University of Wisconsin-Madison Physical Sciences Lab

Hermes Magnet

[Hermes magnet]

This magnet is a central component in a particle detector at DESY in Hamburg Germany. The magnet is required to produce a uniform field intensity of 1500 Gauss ± 0.5% in a region that is a 10mm high by 30mm wide ellipsoidal prism 400 mm long. In this region a particle beam interacts with a gas composed of spin-polarized atoms. Deflected particles then pass to a downstream detector.

Because of the acceptance angle of the detector and its distance downstream, the magnet is required to have a 172mm gap. Location of upstream and downstream components limits the axial length of the magnet’s pole pieces to under 600mm.

PSL’s role in development of the magnet included a design study to simulate the magnetic field, adjusting 5 pole-piece parameters to obtain a suitable field uniformity; construction of the vacuum chamber; and magnetic field mapping measurements of the actual magnet using a 1-meter-square travel XY table, to verify that the design goals were achieved.

The Hermes experiment is described at