Status of the AD’s CCC

1. Status of the AD’s CCC Jocelyn TAN (BE-BI) with the contributions of my colleagues from BI and CRG GSI visit at CERN

2. Agenda Recap on the AD’s CCC Cryolab activities : maintenance, R&D Plans

3. AD CCC Safety valves Pulse tube + He hose Vacuum tank Instrumentation + vacuum equip. Thermal shield 840 LHe Vessel Nb shielding 1032 Courtesy: A. Lees TE-CRG

4. AD CCC status before LS2 Status • Current and intensity measurement provided at end of cycle: resolution of 105 charges • Very good immunity to mechanical vibrations • Fully integrated in FESA (including automatic SQUID set-up) • Expert GUI has been developed • PLC system available to control cryogenic system Limitations • Cryogenic availability : refill every 2.5 months • LHe circuit becomes contaminated blocking the He gas flow in the closed-circuit: • CCC could nevertheless work w/ GHe, up to ~ 7K. • Measurement display only possible at end of cycle • Due flux-jump at injection • Tested: battery power, isolation amplifiers, better calibration cable, … • Superconducting connection in DC coupling circuit kept only for limited range • Currently compensated by imposing a constant DC current

5. AD CCC status before LS2 • Successful run in 2018 with similar problems of LHe reliquefaction (refill every 2.5 month) • Upgraded reliquefier performance 0.89 W + 0.32 W = 1.21 Wequiv. did not help! • No further performance tests possible due to cut of supplies end of 2018 until march 2019 Installed 2 x PV in pumping line protected vacuum from oil back stream (power cut) Courtesy: T. Koettig TE-CRG

6. Investigation of performance degradation • Possible options for performance degradation were identified: • Diffusion of He through the ceramic gap and local influence of insulation vacuum mainly around the beam tube (30 MlI layers and little space) • => excluded by an extensive leak test in May 2019 • with 1 bar GHe @ 293 K in the inner LHe vessel • => insulation vacuum to leak detector LHe or GHe Cryostat insulation vacuum Ceramic gap setup for leak testing before installation. 3 axial mechanical support rods! Test pressure 1.5 bara x 1.25 =1.875 bar differential. Liquid helium vessel inner bore assembly. Configuration for integration into the BCCCA. Courtesy: T. Koettig TE-CRG

7. Investigation of performance degradation • Possible options for performance degradation were identified: • Diffusion of He through the ceramic gap and local reduction of insulation vacuum mainly around the beam tube • GHe impurities due to supply or air diffusion etc. creating layer on 2nd stage HEX Independent GHe supply (not anymore from the central building supply 46 He) Courtesy: T. Koettig TE-CRG

8. Investigation of performance degradation • Possible options for performance degradation were identified: • Diffusion of He through the ceramic gap and local reduction of insulation vacuum mainly around the beam tube • GHe impurities due to supply or air diffusion etc. creating layer on 2nd stage HEX • => 2 x SV are under suspicion to be not backwards leak-tight • => Full metal SV for cryogenic use! • => Plan is to replace it with a combination of a RD and a bleeding valve. Metal sealed SV at 0.5 barg Rupture disk @ 0.5 barg + bleeding valve @ 0.4 barg, O-ring sealed Courtesy: T. Koettig TE-CRG

9. Maintenance plan Maintenance kit for the compressor unit is purchased. Run time is already (~22000 h) for compressor CP1110 with PT415 => CP1110 Molecular Sieve Adsorber, CRYOMECH Description 1 97-20 CP1110 Courtesy: T. Koettig TE-CRG

10. R&D on remote coolingscheme Dry cooling Hegas Gascooling Status and plans: • Currently assessing performance of heat exchanger with coolling circuit connected only to first-stage of cryocooler • Total expected development for a production system of 3 to 4 years • With 2 last years of specific design for any given system Workingprinciple: Use cryocooler withclosedheliumcircuit to delivercoolingpower to remotecryostat Heatexchangers are crucial component Forcedflow of heliumgas (or 2-phase flow) Use cold Joule-Thomsonexpansionvalve for temperaturereduction Project goalsfromcryoperspective: Increasedflexibility in coollingoptionsfor different projects; ReducedependencyonLHe availability Possibility of placing cryocooler awayfromlocations of highradioactivityandmagneticfield Drycoolingandgascoolingoptionspossible

11. Advantages/changes for a future CCC • Cooling pipe with dry coolingoption: no heliumvesselisrequired • Smallerandcheapercryostat design • No ceramic gap in contactwithliquidhelium • Strong pressurechangesperturbations eliminated • Temperaturestability • Shouldnotbeanissuewithcore-less CCC • Mayberequireanactivetemperaturecontrol • Vibrationsfromactivegasflow • Impactshouldbemitigatedwithcore-less CCC • Use single-phasegasflow • To beinvestigated

12. Next steps for AD Study source of flux-jump at injection Re-measure system response, and assess maximum achievable slew-rate Replace Magnicon “Connector box” and “Power supply” by improved electronics, to be installed in a single box Mitigate perturbations through signal processing Install new B-train / “White Rabbit” receiver (same system as for DCCT’s)

13. Next steps for ELENA • There is interest to have a CCC in ELENA • Some pre-requisites though: • Show that AD CCC can run reliably over long periods; • Wait until ELENA is fully commissioned; • If it is shown that intensity measurement is lacking, then we can proceed with an optimised design for an ELENA CCC ; • Timeline: • not before the end of 2021 at the earliest.

14. Next steps for the collaboration Courtesy: T. Dodington BE-BI Cryogenics: FAIR cryostat, new cooling scheme SQUID: new design; outcome on rad hard tests New CCC design: coreless ? Lead? To be presented this Thursday at FCC week

15. Thank you

16. Spare Slides

17. ELENA for experiment efficiency improvement • Factors considered in the synchrotron design • Space constraints: in AD hall • e-cooler: get space + small dispersion • Tune: keep  away from resonances • Bucket to bucket beam transfer from AD • Possibility of a second extraction line

18. Facility overview and layout Transfer line (magnetic)from AD External source for commissioning Electro-static line towardsexisting experimental area Extraction towards new experimental area Courtesy: C. Carli

19. ELENA Cycle eh,v = 15 p mm mrad DP/P = 1x10-3 eh,v [95%]= 6/4 p mm mrad DP/P = 2x10-4 Lbunch (max) = 1.3 m Cycle length about 20 seconds

20. Integration options 1.25m drift tube in Section 1: near septum and kicker LPUs in Section 2