Freiburg 2024 – scientific programme

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A: Fachverband Atomphysik

A 36: Highly Charged Ions and their Applications II

A 36.5: Talk

Friday, March 15, 2024, 12:15–12:30, HS 1010

Developments of microwave filters for the LSym experiment — •Fabian Raab, Maria Pasinetti, Lukas Holtmann, Daniel Rubin, Andreas Thoma, Sangeetha Sasidharan, and Sven Sturm — MPIK Heidelberg

LSym is a new cryogenic Penning trap experiment that intends to test the symmetry of matter and antimatter in the lepton sector. In particular, the experiment will test for differences in mass, charge and g-factor of the positron and electron to achieve the most precise test for a hypothetical CPT violation so far.

In the experiment the positron has to be cooled to its ground state of motion. Therefore, the trap assembly is cooled to about 300 mK, where the trap cavity is largely depleted from black-body photons around the cyclotron frequency of  140 GHz. However, for the sideband cooling and the spin-manipulation we need drives very close to the cyclotron frequency, which can cause adverse heating far above the ground state if not accounted for.

This can be counteracted by implementing a microwave filter structure, which allows the two drives to enter the trap almost unhindered, while blocking almost all of the power close to the cyclotron frequency. Challenges that arise from the close proximity of the drive modes to the cyclotron mode and some ideas to overcome them will be presented here.

Keywords: Penning trap; CPT; Antimatter; QED; Microwave filter