Vladimir Litvinenko, APEX Workshop 11/02/20006
IBS suppression lattice
Mei Bai, Joanne Beebe-Wang, Peter Cameron, Roger Connolly,Angelika Drees, Alexei Fedotov, Wolfram Fischer, George Ganetis,
Vladimir Litvinenko, Nikolay Malitsky, Aljosa Marusic, Christoph Montag, George Parzen, Fulvia Pilat, Vadim Ptitsyn, Thomas
Roser,Todd Satogata, Steve Tepikian, Dejan Trbojevic, Nick Tsoupas, Jie Wei
Vladimir Litvinenko, APEX Workshop 11/02/20006
Content• What is IBS suppression lattice?• What are potential gains from IBS
suppression lattice?• What did we tested?• What should we test?• Conclusions
Vladimir Litvinenko, APEX Workshop 11/02/20006
Motivation•Increase the Au-x Luminosity Life-time
•Reduces Back-ground•Simplify requirements on Electron Cooling
Vladimir Litvinenko, APEX Workshop 11/02/20006
Transverse IBS in RHICThe main contribution to the transverse IBS in RHIC come from the arcs, most of which comprised of FODO cells
€
dεxds
= H s( ) ⋅ dδE2
ds; H s( ) = γ xDx
2 + 2α xDxDx′ + β xDx′2
€
dδE2
ds∝ Nσ sσ r
2σ r'; Hmod s( ) =
H s( )β y (1+α x
2) + β x (1+α y2)
Vladimir Litvinenko, APEX Workshop 11/02/20006
Relative transverse IBS rate in RHICPresent operatingpoint
Qx
Qy
NOTE: Qx.y are tune advances per one FODO cell
Vladimir Litvinenko, APEX Workshop 11/02/20006
Reduction of the IBS rate, i.e. increase of the luminosity lifetime
Qx/cell
IBS(0.22)/ IBS(Qx)
Present operatingpoint
NOTE: Qx are tune advances per FODO cell
Qy = (0.9 or 1 or 1.1) Qy
90o 108o72o 126o 144o
Vladimir Litvinenko, APEX Workshop 11/02/20006
Transverse IBS in RHIC for test lattice
Vladimir Litvinenko, APEX Workshop 11/02/20006
Test lattice for IBS suppression
S.Tepikian
Vladimir Litvinenko, APEX Workshop 11/02/20006
S. Tepikian
Vladimir Litvinenko, APEX Workshop 11/02/20006
Transverse IBS in RHIC for test lattice
A.Fedotov
Vladimir Litvinenko, APEX Workshop 11/02/20006
S. Tepikian
Vladimir Litvinenko, APEX Workshop 11/02/20006
Cu101 Ramp Editor Settings
T. Satogata
Vladimir Litvinenko, APEX Workshop 11/02/20006
Cu101 Beam Experiment, RampingVladimir, Steve, Al, Vadim, Nikolay, Mei, NickL, Roger, Dejan,
Rob, …
T. Satogata
Vladimir Litvinenko, APEX Workshop 11/02/20006
Cu101 Beam Study Ramp Items Circulated beam easily in both rings , injection retuned
Injection emittance is beautiful (6-7 mm mrad), optics okay Four ramps, using only blue ring (yellow q89 PS not swapped)
Two ramps with Cu101, slow factors 2 and 3, still excursions and quench protection trips on q6 power supplies Two ramps with Cu102, to lower energy (=91.4), slow factor 1
Ramp tuning is mainly orbits/tunes, though coupling is an issue Tunes/chroms in Cu101 now match well with model at injection
Chroms within 2-3 units, tunes within 0.03-0.04 Orbit/coupling corrected at injection, propagation up ramp not
good Dispersions re-measured in both rings at injection, looks okay Transition never really explored, timing was always wrong and
should be dead-reckoned for next study
T. Satogata
Vladimir Litvinenko, APEX Workshop 11/02/20006
S. TepikianWent to 31 GeV test
Vladimir Litvinenko, APEX Workshop 11/02/20006
S. Tepikian
Vladimir Litvinenko, APEX Workshop 11/02/20006
S. Tepikian
Vladimir Litvinenko, APEX Workshop 11/02/20006
Vladimir Litvinenko, APEX Workshop 11/02/20006
???
Vladimir Litvinenko, APEX Workshop 11/02/20006
S. Tepikian
31 GeV test
Vladimir Litvinenko, APEX Workshop 11/02/20006
S. Tepikian
er
Vladimir Litvinenko, APEX Workshop 11/02/20006
Hardware Limitations• Power supplies, leads and quenching • Current distribution limitations - H & V strings, the
tree of shunting PS…• Sextupole strength • Growth of t and strength of t quads • Matching with desirable * - Not needed for the
test• Dynamic aperture• Effects on coupling compensations scheme,
diagnostics using specific tune advances, etc….
Vladimir Litvinenko, APEX Workshop 11/02/20006
Latest simulations IBS calculation based on exact Martini’s
model for dedicated experiment on IBS suppression (RHIC run-7):
Au ions, 100 GeV/nex=15 p mm mrad (95% normalized)ey=10 p mm mrad (95% normalized)
RF: 300kV, h=360 to avoid loss from the bucket
Several bunch intensitiesA.Fedotov
Vladimir Litvinenko, APEX Workshop 11/02/20006
Simulations: Bunch with intensity N=1e9, red – standard run-7 lattice; blue – 92 deg. phase advance lattice with the same RF voltage; green – 92 deg. lattice with voltage adjusted to have initial bunch length as for run-7 lattice.
A.Fedotov
Vladimir Litvinenko, APEX Workshop 11/02/20006
Suggestion for the experiment1. Due to possible fluctuation in IPM
measurements, for convincing comparison of various lattices recording of emittance growth over the period of 2 hours or more is desired.
2. Experiment conditions for IBS suppressed lattice should be the same as for typical dedicated IBS experiment: 6 bunches, two for each of 3 different intensities.
3. Higher intensities per bunch are preferred.
A.Fedotov
Vladimir Litvinenko, APEX Workshop 11/02/20006
Conclusions• Already developed lattice (92o) promises to
reduce transverse IBS by 1/3rd • Good injection and reasonable ramp to 31 GeV
(cross the t) had been tested• IBS tests at 31 GeV were indecisive and
confusing• Examine possibility of further increase in the
phase advance with present hardware• Two hours measurements: both the base-line and
IBS suppression lattice are desirable• Requires tests of power supplies before the Run 7• Using both the yellow and the blue is very desirable
Vladimir Litvinenko, APEX Workshop 11/02/20006
Go over the IBS