Summary notes of the LCU meeting on 20/09/2011
Present: CA, RC, RDM, SF, MF, JJ, EM, RM, RT, GV, SW, PH, SC, AL
Report from meetings
- SLM and general information -> MG
The LHC reached peak luminosities of over 3.e33cm-2s-1 which implies that ATLAS and CMS have to cope with a significant pile-up around mu=20. A further increase in luminosity by bunch intensity and reduced emittance could be possible. Increasing the LHC energy for 2012 will be discussed in Chamonix but appears currently not very likely.
JJ studies the preparation of beta*=1m for ALICE for the heavy ion run in 2012. Proton lead collisions will be tried during heavy ion commissioning and physics time.
It is planned that the responsibility for PTC will also go to
Laurent Deniau who prepares a proposal for the future of MAD-X for end of September. It is planned to organize a ABP-forum on this which includes a presentation of
Frank Schmidt and other people on the use and possibilities of these programs.
RT will describe the use for the LHC. In
case, any additional input should be sent to him.
A new health insurance scheme proposal will be described at CERN on Friday.
Concerning office renovation, it is planned to install
temporary barracks for a couple of years between
buildings 8 and 9 to provide office space during the renovation.
Several of us mentioned their concern about reductions in parking space which is already tight now.
A workshop is planned for the 4-5 October (Tuesday-Wednesday) on shorter stronger LHC dipoles to allow for the installation of cryogenic collimators in the dispersion suppressors. It is planned to move our LCU meeting exceptionally to the Monday before this workshop.
- LBS -> HB
The LBS#28 meeting took place on the 19/09. All experiments have seen some vacuum spikes around their interactions regions. ALICE was strongly suffering from very high background levels induced by vacuum bumps to an extend that they could not turn on their detectors for several fills. Among the reasons for an increase in background levels is the heating of the TDI by the presence of the beam during a fill. The main source is more likely electron cloud.
LHC Optics Measurements with AC Dipoles -> RM (slides)
Ryoichi reported about his studies with RT et al. on optics measurements using the AC dipole.
He simulated the effect of the AC dipole and looked for sources of emittance increase and possibilities to minimize these.
This effect was observed for Beam 2 in 2011 and it maybe caused by a synchrotron
sideband.
Optics parameters were derived from the AC dipole data and extended to the case
of the coupling resonance driving terms and tested in simulations and
experiments.
The extension to other nonlinear resonance driving terms does not pose too many
problems.
Measuring LHC beta-functions close to the half integer resonance-> AL (slides)
Andy Langner (summer student working with RT) reported about the work he did in our group as summer student.
He looked at optics measurements with the AC dipole close to the half integer resonance.
The effect of machine imperfections is enhanced when the tune is brought near to
the half-integer. The first step consisted in comparing the values of the beta
function obtained via the amplitude of phase method. The latter proved to be
more precise even when local errors are included. Therefore, a rescaling
algorithm was developed aiming at improving the amplitude method based on the
phase method. This rescaling proved to be rather effective even in presence of
noise and global errors.
AOB
None
Last update: 22-September-2011
MG & HB
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