Overview MESA SRF system and machine design Florian Hug on behalf of MESA SRF team

Outline MESA Machine Overview MESA Cromodule Overview Contamination issues MESA modules @ bERLinPro F. Hug – MESA SRF system and machine design 13.9.2017

MESA Overview MESA will be constructed in existing halls from a former MAMI experiment and in a newly erected experimental hall Additional space for future experiments availiable BDX possible Trade off: some project delay due to civil construction time Picture: D. Simon F. Hug – MESA SRF system and machine design 13.9.2017

MESA Overview Beam parameters: Cryomodule parameters: 2 operation modes Beam used for precision experiments in nuclear-/particle physics Cryomodule parameters: 2 modules with two cavities each Modules are under construction by RI company (exspected delivery in October/November 2017) Parameter Guaranteed by RI (vendor) f0(2K) / MHz 1300.00 ± 0.05 Vtotal / MV ≥ 25 Q0 1.25 x 1010 PFPC / kW ≥ 15 Pdiss,stat / W < 15 Pdiss,dyn / W < 25 Basic Parameter max. beam energy 105 MeV (ERL mode) 155 MeV (external beam) max. current in ERL operation 1 mA (later 10 mA) (0.77-7.7 pC/bunch) Number of recirculations 2 (ERL mode) 3 (external beam) F. Hug – MESA SRF system and machine design 13.9.2017

ELBE/Stanford Cryomodules Ordered cryomodules of the 'Rossendorf'-type (2 x 9-cell TESLA/XFEL cavities), which are in use at ELBE at company Research Instruments due to tight schedule → and applied some adaptations: add tuner with piezo elements (XFEL/Saclay-type) use sapphire windows at HOM feedthroughs in addition: include 2K production (heat exchanger, JT-valve, phase separator) and full cryogenic control system, all provided by the vendor in close contact with Mainz and DESY (t.b.d. by RI) Picture: HZDR F. Hug – MESA SRF system and machine design 13.9.2017

Integration of XFEL Tuner RI received STEP-model of the XFEL tuner by DESY 2K-phase separation of the ELBE module needed to be modified : different bottom plate different heating resistors Adapted position for helium level sensor Pictures: RI F. Hug – MESA SRF system and machine design 13.9.2017

Further Developments by JGU Thermal calculations at HOM antenna ongoing (T. Stengler): → Provide optimised thermal connection design to RI → Limitation by heat input from cable, need for heat sink T / K 11.4 Only 1.25 W heat deposition in 1.8 K LHe bath per HOM coupler in cryo budget 1.8 Picture: T. Stengler F. Hug – MESA SRF system and machine design 13.9.2017

Further Developments by JGU Possible solution: Slotline on cold mass to optimize cooling Steel wire between slotline and 300 K (bad thermal connection) Copper bands as thermal connection between antenna and cold mass Steel wire 1.8 K copper strips to load 300 K 77 K 1.8 K slotline copper wire J. Sekutowicz F. Hug – MESA SRF system and machine design 13.9.2017

HIM infrastructure F. Hug – MESA SRF system and machine design 13.9.2017

Contamination issues at MESA MESA is a new accelerator, so no contamination from old machine parts are existent so far But: extent use of liquid and gas targets for the different experiments MAGIX (ERL experiment): Gas target (Hydrogen, later different gases) P2 (external experiment): Liquid Hydrogen target and Hydro-Möller polarimeter atomic hydrogen at 300 mK) Pictures: S. Aulenbacher F. Hug – MESA SRF system and machine design 13.9.2017

Possible project: MESA@bERLinPro MESA Cryomodule (modified ELBE type) Position to integrate MESA Linac Module (5m free space available) F. Hug – MESA SRF system and machine design 13.9.2017

Summary / Outlook MESA will be a superconducting, recirculating linac for particle and nuclear physics experiments Two operation modes will be used - polarized external beam with up to 150 µA @ 155 MeV - unpolarized ERL beam with up to 1 mA (later 10 mA) @ 105 MeV the experiments need gas targets and poarimeters. Accelerator needs to be protected from accidental venting The building timeline makes a project possible: MESA @ bERLinPro. A grant proposal is in preparation to get funding F. Hug – MESA SRF system and machine design 13.9.2017

Thank you for your attention! F. Hug – MESA SRF system and machine design 13.9.2017