Participants: Simon Albright, Fanouria Antoniou, Jean-Baptiste Bonnamy, Chiara Bracco, Dario Carloni, Gian Piero Di Giovanni, Jose Antonio Ferreira Somoza, Alessandro Floriduz, Vincenzo Forte, Eve Fortescue-Beck, Robert Froeschl, Greta Guidoboni, Matthias Haase, Christoph Hessler, Iñigo Garcia Lamas, Jorge Maestre, Bettina Mikulec, Antony Newborough, Gabor Petrika, Sylvie Prodon, Benoit Riffaud, Andrea Santamaria Garcia, Frank Schmidt, Lorenzo Teofili.

Approval of minutes

The minutes of the LIU-PSB WG #206 were approved.

Communications

Changes in management

• G. P. Di Giovanni takes over as LIU-PSB project leader and will therefore also chair the LIU-PSB Working Group meetings. He thanked K. Hanke and the LIU-PSB team for all the work done in the past.
• The management of the EDMS documents is taken over fully by T. Birtwistle.
• The PSB Beam Dynamics Working Group is now managed by S. Albright and F. Antoniou.

Meetings

• The LIU-PT meetings in December 2017 were focused on the review of the Chamonix talks.
• The first LIU-PT meeting in 2018 was dedicated to a review of the injection losses in SPS by B. Goddard.
• The SRR for the BI.BPM was approved at the IEFC.
• The ECR for the WireGrid was approved only for the installation of the tank, scheduled for this week. The instrumentation and electronics are not yet ready for installation and impedance studies and vacuum acceptance tests need to be carried out before the approval of this ECR.
• The cost and schedule review meeting will happen the 26^th - 28^th of March 2018 and some preparation needs to be done before that.

Follow-up of open actions

C. Bracco, V. Forte (2018-02-06): Study collimation and losses in the injection line.

• C. Bracco reported that the collimation in the injection line would not be to protect the machine but to reduce activation of the distributor by cleaning the halo. This is a long-term study for LS2 that should be carried out by a PhD student, including space charge effects considerations. Action closed.

New action: C. Bracco (2019-06-01): Long-term study for collimation in the BI-line (mid 2019).

E. Grenier-Boley (2017-12-31): Report about the status of the beam stopper certification for the 2 GeV operations (BTP.STP10).

• The topic will be presented at the LIU-PSB meeting of the 6^th of March. Deadline extended to 2017-03-06.

M. Buzio (2018-01-16): Provide document describing the specifications of the B-Train system.

• A document relative only to the 2 GeV PSB B-train specifications is ready for distribution. A second document containing the combined specifications for all six new systems, based on the same electronic and software components, is still under internal discussion and will be released by the end of March. Deadline extended to 2017-02-06.

M. Buzio (2018-01-16): Investigate and report the options for implementing an online field measurement in the switching dipole BT.BHZ10.

• New magnetic sensors needed to carry out acceptance and qualifications test, along with calibration and validation tests of the online system, are currently being procured. These include 3 m long induction coils for the integrated dipole, two different kinds of Hall-effect sensors (Arepoc HHP probes and ASensor HE244T), and the relative mechanical supports. The first test campaign will be carried out as soon as the first unit arrives at CERN, which is foreseen by the end of March. The result of the first measurements, including the proof-of-concept of the method proposed for the online measurement and the optimal choice of sensor, is expected by mid-May. Deadline extended to 2017-06-12.

B. Riffaud (2018-01-16): Provide a proposal for the support of the equipment in the BTP line.

• The topic will be presented today. Action closed.

T. Dobers (2017-12-05): Make a list of starting points of the transfer lines to be sent for approval in an EDMS document.

• Action reassigned to I. Efthymiopoulos.

New action: T. Dobers: Produce the tilt measurement tool and perform measurements on spare / future magnets.

G. Petrika (2018-01-16): Specify the steps to be taken during the removal of the heaters during the YETS.

• The topic will be presented at the LIU-PSB meeting of the 6^th of February. Deadline extended to 2017-02-06.

G. P. Di.Giovanni (2018-01-16): Find space to store the materials for the Finemet cavities installation.

• Space was found in building 192/R-006; M. Haase will check with transport how to move the equipment from B141 to B192. G. Petrika mentioned that a cleaned-up B141 will be needed by August/September to start the CV work. This action will be followed up at the next meeting. Deadline extended to 2017-02-06.

F. Boattini (2018-01-16): Follow-up of the tip-over issue concerning the installation of the power converters in building 245.

• D. Carloni reported that the issue has been tackled in the descriptive part of the safety file. Action closed.

Thermomechanical simulations on the PSB scraper (Iñigo Lamas García)

• The Window Beam Scope (WBS) that currently scrapes the beam and protects the elements downstream needs to be replaced by a new scraper for the 160 MeV injection.
• The new PSB scraper is made of graphite and consists of a mobile mask and a fixed mask. An empty chamber will replace the mobile mask when it is out to improve the impedance.
• The new scraper has been presented in the integration meeting and the SRR was written in February 2017.
• It is important to have a good thermal conductivity between the graphite and the stainless steel of the housing because the graphite can degas considerably and cause vacuum problems. On the other hand, if the housing expands the contact between the graphite and the stainless steel worsens. A compromise needs to be found between a pressure that is high enough to keep a good contact but that also keeps the structural integrity of the graphite.
• To this end thermomechanical simulations were carried out for three different scenarios, namely:
  • Scenario 1: scraping at low energy.
  • Scenario 2: direct impacts (~10 pulses).
  • Scenario 3: shaving bright beams.
• The simulations were carried out on both planes, and for both positions of the mobile mask.
• First, a FLUKA simulation is carried out on the mask model, obtaining an energy density per proton impact. This is later used in an ANSYS simulation.
• It was observed that the press-fitting of the housing and the graphite produces an initial deformation in the aperture of ~150 um. To limit this effect one can chose a material that is more similar to graphite. It was proposed to change the material to titanium alloy and to an octagonal aperture instead of rectangular. The best results were given by the titanium alloy with rectangular aperture.

Thermal simulations (a good thermal contact is lost at ~95°C)

• Scenario 1: reaches ~60°C for both mobile mask positions in 10 hours.
• Scenario 2: reaches ~30°C for both mobile mask positions after 10 pulses.
• Scenario 3: reaches ~39°C with the movable mask in and ~37°C with the movable mask out.

Mechanical simulations

• Scenario 1: the temperature reduces the stresses.
• Scenario 2: shock waves due to traction or compression are very low.

Comments

• S. Albright asked if we could scrape in both planes simultaneously and hit the corner of the aperture. I. Lamas Garcia answered that they would have to check.
• B. Mikulec asked if the change of material to titanium alloy would be a problem for radioprotection. R. Froeschl answered that there should not be any problem.
• B. Mikulec asked about the budget change concerning the titanium alloy and including the special coatings. I. Lamas Garcia answered that studies are ongoing for the coating and that a cost estimate was still outstanding. B. Mikulec also suggested consulting with vacuum if improvements would be necessary.
• G. P. Di Giovanni asked if there were any problems concerning impedance. I. Lamas Garcia answered that the impedance of the device was within the impedance budget. This was presented at the impedance meeting.
• R. Froeschl commented that the EDMS document should be upgraded to the value of 181 MeV for scenario 3 to be consistent.
• I. Lamas Garcia commented that a prototype will be built at CERN and tests will be performed. It will then be sent to a company for the series production. He confirmed that there should not be an issue concerning the equipment readiness during LS2.

AOB

Preliminary design of the BTP line (Benoit Riffaud)

• The preliminary design of the BTP line will be presented at the ICL meeting.
• After LS2 there will be heavier quadrupoles, so a local support will be used. Four identical girders will be used to support the steerers and the BPMs. The vacuum pipe will be embedded in the quadrupole assembly.
• There is an open question on how to insert the pipe that goes through the shielding wall between the PSB and the PS and more in general how to intervene on the equipment in the wall (one quadrupole and two correctors and potential vacuum leaks). Concerning the pipe, J. A. Ferreira Somoza proposed to section it and the welding should be enough robust against vacuum leaks. For the access to the equipment on the wall, LS2 may offer the occasion to redesign this area of the wall. G. P. Di Giovanni/B. Mikulec will contact the ICL team to check if a preliminary design of the wall could be done to help.
• The floor of the support has been partially replaced from concrete to steel plates.
• Concerning the vacuum configuration, all the pipes need to be new.

Comments

• B. Mikulec commented that it might be worth studying intervention scenarios in case of a vacuum leak in the pipe that goes through the shielding wall. J. A. Ferreira Somoza commented that the risk of a leak was small.
• B. Riffaud commented that the table supporting the equipment at the start of BT could be made thinner to avoid interference with the elements of the ring.
• G. P. Di Giovanni commented that an estimation of the budget needs to be made before the 21^st February, which is the deadline for the cost and schedule review meeting.
• B. Riffaud commented that the budget also needs to be estimated for the BT line, where extra quadrupole magnets will be added and their support must be included.
• G. P. Di Giovanni asked about the alignment tolerances. B. Riffaud answered that he does not know how the line was aligned, but he estimates that this should be of +/- 15mm.
• B. Mikulec asked how the quadrupoles would be aligned. B. Riffaud answered that the quadrupole alignment is no problem thanks to the reference targets.
• C. Hessler commented through email that supports for the quadrupole BTP.QNO10 and the two correctors BTP.MCC10 and BTP.MCC15 are not included in the lists of B. Riffaud. He mentioned that this quadrupole was initially not included in the optics files, but that they have been updated now. The two correctors were initially included under different names in the optics files and have been renamed now. B. Riffaud answered that they are going to re-use the same supports for the two correctors and they have to make another local support for the quadrupole.
   

EVM update (Sylvie Prodon)

• The cost variance shows that estimation of the costs is generally correct.
• The schedule variance is behind by 1.5 months compared to November 2017, which is probably due to the lack of reporting at the beginning of the year.
• The charged budget of 2017 will change until the 31^st of January 2018.
• All the work package holders need to extract the EVM metrics before the end of January in order to prepare for the cost and schedule review.
• There will be an opportunity to update the EVM baselines (work units, weights, and deliverables) from the 6^th to the 21^st of February 2018.

Tour de Table

Julie Coupard reported through email that the YETS ECRs are all released except the one for the new SEMGrid in 4L1. She also reported that the LS2 ECRs will be submitted in the coming weeks. Integration will be confirmed at the integration meeting before the submission of the ECR.

Next LIU-PSB meeting: 6^th of February on the status of the installation of the POPS-B converters in B245 by F. Boattini and a summary of the removal of the heating units in the BTM by G. Petrika.