Presents: RA, CB, HB, SF, MG, JBJ, JJ, GRdM, YP,
SR, TR, FS, TWFollow-up of actions from previous meetings
- Aperture model of LHC (Action: JJ
- pdf file )
- Functional layout
database is still not completely correct. The errors found are collected in
CSV files.
- Comparison between
the aperture model extracted from the database and the one developed by SR
shows differences: these might be due to slight changes in the longitudinal
position of the markers.
- Next steps (to be
reported at next meeting):
- Communicate errors
found in database to S. Chemli (Action: JJ).
- Complete
comparison between model from database and model used by collimation team
(Action: JJ+SR).
- Prepare an
aperture model for beam 2, once the tracking tools will be fully
cross-checked (Action: JJ).
Report from meetings
- TCC -> JBJ
- Sector 7-8 installed first: 24th
October 2005 until 1st April 2006. Critical issue: no SSS for this sector
with jumper was cold-tested so far. It is proposed to change the schedule
of the SM18 shut-down: discussions are still in progress.
- Sector 8-1: QRL test until November
2005. In case of positive outcome, installation will be resumed soon
after.
- Sector 4-5: installation is foreseen
for January February 2006.
- Electrical tests of SSS062 in the
tunnel failed: power in MQT in V1 generates a signal on MQT in V2l.
Further checks are on-going.
- MPWG -> RA
- Software
interlocks are under discussion: feedback from ABP Group is needed. The
time-scale is few weeks. The topics will be discussed in more details in a
future meeting.
- CWG -> RA
- Analysis of
radiation levels for dog-leg dipoles in IR7 showed that they are about a
factor of 3 too high. Solutions are under investigation to protect the
coils. The reason for the difference between IR3 (for which no problem
with radiation levels is expected) and IR7 is also under investigation.
- Tracking beam 2
to establish beam loss maps was requested by B. Dehning.
- SLM -> MG
- Administration:
- Negative balance
of leaves will be automatically compensated at the end of the year from
the saved leaves account (if existing). A moderate unbalance (few days)
will be tolerated.
- Feedback for the
BDI systems commissioning is required (already presented at the LOC
meeting held on September 27th). The deadline is set to Wednesday October
12th).
- Feedback on the
participation to the LHC commissioning is needed: a new LTC presentation
by R. Bailey on the subject is schedule within few weeks.
- HEPP-EPS -> HB (pdf
file)
- A dedicated
Group (CERN Council Strategy Group) was created with the aim of proposing
long-term scenarios for CERN. Input is expected and a special session of
the CERN Council in Lisbon is planned for 2006.
- Survey of LHC
transfer lines -> TR
- Different
reference systems are used at CERN to define the coordinates of the
elements of the various accelerators. It was found that elements in common
to various machines, e.g. magnets in TT40 in common between CNGS transfer
line and LHC transfer line, will have different coordinates depending on
the context. Conversion between the reference systems is not
straightforward! Cross-checks are in progress: no problem was found so
far.
New staff in LOC Section -> Yannis
Papaphilippou
- MG introduces Yannis
Papaphilippou (YP): he joined the section on October 1st. He will take over
the responsibility for SSS from AL by the end of the year. He will be also
in charge of the optics of IR8.
Beam 2 in MAD-X -> TR
- A new sequence to
describe beam 2 counter-clockwise was prepared (it is also called beam 4).
The thick version proved to agrees with the standard beam 2 (the optics
results are the same).
- Next steps (to be
reported at next meeting):
- test thin
version (Action: MG, TR).
- test
chromaticity correction (Action: MG, TR).
- test generation
of SixTrack input files (Action: MG, FS).
- test of tracking
with Sixtrack (Action: MG, FS).
- During the
discussion it is raised the issue of the impact of the experimental
solenoids on beam dynamics. SF reports that this item was checked in the
past and it was found to be negligible. This topic will be considered in the
future as the subject for a study.
Squeeze of the crossing scheme in IR1 & IR5 -> SF (pdf
file)
- In the nominal scenario the IP is shifted
in IR1 and IR5 transversally in order to optimise the available aperture.
- A parametrisation of the crossing angle
vs. beta* is given, which allows choosing how and when the initial aperture
margin is reduced during the squeeze sequence.
- No particular issue is observed for the
proposed sequence of crossing angles: the variation of the strength is
smooth and there is enough safety margin for the strength of the correctors.
- It is decided to store the proposed
sequence of crossing angles in the official database (Action: TR).
- Next steps:
- Define the shift of the IP in IR8 at
injection to
improve the aperture.
- Define the appropriate crossing angle
for IR8 with beta*=1 m or 2 m.
- Define the shift of the IP in IR2 at
injection to
improve the aperture.
- Define the criteria for the crossing
angle during beta squeeze in IP2 (for ions only).
- In particular items 1. and 2. are urgent
to allow MEB activities with the allocation of triplet quadrupoles. A
proposal to deal with these issue will be found off-line and reported at the
next meeting.
AOB
- JBJ proposes
to have a discussion on the geometrical measurement of the triplet
quadrupoles in the context of MEB activities: MG proposes to have a
discussion within the Magnet Team and to report back at the next meeting.
Colour code:
Black: proposed agenda
Red: outcome of discussion at the meeting
Last update on 13-10-2005 11:45:00
MG