Students presentation

 

Velocity Map Imaging without Spherical Aberrations  

 

Abstract
In Photoelectron Spectroscopy (PES), the goal is to measure the kinetic energy of electrons emitted from atoms or molecules following photon absorption, providing insights into their quantum structure. A powerful method for achieving this is Velocity Map Imaging (VMI), which utilizes an electrostatic lens to direct electrons with identical kinetic energy toward a specific point on the detector, regardless of their initial positions.

The Cryogenic Storage Ring (CSR), located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, is one of the world's most advanced facilities for laboratory astrophysics. This is an electrostatic ring, with a circumference of approximately 35 meters, that can store ions for extended periods, enabling studies of their interactions with photons and other particles under the low temperature and pressure conditions typical of the interstellar medium. Recently, a Reaction Microscope (CSR-ReMi) has been installed in the CSR. The CSR-ReMi is a spectrometer composed of electrodes and Helmholtz coils, utilizing electric and magnetic fields to achieve a complete kinematic description of chemical reactions involving stored ions and interacting particles.

In this lecture, I will present a novel theory for a 'perfect' VMI and demonstrate its implementation in the CSR-ReMi. The results suggest that the CSR-ReMi exhibits an electron acceptance volume exceeding the current state-of-the-art by more than an order of magnitude. This advancement will enable a wide range of experiments to be conducted, significantly expanding the research possibilities within the CSR.