Participants: Simon Albright, Maria Elena Angoletta, Fanouria Antoniou, Fernando Baltasar Dos Santos, Wolfgang Bartmann, Aurelio Berjillos Barranco, Thomas William Birtwistle, Louis De Mallac, James Devine, Gian Piero Di Giovanni, Robert Froeschl, Georgi Minchev Georgiev, Matthias Haase, Andrea Santamaria Garcia, Frank Schmidt, Jocelyn Tan, Wim Weterings.

Approval of minutes

The minutes of the LIU-PSB WG #212 meeting were approved.

Communications

• An LIU Project Team Meeting/LIU Beam Performance Meeting was held, where the Linac4 commissioning was presented. The descriptive document for building 245 was reviewed by the Complex Safety Advisory Panel (CSAP) and has been postponed from the beginning of April to mid-May. The document will also include fire and flooding hazards.

Summary of the cost and schedule review (G. P. Di Giovanni)

• The summary given here only concerns the status and recommendations given during the cost and schedule review that impact the LIU-PSB project.
• In general, the review committee acknowledged the remarkable work progress on the LIU project. The advanced use of EVM and management tools was recognized as well.
• The LIU-PSB project is 2.4 months behind the cost and schedule review baseline, with a cost variance of +1.477 kCHF. The positive cost variance is due to savings and couple of large invoices (BE-RF and cabling) to be paid by the time of the review.
• Concerning risks and mitigation, no major risk was identified. The only risks are inherent to planning and equipment installation, so the project was ranked as a minimum risk project, level 1.
• There have been no major changes in the baseline, apart from the request for new BPMs in the BI and BTP lines and new vacuum chambers for extraction bending magnets due to un-anticipated non-conformities.
• Concerning the Linac4, it was recommended to verify that the compensation of the reduced current by increasing the number of injected turns does not impact the performance of the PSB.
• 3.5 MCHF was previously granted to hire new fellows. Now the extension of fellows needs to be approved at the project level and only a limited number of extensions can be given.

LN-to-PSB connection project (A. Berjillos Barranco)

The Linac4 to PSB connection will start during LS2 and the work will be divided into:

Activities outside of the access controlled area (starting the 12^th of November 2018)

• The activities will mainly consist of cabling and de-cabling campaigns, which are recommended to start as soon as December 2018.
• The removal of the Linac2 access system and of the access chicane is foreseen for November 2018.
• The buffer zone in Linac2 is too small, so a temporary buffer zone only for the installation phase will be set-up. This will require the installation of a new access point with a SUSY system and a guard.
• The electrical power consolidation inside the tunnel is managed by J. Devine and will be ready by January 2019.

Activities inside of the access controlled area (starting the 7^th of January 2019)

• Jan-Feb 2019: removal of the LT-LTE-LTL beamlines. Full removal of the LBE-LBS-BI line. This will imply the removal of the concerned magnets, i.e. the kickers and the LT.BHZ10 magnet. The kickers will be removed by TE-MSC.
• Feb-Apr 2019: modification of infrastructures to include shielding.
• March 2019: installation of the new LT.BHZ20 magnet and completion of the beamline.
• May-June 2019: installation and commissioning of the access system in the tunnel.

Activities in the switchyard area (starting on February 2019)

• Re-installation of beam instrumentation and new LBE lines.
• The re-installation of the LBS line is out of the scope of the Linac4 connection project.
• A dedicated person will be needed on site to follow the activities.

The Linac4 connection coordination kick-off meeting will take place on the 7^th of May 2018, and a second meeting will be done if many modifications are demanded. From June onwards the Linac4 will be included in the PS/PSB/Linac2/3 coordination meeting.

Comments

• The removal of the LT.BHZ10 magnet was discussed since it is not known which group was originally responsible for it. It was pointed out that the magnet supports are also common for other types of instrumentation.
• G. M. Georgiev commented that separating the project by area would not work for the cabling since it goes across different areas.
• W. Weterings asked if the thickness reduction of the SWY-PSB shielding wall from 6 to 4 meters will have an impact on the PSB side. A. Berjillos Barranco answered that it won’t.
• G. P. Di Giovanni commented about the several issues affecting the commissioning of the SEMGRIDS for the LBE line. The current wires were found to be melted together. New SEMGRIDS with different material might be installed during the next technical stop of the Linac4. A new design has been promised on time for 2019 by BE-BI but it needs to be followed up closely.

AOB

Report on the ECRs for LS2 (T. Birtwistle)

Multiple groups

• PSB transfer lines (BT, BTM, BTP): magnet modifications, beam instrumentations, beam stopper, vacuum changes.
• New BPM on the BI line: no news.
• Modifications to the PSB extraction main unit: work ongoing.

TE-ABT

• Very good progress.

TE-MSC

• Will take several weeks, work is ongoing.

TE-EPC

• Most of them under approval.
• Potential impact on the septum transformers. Experts working on it.

BE-BI

• Needs to be contacted about the BPMs. T. Birtwistle will organize a meeting with BE-BI.

BE-RF

• The work is advancing.

EN-STI

• The ECR will be sent very soon.

EN-CV

• The ECR of the consolidation of the PSB cooling plant will be sent next week.

PSB Transmission Line Measurements (F. Schmidt)

• The damping resistors of the PSB have a resistance of 10 Ohms and their temperature will considerably increase after the injectors upgrade.
• Studies involving measurements and simulations of the damping resistors were carried out, including four PSB dipoles connected in series and a focusing and a defocusing quadrupole.
• The simulations of the system were carried out by using a 4-pole model of the dipoles, where the vacuum chamber shielding effect is modeled by splitting the inductance into two parts and a small resistance is needed to shield the capacitance. The 4-pole model approximates a transmission line with an incoming forward wave and a reflected wave with a damping term.
• For the dipole in series with an open damping resistor, the measurements and simulations fit very well up until certain frequencies. Higher order models would be needed to simulate the complete behavior.
• For the dipole in series with an open damping resistor of 20 Ohms the simulations and data fit very well.
• It is observed that the damping resistors will damp frequencies above 10⁴ Hz.

Next LIU-PSB meeting: 8^th of May 2018 on the EVM report and ECR follow up.