2,134 research outputs found
Three-beam instability in the LHC
In the LHC, a transverse instability is regularly observed at 4TeV right
after the beta-squeeze, when the beams are separated by about their ten
transverse rms sizes [1-3], and only one of the two beams is seen as
oscillating. So far only a single hypothesis is consistent with all the
observations and basic concepts, one about a third beam - an electron cloud,
generated by the two proton beams in the high-beta areas of the interaction
regions.Comment: 7 pages, 3 figure
Transverse modes for flat inter-bunch wakes
If inter-bunch wake fields are flat, i.e. their variations over a bunch
length can be neglected, all coherent modes have the same coupled-bunch
structure, provided the bunches can be treated as identical by their inner
qualities (train theorem). If a flat feedback is strong enough, the transverse
modes are single-bunch, provided the inter-bunch wakes are also flat (damper
theorem).Comment: 2 pages, 1 formula, no figure
Antiproton Stacking in the Recycler
Possibilities to accumulate antiprotons in the Recycler are considered for
three different cases: with current stochastic cooling, with upgraded
stochastic cooling and with electron cooling. With stochastic cooling only,
even upgraded, Recycler looks hardly useful. However, with electron cooling at
its goal parameters and reasonably good vacuum in the Recycler, this machine
would be efficient
Circular Modes for Flat Beams in LHC
Typically x/y optical coupling is considered as unwanted and thus
suppressed--particular exclusions are electron and ionization coolers. Could
some special coupled modes be effectively applied for the LHC complex?
Apparently, the answer is positive: use of the circular modes in the injectors
with their transformation into planar modes in the LHC allows both the space
charge and beam-beam luminosity limitations to be significantly reduced, if not
practically eliminated.Comment: 3 p
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