TS-LEA
LEMIC 94
4th December 2007
LHC EXPERIMENT MACHINE INTERFACE COMMITTEE
(LEMIC)
Minutes of the 94th meeting held on 4th December 2007
Present:
1.
A. Ball, P. Ciriani, P. Collier, C. Fabjan, M. Gastal, A. Gonidec,
R. Hall-Wilton, D. Macina (Scientific Secretary), M. Nessi,
M. Pepe- Altarelli, A.L. Perrot, E. Radermacher, J.P. Revol,
R. Saban, C. Schaefer, D. Swoboda, E. Tsesmelis (Chairperson),
R. Veness, W. Zeuner, S. Weisz, W. Witzeling
MINUTES OF THE LAST MEETING
There were no comments to the minutes of the last meeting.
2.
STATUS OF THE LHC INSTALLATION
(S. Weisz)
S. Weisz gave an overview of the status of the machine installation. In
particular:
 All interconnections are completed in the Arcs and Matching
Sections. Seven arcs have been pressure tested and the test of
Arc 12 is scheduled for this week (week 49). In addition,
consolidation work, leak tests and repairs are on-going.
 The work on all low-β triplets has been completed except in
5L (pending the warm-up of Sector 45).
 The DSLC superconducting links have successfully passed the
pressure tests, the ELQA and the leak tests. The
interconnections DFBLC-DSLC (UJ33) and DSLC-DFBAF (4R)
have been completed.
 In the IR7 collimation region, 18/34 collimators are in place
and 7/11 beam-pipe sub-sectors have been installed. In the
2
IR3 collimation region, 8/20 collimators are in place and the
beam-pipe installation is on-going.
The experiments asked to get a detailed written documentation on the
global access test which will be performed during week 2 in 2008. The
documentation has been provided shortly after the meeting.
D. Macina presented the installation planning of the forward
detectors in the LHC tunnel. She focused on the installation of the TAN
detectors. The installation and commissioning plans are mainly dictated by
the access in the tunnel prior and during the cool-down period. All teams,
belonging to 4 different experiments, come from outside Europe and it is
sometimes difficult to combine their schedule with the rather dynamic
schedule of the LHC commissioning. Nevertheless, all detectors are planned
to be installed and commissioned by April 2008. E. Radermacher asked to
include also a detailed schedule for the installation and commissioning of the
TOTEM Roman Pot detectors.
P. Collier presented the 2008 Injector Accelerator Schedule approved
by the Research Board on 28th November 2007. The schedule is available on
the
WEB
page:
http://ab-div.web.cern.ch/abdiv/Schedules/Schedule2008.pdf He pointed out that the end of Physics for
the PS, SPS, AD and ISOLDE is foreseen for the middle of November 2008 in
order to allow an effective cool-down prior to the winter shut-down.
However, they could be used merely as LHC injectors for an additional
month allowing a possible LHC operation until the middle of December 2008.
3.
STATUS OF THE LHC HARDWARE COMMISSIONING
(R. Saban)
R. Saban gave an overview of the status of the LHC Hardware
Commissioning. The status of the machine cool-down is available on the LHC
drawing posted on the LHC Main WEB page. Currently, only Sector 45 and 56
are being cooled-down. All additional information can be found on the
Hardware Commissioning WEB page: http://hcc.web.cern.ch/hcc/ which is
regularly updated.
The aim of the cool-down in Sector 45 is to power the main circuits at
nominal current. However, there are some difficulties to reach nominal
cryogenic conditions for the ElQA and powering. These difficulties are linked
with problems with controls and instrumentation, the suspected assembly
non conformity in the bayonet heat exchanger and with the pollution of the
sub atmospheric heat exchanger volume with air. In order to circumvent the
suspected assembly non conformity in the bayonet heat exchanger, the
circuits for the beam screen and to the magnet cold supports are being
commissioned for those magnets exhibiting the assembly non conformity in
the bayonet heat exchanger. The commissioning program was revisited and
degraded to include only the main circuits. Presently, the DFBAs are ready
for the ELQA and the RF cavities are being tested.
3
In Sector 56 the cool-down is in progress. After a few days, it had to be
interrupted because of a short in a diode box. The concerned cell and the two
adjacent cells were warmed-up and the diode box was opened. Its contents
have been removed, the diode box closed and the insulation vacuum was reestablished and the cool-down restarted. It is expected to be around 80K
before the end of the year.
Following the experience in Sector 78, automated sequences for the
tests of the superconducting circuits have now been defined, implemented
and are being tested as each circuit type becomes available. Computer
assisted analysis tools have also been developed. Extensive training of
engineers and operators is taking place in order to cope with the avalanche of
sectors that need to be commissioned in the first half of next year. The
commissioning program for the other systems (RF, injection, beam dumping,
beam instrumentation, etc.) is well in hand.
4.
STATUS OF THE INSTALLATION AND COMMISSIONING OF
THE CMS EXPERIMENT
(A. Ball)
A. Ball gave a status report on the installation and commissioning of
the CMS experiment. CMS has been designed with a modular structure. This
has allowed a pre-assembly on the surface independent of the underground
Civil Engineering and it will allow a rapid access for maintenance.
Starting in summer 2006, the CMS collaboration took advantage of the
magnet commissioning tests and of the partial installation of some of the subdetectors in the SX5 surface hall to launch the Magnet Test and Cosmic
Challenge (MTCC). At the MTCC, a fraction of all sub-detectors (with the
exception of the pixel system) was operated up to 4 T magnetic field delivered
by the superconducting solenoid and read out with a reduced scale
implementation of the final global data acquisition system (DAQ). Cosmic
muon data have been reconstructed and are in reasonable agreement with
simulation. The MTCC has also provided a preliminary magnet fieldmapping at 3.8 T and 4 T. The preliminary results show that CMS is on target
for 10-4 precision as planned. The final maps need the alignment of the closed
experiment. A number of lessons have been learned during the MTCC: run
operations have shown that there is a good foundation for the final model;
almost every procedure and set of tooling for the detector installation has
been modified or tuned; the closing and opening of the yoke was successfully
tested with minor modifications of the procedure (it takes 3 days to open the
end-cap).
The lowering of the Heavy Elements started in November 2006: both
Hadron Forward (HF) calorimeters have been lowered and put in the garages
for the local commissioning. Between November 2006 and February 2007 the
+z side Endcap Disks (YE+), the Barrel Wheels (YB+) and the Central Wheel
(YB0) have been lowered down. HCAL has been inserted in the YB0 on April
4
2007 while ECAL in July 2007. The assembly of the YB0 services has been on
the critical path for the last 7 months but now all internal milestones have
passed (the work has been completed in November 2007). This implies that
CMS is now ready for the tracker and the central beam-pipe installation.
Finally, the magnet system has also moved underground: the cool-down test
is scheduled for middle of December 2007 and the full cool-down between
January and February 2008. A low current test is foreseen at the end of
February 2008 while full field is scheduled for the cosmic/beam run in AprilMay 2008. Meanwhile, a number of operations, to be repeated in Spring 2008,
were carried on the minus side: installation of the forward vacuum system
(beam pipe, bake-out etc), test of the HF- movement and, consequently, the
correction of some problems with the HF logistics and the test of the closure
of the Rotating Shielding RS- .
While operations were carried on underground, work continued on
the surface: the Barrel Wheels (YB-) were assembled and commissioned and
lowered in October 2007. The CMS Tracker was assembled in 2007 and its
performance tested with cosmics: the quality is excellent with less than 0.3 %
dead/noisy strips. The tracker is now ready for transport to Point 5 and no
problems are foreseen for its installation. The cooling problems which have
affected CMS during the last 3 months are now off critical path.
The latest CMS Schedule is v36.6: the aim is to be closed for 4 T
operation with a complete initial detector (i.e. without the minus side
Electromagnetic Calorimeter Endcaps EE- and Electromagnetic Calorimeter
Preshower ES-) as soon as possible (April-May 2008). ES-/EE- will be ready
for installation at the end of June 2008 and will be installed as opportunity
permits. As soon as the detectors are lowered and installed underground,
they are included in the CMS Global Runs and re-commissioned together
with the other detectors from the CMS underground control room. A. Ball
concluded telling that, of course, the CMS schedule will be adapted to the
machine one as soon as the last one is clarified.
5.
NEXT LEMIC MEETING
The complete list of the 2008 meetings can be now found on the
LEMIC WEB Page. The next meeting of LEMIC will be held at 14:00 on
Tuesday 29 January 2008.
Daniela Macina