Participants: Simon Albright, Fanouria Antoniou, Wolfgang Bartmann, Hannes Bartosik, Giulia Bellodi, Aurelio Berjillos Barranco, Jean-Baptiste Bonnamy, Jan Borburgh, Louis De Mallac, Gian Piero Di Giovanni, Tobias Dobers, Alessandro Floriduz, Eve Fortescue-Beck, Robert Froeschl, Joel Gomes, Matthias Haase, Bettina Mikulec, Antony Newborough, Federico Roncarolo, Andrea Santamaria Garcia, Jocelyn Tan.

Approval of minutes

The minutes of the LIU-PSB WG #214 meeting were approved.

Communications

• LIU-PT meetings/LIU Beam Performance Meeting: M. Meddahi has sent an Excel sheet to summarise the possible cost reduction analysis per machine. PSB gave back only a few percents of its uncommitted budget, that's the reason for the deep scrutiny we had to undergo. The complete analysis will be presented to the CERN management next week.
• F. Bordry will report the EVM metrics during the June council, for which the EVM data will be extracted and compiled on the 1^st of June by S. Prodon.
• A dedicated meeting is foreseen in two weeks with EPC, integration, and design offices, during which actions will be defined for the ECRs.
• The process of work package analysis (WPA) has started this week with the review of the works for the installation of the new Finemet cavities in the PSB. BE-RF confirmed that they have more flexibility in term of teams (FSU teams) and detailed the schedule of hardware commissioning, which will be reported by D. Hay in mid-June.
• Three documents linked to the demonstrative part of the B245 (POPS-B) safety file are being produced:
  • The water leaks study was circulated in EDMS for engineering check and the comments are being integrated.
  • The access control for the magnet reference room is being circulated in EDMS.
  • The document related to the fire safety analysis is being finalized.
  • The aim is now to present the document to the PS-CSAP on the 21^st of June 2018.
• PSB Ventilation System renovation (CONS item) was dropped for lack of budget, so even the heaters removal is now under review.

Follow-up of open actions

M. Buzio (2018-06-12): Investigate and report the options for implementing an online field measurement in the switching dipole BT.BHZ10.

• A. Newborough reported that the delivery of the magnet is the 1^st of July, so the deadline for the action can be extended. Deadline extended to 2018-08-28.

I. Efthymiopoulos (2018-04-03): Make a list of starting points of the transfer lines to be sent for approval in an EDMS document.

• T. Dobers reported that the document was reviewed together with I. Efthymiopoulos and T. Birtwistle and that almost all the content is there. Will report at the next meeting. Deadline extended to 2018-06-19.

T. Dobers (2018-05-29): Produce the tilt measurement tool and perform measurements on spare/future magnets.

• T. Dobers reported that he will report on the action at the next meeting. Deadline extended to 2018-06-19.

Status of H0/H- Electronics, SEM Grids in LBE and PSB WS Prototype (F. Roncarolo)

SEM grid monitors and wire scanners in the L4T and LBE lines

• The L4T and LBE transfer lines will host the same kind of beam instrumentation to measure the beam profile. The instrumentation consists of a horizontal wire grid, a vertical wire grid, and a wire scanner that measures in both planes placed in a diagnostic tank.
• Six diagnostic tanks are currently installed in the L4T line, while three tanks will be installed during LS2 in the LBE line.
• During the tests in the L4T line, systematic problems were observed, such as non-Gaussian profiles. The grids were removed during the YETS and it was found that some of the wires from the grid had melted together.
• The installed wires were made of tungsten with a gold coating, which melted in some cases and acted as glue. The current hypothesis is that the cables elongated and lost some tension and that they were attracted to each other by some electromagnetic, beam induced force. It is still being investigated if it was a design problem or an operational limit that was exceeded.
• The future plan is to install a new prototype with carbon wires in the L4T line in August 2018. A weaker signal is expected. Another solution under investigation is to have carbon strips which on the other hand will have a reduced special resolution. The aim is to have the final design of the SEM grid by the autumn.

H0-H- monitors

• The monitor consists of two plates, one for H0 and one for H-. The current at each plate is continuously integrated and fed to the interlock. The number of charges will indicate the degradation of the stripping foil.
• The monitors were successfully tested, including improvements in the electronics design. There are still some open points such as the trigger logic, which can be based on the internal 8ns clock or on an external trigger from RF. Another open point is the influence of the E.M.I (Electro Magnetic Interference) noise in the PSB injection region, which should be tested during LS2 (RF pulse will be needed for the tests).
• The system is completely new and will need extensive commissioning, calibration, and threshold studies.
• Additional 16 kCHF will be needed for the series production.

LIU BWS PSB prototype

• In the new fast wire scanner prototypes, the wire position can be retrieved by reading the position of the rotating disk with a laser. The first disk tested was glass, which is optimal for the laser reading, clamped by metal. It was extensively tested in the accelerator and it was found that the glass disk slipped.
• A new metallic disk was installed during the YETS, with Kapton wires. It was found that the Kapton wires were loose and broken before starting the tests. The cause of this is unknown since there is no evidence of control issues.
• The wire scanner will be repaired during ITS1 either by an in-situ intervention or by the exchange of the full scanner.

Comment

• J. Tan asked about the role of the gold coating. F. Roncarolo answered that it helps the fixation of the cable, but it is not needed for the measurements.
• B. Mikulec asked if they will fix the final design of the grids by autumn. F. Roncarolo answered that he thinks it is possible, relying on first results from measurements with the instruments installed in August 2018 and on results from detailed simulations.
• F. Roncarolo commented that it will be challenging to have six of these devices ready by January 2019. B. Mikulec answered that they don’t need to be ready by January, but maybe by May 2019.
• G. Bellodi asked if a last-minute installation of the grids would be possible, provided that the final design is ready by October 2018. F. Roncarolo answered that it is possible, but that it would need to be discussed with the vacuum team.
• G.P. Di Giovanni mentioned that it would be important to also know the associated budget cost with the production of the new equipment.
• B. Mikulec asked what would be the alternative in case the SEM grids are not finalized. F. Roncarolo replied that the wire-scanner could be used instead as they could provide higher resolution, although they may suffer from shot-to-shot variations given that multiple shots would be needed for the reconstruction of the profile. B. Mikulec said that for BE-OP the baseline is still to use the SEM grid.

AOB

Report on the ECRs for LS2 (T. Birtwistle)

Integration studies are the main bottleneck for the ECRs. Only the groups that present changes are reported here:

Multiple groups

• PSB transfer lines (BT, BTM, BTP): work is advancing.
• New BPM on the BI line: waiting the final integration validation and the ECR draft, where only a few more details are needed.

TE-ABT

• The new BT.KFA10 kicker ECR is now under approval and the BEr.KFA14L1 ECR is waiting on impedance studies.

TE-EPC

• The septa transformers for the extraction line components will fit in the existing volumes, so probably no ECR is required.

EN-CV

• They will work on ventilation in low priority to be ready for an unforeseen event.

Next LIU-PSB meeting: 19^th of June 2018, report on the WP analysis for LS2 by D. Hay.