Minutes of the LIS Section meeting held on 10^th October 2011

Present: G. Arduini, H. Bartosik, S. Gilardoni, C. Hernalsteens, A. Lachaize, S. Maury, M. Newman, Y. Papaphilippou, G. Prior, R. Wasef

General Information (Gianluigi)

Gianluigi welcomed two new members of the section Raymond Wasef (VIA fellow to work on the PS Upgrade under the supervision of Simone) and Cedric Hernalsteens (doctoral student to work on MTE under the supervision of Massimo Giovannozzi).

The preparations for the publication of the flexibility posts are finished.

A BE retreat has taken place: go ahead for the publication of 4 additional posts on top of flexibility ones already mentioned last time and on top of those already published (in LIS and LCU): (survey technician, engineer/physicist for impedance and collective effects, engineer/physicist for ions and collective effects, engineer/physicist for replacement of Christian and Stephan who are now leading the effort for ELENA). These post should be published by the end of the year.

Contribution to LAGUNA-LBNO EU initiative: Yannis will contribute to the design of a High Power Proton Synchrotron (HP-PS). This will be a 30-50 GeV machine with the Low Power SPL as injector and capable of delivering a 2 MW beam in the CERN North Area. We can certainly make use of the experience gained with the design of the PS2 for this machine and go for a simplified design. A second subject of study will be an accumulator ring coupled to a 5 GeV High Power SPL. Two fellows will be assigned to ABP for that. One of them in collaboration with RF (F. Gerigk)

Simone asked whether it would make sense to combine this study with a possible replacement of the PS as LHC Injector. Gianluigi thinks that at this stage it is better to keep the injector upgrade study and the neutrino study separate in order to optimize the design and costs for neutrino physics and only later evaluate which modifications and additional costs (if any) would be required for using this machine as LHC injector.

LHC: Reached a luminosity of ~3.4x10³³ cm^-2s^-1. More than 400 pb-1 have been accumulated during last week. This is a good production rate taken into account that 12 hours have been dedicated to a 25 ns MD followed by a short physics fill with 25 ns beam and a small number of bunches. Furthermore 6 hours have been devoted to the setting-up of the Abort Gap cleaning at 3.5 TeV.. The total integrated luminosity is now close to 4.6 fb^-1.

CNGS: at the last IEFC a proposal has been presented to deliver beams with LHC type structure and sufficient spacing to allow a precise reconstruction and comparison among the proton distributions and the neutrino distributions.

ELENA Project (Stephane) - slides

Motivation: Gain of a factor 100 in antiproton flux at low energy by decelerating the antiprotons to 100 KeV. Presently done with RFQ and degraders.

An electron cooling system will be installed only and no stochastic cooling as the latter is not effective at low energy. Low beta and dispersion are required at the electron cooler position. Compensators for electron cooling (both for compensating coupling and kicks) will be required.

One of the challenges ELENA design will have to face is the extreme sensitivity to stray fields. This is already visible in AD at low energy. Orbit distortions are observed and depend on the crane position and on the entrance door position for the experimental area.

Other design challenges include: space charge, IBS, impedance effects. Bunch length and transverse emittance are critical parameters as they could further enhance these low energy effects.

A new experimental area is now requested (for the experiment GBAR) and this will require moving the kicker platform outside.

AD consolidation is now required in order to extend the lifetime and enhance reliability of AD over a period of at least 10 to 15 years as the the low energy part of the project FAIR in Germany is not yet financed and likely it will not be built before 10-15 years.

The installation of a gas jet target in ELENA might be requested and in that case deceleration to 50-60 keV might be required.

Plan: 1 year for TDR, 1 year to build the HW, installation in 2014 and commissioning in 2015.

Round table (all)

Simone:

IEFC has approved the installation of the shielding on top of the Goward road.

ZERO cycles perturb the transition crossing in the following cycle. The correlation with the cycle composition has been evidenced but the origin not yet clearly identified and solved

On a question from Gianluigi Simone replied that the fluctuations in the capture efficiency could be due to fluctuations in the pole face windings currents. An enhancement of the noise could be envisaged to establish a possible correlation.

A discussion has taken place last week on the possibility to enhance the brightness of the LHVC beams in the existing machines. Elias proposed two possible methods:

• triple batch injection in the PS (4 bunches/extraction) into harmonic 14 in the PS. This seems not to be feasible as the bunches extracted from the PSB are not short enough to be compatible with the PS injection kicker rise-time and with the PSB recombination kicker rise-time.
• Increase the bunch length at injection in the PS to minimize space charge. In order to obtain that larger longitudinal emittances would be required from the PSBooster and in that case it would not be possible to blow-up longitudinally the beam before the triple splitting and larger bunch to bunch intensity variations are expected. Yannis suggested to investigate the option of increasing the gamma transition in the PS. This would imply reduing the capture voltage in the PS and therefore increasing the bunch length for a constant longitudinal emittance from the PS. Gianluigi encouraged to investigate this option.

Stephan

MSWG this Friday will be dedicated to ions (LHC and north area).

Gersende

Working on the Proceedings  for Nufact11

Hannes

25 ns beam has been accelerated with low gamma transition. Beams stable up to the flat-top. It seems that with the Q20 optics no longitudinal blow-up is required for getting stable conditions longitudinally. 800 MHz in bunch shortening mode was sufficient. At present we do not have a detailed model explaining the longitudinal coupled bunch instability occurring at high energy and therefore we cannot simulate the effect of the lower gamma transition on longitudinal beam stability.

The distortion of the orbit in the horizontal and vertical plane resulting from the voluntary misalignment of the quadrupoles in the injection and beam dump area and optimized for the Q26 optics does not pose a problem for the machine protection. The beam is still correctly dumped on the beam dump absorber.

Next meeting

Monday,7^th November 2011 at 14:00 in room 6-R-012

Agenda to be defined

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