Summary of discussions Modularity: agree to focus on modular approach due largely to: Emma requirements document Risks - do not want an issue with one magnet to bring FEL down

Features and characteristics good agreement on key features/characteristics concept of three 1.5m units on a rigid cold strong back: 1.5m cold mass assembly=>test=>fiducialization&K-value assembly of 3x1.5m assemblies on a cold strongback via (fixed) mechanical alignment installation of cold mass on a rigid warm structure compatible with longitudinal shrinkage of cold mass on cooldown Agree on concept of sliding beam chamber through aligned magnet system, then weld transition piece on (need to verify that this is possible technically); This constitutes “Plan A”, and its feasibility should be a major focus of the next phase (phase II prototype) At this level the new end-loaded cylindrical cryostat concept shown by Joel, and bottom-loaded box concept developed by Matthaeus, are compatible. plan B is to provide mechanism for independent transverse positioning of the 1.5m sections; concept is envisioned

Additional considerations Details of cold mass support system should be engineered after a review/survey of concepts used on other projects, e.g. FRIB (as shown by Matthaeus), JLAB, FNAL, etc. Should consider windows for cold fiducial access to support verification of cold mass position after installation on the FEL.

Measurements and Alignment Agreed on magnetic alignment concepts: 1.5m measurements used to determine K-value and assure phase errors meet requirements; important that these are done based on mechanical center determined from poles and/or magnetic center, and that cold fiducials are determined 1.5m segments are mechanically aligned on strongback based on the cold fiducials measurements on complete system are used to calibrate end correctors and phase shifters This process needs to be verified/demonstrated in the prototype phase. The assumptions is that the K-value calibration established on the 1.5m sections continues to hold for each (this is much more challenging to do on the 5m object).

Distribution system High-level concept identified need to identify space requirements functionality needs to be documented Sizing has yet to be established, but basis exists from other systems

Segmented SCU Design Satisfies Physics Layout: Layout Is Space Effective And Provides Flexibility

Vertically loaded box concept

Cylindrical end-loading concept

Present Status of our two concepts Common ground: tunnel layout (modular approach) cold mass layout (strongback) cryogenic connections (external dist. sys.) Two alternative packaging concepts: Vertically-loaded box End-loaded cylinder Selection criteria: ease of assembly cost …