TU Darmstadt, Darmstadt, Germany
The r-process fission cycle terminates the natural synthesis of heavy elements in binary neutron-star mergers. Fission processes of transuranium nuclides will be studied in electrofission reactions at the S-DALINAC*. Due to the minuscule fissile target, the experimental setup requires an active electron-beam-stabilization system with high accuracy and a beam position resolution in the submillimeter range. In this contribution, requirements and concepts of this system regarding beam-diagnostic elements, feedback control and readout electronics are presented. The usage of a beam position monitor cavity and optical transition radiation targets to monitor the required beam parameters will be discussed in detail. Additionally, various measurements performed at the S-DALINAC to assess requirements and limits for the beam-stabilization system will be presented. Finally, the option of using advanced machine learning methods such as neural networks and agent-based reinforcement learning will be discussed.
*N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018)
TU Darmstadt, Darmstadt, Germany
The S-DALINAC is a thrice recirculating electron accelerator for high resolution electron scattering experiments with a continuous-wave beam at a frequency of 2.9972(1) GHz. Short bunches are crucial to enable tuning of the machine for operation as an energy-recovery linear accelerator* **. Currently, measurements of this beam parameter are accomplished by using the radio-frequency zero-crossing method: here, a momentum spread chirp is induced and the transverse beam profile in a downstream located dispersive section is measured with a scintillating screen providing an upper limit of the bunch length. Since this method is time consuming, a new setup for these measurements using a streak camera is developed. Optical transition radiation from an aluminum-coated Kapton target is used to map the bunch length information to a light pulse which enables an accurate measurement compared to a scintillating screen. The light pulse can then be evaluated with the streak camera by projecting its length onto the transverse dimension on a phosphor screen. This contribution will present the current status of the measurement setup as well as its design and properties.
*Michaela Arnold et al., Phys. Rev. Acc. Beams 23, 020101 (2020).
**F. Schliessmann et al., Nat. Phys. 19, 597-602 (2023).