Conceptual Model of a Variable Gap Magnet for a GeV Electron Spectrometer

This paper presents a conceptual model of a variable gap magnet aimed to work as spectrometer for electrons with high energy in GeV range. The magnet could be part of an experimental arrangement for e- energy spectra measurements for nuclear physics experiments. A one meter long magnet with a variable gap size, between 20 and 70 mm, has been designed. The magnet has a modular structure and will be fabricated using NdFeB magnets and iron yoke. The maximum magnetic flux density will be 1.58T. 3D numerical simulations of the magnetic field inside the gap were performed using the finite element method. The forces between poles were also computed in order to compensate them adequately. A special symmetric displacement system was conceived in order to adjust the gap size.