Bastian Steiner

Wien filter as a spin rotator at low energy

The Wien filter is well known as a common energy analyzer and is also used more and more as a compact variant of a spin rotator at low energy for electrons. The Wien filter is based on homogenous magnetic and electric fields which are perpendicular to each other and transverse to the direction of the electrons. The rotation of the spin vector is caused by the magnetic field. If the force equilibrium condition is fulfilled the beam should not be deflected at the Wien filter. Simulations show that in the fringe fields the electrons get a kick. Therefore full 3D simulations of the electromagnetic fields and beam dynamics simulations are studied in detail at the example of the Wien filter at the new polarized 100 keV electron injector at the S-DALINAC. The results of the simulations with CST Design Environmenttradeand V-Code are presented.

Simulation for a New Polarized Electron Injector (Spin) for the S-DALINAC

The Superconducting DArmstädter LINear ACcelerator (S-DALINAC) is a 130 MeV recirculating electron accelerator serving several nuclear and radiation physics experiments. For future tasks, the 250 keV thermal electron source should be completed by a 100 keV polarized electron source. Therefore a new low energy injection con cept for the S-DALINAC has to be designed. The main components of the injector are a polarized electron source, an alpha magnet, a Wien filter spin-rotator and a Mott polarimeter. In this paper we report about the first simulation and design results. For our simulations we used the TS2 and TS3 modules of the MAFIA programme which are PIC codes for two and three dimensions and the CST PARTICLE STUDIO™.

Polarized Electrons in Darmstadt: Recent Developments

The injector of the superconducting Darmstadt electron linear accelerator S‐DALINAC will soon be extended by a source of polarized electrons. A test set‐up of the future source consists of a 100 keV GaAs polarized gun and associated beamline including an assembly for polarization manipulation and determination. We give a short overview of the existing and planned polarimeters at the different accelerator sites, introduce briefly the future implementation of the polarized source at the S‐DALINAC and list experiments that are planned with polarized electron and photon beams.

Utilizing a wien filter within the beam dynamics simulation tool V-code

Beam dynamics simulations for computationally large problems are challenging tasks. On the one hand, for the accurate simulation the electromagnetic field distribution within the whole device and the surrounding environment, it is essential to consider all necessary device components including even small geometry details, complicated material distributions and the field excitations. On the other hand, additional computational effort has to be put into precise modeling of the injected particle beam for accurate beam dynamics simulations. Under linear conditions, it is possible to separate the field calculation of the device from the computation of the particles self-field which can result in the proper application of diverse numerical schemes for the individual field contributions. In the paper, a technique is presented by means of which the static electric and magnetic fields of a Wien filter beam line element can be treated as applied external fields within the beam dynamics simulation tool V-code under the assumption that the interaction of the particle beam with the surrounding materials can be neglected.

Status Report of the New Darmstadt Polarized Electron Injector

We present the status of the polarized injector for the superconducting Darmstadt electron linear accelerator S‐DALINAC. An offline teststand of the source was built to test all components of the S‐DALINAC polarized injector SPIN. The new electron source will deliver a 100 keV polarized beam and complement the present thermionic source operating at 250 kV. Results of the beam properties measurements will be introduced and an outlook on the upcoming installation of the new injector at the S‐DALINAC will be given.

Polarized Electrons for Experiments at Low Momentum Transfer SPIN @ S‐DALINAC

The superconducting Darmstadt linear electron accelerator S‐DALINAC will be expanded by a newly developed polarized injector concept called SPIN. The polarized beam program includes experiments to search for parity violation in photo induced fission, the investigation of the 5th structure function at low momentum transfer and break up reactions of few body systems. These experiments and an overview of the current experiemental program will be covered in this paper.

Polarimetry at the Superconducting Darmstadt Electron Linac S‐DALINAC

A spin polarized electron source will be installed at the S‐DALINAC to extend the existing experimental capabilities polarization. In order to manipulate and monitor the beam polarization a Wien filter and different polarimeters will be installed. The already installed Wien filter and 100 keV Mott polarimeter and the planned 5 MeV Mott, 30–130 MeV Mo/ller and Compton transmission polarimeters are described.