Minutes of the LIS Section meeting held on 29^th August 2011

Present: G. Arduini, S. Aumon, H. Bartosik, J. Brenas, C. Carli, S. Gilardoni, A. Lachaize, E. Métral, M. Newman, Y. Papaphilippou, G. Prior

General Information (Gianluigi)

3 ABP posts have been published (2 physicists positions: optics and PSB Injectors and 1 technical engineer for SU).

A sector retreat has taken place on 4^th August. 5 (out of 6) "flexibility" posts have been approved for ABP (LHC Collimation engineer, Ion Operation Engineer, Survey Engineer for experimental areas in the LHC, PSB and PS upgrade, Applied physicist for ion sources) and they will be opened in the period 2012-13.

The opening of the posts for the ELENA project will be discussed in September.

Gianluigi asked Christian whether he has identified a candidate for the VIA fellowship. Christian replied that hi is still looking into that. Gianluigi replied that we need to take a decision within the next two weeks.

Safety structure : The DG send a memo to inform of  a new safety structure  for the whole accelerators complex (not base on the department). Steve Myers has been appointed as the Complex Manager.

LHC: The LHC has reached a luminosity of ~2.4x10³³ cm^-2s^-1 with bunch population of 1.35x10¹¹ p. The availability of the machine has been rather low in the last month although more than 400 pb^-1 could be accumulated in 1 week. The total integrated luminosity is now close to 2.7 fb^-1. Although initially we have suffered from Single Event Upsets in the second half of the month faults have causes which are not related to intensity. During the last Machine Development Session the optics with 1 m beta* has been tested. Operation with tight collimator settings (4 nominal sigmas) and lower crossing angles (100 microrad half angle) seems to be difficult. Measurements of the triplet aperture have been performed and showed that there enough aperture to run with standard collimator settings and 120 microrad half crossing angle. This will be discussed at the next LBOC and LMC.

Gianluigi informed the meeting that he will be absent on 31/8-1/9 and from 5/9 to 10/9 (IPAC 11) for a duty trip.

PS simulations using PTC-ORBIT (J. Brenas) - slides

Jon presented the work done with PTC-ORBIT during his training at CERN. Simulations for the PS have been conducted initially with no space charge. Magnetic errors have been included. These have been provided by M. Juchno taking into account that the initial estimations of the magnetic errors done at the time of the PS construction were larger than those measured later.

The information available on the functionalities of PTC-ORBIT is still rather poor and it is not easy to get information from the authors.

The representation of the time dependence of machine parameters (like tune and injection bump) seems to work.

Dipolar errors have been introduced to study the width of the integer resonance

The following issues have been found:

• Aperture module not working in PTC-ORBIT while it was in ORBIT.
• Injection module seems not to work and path manager has been used instead.
• The lattice functions provided by PTC-ORBIT are not correct while the values extracted from the statistical distributions seem to be correct.
• A modulation of the tune signal has been observed and its amplitude seems to increase when we approach the integer
• A continuous growth of the emittance has been observed even without space charge. Yannis noted that fringe fields are likely included in the model and this could be the reason. The evolution of the sum of the emittances should be checked.
• Huge emittance blow-up is observed when the space charge switched on. The definition of the macroparticle charge should be checked. The neck-tie in the tune diagram should be shown.
• Orbit oscillations (by more than 8 mm) and unexplained feature of the synchrotron motion have been observed while Christian has already tested this feature. Jon should discuss with Christian and Hannes. Once more the definition of the input parameters should be chacked.

Elias suggested to compare the evolution of the simulated emittance with the measured one. Simone replied that the sextupolar component is not known. Elias replied that this could be a mean to see whether the sextupolar component is important.

Round table (all)

Hannes

Hannes has participated to the 25 ns MD (more than half of the time has been lost due to a cryogenics problem in Sector 23).Instabilities have been observed with the damper pick-up and are being analyzed by him. No sign of instability is visible with the BBQ.

Q20 optics: setting-up of the extraction and transfer to TI2 have been performed. An important orbit distortion has been observed at high energy. This is due to the dogleg (voluntary misalignment of the quadrupoles in the beam dump area. This is at the origin of he dispersion mismatch observed in the transfer line. Gianluigi suggested to verify the trajectory of the dumped beam for the Q20 optics to make sure that the beam is properly dumped in particular when high intensity is accelerated.

Antoine

MTE: study are continuing to understand the origin of the fluctuations in the position of the MTE islands. A dependence of the island separation on the cycle preceding the MTE cycle has been observed.

Gersende

Studies have been performed with the 44-88 MHz scheme. Performance looks very poor. Verifications are ongoing.

Christian

New layout of the Linac 4 to PSB line has been finalized.

Izumi Sakai is going to visit CERN at the end of the week with K. Okabe. A visit of K. Okabe for a few months looks possible.

Christian has discussed with S. Damjanovic Sania to run possible simulations for evaluating the radiological impact of running LEIR with light ions (for radiobiological studies). She has not the time to do this study. Gianluigi suggested to contact Doris.

Simone

The setting-up of the slow extraction at 2 GeV should be performed on Thursday or Friday. Oliver Hans will measure linear and non-linear.chromaticity

Next meeting

Monday, 26^th September 2011 at 14:00 in room 6-R-012

Agenda to be defined

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