Simple Lattice for the Precoo1er/Accumu1ator Scheme Page: 1 of 3
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P NOTE #98
Simple Lattice for the Precooler/Accumulator Scheme
James MacLachlan
October 23, 1980
The Precooler/Accumulator scheme uses RF stacking to collect antiprotons
produced by a multipulse proton extraction from the Main Ring. The stacking
requires X i 2.5m at the injection septum; therefore, a simple expansion of the
p--
present precooler lattice from R= 75m to R =101m is not practical. It is
possible that an appropriate high-X insertion could be designed so that the in-
crease in yT from the larger ring would cancel the decrease caused by the insertion,
but one may wish also to consider lowering YT to run the ring always above transi-
tion so that the p acceleration could go not to 8 GeV but something on the order
of 22 GeV thereby avoiding transition in the Main Ring and helping the Main Ring
aperture bottleneck. This note discusses the possibility of a simple FODO
lattice with missing magnets for dispersion killing and the stochastic cooling
straight sections. For transverse cooling one would need to replace the FODO
straight sections with high a drifts to keep the phase advance over the cooling
section sufficiently small. The same type of insertion as used in the current
precooler design could be employed in the proposed lattice as well.
To obtain a mixing factor n=1/y2l/yT 2=.x.02 requires YT= 4.48 or 10.14
for y =5.8 (4.5 GeV). The lower value is very low for a ring with 100m radius
and almost any insertion tends to raise YT. The present design aims to go about
as low as practical in a simple lattice with the thought that neither y = 5.8 nor
n - .02 are nessarily sacred numbers. If the simulations show n = i.01 works
satisfactorily then yT= 5.0 is adequate; this has been taken as the criterion.
On the other hand going to a production y " 7 might have independent merit and
would result in the larger mixing factor.
Lowy means weak focussing; therefore the X needed for RF stacking will
arise naturally without need for a special insertion. From the standpoint of
betatron envelope economy one does not want to go to much less than x/3 phase
advance. Therefore, the choice was made to work with w/3 cells and the dis-
persion suppression is implimented by missing bending magnets as discussed in
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MacLachlan, James. Simple Lattice for the Precoo1er/Accumu1ator Scheme, report, October 23, 1980; Batavia, Illinois. (https://digital.library.unt.edu/ark:/67531/metadc1015274/m1/1/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.