9th Meeting of the HL-LHC TCC, 23.06.2016
A. Apollonio
9th Meeting of the HL-LHC Technical
Coordination Committee
Participants: C. Adorisio, M. Alcaide Leon, A. Apollonio, G. Arduini, M. Bajko, A.
Ballarino, I. Bejar Alonso, F. Bertinelli, F. Bordry, C. Bracco, R. Bruce, O. Brüning (chair),
H. Burkhardt, R. Calaga, O. Capatina, F. Cerutti, P. Chiggiato, P. Collier, R. De Maria, D.
Delikaris, B. Delille, B. Di Girolamo, S. Fartoukh, P. Ferracin, B. Ferrari, P. Fessia, J. M.
Jimenez, J. Jowett, T. Lefevre, R. Losito, H. Mainaud Durand, P. Mattelaer, L. Miralles,
D. Missiaen, C. Noels, T. Otto, V. Parma, S. Redaelli, F. Rodriguez Mateos, L. Rossi, F.
Sanchez Galan, L. Scibile, A. Siemko, P. Sollander, L. Tavian, J. P. Tock, E. Todesco, R.
Tomas, D. Wollmann, M. Zerlauth, I. Zurbano.
Excused: Y. Papaphilippou, M. Giovannozzi.
The slides of all presentations can be found on the website and Indico pages of the
PLC:
HL-LHC PLC/TC homepage: https://espace.cern.ch/HiLumi/TCC/Default/Home.aspx
Indico link: https://indico.cern.ch/event/515632/
O. Brüning recalled the action from the 8th HL-TCC for the TE-VSC group, regarding the
assessment of the necessity of bellows for each element in the Q1- TAXS area in view
of the future discussion for the BPM integration.
No further comments were received on the minutes, they are therefore considered
approved.
9th Meeting of the HL-LHC TCC, 23.06.2016
A. Apollonio
Draft program for the next HL-LHC collaboration meeting in
November (C. Noels - slides)
C. Noels presented an overview of the programme and available meeting rooms for
the next HL-LHC collaboration meeting, which will take place in Paris on November
14th-18th 2016. A collaboration board meeting will be held on Monday November 14th
morning.
C. Noels reminded that a feedback for the topics of plenary sessions is expected from
WP leaders before June 30th (to be sent to L. Rossi and O. Brüning). For parallel
sessions, the proposed topics should be sent to R. Tomas Garcia before July 7th.
L. Rossi stressed the importance to receive a list of participants for the meeting from
the WP leaders by July 7th. The aim is to present a draft programme to the TCC on July
21st.
J. Jowett pointed out that the dates coincide with the 2016 setup for the ion run, so
some people might not be available for the meeting.
Outcome of the HL-LHC budget review – Part 1 (L. Rossi - slides)
F. Bordry gave an introduction to the outcome of the recent Council week, where the
formal approval of HL- LHC was discussed along with the new CERN Medium-Term
Plan (program and budget), also presented the same day by the CERN DG, F. Gianotti.
Following intense weeks of work with the finance committee, the HL-LHC project has
been formally approved, as well as the CERN 2017-2021 MTP, by the Council of June
2016. Discussions for the possibilities of financing of the cumulative budget deficit will
be carried out in September.
F. Bordry stated that having the formal project approval is a very important milestone.
He nevertheless stressed that the project Cost-to-Completion of 950 MCHF was
already difficult to approve, therefore the possibility for a future increase is excluded.
There will be a thorough scrutiny of the project costs and schedule by the finance
committee and reports will be due at every Council meeting in June and December. F.
Bordry emphasized the importance of the preparation of the next HL-LHC Cost and
Schedule review in October.
He concluded that following the increase in civil engineering costs, a new global
optimization of machine performance must be found, through a close collaboration
between the different WPs.
9th Meeting of the HL-LHC TCC, 23.06.2016
A. Apollonio
L. Rossi presented the outcome of the recent discussions for the review of the HL-LHC
baseline, following the cost-reduction process of June 2016.
He recalled the evolution of the costs related to WP17. In the cost and schedule review
in March 2015, a budgetary envelop of 170 MCHF was estimated, including
infrastructures, logistics and civil engineering (the 10 MCHF dedicated to the SM18
upgrade are not included in the 170 MCHF). At the beginning of 2015, the evaluation
for both surface-based and underground-based options amounted to about 100
MCHF. In June 2015 the decision was taken to adopt the underground-based option,
then the work of WP15 started to define the detailed layout and the required amount
of space to be reserved for the different WPs. Based on the identified space
requirements (larger underground volume and additional surface buildings), a
significant increase of the costs (55 MCHF) was announced. The efforts for the
reduction of the underground volume and the surface building were offset by a further
increase of the civil engineering cost estimate.
In the internal cost and schedule review of WP17, held on May 27th 2016, it was
estimated that 180 MCHF are required for civil engineering and 110 MCHF for all other
technical infrastructures and logistics. This brings an extra cost for the project of 120
MCHF with respect to the 2015 budget estimates and hence in addition to the
approved 950 MCHF.
At the HL-LHC TCC on June 2nd 2016, it was decided to review and identify with all WP
leaders a possible reduction of technical equipment, which would in turn generate
savings on civil engineering and technical infrastructures, while minimizing the loss of
machine performance. These discussions have implications also on the contracts being
signed for civil engineering consultancy (10 MCHF). In order to minimize the impact
on the CE consultancy contracts and avoid costly delay, the ultimate goal of this review
process was to define in three months a new layout, which implied that a new baseline
should have been defined in the next three weeks (i.e. by June 25th).
L. Rossi stressed that this process of minimization of performance loss can be turned
into an opportunity for a further refinement of the ongoing studies.
The focus of the project should now be fully directed to the achievement of nominal
parameters (Llev = 5*1034 cm-2s-1, total HL-LHC integrated luminosity production of
3000 fb-1, with 250 fb-1 accumulated per year). All assumed margins could be exploited
to reach ultimate parameters, if possible: however no additional contingency and
margins must be included to reach ultimate performance, as that is not a
commitment. The possibility of de-scoping of some baseline items, keeping the option
of being recovered later in the project, should also be explored.
9th Meeting of the HL-LHC TCC, 23.06.2016
A. Apollonio
Following these considerations, the HL-LHC project management organized two
weeks of reviews with all WP leaders and group leaders, for a total of 10 formal
meetings. L. Rossi thanked all the people involved in the meetings for their availability
and CERN-interest attitude.
L. Rossi recalled the already ongoing optimization and cost reduction following the
cost and schedule review in 2015 (lamination in MQFX structure, one circuit for triplet
powering, no 11 T dipole in the DS around IP2 for ions, etc.). This process led already
to a cost reduction of 30 MCHF, which combined with a parallel increase of 20 MCHF
(e.g. for the crab cavity tests in the SPS, inclusion of budget for the IT string, increase
in M4P, etc.), brought a net saving of 10 MCHF.
L. Rossi then listed the main outcomes of the review process of June 2016. The crab
cavities have been reduced to two cavities per beam per IP side (for a total of 16 plus
4 spares). The expected impact on performance seems acceptable (see the
presentation by G. Arduini) and it brings additional savings thanks to the reduction of
powering, cooling and ventilation equipment.
It was decided to remove the installation of the new MQYY as new Q4 from the HLLHC baseline (for LS3) and to keep it as a recommended option for implementation in
LS4 and to maintain the current MQY for the nominal HL-LHC. The QUACO program
will continue, as this relies on European funds. Only a small impact on the baseline
performance is expected. The resulting impact will be more pronounced for operation
with flat beams.
The number of systems for quench protection of the MQXF (open options in addition
to the outer quench heaters are: inner quench heaters, CLIQ and – maybe – intra-layer
QH) will feature the minimum required level of redundancy for safe operation.
Concerning collimators, it was decided to reduce the DS collimators in P7 from 4 to 2
per side, implying no 11 T in LS3. The reduction of TCTPM to 8+2 (from 16 + 3) was
also approved.
It was decided to adopt a more integrated layout for TAXN-D2.
A new cold box layout with external distribution box was approved.
The vacuum layout in LSS was improved and a redistribution and optimization of group
resources discussed.
A minimal reduction of beam diagnostics was approved.
A modular optimization of TCDS was discussed with WP14.
Powering of IPQs (Q4-5-6) will be done from the existing RRs via existing power
converters, DFBLs and links.
9th Meeting of the HL-LHC TCC, 23.06.2016
A. Apollonio
L. Rossi summarized the implications following the illustrated baseline changes. An
expected saving of about 75 MCHF compared to the nominal cost and schedule review
in 2015 was quantified. Additional 12 MCHF could be saved on the spares and
consolidation budget. These calculations were done in a very limited time, therefore
it is important to verify their coherency and evaluate the related consequences. An
uncertainty of 5 MCHF is expected, leading to a possible saving of 70 MCHF on the
construction costs.
Despite the cut, there hasn’t been a significant change of project scope and at the
same time no loss of project landmarks and technology innovation. No cut was done
to the approved R&D studies.
Performance reach update (G. Arduini, slides)
G. Arduini illustrated the impact of the changes from the previous baseline on the
performance. Considering the reduction of the triplet gradient (leading to an
increased length), reduction of triplet aperture due to tolerances for cold bore and
beam screen and the reduction of the Q4 aperture from 90 mm to 70 mm, the
minimum achievable β * for round optics is 20 cm, limited by the triplet, while for flat
optics it is about 40/15 cm, limited by the Q4 magnet.
Considering operation with half of the crab cavities, operated at nominal cavity
voltage of 3.4MV (resulting in a total voltage of 6.8 MV as compared to the nominal
10.5MV), the expected performance loss is in the order of 10 % for integrated
luminosity. In this regime the optimal fill length becomes shorter, implying that
efficient machine cycling will become even more relevant.
Such performance loss could be overcome by reducing the crossing angle, which
requires BBLR compensation, presently not in the baseline, or pushing flat optics,
which is limited by the Q4 aperture. The performance loss is larger for ultimate
parameters, assuming the same maximum average pile-up density as in the nominal
case.
F. Bordry pointed out that while the decisions related to civil engineering are
irreversible, the possibility for the Q4 to be changed in LS4 remains open.
A. Siemko commented that the implications of changes to the baseline should be also
evaluated from the machine protection perspective. In particular, a reduction of the
number of cavities (if operated in turn at higher gradient) can have an effect on the
expected failure scenarios. The consequences of one cavity failing can be more severe
if only two cavities are present. This aspect is currently being studied, as confirmed by
H. Burkhardt. O. Brüning agreed that all the implications following the baseline
changes should be evaluated in view of the cost and schedule review in October; it is
important to keep track of all items to be followed up. He stressed the importance of
9th Meeting of the HL-LHC TCC, 23.06.2016
A. Apollonio
not overlooking any aspect that can have an impact on schedule and costs, as was
recently the case for a missing powering cable for the crab cavities.
L. Rossi recalled that the BBLR wire compensator is not an approved item of the
baseline, further R&D in addition to the approved LHC wire test is possible, but the
budget for this has to be found outside of the project. He added that the main driver
for the performance reduction is the reduction of the number of crab cavities.
S. Fartoukh pointed out that the 15 cm β* for flat optics seems pessimistic. G. Arduini
replied that this is a preliminary estimate and a detailed optics analysis is ongoing. S.
Fartoukh and E. Metral noted that scenarios without crab cavities have been proposed
in the past combined with flat optics and long range beam-beam compensation. G.
Arduini replied that this has been considered as an alternative scenario in case of
issues with the operation of crab cavities but it has still to be demonstrated (tests are
planned).
O. Brüning announced that it is planned to give in the TCC an update of layout and
parameters before the cost and schedule review. The total loss of performance should
be less than 10% in order not to redefine the scope of the project. G. Arduini
commented that the pile-up density was kept as for the nominal scheme for the given
estimates. Further optimizations are under investigation.
Outcome of the HL-LHC budget review – Part 2 (L. Rossi - slides)
L. Rossi continued by listing the impact of the change proposals on civil engineering
costs. As an example, the reduction of the number of crab cavities allows for a
reduction of the UA diameter or the suppression of the UL, the reduction of the UW
volume, etc. (see slide 11 for details). The civil engineering, cooling and ventilation and
electrical infrastructure savings will be quantified systematically in the coming weeks.
F. Bordry commented that the reduction of the equipment will have a positive impact
on machine reliability and, thus, on integrated luminosity. He stressed that reliability
will be a key for HL-LHC operation, as demonstrated by the excellent performance of
the LHC over the last weeks.
The HL-TCC will be responsible of ensuring the coherency of the decisions and
coordination between WPs, while the project office will continue the discussions with
WP leaders and group leaders to examine the possibility of further cuts.
The project management will ask all WPs to write a short document in preparation for
the 2016 cost and schedule review, followed by an ECR. As a result, a new version of
the project description will be issued and will be validated by the CERN management.
9th Meeting of the HL-LHC TCC, 23.06.2016
A. Apollonio
L. Rossi stated that following these activities the technical and performance challenges
can become again the main focus of the project.
P. Collier recommended concentrating the project resources on the baseline elements
and not keeping too many options open (e.g. additional RF system options) if not
necessary and if not justified by potential savings or if there is no identification of
potential funding for their implementation. He also encouraged the coordination with
the LIU project for decision making. L. Rossi agreed with the comment, but stressed
that for some elements it could be too early to suppress the studies. As an example, if
crab cavities wouldn’t work, the same budget could be re-distributed to alternative
solutions possibly ensuring a similar performance reach (e.g. 200 MHz system). This is
currently being studied by the ABP and RF groups. In this respect, the SPS crab cavity
test will be an important milestone. F. Bordry agreed with the remark from P. Collier
and added that the outcomes of SPS tests might not be conclusive. L. Rossi concluded
that a final decision will be probably taken in two years, following the tests of BBLR
wires next year and the SPS crab cavity tests.
E. Todesco pointed out that we are currently running at 40 cm β*, which is significantly
better than the design LHC performance. He therefore suggested investigating why
such good performance can be achieved and inject the acquired knowledge into the
HL-LHC project. G. Arduini explained that the gain is mainly related to the exploitation
of margins and tolerances and that this knowledge is already being used for the HLLHC project. O. Brüning added as an example that the achieved very small β-beating
(of the order of 10 %) was not expected at the time of the LHC design report.
E. Todesco then asked how external collaborations are accounted for in the 950 MCHF
project budget and whether additional collaborations could help reducing the budget
cut. L. Rossi explained that they are included in the 950 MCHF and that additional
collaborations will not alter in principle the project budget: collaboration
contributions are accounted as CERN income. F. Bordry added that the management
strongly encourages collaborations and partnerships with industry.
F. Bordry concluded by recalling the importance to have a comprehensive review of
all aspects of the project in preparation of the 2016 cost and schedule review, paying
special attention not to forget anything belonging to system interfaces.
AOB
R. De Maria commented on an action for WP2, confirming that the Q6 in IR1/5 does
not need to be moved in order to achieve the design optics for HL-LHC.