1. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 1 Dipole magnet for CBM: current status P.G. Akishin, A.V. Alfeev, V.S. Alfeev, V.V. Borisov, V.V. Ivanov, E.I. Litvinenko, A.I. Malakhov, E.A.Matyushevskiy JINR, Dubna

2. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 2 The task definition The main task is to provide the design of a magnet with: the working angular acceptance at least of 50° for the height of a gap (1.2 m) and 60° for the width of a gap (1.4 m), and, for the mounting inside the gap MVD/STS detectors, the sizes of its rectangular part should be at least 1.2 x 1.2 m ; the magnetic yoke size along the beam is equal to 1 m; the integral of the magnetic field in the region of the yoke of the magnet along the beam from 1 to 1.2 T*m; the magnetic field distribution, which is similar to the map “FieldMuonMagnet”, that is the current standard for the magnetic field for CBM simulations.

3. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 3 Technical drawing 1. Beam; 2. Rack; 3. Coil; 4. Adapter; 5. Filler; 6. Support of a magnet; 7. Magnetic screens.

4. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 4 The conceptual project of a magnet

5. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 5 Yoke of the magnet Yoke material: magnetically soft steel with the low content of carbon Yoke sizes: 280 (310) x 260 x 100 [cm] 2.8 m 1.4 m 1.2 m 2.6 0.33 m 1m

6. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 6 Windings («the Cossack saddle») The top part of a winding with cryostat Coil Nitric screen

7. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 7 Cryostat Top part of cryostat (front view) Top & bottom cryostats with connectors (back view) 1.216 m 0.328 m two adapters: - current connection; - elements of monitoring systems; - transportation of helium and nitric.

8. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 8 SC winding cross-section Vacuum casing 4.5˚K < 80˚K 300˚K Nitric screenHelium vessel SC cable Cover of a vacuum casing Helium pipe Support of the nitric screen Hatches Pipe of the nitric screen (circulating liquid nitrogen) 328 mm 143.8 mm

9. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 9 General view of the magnet Filler facility: - evacuation of energy; - inputs for submission of liquid helium and liquid nitrogen.

10. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 10 Magnet geometry implementation for TOSCA

11. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 11 Comparison with “MuonMagnet” Used in CBM: “MuonMagnet”New design: “Muon4”

12. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 12 Blue – FieldMuonMagnet Red - FieldMuon4 |By| (z) x=y=0 (target: z=0 cm)

13. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 13 |B| (z,y) x=0 (target: z=0 cm) Vertical plane along the beam:

14. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 14 |By| (z,y) x=0 (target: z=0 cm) Vertical plane along the beam:

15. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 15 |B| (x,y) z=0 (target position) z=0 Vertical plane perpendicular to the beam:

16. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 16 |By| (x,y) z=0 (target position) z=0 Vertical plane perpendicular to the beam:

17. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 17 |B| (x,y) z=50 cm (magnet yoke center) z=50

18. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 18 |By| (x,y) z=50 cm (magnet yoke center) z=50

19. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 19 |By| (x,y) z=50 cm (in the limits of Station 4)

20. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 20 |B| (x,y) z=100 cm (edge of the magnet yoke) z=100

21. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 21 |By| (x,y) z=100 cm (edge of the magnet yoke) z=100

22. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 22 z=160 |B| (x,y) z=160 cm (RICH entrance)

23. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 23 |Bxy| (x,y) z=160 cm (RICH entrance) |Bxy| = sqrt (Bx 2 +By 2 )

24. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 24 Let us consider Standard and Compact RICH cases: Data obtained from materials published on the site CbmRichMeeting Twiki

25. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 25 z=180 |B| (x,y) z=180 cm (photodetector plane for Compact RICH)

26. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 26 |B| z=180 cm (photodetector areas for Compact RICH) 0.047 (->0.04)0.058 0.042 (0.04->0.036)

27. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 27 z=180 |Bxy| z=180 cm (photodetector plane for Compact RICH) |Bxy| = sqrt (Bx 2 +By 2 )

28. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 28 |Bxy| z=180 cm (photodetector areas for Compact RICH) 0.047 (->0.03)0.0494 0.028 (->0.015)

29. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 29 |B| z=190 cm (photodetector plane for Standard RICH) z=190

30. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 30 |B| z=190 cm (photodetector areas for Standard RICH) 0.034 (->0.03)0.068 (->0.03) 0.034(->0.029)

31. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 31 |Bxy| z=190 cm (photodetector plane for Standard RICH) 0.038 (->0.03) 0.033 0.023 (->0.02)

32. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 32 Geometry implementation for Geant (cbmroot) Yoke +Coils +Nitric Screen +Cryostat +Magnetic Screens & Basement

33. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 33 Compatibility with STS geometry

34. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 34 I) The suggested engineering design of the superconductive dipole magnet for CBM provides the following characteristics: angular acceptance is 50° for the height of the gap (1.2 m) and 60° for the longest part of the width of the gap (1.4 m), and the sizes of the rectangular part of the gap 121.6 x 120 cm should be suitable for the mounting of MVD/STS detectors; the magnetic yoke size along the beam is equal to 1 m; the integral of the magnetic field in the region of the yoke of the magnet along the beam is equal to 1.07 T*m when the current through the coils is set to a value 0.781 MA (in the case of “MuonMagnet” the current equal to 1.447 MA corresponds to the integral equal to 1.01 T*m); the distribution of By component of the magnetic field along the beam axis is very close to the map “FieldMuonMagnet”; the mean values of the the new magnetic field in the regions, in which the RICH photodetectors are to be placed, are about 300 Gs for the last calculated field map. II) The 3D model of the magnet was developed for TOSCA. The magnetic field map was calculated and converted for cbmroot. A new C++ class was developed to support the changes in the symmetry of the field. III) The Geant geometry of the magnet was created for cbmroot and tested together with the latest available STS geometry. IV) The final decision about the sizes, shape and positions of the magnetic screens and the basement (and material of the basement) will be made after further studies directed to the magnet optimization. Conclusion and outlook

35. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 35 Backup slides …

36. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 36 |B| (x,y) z=154 cm (end of the magnetic screens) z=154

37. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 37 |By| (x,y) z=154 cm (end of the magnetic screens) z=154

38. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 38 |Bxy| (x,y) z=154 cm (end of the magnetic screens) |Bxy| = sqrt (Bx 2 +By 2 )

39. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 39 |B| and |By| (z,y) in linear scale

40. Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 40 “No magnetic screen” vs “Screen” cases