Dipole magnet for CBM: current status

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 Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 1

2. 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. The task definition Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 2

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

23. |Bxy| (x,y) z=160 cm (RICH entrance) |Bxy| = sqrt (Bx2+By2) Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 23

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

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

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

27. |Bxy| z=180 cm(photodetector plane for Compact RICH) |Bxy| = sqrt (Bx2+By2) z=180 Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 27

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

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

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

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

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

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

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 Gsfor 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 Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 34

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

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

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

38. |Bxy| (x,y) z=154 cm (end of the magnetic screens) |Bxy| = sqrt (Bx2+By2) Elena.Litvinenko CBM Collaboration Meeting Dubna 17 Oct 2008 38

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

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