AI Article Synopsis
Article Abstract
The rate of the 18F(p,γ)19Ne reaction affects the final abundance of the γ-ray observable radioisotope 18F, produced in novae. However, no successful measurement of this reaction exists and the rate used is calculated from incomplete information on the contributing resonances. Of the two resonances thought to play a significant role, one has a radiative width estimated from the assumed analogue state in the mirror nucleus, 19F. The second does not have an analogue state assignment at all, resulting in an arbitrary radiative width being assumed. Here, we report the first successful direct measurement of the 18F(p,γ)^19Ne reaction. The strength of the 665 keV resonance (Ex=7.076 MeV) is found to be over an order of magnitude weaker than currently assumed in nova models. Reaction rate calculations show that this resonance therefore plays no significant role in the destruction of ^{18}F at any astrophysical energy.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1103/PhysRevLett.110.262502 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
A wideband coaxial-to-waveguide transition devised with topology optimization.
Sci Rep
January 2025
Department of Electrical Engineering, University of New Mexico, Albuquerque, NM, 87606, USA.
Topology optimization is a powerful technique that utilizes the distribution of material properties along with surface topology as parameters to expand a specified performance. While primarily used as a foundational step in regenerative design for structural mechanics, the general TO framework is also applicable to many of the complex issues in electromagnetics such as frequency agile mode converters. This is considered a difficult parameter to optimize since RF components operate on resonance.
View Article and Find Full Text PDFTowards non-blinking and photostable perovskite quantum dots.
Nat Commun
January 2025
Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, OK, 73019, USA.
Surface defect-induced photoluminescence blinking and photodarkening are ubiquitous in lead halide perovskite quantum dots. Despite efforts to stabilize the surface by chemically engineering ligand binding moieties, blinking accompanied by photodegradation still poses barriers to implementing perovskite quantum dots in quantum emitters. To date, ligand tail engineering in the solid state has rarely been explored for perovskite quantum dots.
View Article and Find Full Text PDFA dual-decoder banded convolutional attention network for bone segmentation in ultrasound images.
Med Phys
December 2024
Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin, China.
Article Synopsis
- Ultrasound (US) shows promise in computer-assisted orthopedic surgery (CAOS) due to its advantages, but bone segmentation is hindered by low-quality images and inadequate traditional methods.
- This research focuses on improving feature extraction and segmentation of bone US images by proposing a novel convolutional neural network (CNN) called BCA-Net.
- The BCA-Net utilizes a dual-decoder system with multiscale banded convolution kernels, incorporates prior knowledge of bone features, and introduces a new task consistency loss to enhance performance, validated using a dataset of 1623 US images.
Enabling High-Performance Multi-Resonant TADF Emitters via Intramolecular Hydrogen Bond.
Chemistry
December 2024
Hebei Key Laboratory of Organic Functional Molecules, Hebei Technology Innovation Center for Energy Conversion Materials and Devices, College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang 050024, PR China E-mail address.
Hydrogen bonds (HBs), prevalent strong interactions in organic compounds, can effectively constrain single bond rotation, leading to rigid planar configurations. This rigidity enhances emission efficiency and narrows the emission spectrum of luminescent materials. Recent advances have leveraged HBs to advance high-performance donor-acceptor thermally activated delayed fluorescence (TADF) materials.
View Article and Find Full Text PDFEffectiveness of multi-junction cells in near-field thermophotovoltaic devices considering additional losses.
Nanophotonics
March 2024
Department of Mechanical Engineering, KAIST, 291, Daehak-ro, Yuseong-gu, Daejeon-si 34141, South Korea.
Article Synopsis
- Thermophotovoltaic (TPV) energy converters can efficiently transform thermal radiation into electrical energy, with diverse applications including solar energy collection and waste heat recovery.
- Near-field TPV (NF-TPV) devices use photon tunneling to enhance power output density but face challenges from losses related to high photocurrent densities and scalability issues.
- This study evaluates multi-junction NF-TPV devices, introduces methods to assess additional loss impacts, and offers a framework for improving performance across various parameters, ultimately guiding the design of scalable and high-performing TPV systems.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!