 |
| Polarized
electron guns at Jefferson Lab. |
Electron accelerators are widely
used to investigate subatomic particles
and forces because scientists learn
a lot by examining how the electrons'
charge and angular momentum (or spin)
interact with heavier particles during
a collision. Polarized electrons,
which act like tiny magnets whose
axes are aligned in one fixed direction,
produce the cleanest and most informative
signals. Recently, Thomas Jefferson
National Laboratory developed and
installed a very intense and stable
source of polarized electrons, the
Continuous Electron Beam Accelerator
Facility (CEBAF). Using new superconducting
radiofrequency (SRF) technology to
accelerate the beam, CEBAF produces
more polarized electrons in one month
than all other electron accelerators
have produced in their lifetimes.
Unique features of the beam include
its precise energy, tiny diameter,
high polarization, and continuous
time structure (previous electron
beams were pulsed). A high-power,
continuous beam allows scientists
to accumulate data at a high rate,
with each interaction sufficiently
separated in time to be fully observed.
CEBAF is used by more than 1,500 physicists
who have submitted more than 300 proposals
for use of the unique machine.
Scientific Impact:
The facility satisfies a demand for
high-current, long-lifetime sources
of polarized electrons, which enable
scientists to extract otherwise inaccessible
information. SRF technology has been
adopted for use in several large accelerators
abroad and several other Office of
Science facilities.
Social Impact: Such
facilities help answer questions about
the constituents and history of the
universe, extending human understanding
of nature and contributing to improvements
in science education. The development
and use of such facilities often has
practical implications; accelerators
have contributed to medical treatments,
for example.
URL:
http://www.jlab.org/news/news_letter/news_oct99/machine.html
Technical Contact:
Dr. Charles Sinclair, Sinclair@jlab.org
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of High Energy and Nuclear
Physics |
