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While two accelerators have been operating at Jefferson Lab for more than a decade, only one was known for its research probing the particles that make up our universe. But things have changed. A particle physics experiment recently performed with Jefferson Lab's Free-Electron Laser, powered by the lesser-known and smaller accelerator, has had its results published in Physical Review Letters.

The US Department of Energy's Thomas Jefferson National Accelerator Facility today received approval from DOE to begin construction on a $310 million project that will provide physicists worldwide with an unprecedented ability to study the basic building blocks of the visible universe.

New theory work at the US Department of Energy's Thomas Jefferson National Accelerator Facility has shown that more than half of the spin of the proton is the result of the movement of its building blocks: quarks. The result, published in the Sept. 5 issue of Physical Review Letters, agrees with recent experiments and supercomputer calculations.

Research performed at the US 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.

A recent Jefferson Lab experiment may have demonstrated the onset of color transparency for pions, a necessary ingredient for interpreting related experimental results in nuclear and particle physics. The experiment was performed in Jefferson Lab's Experimental Hall C.

Physicists were in a whirl after measurements in the '80s revealed that the spins of the individual building blocks of the proton don't add up to the proton's actual spin. The so-called "proton spin crisis" spurred efforts to pin down where protons -- and neutrons -- get their spin. Pioneering measurements in Jefferson Lab's Hall A have opened the door for measuring some suspected sources of the neutron's spin.

A new medical imager for detecting and guiding the biopsy of suspicious breast cancer lesions is capable of spotting tumors that are half the size of the smallest ones detected by standard imaging systems, according to a new study. The results of initial testing of the PEM/PET system will be published in the journal Physics in Medicine and Biology on Feb. 7.

A proposed $310-million project that will double the energy of the electron beam at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) achieved a critical milestone on Nov. 9, 2007, when the Department of Energy approved the project's performance baseline. The approval, known as Critical Decision 2 or CD-2, Approve Performance Baseline, caps years of planning, preparation and review.

When it comes to energy savings, Jefferson Lab has given a new meaning to dirt cheap. The lab uses a geothermal well system to control heating and cooling on two floors of one wing of its main administrative building. The wing, known as the F Wing, is a three-story, 61,000-square-foot addition that was constructed in 2005.

A sophisticated, new analysis has revealed that the next frontier in particle physics is farther away than once thought. New forms of matter not predicted by the Standard Model of particle physics are most likely twice as massive as theorists had previously calculated, according to a just-published study.