Outline of Publicly Offered Research

Program A01-5 Quantum electrodynamics of highly charged heavy ions studied with state-of-the-art cosmic X-ray detectors
Principal Investigator NAKAMURA, Nobuyuki (The University of Electro-Communications)

Energy levels and interaction of highly charged heavy ions are strongly affected by the quantum electrodynamics (QED) effects. One of the typical results of QED effects is the Lamb shift, which arises in the interaction between an electron and a nucleus. On the other hand, the QED effect in the electron-electron interaction is called the Breit interaction. Although the Breit interaction is generally small correction to the main Coulomb interaction term, we recently showed that it can play a dominant role in the resonant recombination processes of highly charged heavy ions. However, the detailed mechanism is still unknown due to the experimental uncertainty limited by the present method with a commercially available detector. In this project, by using a Si/CdTe Compton camera and a superconducting transition edge sensor, which are the state-of-the-art detectors developed for cosmic x-ray observations, we break through the limitation in the present existing method to provide a critical test of the QED theory describing the interaction between electrons. Applications of the state-of-the-art astronomical detectors in the pure atomic physics area enables us to perform unique and original studies which cannot be done elsewhere. This study shares the common aim of the precise test of atomic and molecular physics with the planned research A01. In addition, there is an analogy between the physics of highly charged ions and that of muon; thus a close cooperation with the planned research A01 can deepen the both studies mutually. We also aim to explore new studies by applying the seeds of our highly charged ion source, an electron beam ion trap, to the needs in astrophysics.

(Left) The Tokyo electron beam ion trap: a highly charged heavy ion source at ILS/UEC.
(Right) Alignment parameters for the X-rays emitted in resonant recombination of highly charged ions. Strong QED contribution can be confirmed in the angular distribution and the polarization of the radiation.

Members

Principal Investigator
NAKAMURA, Nobuyuki
(Institute for Laser Science, The University of Electro-Communications)
Research Collaborators
TAKAHASHI, Tadayuki (The University of Tokyo)
WATANABE, Shin (JAXA/ISAS）
UCHIDA, Yusuke (Hiroshima University)
AZUMA, Toshiyuki (RIKEN)
OKUMURA, Takuma (RIKEN)
OKADA, Shinji (Chubu University)
KATO, Daiji (NINS National Institute for Fusion Science)
TONG, Xiao-Ming (Tsukuba University）

Reference Materials

  • N. Nakamura, “Breit interaction effect on dielectronic recombination of heavy ions,” J. Phys. B 49, 212001 (2016).
  • X. M. Tong et al., “Mechanism of dominance of the Breit interaction in dielectronic recombination,” J. Phys. B 48, 144002 (2015).
  • Z. Hu et al., “Experimental demonstration of the Breit interaction which dominates the angular distribution of X-ray emission in dielectronic recombination,” Phys. Rev. Lett. 108, 073002 (2012).
  • N. Nakamura et al., “Asymmetric profiles observed in the recombination of Bi79+: A benchmark for relativistic theories involving interference,” Phys. Rev. A 80, 014503 (2009).
  • N. Nakamura et al., “Evidence for strong Breit interaction in dielectronic recombination of highly charged heavy ions,” Phys. Rev. Lett. 100, 073203 (2008).