- The HERA Interaction Region - The ZEUS Detector - The Quadrupoles

1. - The HERA Interaction Region - The ZEUS Detector - The Quadrupoles Superconducting Quadrupoles inside the HERA Experiments M. Bieler, DESY,LHC LUMI 05 Workshop, Arcidosso, September 2005

2. The HERA Interaction Region 920 GeV Protons 27.5 GeV Electrons

3. ZEUS Detektor Zentrale Driftkammer CTD Mikrovertex-Detektor Solenoid Magnet p e Rückwärts-Kalorimeter Vorwärts-Kalorimeter Zentrales-Kalorimeter

4. GG

5. GO

6. Design Parameters As part of the HERA luminosity upgrade, 6 superconducting Interaction Region quadrupoles were delivered, accepted, and are in service. These 6 layer magnets were designed to include the main quadrupole focus, a skew quad, a normal and skew dipole, and a final sextupole layer.Because of the physical space constraints imposed by the existing detector region components, the DESY magnets were of necessity designed to be very compact. In addition, they are also are required to operate within the solenoidal detector fields at the collision points, so all construction materials had to be non magnetic.Two types of DESY magnets were fabricated. The first, designated as G0, was a two meter long, constant radius magnet. The second, designated GG, is a one meter long, tapered tube, with a continuously increasing field strength from the lead end towards the collision point. From http://www.bnl.gov/magnets/HERA/default.asp

7. Magnet Parameters

8. The GG Magnet

9. The GO Magnet 3.7m 75cm 17cm

10. The GO Magnet

11. Cross Section of the GO Magnet Stainless Support Key Slotted G-10 Spacer 4K He Return 40K He 3mm Beam Pipe 60mm 5mm Coil Support Tube (102mm ID) 39mm 90mm Coil Layers 40K He 3mm He containment (144mm OD) 39mm for magnet and cryostat

12. Magnet Production at BNL • - 11 axis wiring machine • - 6 layers • Ultrasonic wire bonding • Pattern modulation to • correct for field errors • in lower layers • - 5 circuits

13. Radial Magnet Design Outer Helium Tube (3 mm) LHe at 4K Ca. 2mm Sextupole Skew Quad GO: Dipole Coils ca. 11 mm Quadrupole S-Glas Kompression Coil Support Tube (5 mm) CoilsinSubstrat Kapton Insulation

14. „6 around 1“ Cable Filament: 8 m Cu/NbTi: 1.8:1 51 m

15. The ‘End Can’

16. Cryogenics The magnet coils are cooled with supercritical single phase helium between 4K and 4.4K whereas the beam pipe is cooled between 40K and 80K. Measured static heat loads for the magnets and transfer lines (dynamic heat load: 6 – 15 W/m).

17. Problems with GG and GO Water: The temperature of the outer magnet surface was so low, that water was condensing on the magnet, dripping down into the detector. Solution: Armaflex for thermal insulation, plastic bag to collect the water. Magnet position: Inner tip of the magnet supported by steel cables or hydraulic movers. Exact position of the tip can not be surveyed. Magnetic forces between the magnet and the experiment’s solenoid move the magnet by 1 mm during the energy ramp. Solution: Electron orbit feedback system. Cryogenics: Pressure drop in the magnets 3 times higher than expected. Solution: Additional circulation pumps.

18. References Brück et al, Operational Experience with the new Superconducting luminosity upgrade magnets at HERA, ICEC 19, Grenoble, France, 2002