Brightsurf Science News and Current Science News Events
 
Email a Friend Send to a friend
Printer Friendly Print Protons pair up with neutrons

Protons pair up with neutrons

May 30, 2008

NEWPORT NEWS, VA - Research performed at the U.S. Department of Energy's Thomas Jefferson National Accelerator Facility has found that protons are about 20 times more likely to pair up with neutrons than with other protons in the nucleus. The result will be published online by the journal Science, at the Science Express website.

The result, based on the first-ever simultaneous measurement of such pairings and their constituents, could have implications for understanding the structure of nuclear systems from light nuclei to neutron stars.




Protons and neutrons, or nucleons, in the nucleus of the atom can form a brief pairing with another nucleon, a phenomenon known as a short-range correlation. Previous experiments have shown that roughly one-fifth of nucleons at any one time were in short-range correlations.

Jefferson Lab Staff Scientist Douglas Higinbotham and his colleagues conducted an experiment in Jefferson Lab's Experimental Hall A to directly and simultaneously measure the constituents of the short-range correlations in the carbon nucleus.

"These correlated nucleons have a high relative momentum. If you knock one out one way, the correlated nucleon will fly out in the opposite direction," noted Higinbotham. "We set up our detectors to take advantage of this."

The experiment found that 18 percent of all protons in the nucleus were paired with neutrons. Another one percent of protons were paired with protons, with about the same percentage of neutron/neutron pairs.

"I think it shows, for the first time in a very clear and unambiguous way, this fact that the large momentum nucleons in nuclei are coming in pairs. And they're coming mainly in proton/neutron pairs," said Eli Piasetzky, a professor at Tel Aviv University and a spokesperson on the experiment.

Higinbotham agreed. "The result from this experiment is like finding that missing piece needed to finish a puzzle. This experiment, combined with others, gives us a very coherent picture of these short-range correlations in the nucleus."

In the experiment, a beam of energetic electrons was sent into a thin sheet (0.25 mm) of Carbon-12. The scientists were interested in the electrons that interacted with a member of a short-range correlation. Recoil electrons and knockout protons were measured in Jefferson Lab Experimental Hall A's High Resolution Spectrometers. Correlated protons and neutrons were measured in the BigBite large acceptance spectrometer and a neutron detector. The ability to clearly resolve the short-range correlated pairs is due to the high energy and large intensity beam at Jefferson Lab.

When combined with a theoretical calculation of the effects of proton/neutron correlations on the momentum distribution of the nucleons in neutron stars, the result also indicates that the presence of short-range correlations may have a disproportionately large effect on neutron star structure.

DOE/Thomas Jefferson National Accelerator Facility



Related Protons News Articles Protons News and Current Protons Events RSS Protons News and Current Protons Events RSS
Explosives go "green"
Certain explosives may soon get a little greener and a little more precise.

Future for clean energy lies in 'big bang' of evolution
Amid mounting agreement that future clean, "carbon-neutral", energy will rely on efficient conversion of the sun's light energy into fuels and electric power, attention is focusing on one of the most ancient groups of organism, the cyanobacteria.

Carnegie Mellon MRI technology that non-invasively locates, quantifies specific cells in the body
Magnetic resonance imaging (MRI) isn't just for capturing detailed images of the body's anatomy. Thanks to novel imaging reagents and technology developed by Carnegie Mellon University scientist Eric Ahrens, MRI can be used to visualize - with "exquisite" specificity - cell populations of interest in the living body.

University of Pennsylvania Scientists Move Optical Computing Closer to Reality
Scientists at the University of Pennsylvania have theorized a way to increase the speed of pulses of light that bound across chains of tiny metal particles to well past the speed of light by altering the particle shape.

Toward plastic spin transistors
University of Utah physicists successfully controlled an electrical current using the "spin" within electrons - a step toward building an organic "spin transistor": a plastic semiconductor switch for future ultrafast computers and electronics.

Monash team learns from nature to split water
An international team of researchers led by Monash University has used chemicals found in plants to replicate a key process in photosynthesis paving the way to a new approach that uses sunlight to split water into hydrogen and oxygen.

A world-leading UK science project switches on first neutrons
The UK's ISIS Second Target Station Project moved a major step closer to completion today when the first neutrons were created in the ISIS Second Target Station.

Scientists discover that protons partner with neutrons more often than with other protons
Fast-moving protons are much more likely to pair up with fast-moving neutrons than with other protons in the nuclei of atoms, according to a recent experiment performed at the U.S. Department of Energy's Thomas Jefferson National Accelerator Facility.

Argonne scientists develop way to predict properties of light nuclei
Scientists have spent 70 years trying to predict the properties of nuclei, but have had to settle for approximate models because computational techniques were not equal to the task.

Researchers 'see' structure of open nicotinic acetylcholine ion channels
The neurotransmitter acetylcholine is an essential chemical communicator, carrying impulses from neurons to skeletal muscle cells and many parts of the nervous system.
More Protons News Articles


MRI from Picture to Proton
by Donald W. McRobbie, Elizabeth A. Moore, Martin J. Graves, Martin R. Prince

MRI from Picture to Proton presents the basics of MR practice and theory in a unique way: backwards! The subject is approached just as a new MR practitioner would encounter MRI: starting from the images, equipment and scanning protocols, rather than pages of physics theory. The reader is brought face-to-face with issues pertinent to practice immediately, filling in the theoretical background as...



MRI for Technologists
by Peggy Woodward

“…a welcome change from the many highly technical MRI texts on the market. It provides a solid foundation of MR technology and serves well as a study guide or reference text to use in practice.” RADIOLOGIC TECHNOLOGY review of prior edition For optimal knowledge of MR imaging, look no further than this user-friendly guide. Highly-experienced technologists clearly...



Organica (Organica)
by Guy Aitchison

World-renowned painter and tattooist Guy Aitchison's book, Organica, covers the last 18 years of his career and focusses in particular on the abstract, free-form imagery that he is known for. Showing tattoos and paintings side by side, the book aims to emphasize the connection between these two very different art media, and the wide variety of unusual offspring that have resulted from this...



PEM Fuel Cell Modeling and Simulation Using Matlab
by Colleen Spiegel

Although, the basic concept of a fuel cell is quite simple, creating new designs and optimizing their performance takes serious work and a mastery of several technical areas. PEM Fuel Cell Modeling and Simulation Using Matlab, provides design engineers and researchers with a valuable tool for understanding and overcoming barriers to designing and building the next generation of PEM Fuel Cells....



Proton and Charged Particle Radiotherapy

This volume is the first comprehensive and practical clinical reference on proton and charged particle radiotherapy. The first half of the book explains the treatment delivery systems used, offers detailed guidance on treatment planning techniques, examines key clinical issues in proton radiotherapy, and reviews recent experience with heavier charged particle radiotherapy. The second half of the...



CCIE: Cisco Certified Internetwork Expert Study Guide, Second Edition
by Rob Payne, Kevin Manweiler

Here's the book you need to prepare for Cisco's CCIE Qualification and Lab Exams. This Study Guide provides: Assessment testing to focus and direct your studies In-depth coverage of all exam objectives Hundreds of challenging practice questions, in the book and on the CD Authoritative coverage of all official exam topics, including: Hierarchical...



PROSTATE CANCER MEETS THE PROTON BEAM: A Patient's Experience
by Fuller Jones

Proton Beam Therapy is an advanced cancer treatment based on the elegant physics of the proton. It is not well known, because there are currently only five hospitals in the U.S. that have the expensive and complex equipment to administer it. Protons have been used for cancer treatment in the U. S. since 1990 with success comparable to all other options, but with minimal side effects. Proton...



Risk-adapted Optimization in Intensity Modulated Proton Therapy (IMPT)
by Daniel Pflugfelder



Scratch Art
by Bob Tyrrell, Nick Baxter, Jon Clue, Filip Leu, Timothy Hoyer, Michele Wortman, Guy Aitchison and many others Aaron Cain

Scratchboard is not a medium that most artists think about much. Many of us played around with crude scratchboards in grade school and never picked up the medium again. However, it turns out to be a versatile fine art medium that has a number of interesting parallels with tattooing, including the need for planning and the lack of any way of erasing. In the new book Scratch Art, this medium is...



Don't Fear the Big Dogs
by Bill Vancil

A heartwarming story of one man's positive-charged resolve to conquer prostate cancer and the incredible journey that unfolded for him and his teenage daughter. Emotion flows through tears and laughter in this tale of a triumphant cross-country...

© 2008 BrightSurf.com