1. SC dipole magnet for CBM E.A.Matyushevskiy, P.G. Akishin, A.V. Alfeev, V.S. Alfeev, V.V. Ivanov, E.I. Litvinenko, A.I. Malakhov JINR, Dubna CBM Collaboration Meeting February 2008

2. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 2 Outline Original specifications Conceptual design Cryostat and the excitation windings Field map calculations Geant geometry Further steps

3. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 3 The original specifications for the magnet The magnet should provide: An integral value of the magnetic field along Z-axis about 1.5-2 T x m. The maximal value of the magnetic field in a magnet gap should amount to 2 T. The working gap acceptance should be within 50º in height (1.4 m) and 60º in width (1.6 m).

4. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 4 The conceptual project of the magnet

5. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 5 3D view of the magnet yoke

6. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 6 The details of the magnet design  Yoke shape: window frame (consists of top and bottom beams and lateral racks). The set of three pairs of the top and bottom beams forms the magnet’s poles.  Yoke material: the magnetic steel with low carbon content (Steel 1010).  Cryostats for excitation windings position: fixed on the magnet’s yoke.  Cryostat vacuum casing material: stainless steel (12Ch18N10T)  Windings shape - ‘Duck nose’ form  Winding material - superconducting cable with the cross-section of 7 x 4.5 mm². The cable consists of superconducting wires with niobium-titanic strings put in a copper matrix. The ratio of the cross-section of the superconductor area to the copper’s matrix is 1/3; the ratio of the superconducting wires to the aluminium matrix is 1/12.  Magnetic screen covers the winding in the magnet’s outlet to reduce a field outside of the magnet.

7. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 7 The conceptual project of the magnet (x-y projection) Lateral racks: Fill in device

8. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 8 The conceptual project of the magnet (z-y projection) 3 top beams: 3 bottom beams Magnetic screen Connector (vacuum- cryostats adapters) Support basic Top winding

9. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 9 The excitation windings (top winding)

10. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 10 The conceptual project of the magnet (winding cross-section) Tubes with circulating liquid helium Support legs (made from Kevlar) Copper tubes Vacuum casing Helium vessel Nitric screen Super isolation 4.5˚K70-80˚K300˚K

11. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 11 (X-Y) gap of the magnet along the beam from left to right yoke edges left screen edgeright screen edge 1.07 m 1.4 m1.6 m 1.1 m0.77 m last STS station (needs >=1.12m) from left to right yoke edges left screen edgeright screen edge 1.07 m 1.4 m1.6 m 1.1 m0.77 m last STS station (needs >=1.12m)

12. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 12 (X-Y) gap of the magnet available for the detector replacement from targetfrom magnet outlet 1.07 m 1.4 m1.6 m 1.1 m0.77 m last STS station (needs >=1.12m)

13. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 13 Software used for the field calculation TOSCA finite element solver for the analysis of all magnetostatic, electrostatic and current flow problems in 3 dimensions (part of the OPERA 3D Software for electro-magnetic design by Vector Field) http://www.vectorfields.com/content/view/27/50/ Preliminary field calculations have been performed using RADIA - multiplatform software dedicated to 3D magnetostatics computation, optimized for the design of undulators and wigglers made with permanent magnets, coils and linear/nonlinear soft magnetic materials. http://www.esrf.eu/Accelerators/Groups/InsertionDevices/Software /Radia/Documentation Interfaced to Mathematica (http://www.wolfram.com/ ) via MathLink.

14. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 14 Magnet geometry under Opera 3D

15. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 15 The field map “FieldMuon2”

16. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 16 |B|(x,y) after the magnet 10 cm after the magnet screen edge End of the magnetic screen

17. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 17 Comparison of |By| (z,y) x=0 and x=100: MuonMagnet and Muon2a

18. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 18 Comparison of |B| (z,y) x=0 and x=100: MuonMagnet and Muon2a

19. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 19 The Geant geometry created for cbmroot framework

20. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 20 “magnet_muon2.geo” & “sts_standard.geo” 0.5 m

21. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 21 Option: Muon2 -> Muon2a The study: the magnet length along Z axis was decreased to 20 cm

22. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 22 Comparison of |By| and |B| (z,y) x=0: Muon2 and Muon2a

23. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 23 By(z) for Muon2 (blue) and Muon2a (green) Field Integral [Tm] for Muon2 and Muon2a: [-50,50]: (2) 1.21699 (2a) 1.09416 [-30,70]: (2) 1.18609 (2a) 1.0205 [-20,80]: (2) 1.13681 (2a) 0.952771 [-10,90]: (2) 1.06949 (2a) 0.871026 [10,110]: (2) 0.896442

24. Elena Litvinenko CBM Collaboration Meeting 29 February 2008 24 Conclusion The engineering design of the window-frame dipole magnet for CBM on the basis of superconducting winding with indirect cooling is proposed. The proposed magnet yoke construction ensures the formation of the magnetic field in the gap which corresponds to CBM requirements. The cryostat design with indirect cooling system for windings with using liquid helium and nitric is proposed. Weight of the magnet is about 80 tons (the basement is not included ), and the flow rate of helium should be about 7 liters per hour. The windings can be produced in Dubna, and the yoke - in Kramatorsk. Magnet meets the requirements laid down in the draft, which, however, were slightly overstated for the integral of the field. The design of the magnet yoke (and cryostat) allows for a change of certain sizes while maintaining the required angular acceptance and retention integral field at 1 Tm. The corresponding field map and the Geant geometry for this magnet were created and can be used under cbmroot framework.