BASE - The Baryon Antibaryon Symmetry Experiment

TL;DR

The BASE experiment at CERN aims to test CPT symmetry by precisely comparing the magnetic moments of protons and antiprotons using advanced Penning trap techniques, achieving unprecedented measurement accuracy.

Contribution

This work introduces a new experimental setup employing double Penning traps and non-destructive detection to significantly improve the precision of proton and antiproton magnetic moment measurements.

Findings

Achieved a fractional precision of 10^{-9} in g-factor measurements.

Constructed and commissioned a new experiment at CERN's Antiproton Decelerator.

Expected to improve the precision of antiproton magnetic moment measurements by a factor of 1000.

Abstract

The Baryon Antibaryon Symmetry Experiment (BASE) aims at performing a stringent test of the combined charge parity and time reversal (CPT) symmetry by comparing the magnetic moments of the proton and the antiproton with high precision. Using single particles in a Penning trap, the proton/antiproton $g$-factors, i.e. the magnetic moment in units of the nuclear magneton, are determined by measuring the respective ratio of the spin-precession frequency to the cyclotron frequency. The spin precession frequency is measured by non-destructive detection of spin quantum transitions using the continuous Stern-Gerlach effect, and the cyclotron frequency is determined from the particle's motional eigenfrequencies in the Penning trap using the invariance theorem. By application of the double Penning-trap method we expect that in our measurements a fractional precision of $\delta g/g$ 10$^{-9}$ can be achieved. The successful application of this method to the antiproton will represent a factor 1000 improvement in the fractional precision of its magnetic moment. The BASE collaboration has constructed and commissioned a new experiment at the Antiproton Decelerator (AD) of CERN. This article describes and summarizes the physical and technical aspects of this new experiment.