Attendees: Jose Miguel Jimenez, Ismael Martel Bravo, Javier Resta Lopez, Davide Tomasini, Glyn Kirby, Stephan Russenschuck, Diego Perini, Amalia Ballarino, Matthias Bonora, Helene Felice, Sean Freeman, Ariel Haziot, Melvin Liebsch, Carlo Petrone, Germana Riddone.

Introduction by JMJ

• Good news: the documents for the funding from the Spanish ministry were finally signed on the 31st of December after hours of phone call.
• The scope of this meeting is to agree on the framework and the objectives of this project. Be sure that they are matching between the ISRS and the TE department at CERN.

Presentation by IMB: The ISRS project

• The Isolde Superconducting Recoil Separator (ISRS) will increase the capability of Isolde experiment for all detectors as well as being a stand alone detector, thus bringing lots of new physics opportunities. The space limitation in the experimental hall is one of the main constraint.
• Objective is to carry out R&D program to study a compact separator using innovative concepts. Good synergy with other communities.
• Conceptual design article in Nuclear Inst. and Methods in Physics Research, A 969 (2020)

Q&A

1. JMJ and IMB agree that although the ISRS project goes a lot beyond the magnet, the framework of the collaboration with TE is only the R&D on the magnet.
2. SR asks weather or not the magnet will have Iron as this has enormous effect on the computation. Everybody agrees that Iron free is the baseline although it is not completely a requirement.

Presentation by JRL: Req. magnets and optics

• Design went from originally 20 compact superconducting multi-functions magnets down to 10. Tracking over multiple turns allows to define the required aperture. Radius/dipole field is set using beam rigidity for different ions.
• More recent design includes 4 sets of 3 magnets at each corner with an FDF functions able to work either in high momentum mode or in isochronous conditions. Finally, the 3 magnets are replaced by a combined function curved CCT in the conceptual design
• ISRS magnet specifications:
  • Aperture: 200 mm
  • Curvature: 1m
  • Bend: 90 degrees
  • Dipole field: 2.2 T
  • Gradient 14 T/m
  • Stray field shield replaces Iron yoke

Q&A

1. SR wonders why the first design, more conservative and easily doable, was replaced by complex curved CCT magnets. Is it ok to sacrifice the improvement of physics and the community behind it in order to develop a fancy demonstrator instead of going with a conservative project?
   • JRL reminds that the objectives of the ISRS project were driven by novelty to have a challenging  and more innovative project. It is also a way to force beam dynamic section to adapt to new designs and not the other way around as it usually happens. It is also highly inexpensive (GK).
   • JMJ reminds that the objectives remains to serve the ISRS. We want something breakthrough but also doable and successful. Compromise will be made on the technology development to be sure that this is not too much. It is important to have a graduation between mandatory requirements and technological breakthrough opportunities.

Presentation by DT: Development plan

• Demonstrator specifications:
  • aperture: 250 mm
  • curvature: 1m
  • bend: 90 degrees
  • Dipole field: ~2.2 T
  • Gradient: ~13 T/m
  • Peak field: ~4 T
• Not totally new: LBNL (290 mm, 0.9 m, 50 degrees, 2.4 T) is curved but has no combined functions. We introduce the gradients as well as a considerably higher peak field. Still we are not starting from zero.
• Deliverables are:
  • 12 months: small scale straight CCT with combined function
  • 15 months: conceptual design including inputs from first small scale and winding tests
  • 18 months: small scale curved CCT with combined function
  • 20 months: Curved dummy demonstrator
  • 24 months: Demonstrator
• Parallel activities: develop design tool box (6 months), winding tests (9 months).

Q&A

1. When is T0?
   • IMB: around march is T0
   • JMJ: TE is ready to start earlier, to be discussed
2. IMB asks about collaboration with Spain ? DT answers that collaboration in order to make the magnet somewhere else will be hard to setup considering the short timescale. That does not exclude that material could be purchased/machined in Spain.

Presentation by GK: Status of the art of Nb-Ti CCTs and first concepts for the ISRS

• Designs are already being studied for the demonstrator and the small scale magnets.
• Important challenges are:
  • Bounding the conductor in the channel is a main challenge to address (new resins, new products). The box program at PSI is a good way to investigate.
  • Manufacturing techniques
  • Cable configurations, first priority

Q&A

1. IMB wonders if with all this parallel activities, the number of person is enough. GK confirms that it is.

Presentation by SR: Magnetic measurements

• The way measurements are usually done should change for this type of magnet. There are no proper harmonics for bent magnet. The solution are Legendre Polynomial functions (including a term carrying transversal gradient field, Q1/2)
• One must first:
  • define field quality
  • find how to extract it
  • link this field quality to beam simulations
• Strip shape conductors are not as easy as single conductor to compute
• A physical model called the Avatar should be build allowing to extract observation quantities that we can compare to the measurement and also predict the quantity of interest once this comparison is made.
• Many sensors exist in the toolbox depending on the accuracy we want as well as the time and the cost we are willing to pay. An array of Hall probes with pick-up coils (to calibrate them) seems to be a good compromise and work well at cryogenic temperature.

Presentation by DP: Budget

• For magnet:
  • Material: 596 kCHF including 180 kCHF for assembling FSU.
  • Manpower: for 2 years 220 kCHF fellow and 1FTE per year
• For magnetic measurements:
  • Material: 50 kCHF to 250 kCHF
  • Manpower: 0.1-0.5 engineer and 0.5 student

Q&A

1. IMB wonders about the wide range for the measurement budget.
   • DP answers that it depends a lot on what is asked, what is the request for the field quality.
   • DT reminds the novelty of the combined function and the difficulty to measure it compare to other projects.
   • SR reminds that for example Q1/2 is very hard to extract for example but is it needed at this stage?
2. IMB asks then how to define the field quality requirements in these unknown conditions.GK propose to set this up after measurements on the first small scale version.

Discussion

1. SF raises the discussion of the necessity to do our best efforts to spend the Spanish funding in Spain. Otherwise we should really document why we don't.
   • According to DP, most if not all of the material for magnet can be spent in Spain. Only question marks remains on the GRP former manufacturing.
   • JMJ and IMB propose to organize meetings with Spanish partners (scientific and industrial) once they are defined. Also this could bring more funding asked by these partners. DP proposes to include industrial partner from the the small tests level and not use the main workshop although this will delay things according to GK from his Swedish experience.
   • About intellectual properties, the KT office at CERN should be involved as soon as the partners are defined.
   • Also, every publications within the project should have the correct funding acknowledgments and logos.
2. SF asks if the budget exposed today reflect what we want from the Spanish funding. JMJ explains that it is not necessarily the case. There will be arrangements depending on the calendar or the type of activity. Also this project is a mutual development meaning that CERN will also contribute. This should be clarified in the coming weeks as well as the compromise on the the cost of the magnetic measurements.
3. Finally JMJ reminds IMB that CERN is not the final destination of the money as Isolde is no legal entity. What will be the legal Spanish institution holding the funding on the behalf of Isolde? It will be good to know within 2 weeks and the Spain ministry should state formally the chosen legal institution.
   • IMB has no answer right know and needs to discuss with Maria.

Conclusion

• JMJ and IMB agree on the project framework, the demonstrator specifications and the calendar as it was exposed today.
• JMJ reminds that is is important to make something feasible in 2 years even if it is not the expected final objective. If we need 2 phases then we make phase 1 and phase 2.
• Thanks everybody far all the presentations and clear material. Let's meet in around 2 weeks.