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1. DRAFT MINUTES OF THE 117th MEETING OF THE SPSC HELD ON 14 APRIL AND 15 APRIL 2015
The minutes of SPSC117 were approved (CERN-SPSC-2015-0XX, SPSC-117).
2. CHAIRMAN’S REPORT FROM RB211
The Chairman reported on the Research Board (RB) meeting, RB212.
The following points were presented and, where necessary, discussed:
1) The SPSC congratulated the NA62 Collaboration for the successful commissioning of the Kaon beam and of the quasi-complete detector in their autumn 2014 run, and presented their plans to finalise the detector for 2015 physics data taking. 2) New results from the RD52/DREAM calorimetry Collaboration, based on new data taken in 2014, were presented, as well as their plans and the recommendation by the SPSC for two weeks of running in 2015. 3) The SPSC presented its review of the neutrino platform activities, with a focus on the WA104 and WA105 projects, and expressed its satisfaction about the successful development of the liquid argon time-projection chamber activities, as well as its request to clarify the status of the R&D programme on spectrometers. 4) The SPSC summarised the plans and motivation of the ArgonCube Letter of Intent (SPSC-I-243), and its recommendation to first solve the main open issues within the first stage of the R&D phase at the University of Bern/Switzerland before submitting a proposal for a larger project at CERN. 5) The Committee presented the result of its review of the OSQAR proposal for a search for chameleon particles, and its recommendation for OSQAR data taking in 2015.
The Research Board noted points 1), 3) and 4) and endorsed points 2) and 5).
3. STATUS OF ACCELERATORS
Rende Steerenberg presented the status of the accelerator.
The delivery of beams to ISOLDE, nTOF, the East and the North Areas has started successfully according to the schedule. In parallel to the preparations of the beams for the experiments at the injector accelerators, different LHC beams have been prepared, e.g. the beams for scrubbing. At the AD an important milestone has been reached with the first circulating beam mid of June.
On the LINAC2 side the beam current is still 10% to 15% lower than in 2014. Studies to increase the beam current are ongoing. However the low intensity mainly affects LHC beams and not the beams for the fixed target experiments as for them beam intensities are sufficient for their requirements. LINAC3 is currently restarting with lead ions. The PS Booster is running well and delivers the fixed target beams according to the required characteristics. In parallel to the routine operation the Booster team is also preparing the machine for a future upgrade and successfully tested the new accelerating cavity. The
2 CERN-SPSC-2015-028 construction of the new building for the main Booster power supply has started in view of the extraction energy upgrade from 1.4 GeV kinetic energy today to 2 GeV after LS2. The beam availability of the PS has been very good since the start of the 2015 run and is around 90% or above. Compared to the start-up of the PS in 2014 when the machine had to recover from the modifications made during LS1, the start in 2015 has been very smooth. Nevertheless the gradual increase intensity for COMPASS could not immediately be achieved as at some point the losses at the PS extraction became too high and a slightly lower intensity was delivered for about 2 weeks. During this period the beam was readjusted and losses were reduced and the nominal intensity for COMPASS was reached. The AD start up is also progressing according to plan following the successful relocation of the kicker pulse generators to the new building. The start of physics is foreseen for 6 July 2015. Following the relocation of the kicker generators, the space for the construction of ELENA became available and the installation of the false floor for cable trays and water pipes is progressing well. The SPS is running with about 2x1013 protons per cycle and 85% beam availability to the North Area. The new spill control provides better stability for the TT20 steering and beam to NA62 started on 22 June 2015 as planned. The quality of the SPS spill with slow extraction has improved, resulting in a suppression of a 75 Hz noise. Further improvement on a 50 Hz ripple is required and work for this is ongoing. During the technical stop an endoscopy revealed that the vacuum chamber in one of the dipole magnets was damaged by a beam loss. The vacuum chamber does not yet present a leak, but it might evolve during the run under the influence of pulsing the magnet. The magnet and vacuum chamber will be replaced during the year-end technical stop, but if a leak develops before, a spare magnet and chamber is available and can be installed, which will require a 24-hour beam stop.
4. STATUS OF EXPERIMENTAL AREAS
Lau Gatignon summarised the status of the experimental areas.
The East Area start-up was very smooth, in spite of some last minute issues, in particular cooling problems on several magnets. The marguerite TV beam observation screens did not work initially. This was fixed and a renovation is now considered for the yearly shutdown and maintenance period at the end of 2015. The new timing strategy, which depends on the beam destination, caused some problems for the secondary beam instrumentation, without compromising the operation of these beam lines. The alignment of the multi-target, producing the T9, T10 and T11 beams, was studied and now all target heads can be used. New uninterruptable power supplies have been connected, which should avoid problems with the beam instrumentation and the access system after a power glitch. Already before the official start-up, the secondary emission monitors of the IRRAD and CHARM facilities have been calibrated with a fast extracted beam. Since then the optics configurations required for the 2015 run have been commissioned and the area is operating in a routinely manner. During the technical stop on 15 June 2015, a small water leak was detected on a septum magnet. The leak was located at a very delicate place and is considered to be particularly dangerous for the magnet. The repair has been carried out and the magnet is now working fine, however three days of operation were lost for the North branch of the East Area. The recognised experiment NEXT (RE27) has been approved to use the HARP solenoid in the East Hall without beam, starting in spring 2016. The SPS Committee has selected the winners of the 2015 Beamline-for-schools competition. The winners are
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• Team “Accelerating Africa” from South Africa, who proposed an experiment using a crystal undulator; • Team “LEO4G” from Italy, who proposed using a web cam as beam monitor. The winners will carry out their experiments in the T9 beam line 9 until 20 September 2015.
The North Area has started up well and without major problems. Rather early in the run the T2 target became impossible to move to the ‘target out’ position. The target has now been blocked in a fixed position, which is sufficient for the entire proton run in 2015. The position only constraints the rare access to the gallery from the target area to the experimental hall, which now implies a stop of the whole North Area. In the investigations that followed, it was noticed that T6 showed signs of the same problem developing. Similarly the target has been blocked in the 500 mm BE position that is required for the COMPASS Drell-Yan run. In this case, similar access restrictions are implied for some maintenance areas. Investigations of the cause of the problems are ongoing. The NA61 VTX2 magnet has been repaired and the magnet is ready for the 2015 ion run. The COMPASS experiment is taking data, however it has suffered again from delay with the commissioning of the polarised target magnet control. Moving the concerned access doors has mitigated the radiation problems that were observed at the end of the 2014 run. COMPASS suffers from regular trips of a power converter during hot days, due to high temperature in the building. The NA62 run started on schedule. The hardware and controls software for the ventilation upgrade has been completed in the beginning of June. The experiment is ready for the setting up of beam and detectors, starting at low intensity. The GIF++ facility is now operational with source radiation and beam. It is already heavily exploited and is hosting many user teams. The implementation of a feed-forward system instead of a feedback loop in the extraction servomotors has been successful. Contrary to the run in 2014, in 2015 the two extractions in the super-cycle are now identical, which is a requirement for the NA62 physics operation.
The shutdown work in the AD experimental areas has been completed. For ELENA, space was made available by moving the kicker pulse generators, reshuffling of racks and removing unused cables. The storage space in the new service building is now available for the users and the workshop has been moved there as well. Outside control rooms and barracks are being completed. Special touch panels for beam stopper control were installed last week on the access doors in the hall. The start of the physics run is still confirmed for 6 July 2015.
As the design of the AWAKE facility is now advanced to a level, which allows a proper cost and manpower estimate, the CERN contributions to the project were reviewed in April 2015. Costs adding to the first estimates mainly arise from the electron beam line magnets, power converters, vacuum and RF synchronisation. The total cost at completion are predicted to be 14.9 MCHF with an uncertainty of 15%. The missing costs to completion are 2.6 MCHF in total. Estimated risks are mainly related to manpower for the RF system, the late delivery of equipment and of the related specification documents. The project is taking measures to mitigate these risks. Contingency in resources shall allow for unexpected changes in costs and schedule. The Review Committee noted the high level of external contributions of 6.5MCHF to the project and the very good relationship between CERN and the external partners. The committee endorses the present schedule of completing the two phases of AWAKE, the study of the self-modulation instability and the electron acceleration, to be carried out before the Long Shutdown 2. It also recommended making resources available at CERN to meet this goal.
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The CERN management fully adopted the recommendations and included the additional required resources of 2.6 MCHF in the CERN Medium Term Plan. The recommendations by the Committee to the CERN AWAKE project included to prepare a baseline design document, establish a design change request process, monitor closely the progress of contributions from institutes and to provide on-time documentation of requirements and interface issues. At CERN, the preparation of the infrastructure is continuing, in particular concerning the control rooms and the laser room. A dedicated area in the North Area has been prepared to house the first 10-meter plasma cell. Electron beam injection studies are in full swing to optimise the injection settings.
5. PS AND SPS USER SCHEDULES
Henric Wilkens presented the status of the planning for the SPS lead ion run at the end of 2015 and the requests from the experiments.
The NA61 collaboration requested fifteen days of operation with lead ions during 2015, which was approved at the 210th meeting of the Research Board. Six more requests for heavy ion test beams were made by a number of other projects, the cosmic ray experiments HERD, SuperTIGER, NUCLEON and DAMPE (RE29), the CBM experiment at FAIR (RE21) and the UA9 experiment. The ion run is scheduled from 16 November until 1 December 2015. As it is possible to send lead or fragmented ions to the H4 and in the H8 beam lines in parallel to the ion beam for the NA61 experiment, all requests can be fulfilled.
6. DISCUSSION OF THE OPEN SESSION
6.1 CLOUD
The SPSC is pleased with the progress achieved by the CLOUD consortium, in particular with recent publications of results from the run in 2014 on cloudy experiments (aqueous phase and ice) and small ion studies (CLOUD9) as well as with the accomplishments of the technical run to prepare for biogenic nucleation and growth measurements (CLOUD10).
The SPSC looks forward to the CLOUD10 run in 2015 and encourages both CERN and the CLOUD consortium to provide the adequate support to perform the experimental activity.
6.2 COMPASS
The SPSC notes with satisfaction the progress achieved by the COMPASS collaboration in the analyses of the existing data sets and in publishing the results.
The SPSC is pleased to see the COMPASS experiment ready for taking polarised Drell-Yan data in 2015. The Committee however notes problems with the large drift chamber DC05, the scintillating fibre vertex detector and the magnet’s power supply, and encourages the collaboration and CERN to find timely solutions to make best use of the Drell-Yan beam time in 2015.
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The Committee is pleased with the improvements of the detectors components for the deep virtual Compton scattering (DVCS) programme based on the experience from the DVCS pilot run in 2012.
6.3. ICARUS
The Committee is pleased with the progress made by the ICARUS Collaboration on the analysis of the cosmic ray and CNGS beam data sets. The SPSC encourages the Collaboration to complete the analysis of the full statistical sample collected up to June 2013.
The SPSC recognises the potential interest of the atmospheric neutrino data sample to further develop and tune automatic event reconstruction tools. The Committee encourages the ICARUS collaboration to perform these developments in close collaboration with the liquid Argon-detector communities.
6.4 OPERA
The SPSC congratulates the OPERA collaboration on the identification of the fifth tau- neutrino interaction candidate, and on achieving the observation of tau-neutrino appearance in the muon-neutrino CNGS beam.
The SPSC encourages the collaboration to continue with the oscillation search analysis efforts on the full data set, and to plan for long-term storage of the data.
6.5 P-350 (SHIP)
The SPSC was pleased to hear in its open session the presentation by the SHIP collaboration about the proposal for a facility to search for hidden particles at the CERN SPS. The Committee looks forward to continued productive interaction with the proponents as part of its review procedure.
6.6 P-351 (DUNE-PT)
The SPSC received with interest the proposal describing the DUNE-Prototype (DUNE-PT) project to test full-scale components of a single-phase liquid argon time-projection-chamber (SPSC-P-351).
The Committee supports the motivation of the project and recognises the importance of the engineering and physics goals expressed in the proposal. The Committee notes with pleasure the progress achieved by the collaboration in defining the project at CERN and will review the technical implementation of the project.
6.7 NA63
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The SPSC congratulates the NA63 collaboration for its publications in the last year.
The Committee notes with pleasure the promising results achieved by NA63 during the successful electron data-taking in 2015 and encourages the collaboration to proceed further with their studies in this field. The Committee notes the unexpected background observed in their studies in 2015 with argon ions and encourages the collaboration to understand its origin.
7. FOLLOW-UP ON EXPERIMENTS AND PROPOSALS
7.1 GBAR
The SPSC was informed about the ongoing discussion about the shielding bunker for the GBAR LINAC. The Committee encourages the collaboration to seek the best practical solution together with CERN.
7.2 ACE
The SPSC notes with pleasure the progress made by the ACE collaboration in the analysis of the benchmark measurements. The Committee encourages the collaboration to improve the simulation and to quantify the associated systematic errors.
The Committee encourages the collaboration to work towards the final results and is looking forward to the presentation of these results in the annual review.
7.3 NA61
The Committee received a request from the NA61 collaboration to be provided with higher proton energies as foreseen also for this year’s data taking. The SPSC recommends the modified programme with the condition that the beam energy should be configured such that it is compatible with the scheduled experimental programmes in the other beam lines.
7.4 CAST
The SPSC received with interest the document by the CAST collaboration describing a search for solar chameleon particles and relic axions (SPSC-P352). The Committee will further review the proposal.
7.5 OSQAR
The Committee received additional information from the OSQAR collaboration on the 2015
7 CERN-SPSC-2015-028 run and is looking forward to the results of this run and the chameleon particle search.
8. AOB
8.1 SPSC MEETINGS IN 2016
The following provisional schedule for meetings of the Committee in 2016 was presented and agreed:
• 19./20. January 2016; • 19./20. April 2016; • 21./22. June 2016; • 18./19. October 2016.
9. DOCUMENTS RECEIVED
• Short Status Update on LBNO-DEMO/WA105 (2015), CERN-SPSC-2015-027; SPSC-SR-166-2015; • 2014 Progress Report on PS215/CLOUD, CERN-SPSC-2015-026; SPSC-SR-165- 2015; • Status report of the OPERA experiment, CERN-SPSC-2015-025; SPSC-SR-164-2015; • ICARUS report to the CXVIII Meeting of SPSC, June 23-24, 2015, CERN-SPSC- 2015-024; SPSC-SR-163-2015; • COMPASS Status Report 2015, CERN-SPSC-2015-023; SPSC-SR-162-2015; • Status for 2015, CERN NA63, CERN-SPSC-2015-022; SPSC-SR-161-2015; • Draft Minutes of the 117th meeting of the SPSC, Tuesday 14 and Wednesday 15 April 2015, CERN-SPSC-2015-018; • Search for solar chameleons and relic axions with CAST, CERN-SPSC-2015-021; SPSC-P-352-2015; • Proposal for a Full-Scale Prototype Single-Phase Liquid Argon Time Projection Chamber and Detector Beam Test at CERN, CERN-SPSC-2015-020; SPSC-P-351- 2015; • Agenda of the 118th Meeting of the SPSC, Tuesday and Wednesday, 23-24 June 2015, CERN-SPSC-2015-019; SPSC-A-118-2015.
SPSC documents on the CERN Document Server (CDS): http://cdsweb.cern.ch/search?sc=1&p=SPSC
Christoph Rembser E-mail: Christoph.Rembser@cern.ch
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