The breakdown of spin statistics in ion-atom charge exchange collisions has been directly demonstrated by a recent study that was published in Physical Review Letters on October 22nd, 2024. Scientists from the Chinese Academy of Sciences’ (CAS) Institute of Modern Physics (IMP) led this study.
The reaction microscope at IMP. Image Credit: IMP
The study of charge exchange in collisions between highly charged ions and atoms or molecules has become a popular area of research since the first comet X-ray image was captured with an X-ray telescope in 1996.
To model observed X-ray spectra, astrophysicists need precise atomic data. Conventionally, the charge exchange is assumed to obey statistical laws concerning the total spin quantum number. These pure spin statistics presumptions are fundamental to many different fields.
The experiment was carried out using a high-resolution reaction microscope, which is distinguished by its high precision, sensitivity, and detection efficiency at the low-energy terminals of the Heavy Ion Research Facility in Lanzhou. Neutral helium was used as a target for collisions with C3+ ions.
The C3+ ion is a good candidate for this study because it has no long-lived excited states and is always in its ground state in the collision region. Using the reaction microscope, we can easily determine the atomic states at the moment of electron capture in collisions, overcoming the difficulties encountered in previous experiments. Thus, it is relatively easier to accurately analyze the underlying mechanisms.
Xiaolong Zhu, Study First Author and Professor, Institute of Modern Physics, Chinese Academy of Sciences
Scientists using both experimental and theoretical methods to directly measure spin-resolved cross-section ratios as a probe of spin statistics demonstrated the breakdown of spin-statistics assumptions at high impact energies, where they are typically expected to be valid.
The novel finding raises intriguing questions both in understanding the electronic dynamics during such fast collisional processes and in exploring quantum manipulation of atomic and molecular reactivity.
Xinwen Ma, Study Corresponding Author and Professor, Institute of Modern Physics, Chinese Academy of Sciences
Journal Reference:
Zhu, X., et. al. (2024) Direct Evidence of Breakdown of Spin Statistics in Ion-Atom Charge Exchange Collisions. Physical Review Letters. doi.org/10.1103/PhysRevLett.133.173002