ISABELLE: superconducting storage accelerator Page: 3 of 9
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For a warm vacuum, the requirements imposed by the pressure bump consider-
ations are summarized in Fig. 4. Here I is the surface desorption co-
efficient. We have chosen aluminum as the material for the vacuum pipe.
This material is cheap and easy to fabricate. Its high electrical conduc-
tivity is advantageous for all types of coherent instabilities. With prop-
er surface cleaning and bakeout at 2000 a vacuum better than 10 torr
can be achieved with an I value of about 2. Thus an 8 cm bore should con-
servatively permit the design current of 10 A.
Given this aperture, a current of 10 A is readily stored in each ring
using the momentum stacking scheme currently in use at the CERN ISR. No
extrapolation above current AGS performance is implied. In fact, we anti-
cipate injecting about 2 X 1012 protons per pulse whereas the AGS is capable
of operating at 1013. Once the stack is formed, it would be rebunched on
the second harmonic. The choice of this low harmonic along with a low im-
pedance for the rf system should prevent bunched beam longitudinal insta-
bilities of the type studied by Sacherer.4
All types of instabilities must be examined at 30 GeV, during acceler-
ation, and in the final 710 GeV stack. So far no cases of instabilities
have been found which imply any particular difficulty.
A variety of options can be considered for addition to such a facility.
We have considered, for example, the addition of a 15 GeV electron ring per-
mitting e-p interactions with maximum center-of-mass energies greater than
100 GeV and with luminosities ~ 10 /cm sec at E = 75 GeV. Another inter-
esting suggestion consists of using one ring as an ordinary accelerator pro-
ducing large numbers of anti-proton at energies - 30 GeV which would be in-
jected and stacked in the other ring. After stacking the anti-protons would
be accelerated to 200 GeV and made to collide with a 200 GeV proton beam in
the first ring. It is believed that luminosities of - 7.7 X 10 /cm- sec can
This proposed facility has attracted favorable attention from a large
fraction of the high energy physics community. Because of this interest and
simultaneous interest in the PEP proposal submitted by SLAC-LBL and possible
new facilities at the Fermi National Accelerator Laboratory, the USAEC Re-
search Division appointed a panel of distinguished physicists chaired by
Professor V.F. Weisskopf to examine the physics and technical arguments for
the various machines and to recommend a course of action for the next few
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Barton, M.Q. ISABELLE: superconducting storage accelerator, article, January 1, 1974; Upton, New York. (digital.library.unt.edu/ark:/67531/metadc1024398/m1/3/: accessed November 15, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.