- 2015-05-28 07:05:00
- Article ID: 634665
Protons Hog the Momentum in Neutron-Rich Nuclei
New research could change our view of neutron stars and other systems with neutron-rich nuclei.
-
Credit: Image courtesy of Jefferson Lab
Illustration of Jefferson Lab's CEBAF Large Acceptance Spectrometer (CLAS), along with an event reconstructed from the data. In this experiment, an incident 5-GeV electron scatters from a nucleon (a proton or a neutron) that has briefly paired up with another. As particles flying out of the target enter the CLAS, their paths are bent by a magnet and measured by successive layers of different types of particle detectors.
The Science
Like dancers swirling on the dance floor with bystanders looking on, protons and neutrons that have briefly paired up inside an atom’s nucleus have a higher-than-average momentum, leaving less energy for non-paired nucleons. This phenomenon allows more protons than neutrons to have high momentum in a relatively neutron-rich nuclei, which is contrary to long-accepted theories. Using data from nuclear physics experiments carried out at the Department of Energy's Thomas Jefferson National Accelerator Facility, researchers have shown – for the first time – that this phenomenon exists in nuclei heavier than carbon, including aluminum, iron, and lead.
The Impact
The results of this study show that the Pauli exclusion principle, long used to describe the distribution of protons and neutrons in nuclei, does not accurately describe proton-neutron pairing. These results could change our understanding of the internal structures of systems where these pairings occur, including neutron stars.
Summary
In 2008, researchers obtained direct evidence that protons and neutrons in light nuclei (up to carbon, with six each protons and neutrons) pair up briefly in the nucleus, a phenomenon called a short-range correlation. In this pairing, protons preferred neutrons to other protons by 20 to 1. The protons and neutrons involved in a short-range correlation carry higher momentum than unpaired ones. Now, researchers have extended that result into heavier, neutron-rich nuclei, including aluminum (13p/14n), iron (26p/30n), and lead (82p/126n). They found that in these imbalanced nuclei, the minority protons tended to more likely to be found in a short-range correlation than the majority neutrons. The result comes from an initiative in which data from a completed experiment conducted in 2004 were re-analyzed to look for this phenomenon. It was made possible by the CEBAF Large Acceptance Spectrometer (CLAS) that was used to collect the data. The CLAS detectors almost completely surround an experimental target and can collect more than 2 terabytes of data a day. The result can likely be extended to other imbalanced systems, such as the atoms in ultra-cold atomic gases and in the cores of neutron stars.
Funding
This work was supported by the U.S. Department of Energy's Office of Science, the U.S. National Science Foundation, Israel Science Foundation, Chilean Comisión Nacional de Investigación Científica y Technológica, French Centre National de la Recherche Scientifique and Commissariat a l'Energie Atomique, French-American Cultural Exchange, Italian Istituto Nazionale di Fisica Nucleare, National Research Foundation of Korea, and the U.K.'s Science and Technology Facilities Council. CEBAF is a DOE Office of Science user facility.
Publications
O. Hen, et al., "Momentum sharing in imbalanced Fermi systems." Science 346, 614 (2014). [DOI: 10.1126/science.1256785]
MORE NEWS FROM
Department of Energy, Office of Science
comments 
commenting policy
Participating Labs
- DOE Office of Science
- Argonne National Laboratory
- Oak Ridge National Laboratory
- Pacific Northwest National Laboratory
- Iowa State University, Ames Laboratory
- Brookhaven National Laboratory
- Princeton Plasma Physics Laboratory
- Lawrence Berkeley National Laboratory
- Thomas Jefferson National Accelerator Facility
- Fermi National Accelerator Laboratory (Fermilab)
- SLAC National Accelerator Laboratory
What's MER? It's a Way to Measure Quantum Materials, and It's Telling US New and Interesting Things
Experimental physicists have combined several measurements of quantum materials into one in their ongoing quest to learn more about manipulating and controlling the behavior of them for possible applications. They even coined a term for it-- Magneto-elastoresistance, or MER.
Scientists pioneer new generation of semiconductor neutron detector
In a new study, scientists have developed a new type of semiconductor neutron detector that boosts detection rates by reducing the number of steps involved in neutron capture and transduction.
Connecting the dots in the sky could shed new light on dark matter
Astrophysicists have come a step closer to understanding the origin of a faint glow of gamma rays covering the night sky. They found that this light is brighter in regions that contain a lot of matter and dimmer where matter is sparser - a correlation that could help them narrow down the properties of exotic astrophysical objects and invisible dark matter.
Nano-objects of Desire: Assembling Ordered Nanostructures in 3-D
A new DNA-programmable nanofabrication platform organizes inorganic or biological nanocomponents in the same prescribed ways.
New computer code could reach fusion faster
Scientists often make progress by coming up with new ways to look at old problems. That has happened at PPPL, where physicists have used a simple insight to capture the complex effects of many high-frequency waves in a fusion plasma.
Scientists observe ultrafast birth of radicals
An international team of researchers have, for the first time, glimpsed the ultrafast process of proton transfer following ionization of liquid water, shedding light on how radical cations separate from their electron partners, neutralize and subsequently drift about creating damage.
An Out-of-the-Box Attack on Diabetes
A protein newly identified as important in type 1 diabetes can delay onset of the disease in diabetic mice, providing a new target for prevention and treatment in people, according to research led by scientists at the U.S. Department of Energy's Pacific Northwest National Laboratory and Indiana University School of Medicine.
The CUORE Underground Experiment Narrows the Search for Rare Particle Process
The largest set of data yet from an underground experiment called CUORE sets more stringent limits on a theoretical ultra-rare particle process known as neutrinoless double-beta decay that could help to explain the abundance of matter over antimatter in the universe.
Story Tips: Weather days, grid balance and scaling reactors
From the Department of Energy's Oak Ridge National Laboratory, January 2020
Exploring the "dark side" of a single-crystal complex oxide thin film
A new study offers a nanoscopic view of complex oxides, which have great potential for advanced microelectronics.
Team led by PPPL wins major supercomputer time to help capture on Earth the fusion that powers the sun and stars
PPPL will use INCITE-award time on Summit and Theta supercomputers to develop predictions for the performance of ITER, the international experiment under construction to demonstrate the feasibility of fusion energy.
Department of Energy Announces $625 Million for New Quantum Centers
The U.S. Department of Energy (DOE) announced up to $625 million over the next five years to establish two to five multidisciplinary Quantum Information Science (QIS) Research Centers in support of the National Quantum Initiative.
Department of Energy to Provide $75 Million for Bioenergy Crops Research
The U.S. Department of Energy (DOE) announced a plan to provide up to $75 million over five years for research to develop sustainable bioenergy crops tolerant of environmental stress and resilient to changing environmental conditions.
Jefferson Lab to be Major Partner in Electron Ion Collider Project
The Department of Energy announced that it has taken the next step toward construction of an Electron Ion Collider (EIC) in the United States. DOE announced on Thursday that the collider will be sited at DOE's Brookhaven National Laboratory in Upton, N.Y. In addition, DOE's Thomas Jefferson National Accelerator Facility will be a major partner in realizing the EIC, providing key support to build this next new collider, which will be the most advanced particle collider of its type ever built.
Department of Energy Selects Site for Electron-Ion Collider
UPTON, NY-- Yesterday, the U.S. Department of Energy (DOE) named Brookhaven National Laboratory on Long Island in New York as the site for building an Electron-Ion Collider (EIC), a one-of-a-kind nuclear physics research facility. This announcement, following DOE's approval of "mission need" (known as Critical Decision 0) on December 19, 2019, enables work to begin on R&D and the conceptual design for this next-generation collider at Brookhaven Lab.
Department of Energy Announces $32 Million for Small Business Research and Development Grants
U.S. Secretary of Energy Dan Brouillette announced that the Department of Energy (DOE) will award 158 grants totaling $32 million to 118 small businesses in 32 states. Funded through DOE's Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs, these selections are for Phase I research and development.
Summit Charts a Course to Uncover the Origins of Genetic Diseases
Gene mutations can interfere with how the body expresses genes and cause disease. To better understand this connection, researchers recently developed a model of the transcription preinitiation complex (PIC).
Alex Nagy, a "creative and energetic" engineer, is named a Distinguished Engineering Fellow
Feature profiles PPPL Distinguished Engineering Fellow recipient Alex Nagy
PPPL honors physicists Igor Kaganovich and Yevgeny Raitses with Kaul Foundation Prize
Profiles of winners of PPPL's 2019 Kaul Foundation Prize recipients.
The Quantum Information Edge Launches to Accelerate Quantum Computing R&D for Breakthrough Science
A nationwide alliance of national labs, universities, and industry launched today to advance the frontiers of quantum computing systems designed to solve urgent scientific challenges and maintain U.S. leadership in next-generation information technology. The Quantum Information Edge strategic alliance is led by Lawrence Berkeley National Laboratory (Berkeley Lab) and Sandia National Laboratories.
Harvesting Energy from Light using Bio-inspired Artificial Cells
Scientists designed and connected two different artificial cells to each other to produce molecules called ATP (adenosine triphosphate).
Engineering Living Scaffolds for Building Materials
Bone and mollusk shells are composite systems that combine living cells and inorganic components. This allows them to regenerate and change structure while also being very strong and durable. Borrowing from this amazing complexity, researchers have been exploring a new class of materials called engineered living materials (ELMs).
Excavating Quantum Information Buried in Noise
Researchers developed two new methods to assess and remove error in how scientists measure quantum systems. By reducing quantum "noise" - uncertainty inherent to quantum processes - these new methods improve accuracy and precision.
How Electrons Move in a Catastrophe
Lanthanum strontium manganite (LSMO) is a widely applicable material, from magnetic tunnel junctions to solid oxide fuel cells. However, when it gets thin, its behavior changes for the worse. The reason why was not known. Now, using two theoretical methods, a team determined what happens.
When Ions and Molecules Cluster
How an ion behaves when isolated within an analytical instrument can differ from how it behaves in the environment. Now, Xue-Bin Wang at Pacific Northwest National Laboratory devised a way to bring ions and molecules together in clusters to better discover their properties and predict their behavior.
Tune in to Tetrahedral Superstructures
Shape affects how the particles fit together and, in turn, the resulting material. For the first time, a team observed the self-assembly of nanoparticles with tetrahedral shapes.
Tracing Interstellar Dust Back to the Solar System's Formation
This study is the first to confirm dust particles pre-dating the formation of our solar system. Further study of these materials will enable a deeper understanding of the processes that formed and have since altered them.
Investigating Materials that Can Go the Distance in Fusion Reactors
Future fusion reactors will require materials that can withstand extreme operating conditions, including being bombarded by high-energy neutrons at high temperatures. Scientists recently irradiated titanium diboride (TiB2) in the High Flux Isotope Reactor (HFIR) to better understand the effects of fusion neutrons on performance.
Better 3-D Imaging of Tumors in the Breast with Less Radiation
In breast cancer screening, an imaging technique based on nuclear medicine is currently being used as a successful secondary screening tool alongside mammography to improve the accuracy of the diagnosis. Now, a team is hoping to improve this imaging technique.
Microbes are Metabolic Specialists
Scientists can use genetic information to measure if microbes in the environment can perform specific ecological roles. Researchers recently analyzed the genomes of over 6,000 microbial species.
Spotlight
Barbara Garcia: A first-generation college student spends summer doing research at PPPL
Princeton Plasma Physics Laboratory
Argonne organization's scholarship fund blazes STEM pathway
Argonne National Laboratory
Brookhaven Lab, Suffolk Girl Scouts Launch Patch Program
Brookhaven National Laboratory
From an acoustic levitator to a "Neutron Bloodhound" robot, hands-on research inspires PPPL's summer interns
Princeton Plasma Physics Laboratory
Brookhaven Lab Celebrates the Bright Future of its 2019 Interns
Brookhaven National Laboratory
PPPL apprenticeship program offers young people chance to earn while they learn high-tech careers
Princeton Plasma Physics Laboratory
JSA Awards Graduate Fellowships for Research at Jefferson Lab
Thomas Jefferson National Accelerator Facility
ILSAMP Symposium showcases benefits for diverse students, STEM pipeline
Argonne National Laboratory
Integrating Scientific Computing into Science Curricula
Brookhaven National Laboratory
Students from Minnesota and Massachusetts Win DOE's 29th National Science Bowl(r)
Department of Energy, Office of Science
DOE's Science Graduate Student Research Program Selects 70 Students to Pursue Research at DOE Laboratories
Department of Energy, Office of Science
Young Women's Conference in STEM seeks to change the statistics one girl at a time
Princeton Plasma Physics Laboratory
Students team with Argonne scientists and engineers to learn about STEM careers
Argonne National Laboratory
Lynbrook High wins 2019 SLAC Regional Science Bowl competition
SLAC National Accelerator Laboratory
Equipping the next generation for a technological revolution
Argonne National Laboratory
Chemistry intern inspired by Argonne's real-world science
Argonne National Laboratory
Argonne intern streamlines the beamline
Argonne National Laboratory
Research on Light-Matter Interaction Could Lead to Improved Electronic and Optoelectronic Devices
Rensselaer Polytechnic Institute (RPI)
Innovating Our Energy Future
Oregon State University, College of Engineering
Physics graduate student takes her thesis research to a Department of Energy national lab
University of Alabama at Birmingham
"Model" students enjoy Argonne campus life
Argonne National Laboratory
Writing Code for a More Skilled and Diverse STEM Workforce
Brookhaven National Laboratory
New graduate student summer school launches at Princeton Plasma Physics Laboratory
Princeton Plasma Physics Laboratory
The Gridlock State
California State University (CSU) Chancellor's Office
Meet Jasmine Hatcher and Trishelle Copeland-Johnson
Brookhaven National Laboratory
Argonne hosts Modeling, Experimentation and Validation Summer School
Argonne National Laboratory
Undergraduate Students Extoll Benefits of National Laboratory Research Internships in Fusion and Plasma Science
Princeton Plasma Physics Laboratory
Students affected by Hurricane Maria bring their research to SLAC
SLAC National Accelerator Laboratory
Brookhaven Lab Pays Tribute to 2018 Summer Interns
Brookhaven National Laboratory
CSUMB Selected to Host Architecture at Zero Competition in 2019
California State University, Monterey Bay
From Hurricane Katrina Victim to Presidential Awardee: A SUNO Professor's Award-Winning Mentoring Efforts
Brookhaven National Laboratory
Department of Energy Invests $64 Million in Advanced Nuclear Technology
Rensselaer Polytechnic Institute (RPI)
Professor Miao Yu Named the Priti and Mukesh Chatter '82 Career Development Professor
Rensselaer Polytechnic Institute (RPI)
2018 RHIC & AGS Annual Users' Meeting: 'Illuminating the QCD Landscape'
Brookhaven National Laboratory
High-School Students Studying Carbon-Based Nanomaterials for Cancer Drug Delivery Visit Brookhaven Lab's Nanocenter
Brookhaven National Laboratory
Argonne welcomes The Martian author Andy Weir
Argonne National Laboratory
UW Professor and Clean Energy Institute Director Daniel Schwartz Wins Highest U.S. Award for STEM Mentors
University of Washington
Creating STEM Knowledge and Innovations to Solve Global Issues Like Water, Food, and Energy
Illinois Mathematics and Science Academy (IMSA)
Professor Emily Liu Receives $1.8 Million DoE Award for Solar Power Systems Research
Rensselaer Polytechnic Institute (RPI)
Celebrating 40 years of empowerment in science
Argonne National Laboratory
Introducing Graduate Students Across the Globe to Photon Science
Brookhaven National Laboratory
Students from Massachusetts and Washington Win DOE's 28th National Science Bowl(r)
Department of Energy, Office of Science
Q&A: Al Ashley Reflects on His Efforts to Diversify SLAC and Beyond
SLAC National Accelerator Laboratory
Insights on Innovation in Energy, Humanitarian Aid Highlight UVA Darden's Net Impact Week
University of Virginia Darden School of Business
Ivy League Graduate, Writer and Activist with Dyslexia Visits CSUCI to Reframe the Concept of Learning Disabilities
California State University, Channel Islands
Photographer Adam Nadel Selected as Fermilab's New Artist-in-Residence for 2018
Fermi National Accelerator Laboratory (Fermilab)
Showing results
0-4 Of 2215