Here we have the same layout as shown in Figure 1 except that a shield has been added, inside the beam pipe, on the ring outside, in order to intercept the synchrotron radiation generated by the decay electrons in the 5 Tesla dipole field. The shield keeps the synchrotron radiation photons from hitting the beam pipe anywhere near the outer superconduting coils. With this shield the horizontal spread of the beam pipe can be dramatically reduced. The shield cross section is shown in the next figure.
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One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.