Dutch researcher Paul van der Nat investigated more than three million collisions between electrons and protons. In his PhD thesis he demonstrates -- for the first time -- that the spin contribution of quarks to the proton can be studied by examining collisions in which two particles (hadrons) are produced.
The spin of a particle can most easily be compared to the rotating movement of a spinning top. In the HERMES experiment at the HERA particle accelerator in Hamburg, physicists are investigating how the spin of protons can be explained by the characteristics of their building blocks: quarks and gluons.
Van der Nat investigated a method to measure the contribution of the spin of the quarks to the total spin of the proton, independent of the contribution of the spin of the gluons.
For this a quark is shot out of the proton by an electron from the particle accelerator, as a result of which two hadrons are formed. The direction and amount of motion of these two hadrons is accurately measured. This method, which Van der Nat applied for the first time, turned out to be successful.
Spin is a characteristic property of particles, just like matter and electrical charge. Spin was discovered in 1925, by the Dutch physicists Goudsmit and Uhlenbeck. In 1987, scientists at CERN in Geneva discovered that only a small fraction of the proton's spin is caused by the spin of its constituent quarks.
The HERMES experiment was subsequently set up to find this missing quantity of spin, and has been running since 1995. It is expected that spin will play an increasingly important role in many applications. The MRI scanner is a well-known example of an application in which the spin of protons plays a key role.
Source: Netherlands Organization for Scientific Research
Related stories:
A new look at the proton
Dutch researcher Paul van der Nat investigated more than three million collisions between electrons and protons. In his PhD thesis he demonstrates -for the first time– that the spin contribution of quarks to the proton can be studied by examining collisions in which two particles (hadrons) are produced.
Seeking Answers to the Puzzle of Proton Spin
Thanks to a series of machine upgrades, researchers at the Relativistic Heavy Ion Collider (RHIC), the newest and largest particle accelerator at the U.S. Department of Energy's Brookhaven National Laboratory, are making progress in answering a fundamental question that has long puzzled physicists: Where do protons get their spin, a property of elementary particles as basic as mass and electrical charge?
A new face for physics
Graduate student helps to shed stereotype
Physicists have a problem. They are stuck with a stereotype. In this, the World Year of Physics 2005, which celebrates the 100th anniversary of the creation of three seminal papers by one of the most vibrant, engaging and admired personalities of his century, Albert Einstein, the image of physicists has deteriorated.
G-Zero Finds that Ghostly Strange Quarks Influence Proton Structure
In research performed at the Department of Energy's Jefferson Lab, nuclear physicists have found that strange quarks do contribute to the structure of the proton. This result indicates that, just as previous experiments have hinted, strange quarks in the proton's quark-gluon sea contribute to a proton's properties. The result comes from work performed by the G-Zero collaboration, an international group of 108 physicists from 19 institutions and was presented at a Jefferson Lab physics seminar June 17.
HAPPEx results hint at strangely magnetic proton
New results from research performed at the Department of Energy's Jefferson Lab hint that strange quarks may contribute to the proton's magnetic moment. If confirmed by data to be taken later this year, these surprising results would indicate that strange quarks in the proton's quark-gluon sea contribute to at least one of the proton's intrinsic properties. The HAPPEx results strengthen the trend found by the SAMPLE experiment at MIT-Bates and the A4 experiment at the Mainz Laboratory in Germany. Results are being presented by University of Massachusetts at Amherst Physicist Krishna Kumar at the APS April Meeting.
Fermilab physicists discover 'doubly strange' particle
Physicists of the DZero experiment at the U.S. Department of Energy's Fermi National Accelerator Laboratory have discovered a new particle made of three quarks, the Omega-sub-b (Ωb). The particle contains two strange quarks and a bottom quark (s-s-b). It is an exotic relative of the much more common proton and weighs about six times the proton mass.
New book tutors future presidents and public on science behind the headlines
In the event of a standoff between the United States and Iran over uranium enrichment, would Barack Obama, if elected president, know enough about the physics of nuclear weapons to assess the threat? In leading the nation toward reduced greenhouse gas emissions, would John McCain as president understand which technologies would best decrease America's carbon footprint?
Shielding for ambitious neutron experiment
In science fiction stories it is either the inexhaustible energy source of the future or a superweapon of galactic magnitude: antimaterial. In fact, antimaterial can neither be found on Earth nor in space, is extremely complex to produce and thus difficult to study.