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LNO section meeting - Activity report by the staff
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6/2-004 (CERN)
LNO section meeting
LNO section meeting with activity reports by the staff
In the introduction Rogelio says that the LNO section currently has fewer meetings, concentrating more on summaries from more general activities and joint meetings, like our last meeting joint with CAP. He encourages feedback on the frequency and contents of the LNO meetings.
He welcomes the new LNO members that joined this year: Georgios Katsanevakis, summer students Evan Root, Felicia Houng and Marc Jebramcik who joined as staff in May working on FCC-ee and getting involved in LEIR to succeed Felix.
News: the LHC runs well and the performance of the recent special heavy ion runs with, for the first time, oxygen and neon greatly surpassed expectations. Oliver Brüning has been appointed as ATS director from 2026 as also announced in CERN news.
OMC, Ewen, slides
Since the last meeting, 3 PhD thesis related to LHC and PS OMC activities were successfully defended by Mael Le Garrec, Vittorio Ferrentino and Wietse Van Goethem. Ewen also lists many (>10) OMC related contributions to this year’s IPAC conference. The LHC commissioning this year was particularly busy : polarity swaps in 2 IRs, first operational commissioning with flat optics, smallest beta* and strongest ATS so far, multiple VDM cycles and multiple ion cycles including pO, OO, PbPb. The largest peak beta-beat of 275 % so far was recorded in pp commissioning. Corrections with extrapolation of local coupling and local optics corrections worked well for IR1 and IR5 and substantially helped to reduce beta-beating to the typical 10-15% level. Some energy errors re-appeared in spite of specific attempts by OP to control and correct this by adjusting orbit corrector strengths. Collimation hierarchy breaking was observed and reduced using phase knob shifts.
LEIR, Transferring activities, Felix
After 11 years at CERN, Felix will leave end of August and is transferring his various working and supervision activities. Most of the handover is already well advanced.
FCC-ee tuning, EPOL, PPG+WG2a, Jacqueline, slides
Jacqueline briefly reports about 3 activities.
1) FCC optics tuning aims at achieving the design performance in the realistic machine, based on measurements, corrections, hardware specifications and learning from existing machines, She shows some highlights of ongoing studies illustrating improvements in dynamic aperture by using different knobs and sextupole optimization. She illustrates planned FCC-ee commissioning steps starting with threading of beams around the ring in the ballistic (final-focus-off) optics, followed by relaxed optics (reduced beta*) work on the way to design physics operation. Helmut asks when solenoids would be turned on and adds that this could be done in a transparent way and left to the end using the non-local compensation scheme presented later in this meeting.
Rogelio adds that it is planned to return to more frequent FCC tuning meetings following the current conference and summer period.
2) The EPOL studies deal with energy calibration, polarization followed by resonant depolarization and options of monochromatization to reduce the energy spread at interaction points. Jacqueline illustrates current highlights involving ABP members including predictions of polarization levels by Yi Wu and implementation of spin in Xsuite by Giovanni Iadarola et al. and lists the next steps for the pre-TDR phase.
3) ESPPU: PPG and WG2a. Jacqueline is involved in the European Strategy for Particle Physics update process. She acts as the scientific secretary in the PPG - accelerator science and technology subgroup as well as in the WG2A project comparison activity. The next big step is to provide input for the briefing book by end of September providing material for the ESG strategy drafting in early December.
FCC-ee optics and layout, Sofia Kostoglou, slides
Sofia presents the FFC-ee optics and layout working group activities chaired by Ghislain, that is responsible for the technical layout and design of the optics for the FCC-ee collider. A current main activity is the comparative evaluation of different optics with input from all relevant teams to be summarized in a comparison report by December in view of a decision to be taken in early 2026 to select the preferred baseline optics. The input is also based on hardware needs and constraints, like maximum magnet length (12 m), minimal distances between magnets as well as taking into account integration and space reservation for absorbers, shielding, support structures, monitors and RF-specific needs.
FCC-ee non-local solenoid compensation, Helmut, slides
Helmut presents a summary of work performed with Andrea Ciarma, Manuela Boscolo based also on ideas of Pantaleo as well as experience from DAFNE and LEP on a non-local solenoid compensation scheme where the anti-solenoids are moved just outside the final focus quadrupoles. The solenoid bump is closed using orbit correctors starting in the shielding solenoid and by taking into account the small (max. 8 mrad) effective beam rotation by the solenoid in the final focus quadrupoles by adding skew quadrupole windings to these quadrupoles. The quadrupoles and anti-solenoid are aligned on the straight-line solenoid-off orbit. Compared to the local scheme, the synchrotron radiation power and vertical emittance increase in the interaction region are significantly (>2x) reduced. A detailed writeup is ready and will soon be public. Next steps will be to make this generally available in the optics repository and Xsuite.
FCC-ee LCC optics design, Marc, slides
Marc introduced straight sections of the GHC optics sections into the LCC lattice, followed by rematching and first successful dynamic aperture and collimation studies.
Xutils, HL-LHC optics, Kyriacos, slides
Kyriacos reports on introducing Xutil features into Xsuite following the ideas presented in the previous joint LNO+CAP meeting and optimisation of HL-LHC optics.
CLIC & HALHF BDS design, Vera Cilento, slides
Vera reports that the CLIC BDS (beam delivery section) readiness report (RDR) and ESPPU have been finalized. The CLIC baseline design is for 380 GeV, two detectors, with plans for 550 GeV and a maximum of 1.5 TeV. She also reports on the HALHF (hybrid, asymmetric, linear Higgs factory using plasma- and RF-based acceleration) BDS design studies and other linear collider activities including experimental work on ATF2 and the 10 TeV plasma collider studies led by Spencer Gessner from SLAC/Stanford university.
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