Meeting Minutes — CCC Meeting with GSI & Jena

Date: 9 December 2025
Format: Zoom
Topic: Feasibility of copying GSI CCC cryostat design for SHiP-CCC
Participants:

• Gunn (CERN)

• James (CERN)

• Mark (CERN)

• Thomas (GSI)

• Volker (Jena University)

1. Background & Objective

CERN management (department leader) suggested copying an existing GSI CCC design “as is” to avoid additional R&D cost and effort.
The purpose of this meeting was to examine what compromises or modifications would be required if CERN adopts a GSI cryostat design unchanged.

2. Cryostat Copying Feasibility — Summary of Constraints

2.1 Input from Thorsten (Cryogenics Expert, CERN)

Thorsten could not attend due to sick leave, but via a prior phone call raised three concerns about copying the GSI cryostat unchanged:

1. Safety valves — The GSI design may not meet CERN requirements.

2. Additional helium fill port — CERN requires the ability to fill liquid helium manually; GSI design is closed-loop with cold head and compressor.

3. Too many ports on GSI prototype — Excess ports increase long-term vacuum degradation risk.

3. Responses & Clarifications from GSI (Thomas)

3.1 Safety Valves

Thomas has already discussed with ILK (cryostat manufacturer).
ILK proposes installing two asymmetric safety valves:

• 500 mbar

• 400 mbar
  This would satisfy the safety requirement.

3.2 Vacuum Integrity

• All elastomer vacuum seals replaced by Helicoflex metal seals.

• Helium sniffing tests indicate excellent leak tightness.

3.3 Additional Helium Fill Port

• Current prototype has 4 ports, adding a 5th port is feasible.

• Concern: additional heat load, but manageable.

• Mitigation:

  • Increase cryostat height by 5–10 cm.

  • Lengthen warm-to-cold tubes to reduce conductive heat load.

  • Add formed bellows to increase thermal resistance.

4. Constraints of Specific GSI CCC Designs

4.1 HEBT-CCC (GSI)

• Height-restricted design.

• Shorter port length → higher heat load risk.

• Performance of cryostat may be compromised.

4.2 CryoRING-CCC

• Longitudinal length restricted.

• Detector must use only 1 magnetic core instead of 3.

• Result: ~⅔ detector performance (per Volker).

4.3 GSI Prototype CCC

• Fully functional and tested.

• Height is larger—OK for CERN geometrically, but must verify SHiP integration.

• Adding fill port seems feasible.

Ghanshyam asked why the prototype cannot simply be copied with one added fill port.
Thomas confirmed this option is reasonable and should be investigated with ILK.

5. Liquid Helium Operation Considerations

• GSI liquefier requires ~6 weeks to cool from room temperature and fill the volume.

• If CERN copies their design without a fill port, CERN would need to run 6-week cooldown before beam startup → operational inconvenience.

• Reinforces need for manual fill port.

6. Detector Resolution & Design

• SHiP-CCC will use dual-SQUID and axial magnetic shield configuration, so detector resolution remains excellent regardless of cryostat choice.

• Limitations arise only from cryostat geometry, not the SQUID design.

7. Radiation Tolerance Concerns

• MAGNICON SQUIDs and electronics are commercial off-the-shelf, not radiation-hard.

• Only operational experience: AD-CCC for 10 years, low-radiation environment.

• Recent AD-CCC electronics failure — cause unclear (radiation vs aging).

Actions:

• Consult radiation maps of SHiP location.

• Plan dosimetry measurements in AD-RING.

• Request MAGNICON supplier for spare electronics for radiation testing.

  • But lead time is long (≈8 months).

• Radiation test window at CERN beams: Jan–Jun 2026.

Proposal

• CERN may borrow one electronics unit from GSI while waiting for new units.

Mark will request a two-channel SQUID electronics box, compatible with both SHiP CCC and AD-CCC.

8. Noise Reduction Study

• Wolker mentioned ongoing work by his PhD student Svenja on active noise cancellation.

• Successfully removes vibrational background.

• Results to be presented later.

Note: Current cryostat designs do not include vibration mitigation (budget limited to €150k for AD-CCC).

9. Beam Pipe & Integration Constraints

• CryoRING CCC beam pipe: DN100 CF (100 mm)

• HEBT CCC beam pipe: DN150 CF (150 mm)

• CERN must check beam pipe aperture constraints with SHiP integration team for the intended CCC location.

10. Next Steps / Action Items

From CERN

• Verify height and length limits at SHiP installation point.

• Study radiation levels and plan tests.

• Coordinate with integration team on beam pipe aperture.

• Prepare internal comparison of three options:

  1. GSI Prototype CCC (+ added fill port)

  2. CryoRING CCC

  3. HEBT CCC

From GSI / ILK

• Thomas to discuss feasibility of copying prototype CCC + adding fill port with ILK.

• Provide feedback on heat load impact of modified design.

• Clarify safety valve implementation details.

• Support CERN with one borrowed electronics unit (through Mark’s request).

11. Conclusion

• Copying the GSI design “as is” is not recommended due to safety, cryogenic operation, and vacuum concerns.

• The prototype CCC with minor modifications (fill port, adjusted height) appears most promising.

• Radiation hardness of electronics remains the major open risk.

• Further engineering discussion with ILK and follow-up radiation studies are essential before final decision.