09.12.2012 Views

Abstracts Brochure - CERN

Abstracts Brochure - CERN

Abstracts Brochure - CERN

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

MOPLS025<br />

MOPLS026<br />

MOPLS027<br />

26-Jun-06 16:00 - 18:00 MOPLS — Poster Session<br />

Experience in Reducing Electron Cloud and Dynamic Pressure Rise in Warm and Cold Regions<br />

in RHIC<br />

S.Y. Zhang, L. Ahrens, J.G. Alessi, M. Bai, M. Blaskiewicz, P.<br />

Cameron, K.A. Drees, W. Fischer, J. Gullotta, P. He, H.-C. Hseuh,<br />

H. Huang, R.C. Lee, V. Litvinenko, W.W. MacKay, T. Nicoletti, B.<br />

Oerter, F.C. Pilat, V. Ptitsyn, T. Roser, T. Satogata, L. Smart, L. Snydstrup,<br />

P. Thieberger, D. Trbojevic, J. Wei, K. Zeno (BNL)<br />

114<br />

Significant improvement has been achieved<br />

for reducing electron cloud and dynamic<br />

pressure rise at RHIC over several years;<br />

however, there remain to be factors limiting<br />

luminosity. The large scale application<br />

of non-evaporable getter (NEG) coating in<br />

RHIC has been proven effective in reducing<br />

electron multipacting and dynamic pressure rise. This will be reported together with the study of the saturated<br />

NEG coatings. Since beams with increased intensity and shorter bunch spacing became possible in operation, the<br />

electron cloud effects on beam, such as the emittance growth,are an increasing concern. Observations and studies are<br />

reported. We also report the study results relevant to the RHIC electron cloud and pressure rise improvement, such<br />

as the effect of anti-grazing ridges on electron cloud in warm sections, and the effect of pre-pumping in cryogenic<br />

regions.<br />

Monitoring of Interaction-point Parameters Using the Three-dimensional Luminosity Distribution<br />

Measured at PEP-II<br />

B.F. Viaud (Montreal University) W. Kozanecki (CEA) C. O’Grady,<br />

J.M. Thompson, M. Weaver (SLAC)<br />

The 3-D luminosity distribution at the IP of<br />

the SLAC B-Factory is monitored using e +<br />

e − -> e + e-, mu+ mu- events reconstructed<br />

online in the BaBar detector. The transverse<br />

centroid and spatial orientation of the luminosity ellipsoid provide a reliable monitor of IP orbit drifts. The longitudinal<br />

centroid is sensitive to small variations in the average relative RF phase of the beams and provides a detailed<br />

measurement of the phase transient along the bunch train. Relative variations in horizontal luminous size are detectable<br />

at the micron level. The longitudinal luminosity distribution depends on the e± overlap bunch length and<br />

the vertical IP beta-function beta*y. In addition to continuous online monitoring of all the IP parameters above, we<br />

performed detailed studies of their variation along the bunch train to investigate a temporary luminosity degradation.<br />

We also used controlled variations in RF voltage and beam current to extract separate measurements of the e + and<br />

e − bunch lengths. The time-history of the beta*y measurements, collected over a year of routine high-luminosity<br />

operation, are compared with HER & LER phase-advance data periodically recorded in single-bunch mode.<br />

Beam-beam Simulations for a Single Pass SuperB-factory<br />

M.E. Biagini (INFN/LNF) P. Raimondi, J. Seeman (SLAC) D.<br />

Schulte (<strong>CERN</strong>)<br />

A study of beam-beam collisions for an asymmetric<br />

single pass SuperB-Factory is presented*.<br />

In this scheme an electron and a<br />

positron beam are first stored and damped<br />

in two damping rings, then extracted, compressed and focused to the IP. After collision the two beams are re-injected<br />

in the DR to be damped and extracted for collision again. The explored beam parameters are similar to those used<br />

in the design of the International Linear Collider, except for the beam energies. Very flat beams and round beams

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!