Tom Shea, Andreas Jansson, Cyrille Thomas NPM closeout Tom Shea, Andreas Jansson, Cyrille Thomas 2018-07-19

Summary As presented, the overall approach and the path to the December CDR is approved. Observations Great progress, even though more work is required prior to CDR Just one example: excellent development of the minimally-invasive maintenance and replacement solution High voltage requirements are similar to devices deployed at other facilities. Therefore we expect that this can be achieved if good HV design practices are followed.

Recommendations Develop more details about how to clean and make particle free Bring in expertise from the CEA cryomodule team If used, verify that MCP is delivered particle free Assure that sparking will not release damaging particles. Estimate the impact of coupling to electromagnetic fields of the beam This has been an issue in similar devices, and may even be the dominant source of background Estimate lifetime of electronics located near the LWU Do not base technology decision on current state of EPICS integration Choose best technology and then develop plan for EPICS integration Compare low current measurements to beam simulations of IPHI in this regime This may provide valuable information for prediction of ESS performance with an iris-limited beam

Actions Perform additional simulations to determine background from particles due to beam loss and photons from cavities. BP provides primary particle tallies BD provides tallies of all particles entering volume of MCP or other detector elements, including estimate of photons from cavities. CEA estimates contribution to background Assure that diagnostics area in the stub meets requirements as a camera location. Action on ESS BD ESS BD should get written confirmation that Daresbury agrees to vacuum chamber change