CBM Superconducting Dipole Magnet P.G. Akishin, A.V. Alfeev, V.S. Alfeev, V.V. Borisov, V.V. Ivanov, E.I. Litvinenko, A.I. Malakhov, E.A. Matyushevsky Presented by A.Malakhov Joint Institute for Nuclear Research, Dubna 15th CBM Collaboration Meeting April 12-16, GSI 15.04.2010

SC dipole magnet type “Window frame” with the aperture 1. 3x1 SC dipole magnet type “Window frame” with the aperture 1.3x1.3 m2 and 1 m length along a beam

Geometrical parameters of the SC dipole magnet.

The Superconducting dipole magnet consists of the yoke of the magnet executed from soft magnetic steel and superconducting windings of excitation. Two superconducting windings are executed from the superconducting cable and can miss on 1500 А (1200 kA·w) current of excitation everyone. The working current provides the field in the gap of the magnet 1.2 T. The field integral along the beam direction is equal 1 T·m. Low values of the field in the RICH area (250 Gs) is reached by the installation of double magnetic shield between the yoke and RICH.

The cryostat of the dipole magnet with SC coils

The cross-section SC coil of excitation with cryostat

The casing of the SC coil from a stainless steel

Screens The Screen 1 is intended for reduction ponderomotive efforts in SC coils in a horizontal plane The Screen 2 and the Screen 1 reduce a field in the RICH area

TARGET RICH fotodetectors MAGNET 1.9 m 1.7 m RICH

Distribution of the field inside of the SC magnet gap calculated by RADIA |B x.y.z| = f(z), [ T ] (x = 0)

Dependence of |B| as function of distance from a target: from - 1 Dependence of |B| as function of distance from a target: from - 1.0 m up to 5.0 m (left) and from 0 up to 1 m (right) (TOSCA) 1.0 -1.0 5.0

|B| from 1.6 m up to 4.0 m from a target (TOSCA)

Distributions of the field in cross-section of the magnet Distributions of the field in cross-section of the magnet. The left picture is for the magnet with the screens (electron version) and the right picture is for the magnet without screens (muon version).

Distributions of the field along Z axis of the magnet Distributions of the field along Z axis of the magnet . The left picture is for the magnet with screens and the right picture is the magnet without screens.

Distributions of the field in the Х-Y plane on the distance of 1 Distributions of the field in the Х-Y plane on the distance of 1.8 m from the target (the region RICH).

Z=1.9 m

Bxy (T) Z = 1.9 m Y(m) 2.0 TOSCA max Bxy = 0.025 T 1.1 X (m) 1.5

Bxy (T) Z = 1.8 m Y(m) 2.0 TOSCA max Bxy = 0.029 T 1.1 X (m) 1.5

Bxy (T) Z = 1.7 m Bxy (T) Z = 1.7 m TOSCA TOSCA TOSCA Y(m) 2.0 max Bxy = 0.032 T 1.1 X (m) 1.5

Planned industrial partners: Manufacture of the superconducting wire (cable) on VNIIKP (Podolsk, Russia) and Joint-stock company "Ulibinsk metal works" (Kazakhstan). Manufacture of large-size parts of the yoke of the magnet at SMF (Savelovo, Russia), at Kamov DMF (Dubna, Russia) and at NKMF (Novokramatorsk machine-building factory, Kramatorsk, Ukraine).

Anticipated Work Share in the Construction Phase Simulation – 6 % Designing – 11 % Construction – 68 % Test – 15 %

Simulation and design stage (2010-2012) At the simulation stage of the SC magnet its field map inside the magnet and in the RICH area will be determined in more details. The parameters should satisfy the following requirements: field integral about 1 Tm and the field in the RICH area should not exceed 250 Gs on the distance from 1.7 m up to 1.9 m from a target. Calculations will be checked up on the model of the magnet made in the scale 1:5. The devices of the input and output of the current, system of protection of a superconducting winding from transition into the normal condition and evacuation of the current from it after quench, thermometry etc. will be checked up also

Cost (Million Euro) Kinds of the work on SC dipole magnet 0.500 0.200 0.100 Montage, adjustment, test in Russia 4 1.295 0.045 0,250 0.450 Fabrication and assembly of the system of excitation 3 1.000 - 0.250 0.350 Fabrication and assembly the magnet yoke 2 0.050 0.170 0.230 Technical project 1 Total 2015 2014 2013 2012 2011 2010 2009 Cost (Million Euro) Kinds of the work on SC dipole magnet

Not considered charges (reserve) 4.350 0.155 0.395 0.700 1.050 1.370 0.680 Total 0.400 0.050 0.100 0.150 Not considered charges (reserve) 9 0.550 0.250 0.200 Purchase of the additional equipment, build-up stands 8 0.035 Adjustment and test without the beam 7 0.045 Installation on the place 6 0.075 Delivery to Darmstadt 5

Request 1. The STS size optimization to reduce of the SC magnet gap (to reduce the cost) 2. EU grant to prepare technical project.

Plans In order to keep to out schedule for the construction of CBM we want to make some steps towards the Technical Design Reports. One intermediate step is to organize an evaluation of the detector and magnet concepts. As the superconducting dipole magnet is already much advanced, we suggest to organize an evaluation of the magnet concept by external experts at the end of 2010. The first step would be that we write up a report on our plans for the magnet. This report will have 20-30 pages plus drawings, and it will be sent to the experts some month prior the evaluation in July 2010. Therefore we are prepare such report. We hope, that the evaluation will be of benefit for the design, and the magnet TDR might be the first accepted TRD of CBM. This is the condition to get money for construction

Conclusion The engineering design for the magnet with a gap size 1.3х1.3х1.0 m3 (height, width and length) provides a required magnitude of the field inside the gap and good screening of the field within RICH The factor of screening of the magnetic field in comparison with the variant without screens is close to 3.5 times. The gap of the magnet satisfies the available geometry of the STS detector and has no elements which could interfere with moving the detector in the gap and directly in front of the magnet The organization of evaluation of the magnet concept by external experts at the end of 2010 is necessary

Thank you for the attention!