Magnet : Meetings : Magnet0709

Meeting of the Magnet Group, Sept. 2008, GSI

Agenda

• Lars Schmidt: "Considerations on the Magnet Design"
• Evgeny Koshurnikov: "Status of the PANDA solenoid coil design"
• Andrea Bersani: "The PANDA Solenoid Magnet Options: a Comparison"
• Renzo Parodi: "For Discussion"

Participants

AndreaBersani, EvieDownie, EvgenyKoshurnikov, IntiLehmann, BerndLewandowski, HerbertOrth, RenzoParodi, LarsSchmitt, JerzySmyrski, AlexandreVodopianov.

Please let me know if I forgot someone! IntiLehmann

Minutes

Lars gave a brief glimpse on what he will be saying during the technical board on Tuesday. He strongly recommended to work together, suggesting to split the tasks into work packages.

Evgeny showed the new solenoid design from Dubna. The missing space in the downstream region has been accounted for, balancing the force to 10t by increasing the upstream length. This would mean that the Barrel DIRC needs to get 15cm longer. The new design includes a complete redesign of the coil in accordance with the recommendations of the reviewers. His concern on the coil design are shear stresses and tension arising from the fact that the radial force on the coil former is inhomogeneous due to the splitting of the coil in 3 parts. He believes that a flexible spacer between the coils is needed to reduce those forces. Also he believes that a reinforced cable would be needed as the cable may exceed the plastic limit. Renzo argues that the cable would only deform during the first ramping and this is how other similar magnets are constructed.

Andrea showed an overview of the Genoa status. He stressed that the design emphasis was on the field and detector, while the net force has not be considered as important. He showed a new yoke design, which includes a new DIRC readout. It is now fast and easy to change the parameters and check new geometries. They are using 2 different cables for the 3 coils. The cryogenic system, the temperature distributions, and forces have been studied. Only minor modifications were done as a reaction to the review, namely the reduction of the ratio cold-mass to stored energy to about 5MJ/kg and a slight reduction of the net force. The option of stabilised Al cable was studied but price and advantages of it are not clear. Andrea showed a comparison of the Genoa and Dubna version 1 concluding that there are only minor differences. He ended with an moving "Epilogo" saying that this is now really the time to join forces and work together.

Renzo showed two more symmetric yoke designs proposed by Jost (who could unfortunately not be there). There is a long version (with originally proposed space for the downstream endcap) and a short version where the downstream space to the yoke is reduced by about 10cm. In the long and short versions the net force on the coil is only 28 and 10t, respectively. Unfortunately, the field quality is not meeting the required values by far. One might be able to improve that a bit by optimisation, but one observes that the shorter version is significantly worse than the longer one. His conclusion is that keeping the field requirements one needs to either increase the upstream end of the yoke (as in the Dubna design) or to live with a higher net force.

Both groups agree that they prefer to leave the downstream distance between the cryostat and yoke as it is (e.g. in v 0.1.8). The field quality is likely to become worse when one makes the yoke shorter, but this has not been studied in detail yet. At least there is no request from the Magnet Group to shorten the downstream length.

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Magnet : Meetings : Magnet0709

-- Created by IntiLehmann - 18 Sep 2007