Our Universe is almost completely made of matter and only minimal amounts of antimatter. Understanding this imbalance is one of the great challenges in modern physics, which suggests that just after the Big Bang, at the end of the inflation epoch, there was a precise balance between the number of particles and antiparticles.
One of the necessary properties of Nature which are required for explaining the matter-antimatter imbalance is the violation of the CP-symmetry. In a CP-symmetric world, the laws oh physics should not differ if a particle is interchanged with its antiparticle (C symmetry) and the sign of its spatial coordinates is flipped (P symmetry). Predictions given by the Standard Model of particle physics for CP-symmetry violation are orders of magnitude too small to explain the observed preponderance of matter. Therefore, new sources of CP violation, coming from outside the Standard Model, are needed. They can manifest themselves in Electric Dipole Moments (EDM) of elementary particles.
The efforts of the Jülich Electric Dipole Moment Investigations (JEDI) Collaboration concentrate on a direct measurement of EDMs of charged hadrons (protons and deuterons). The principle of the measurement is based on the interaction of a finite EDM with the particle-frame radial electric field in the storage ring. If EDM exists, a beam of particles initially polarized along the particle momentum will develop in time a minuscule vertical-polarization buildup,which can be measured using elastic scattering of the beam particles on a carbon target. Although the principle of the experiment is simple, the smallness of the expected effect makes it extremely difficult.
One of the key challenges is a sensitive and efficient determination of the tiny change of the polarization. During my postdoctoral research within the JEDI collaboration I was involved in activities leading towards precise dedicated EDM polarimetry, including obtaining a solid experimental database of deuteron-carbon scattering.
Learn more about the project:
Selected JEDI publications:
- Phase locking the spin precession in a storage ring
- How to reach a thousand-second in-plane polarization lifetime with 0.97 GeV/c deuterons in a storage ring
- New method for a continuous determination of the spin tune in storage rings and implications for precision experiments
JEDI publications on polarimetry:
- M. Żurek, MESON2018 Proceedings - Polarimetry for a storage-ring electric-dipole-moment measurement
- F. Müller, SSP2018 Proceedings - The EDM Polarimeter Development at COSY-Jülich
- E. Stephenson, PSTP2015 Proceedings - Deuteron polarimeter developments for a storage ring electric dipole moment search