeV of the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility (TJNAF, or JLab). This document was developed with input from a series of workshops held in the period between March 2022 and April 2023 that were organized by the JLab user community and staff with guidance from JLab management (see Sec. 10). The scientific case for the 22 GeV energy upgrade leverages existing or already planned Hall equipment and world-wide uniqueness of CEBAF high-luminosity operations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

The Present and Future of QCD: QCD Town Meeting White Paper – An Input to the 2023 NSAC Long Range Plan

It is currently understood that there are four fundamental forces in nature: gravitational, electromagnetic, weak and strong forces. The strong force governs the interactions between quarks and gluons, elementary particles whose interactions give rise to the vast majority of visible mass in the universe. The mathematical description of the strong force is provided by the non-Abelian gauge theory Quantum Chromodynamics (QCD). While QCD is an exquisite theory, constructing the nucleons and nuclei from quarks, and furthermore explaining the behavior of quarks and gluons at all energies, remain to be complex and challenging problems. Such challenges, along with the desire to understand all visible matter at the most fundamental level, position the study of QCD as a central thrust of research in nuclear science. Experimental insight into the strong force can be gained using large particle accelerator facilities, which are necessary to probe the very short distance scales over which quarks and gluons interact. The Long Range Plans (LRPs) exercise of 1989 and 1996 led directly to the construction of two world-class facilities: the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLab) that is focused on studying how the structure of hadrons emerges from QCD (cold QCD research), and the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab (BNL) that aims at the discovery and study of a new state of matter, the quark-gluon plasma (QGP), at extremely high temperatures (hot QCD research). These past investments have produced major advances. Nucleons and nuclei are being studied with increasing precision with a unified description of the partonic structure utilizing multi-dimensional imaging. Significant progress has been made, paving the way towards a complete picture of how quarks and gluons give rise to the mass, spin, and momentum of the nucleon. In hot QCD, the QGP is created in the collisions of nuclei at RHIC and the Large Hadron Collider (LHC) and is observed to behave like a fluid with very low specific shear viscosity; the current goals are to understand how the fluid behavior emerges from QCD and to characterize the temperature (and chemical potential) dependence of the properties of the QGP. As this White Paper is written, current experimental programs at CEBAF, RHIC and the LHC continue to provide exciting near term opportunities to capitalize on the investments in experimental equipment and accelerator operations. Most importantly, the QCD community looks forward to the construction of the Electron Ion Collider (EIC) as a major new facility to push forward QCD research in the next decades, with significant focus on exploring the properties of gluons, the mediators of the strong force.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2020

Study of Quasielastic Barrier Distributions as a Step towards the Synthesis of Superheavy Elements with Hot Fusion Reactions

The excitation functions for quasielastic scattering of Ne 22 + Cm 248 , Mg 26 + Cm 248 , and Ca 48 + U 238 are measured using a gas-filled recoil ion separator. The quasielastic barrier distributions are extracted for these systems and are compared with coupled-channel calculations. The results indicate that the barrier distribution is affected dominantly by deformation of the actinide target nuclei, but also by vibrational or rotational excitations of the projectile nuclei, as well as neutron transfer processes before capture. From a comparison between the experimental barrier distributions and the evaporation residue cross sections for Sg ( Z = 106 ), Hs (108), Cn (112), and Lv (116), it is suggested that the hot fusion reactions take advantage of a compact collision, where the projectile approaches along the short axis of a prolately deformed nucleus. Overall, a new method is proposed to estimate the optimum incident energy to synthesize unknown superheavy nuclei using the barrier distribution.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2019

Experimental Study of the 249-251 Cf + 48 Ca Reactions: Toward the Magic Neutron Number N=184

Recently several complete-fusion reactions have been studied at the DGFRS setup (FLNR, JINR) with an aim of exploring the boundaries of the “Island of Stability” of the superheavy elements (nuclei around Z=114-126 and N=184). During the 249-251 Cf+ 48 Ca run with mixed Cf target (50.7% of 249 Cf, 12.9% of 250 Cf, and 36.4% of 251 Cf) just one decay chain was detected at the 252-MeV beam energy which was attributed to the previously observed 294 Og isotope, the product of the 249 Cf( 48 Ca,3n) 294 Og reaction; the corresponding reaction cross section was measured. For the 251 Cf( 48 Ca, 3-4n) 295,296 Og reactions no Og decays were detected during this run. Here, future possibilities for synthesis of new nuclides in the region of SHEs, namely more neutron-rich Lv, Ts and Og isotopes and new nuclides with higher Z (119 and 120), are discussed.

alpha decay↗

DOE OSTI2018

Search for the heaviest atomic nuclei among the products from reactions of mixed-Cf with a Ca 48 beam

In this paper, the search for new decay chains of oganesson isotopes is presented. The experiment utilized the Dubna Gas Filled Recoil Separator and a highly segmented recoil-decay detection system. The signals from all detectors were analyzed in parallel by digital and analog data acquisition systems. For the first time, a target of mixed californium (51% $^{249}\mathrm{Cf}$, 13% $^{250}\mathrm{Cf}$, and 36% $^{251}\mathrm{Cf})$ recovered from decayed $^{252}\mathrm{Cf}$ sources was produced and irradiated with an intense $^{48}\mathrm{Ca}$ beam. The observation of a new decay chain of $^{294}\mathrm{Og}$ is reported. Finally, the prospects for reaching new isotopes $^{295,296}\mathrm{Og}$ are discussed.

07 ISOTOPE AND RADIATION SOURCES↗

DOE OSTI2017

Quantum Information Science: Factual Document for the Office of Basic Energy Sciences at the Department of Energy

For decades, scientists have known that devices to store and manipulate information in quantum physical systems such as atoms or photons would provide radical new capabilities in computing, communication, and sensing. These novel capabilities include speed-ups in scientific calculations of quantum materials and chemical systems, enhanced resolution in imaging and detection systems, and greater security for encrypted communication systems. Building these devices requires a detailed understanding of how quantum materials behave, accurate knowledge of how to integrate them, and high-fidelity control of the physical qubits that store information. These goals are fundamental research challenges for materials synthesis, fabrication, and characterization; and the science of quantum information intersects heavily with ongoing basic research into materials science, chemistry, and quantum physics. These systems represent state-of-the-art approaches to building and controlling the basic physical elements of quantum information. Research into quantum sensing and quantum communication strongly leverages these advances for next-generation technologies, e.g., measurements beyond the Heisenberg limit, while applications of quantum computing (QC) as a platform for understanding future quantum material systems highlight its potential for advanced scientific discovery. This factual status document for Quantum Information Science has been developed for the Department of Energy Office of Science, Basic Energy Sciences (BES). The following are several seminal or key references for interested readers; the reference section gives a more exhaustive, but still not complete, list of important papers in this area.

36 MATERIALS SCIENCE↗

DOE OSTI2017

Observation of coherent elastic neutrino-nucleus scattering

The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross section is by far the largest of all low-energy neutrino couplings. This mode of interaction offers new opportunities to study neutrino properties and leads to a miniaturization of detector size, with potential technological applications. In this paper, we observed this process at a 6.7σ confidence level, using a low-background, 14.6-kilogram CsI[Na] scintillator exposed to the neutrino emissions from the Spallation Neutron Source at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the standard model for this process, were observed in high signal-to-background conditions. Finally, improved constraints on nonstandard neutrino interactions with quarks are derived from this initial data set.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2017

The Intermediate Neutrino Program

The US neutrino community gathered at the Workshop on the Intermediate Neutrino Program (WINP) at Brookhaven National Laboratory February 4-6, 2015 to explore opportunities in neutrino physics over the next five to ten years. Scientists from particle, astroparticle and nuclear physics participated in the workshop. The workshop examined promising opportunities for neutrino physics in the intermediate term, including possible new small to mid-scale experiments, US contributions to large experiments, upgrades to existing experiments, R&D plans and theory. The workshop was organized into two sets of parallel working group sessions, divided by physics topics and technology. Physics working groups covered topics on Sterile Neutrinos, Neutrino Mixing, Neutrino Interactions, Neutrino Properties and Astrophysical Neutrinos. Technology sessions were organized into Theory, Short-Baseline Accelerator Neutrinos, Reactor Neutrinos, Detector R&D and Source, Cyclotron and Meson Decay at Rest sessions.This report summarizes discussion and conclusions from the workshop.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗