Joint Institute for Nuclear Research Status of the magnet for the PANDA Target Spectrometer Report from Dubna A.Efremov, E.Koshurnikov, Yu.Lobanov, A.Makarov, A.Vodopianov Moscow,

2 Magnet system for the PANDA experiment Target spectrometerForward spectrometer Beam pipe Instrumented flux return yoke Laminated sliding door Sliding door Dipole magnet coil Cryostat Movable platform Target production Target recovery Antiproton- beam direction Superconducting solenoid coil

3 PANDA target spectrometer Distinctive features warm bore in the cryostat for the target vertical pipe split-type coil (3 subcoils) detectors inside the cryostat bore flux return yoke acts as an active muon range system yoke end caps are the opening doors magnetically self-screening (stray field limitations exist) possibility of movement from the in-beam position to a maintenance place external space constraints in the hall total mass M=350 t General view of the magnet Rails for the door opening DIRC Upstream door Recesses for cables and tubes Upper roller guide for the door opening Recess for the target production system Downstream door Support frames

Before 2007: preliminary studies and elaboration of the conceptual design April 2007, GSI: Review meeting, recommendations by international experts (A.Dael, D.Tommasini, A.Yamamoto), choice of the general concept July 2007, Dubna: XXI PANDA Collaboration Meeting, decision on the further magnet design strategy March 2008, GSI: agreement on the Work Packages and Responsibilities for the magnet parts among the 7 groups from Germany, Italy, Russia, Poland, UK. Dubna group: Flux Return Yoke for the Target Spectrometer, which serves also as a multilayer absorber for a large-angle muon detection system. By the end of 2008: elaboration of the united design project of the solenoid (JINR, Dubna and INFN, Genova), creation of the technical design 2009: "Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets“ has passed the international reviewing process and adopted by the PANDA Collaboration 2010: coordination of the technical details with the detector groups, finalizing the mechanical design and preparation to the tender on the magnet manufacturing Magnet design process

5 Solenoid magnet design

Coordination of the design process 1.Presentations and discussions at the PANDA Collaboration meetings: GSI, 2007 – 2009, 2 times a year; Ferrara, Italy, September 2008; Torino, Italy, June 2009; Julich, Germany, September nd Mechanical Design Workshop, Darmstadt, October International Conference on Magnet Technology, Genova, Italy, Annual discussions and presentations of the magnet status at the JINR- PANDA meetings, Laboratory of Nuclear Problems, JINR 5.EVO videoconferences 6

7 Solenoid magnet design Magnet FE TOSCA model Magnetic field requirements magnetic induction in the central tracker region: B = 2 T field inhomogeneity: ΔB/B < 2% radial component integral: stray fields at the turbo-pump locations: B < 5 mT field at the DIRC readout location: B < 1 T minimization of the magnetic forces

8 Methods of analysis Use of the certified TOSCA computer software for electromagnetic design for precise calculations of magnetic fields and forces Use of the FEMM program for the fast calculations of magnetic field when analyzing various magnet configurations Elaboration of the fast method of calculation of the integral of radial component of magnetic induction, creation of the original Mathcad code Creation of the original FORTRAN code for calculation of the axial magnetic force and radial pressure distribution inside the coil and for transformation of results to the form necessary for mechanical calculations Using the Quench2 computer code (CERN) for the quench analysis Using the COSMOS computer software for calculation of mechanical stresses and deformations in the coil and in the iron yoke

9 Solenoid cross-section Side view The dimensions have been defined from the requirements on magnetic field, forces and necessary space for the target, cryo-chimney and all detectors

10 Top view Solenoid cross-section The dimensions have been defined from the requirements on magnetic field, forces and necessary space for the target, cryo-chimney and all detectors

11 Magnetic flux density distribution JINR PANDA Magnet Group achievements: Uniform current density in all 3 sub-coils Inner accommodation of the barrel DIRC readout becomes possible Small axial magnetic force at the solenoid coil (F < 20 t) Horizontal plane

12 Field homogeneity B 0 = 2T |δ| < 1.6%

13 Radial component integral |I up | < 1.8 mm

14 3D calculations Distribution of the magnetic induction in the area of tracker

15 3D calculations: radial field integral (horizontal plane) Agreement with the axially-symmetric model

16 3D calculations: recess for target YZ plane XY plane |B| 1.9 m solid iron

17 3D calculations: DIRC readout |B|<1.8T |B|<0.1T |B|<1.2T (December 2007) |B|<1.0T (March 2008)

18 Field saturation analysis Solenoid central magnetic field and axial force versus current density

19 Magnet parameters Coil axial dimensions-1025 mm < z < 1735 mm Cable cross-section (without insulation) 3.4 mm × 24.6 mm Design current density59 A/mm 2 Subcoil turns in each of 2 layers232, 104, 232 Winding Mean Radius1075 mm Operation current5 kA Inductance1.7 H Stored energy21 MJ Residual axial force0.2 MN Field inhomogeneityΔB/B < 1.6% Radial component integral|I up | < 1.8 mm

20 Solenoid coil Al cylinder subcoil 1subcoil 2subcoil 3 subcoil intercoil spacer FEM model

21 Solenoid coil Distribution of the axial magnetic force in the subcoil windings Distribution of the radial magnetic pressure in the subcoil windings

22 Solenoid coil Shear stress at the subcoil end face  < 5 MPa 1 0 subcoil solid Al

23 Stresses and deformations Gravity load, magnetic forces and additional vertical and horizontal seismic loads. Design criteria for the Finite Element analysis: building norms and Eurocodes 3. The deformations are at the level of 1 mm The stresses are within the allowable limits

24 Yoke layout

25 Supporting frames

26 Yoke + cryostat (detail) Collaboration with INFN (Genova, Italy)

27 Solenoid front view details of the backward endcap and cryostat suspension

28 Solenoid side view details of the forward endcap suspension (top)

29 Solenoid side view details of the forward endcap suspension (bottom)

30 1.I. Lehmann, A. Bersani, Yu. Lobanov, J. Lühning, J. Smyrski, L. Schmitt, B.Lewandowski, U. Wiedner, P. Gianotti (editors), PANDA Collaboration, “Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets”, 2009, Online: 2.E.K. Koshurnikov, A.A. Efremov, Yu.Yu. Lobanov, A.F. Makarov, H. Orth, A.N.Sissakian, A.S. Vodopianov. Conceptual Design of the PANDA Magnet System // IEEE Transactions on Applied Superconductivity, 2006, v.16, N2, Pp A.A. Efremov, E.K. Koshurnikov, Y.Y. Lobanov, A.F. Makarov, H. Orth, A.N.Sissakian, A.S. Vodopianov. 2 T superconducting detector solenoid for the PANDA target spectrometer // Nuclear Instruments and Methods in Physics Research A, 585, 2008, Pp References CAD model of the PANDA TS Iron Yoke is placed at the EDMS: FAIR Project, PANDA, Magnets, Solenoid yoke ID =

31 Summary 1.The choice of the optimal configuration of the magnet system for the PANDA Target Spectrometer has been made taking into account the requirements on the magnetic field, space limitations, minimization of forces, accommodation of the target, detectors and their supplies, ensuring the necessary stiffness of the whole device. 2.The design of the movable platform, its supports and integration with the Flux Return Yoke is still to be optimized (in collaboration with GSI and Cracow University of Technology). 3.The suspension system for cryostat and detectors will be analyzed; the positions of their attachment to the yoke and the possible deformations at these points must be defined (in collaboration with INFN, Genova, University of Gröningen and other detector groups). 4.Technical drawings and detailed mechanical specifications for the magnet manufacturing will be prepared after all the above problems are fixed.