SC dipole magnet for CBM

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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.
MalakhovJINR, Dubna
CBM Collaboration Meeting February 2008
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Outline

• Original specifications
• Conceptual design
• Cryostat and the excitation windings
• Field map calculations
• Geant geometry
• Further steps

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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).

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The conceptual project of the magnet
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3D view of the magnet yoke
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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
  magnets poles.
• Yoke material the magnetic steel with low
  carbon content (Steel 1010).
• Cryostats for excitation windings position
  fixed on the magnets 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 coppers matrix is
  1/3 the ratio of the superconducting wires to
  the aluminium matrix is 1/12.
• Magnetic screen covers the winding in the
  magnets outlet to reduce a field outside of the
  magnet.

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The conceptual project of the magnet(x-y
projection)
Fill in device
Lateral racks
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The conceptual project of the magnet (z-y
projection)
Top winding
3 top beams
Magnetic screen
Connector (vacuum-cryostats adapters)
Support basic
3 bottom beams
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The excitation windings (top winding)
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The conceptual project of the magnet (winding
cross-section)
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(X-Y) gap of the magnet along the beam
last STS station (needs gt1.12m)
last STS station (needs gt1.12m)
0.77 m
0.77 m
1.1 m
0.77 m
1.1 m
0.77 m
1.07 m
1.07 m
1.4 m
1.6 m
1.4 m
1.6 m
1.6 m
1.6 m
from left to right yoke edges
left screen edge
right screen edge
from left to right yoke edges
left screen edge
right screen edge
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(X-Y) gap of the magnet available for the
detector replacement
last STS station (needs gt1.12m)
0.77 m
1.1 m
0.77 m
1.07 m
1.4 m
1.6 m
1.6 m
from target
from magnet outlet
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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/InsertionDe
  vices/Software/Radia/DocumentationInterfaced to
  Mathematica (http//www.wolfram.com/ ) via
  MathLink.

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Magnet geometry under Opera 3D
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The field map FieldMuon2
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B(x,y) after the magnet
screen edge
10 cm after the magnet
End of the magnetic screen
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Comparison of By (z,y) x0 and x100
MuonMagnet and Muon2a
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Comparison of B (z,y) x0 and x100
MuonMagnet and Muon2a
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The Geant geometry created for cbmroot framework
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magnet_muon2.geo sts_standard.geo
0.5 m
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Option Muon2 -gt Muon2a
The study the magnet length along Z axis was
decreased to 20 cm
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Comparison of By and B (z,y) x0 Muon2
and Muon2a
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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
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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.