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Bates researchers create powerful new electron beam

The MIT Bates Linear Accelerator Center in Middleton, MA, has achieved a major milestone en route to a new frontier in measuring the most basic elements of matter.

Using its stored beam capability, it has created a continuous intense electron beam with a current that is 1,000 times greater than what is normally available.

Electron beams are injected from the Bates Linear Accelerator and stored in the South Hall Ring. These intense polarized electron beams provide a stream of electrons that can be used with internal targets to produce physics events that can be studied more completely and accurately than with a traditional setup.

Physicists from 70 research institutions worldwide conduct research at the Bates center, the physics research lab that the Laboratory for Nuclear Science operates for the US Department of Energy as a national user facility.

To capitalize on the unique internal beam at Bates, a new state-of-the-art detector called the Bates Large Acceptance Spectrometer Toroid (BLAST) is being constructed by an international collaboration of approximately 50 physicists.

The internal beam development and the oversight of BLAST construction is undertaken by the Bates laboratory under the leadership of Professor Richard Milner, director of Bates; Dr. Christoph Tschalaer, associate director; and Dr. George Dodson, BLAST project manager. The facility is due to be completed in 2001.


One of the primary scientific motivations for BLAST is to carry out a precise determination of the charge distribution of the neutron.

"The Bates Laboratory is establishing a unique capability worldwide with the BLAST detector and internal beam," said Professor Milner.

The BLAST detector consists of an eight-sector copper coil array producing a toroidal magnetic field instrumented with two opposing wedge-shaped sections of wire chambers, scintillation detectors, Cerenkov counters and neutron detectors.

The design emphasizes proven technology, commercial electronics and existing data acquisition system software to achieve low cost and short implementation time.

The BLAST project will provide further opportunity to advance the education of a large number of graduate students and postdoctoral associates. More than 180 national and international physicists are members of its user group conducting experiments in basic physics.

A version of this article appeared in MIT Tech Talk on November 25, 1998.

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