Minutes of the LIS Section meeting held on 4th July 2011
Present: A. A. Akimov, A. E. Alexandri, G. Arduini, J. Brenas, C. Carli, M. Fitterer, S. Gilardoni, M. Newman, G. Prior
General Information (Gianluigi)
Gianluigi reminded the deadline for the submission of the IPAC11 papers to Oliver with copy to him: 22nd of August
A staff child (M. Hourican) is working ]to scan documents that are not available in CDS and collect them in EDMS. Whoever has documents that can be of interest for the group and are not available in electronic format should give them to Delphine.
The
MARS form is going to be
changed for next year: CCM introduced (therefore evaluation based on technical
and behavioural skills), no narrative assessment any more but supervisor and
group leader comments (max. 5 lines). Development objectives to be introduced.
Training will be organized in autumn (after Jeune Genevois). Some modifications
will be done to the software. The form will be available in Word and must be
uploaded in EDH by the supervisor.
E. Jensen has taken over as RF Group Leader from 1/7. E. Ciapala will act as deputy group leader until the end of the year.
Rey Veness will join BE and
he will be the new Section Leader of the Mechanics and Logistics Section of the
BI group replacing G. Tranquille who will take over the Experimental Area and
Electron Cooling Section.
SAPOCO: S. Maury will be replaced by V. Mertens.
A Mini-Chamonix Workshop will take place on Friday 15/7. The workshop will examine the possible performance improvement options available during the rest of the LHC's 2011 proton run. It will also consider the experiments' requirements and potential limitations from hardware and beam related phenomena. The principle aim to arrive at a strategy for maximizing the delivered luminosity by the end of the year. The results from, and plans for, machine development will be considered where the knowledge gained might impact the above goal.
LHC: achieved the maximum number of bunches possible with 50 ns spacing (1380 bunches). No significant improvement in luminosity very likely due to instabilities developing just before starting the ramp when the gain of the transverse feedback is reduced to provide sufficient signal for the tune feedback. 1.3 fb-1 have been delivered to ATLAS and CMS and 0.43 fb-1 have been delivered to LHCb. MDs took place from Wednesday: 25 ns has been injected in the LHC (~200 bunches with trains of 24 bunches, bunches with twice the nominal population have been put in collision with small then nominal emittance, the new ATS optics has been tested in IR1 achieving a beta* of 30 cm.
RCS lattice design (Miriam) - slides
Two layouts have been considered having circumferences corresponding to 1/7 and 4/21 of the PS circumference. All solutions have a gamma transition larger than 3.6 (the gamma relativistic factor at a kinetic energy of 2 GeV is 3.13). The main reason for studying the option 4/21 PS is to avoid triple splitting although for that solution the space charge effects will be enhanced and the PS injection kicker rise-time must be shorter.
The aperture of teh magnets has been scaled based on the PS-Booster experience. Gianluigi and Simone noted that the SPS vertical aperture for the fixed target beams is very close to 3 sigmas (SPS) and 4-5 sigmas (PS) for the high intensity beams at injection.
In all cases two families of quadrupoles have been considered.
1/7 PS circumference: a FODO lattice with 2 n pi phase advance has been considered giving almost zero dispersion in the straight sections. This solution is very tight in space given the limit in circumference.
4/21 PS circumference: 3 lattices solutions have been considered: doublet, FODO with 2 n pi phase advance and FODO with missing dipole as a dispersion suppressor. The solution based on doublets gives the smallest beta and dispersion and larger gamma transition.
Work will continue with the analysis of the space charge effects for different lattice designs and to study tunability and correction schemes.
Round table (all)
Simone: the 50 ns beam with double batch injection is being verified in the PS . Blow-up is being prepared in the PS. Gianluigi noted that this beam will be taken very likely at the restart after the technical stop. The integrated number of protons on target for nToF and CNGS are above the expected performance.
Jon and Elena are studying the tune diagram in the PS to determine possible resonances and find an optimum working point for operation with high space charge. For the moment only losses have been considered. Gianluigi reminded that it will be important to consider emittance blow-up. Simone noted that there are still discrepancies among the horizontal emittanee measurements provided by the wire scanners. The measurements in the vertical plane agree well. One of the 3 horizontal wire scanners (64) has almost reach the maximum number of scans. Two other wire scanners are available in the horizontal plane.
Antoine is conducting measurements of the trajectories at extraction. A problem with the tune measurement has been discovered few days ago: there is a jitter (~3 ms) in the timing of the tune measurement and because of that the tune evolution during the raise of the bump in 31 cannot be measured. This could explain why the islands collapse onto the core when the bump in 31 is pulsed.
Jaime is completing an application for the tuning of the slow extraction in collaboration with OP. This will be used as well for the tuning of MTE
The PS 2 GeV non-linear optics model is being measured (Antoine). Once the model will be available the application writen by Jaime could be used to tune the slow extraction at 2 GeV and a slow extraction to the East Hall could be set-up to verify the quality of the slow-extracted spill to verify the feasibility of extracting ions (oxygen) in the East Hall for radio-biological studies. The past attempts made by OP were not successful because the extraction settings have been simply scaled from 24 GeV to injection energy without considering the difference in the non-linear field components between 1.4 and 24 GeV.
Myriam is finalizing the calculation of the settings for the MTE extraction with the electrostatic septum 31.
Gersende is helping Sandra to conduct measurements of the detuning with intensity in the PS at 1.4 and 2 GeV to characterize the total impedance of the machine. No more support is provided by BNL for comparison of the MARS code versions at BNL and CERN. No more manpower is available to run the simulations at BNL after the departure of a Greek post-doc from BNL. Gersende is investigating possible options with H. Kirk and within EuroNu.
Gersende noted that she experienced difficulties to get support for the installation of computers for new collaborators by the BE Desktop. She also noted that not all the office furniture was available (chairs) in the offices were the students were accomodated.
Christian: Transfer line LINAC4 PSB: the switching magnet in front of the LINAC4 dump (should have been a C-type magnet) will be replaced by a series of 3 short dipoles with a different horizontal position. This option is being investigated in collaboration with the integration team.
A beam dynamics PSB meeting took place this morning. Jean-Baptiste Lallement studied the implications of a slower modulation of the energy of the beam delivered by LINAC4 as the previous requirements were not achievable by the ramping cavity (too larger power required). The slower modulation will imply a larger number of hits for the stripping foil but this should not be an issue according to Christian.
Simone asked whether measurements and simulation of the emittance of the various beams delivered by the PSB as a function of intensity exist. Christian replied that measured values exist and he will provide them to Simone (Action: Christian). The expected value of the emittance of the beam delivered by the PSB with LINAC4 are not yet available.
Vivien Raginel (BE-OP-PSB fellow under the supervision of Bettina) is working on determining the possible performance of the LINAC4 - PSB when operated with protons and with injection at 50 MeV.
Gianluigi announced that he will be absent from Thursday 7th July to Friday 22nd July.
Next meeting
Monday, 1st August 2011 at 14:00 in room 6-R-012
Agenda to be confirmed
General information (Gianluigi)
Round table (all)
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