In a lot of cases, the discovery of brand-new physics requires the advancement of brand-new speculative techniques and improved precision of measurements. The most exactly checked theory of physical laws is Quantum ElectroDynamics (QED), which explains the tiny interactions in between charged particles and light. Scientists are constantly pressing the limitations of how far QED accurately describes our physical reality.
In this paper, the cooperation, including Dr. Takuma Okumura (Postdoctoral Researcher, RIKEN at the time of the research, now Assistant Professor at Tokyo Metropolitan University), Professor Toshiyuki Azuma (Chief Scientist, RIKEN), Dr. Tadashi Hashimoto (Assistant Principal Researcher) of Japan Atomic Energy Agency (JAEA), Visiting Researcher Hideyuki Tatsuno of Tokyo Metropolitan University, Associate Professor Shinya Yamada of Rikkyo University, Professor Paul Indelicato of the Kastler-Brossel Laboratory, Professor Tadayuki Takahashi of Kavli IPMU, the University of Tokyo, Professor Koichiro Shimomura of Institute for Materials Structure Science, KEK, Professor Shinji Okada of Chubu University, injected a low-velocity unfavorable muon beam from the J-PARC facility into neon gas, and the energy of characteristic X-rays discharged from the resulting muonic neon (Ne) atoms was exactly measured utilizing a superconducting Transition-Edge Sensor (TES) detector.
By taking complete advantage of the outstanding energy resolution of the TES detector, the energy of the muonic characteristic X-rays was determined with an absolute unpredictability of less than 1/10,000, and contributions from vacuum polarization in strong-field quantum electrodynamics were successfully confirmed with a high precision of 5.8 %.
The TES detector was originally established for area X-ray observation. Takahashis current task at Kavli IPMU has been to bring out unmatched cross-disciplinary research study using this detector. His team consists of Kavli IPMU Project Assistant Professor Shin ichiro Takeda, Project Researcher Miho Katsuragawa, and at-the-tune college student Kairi Mine, who participated in the muon experiments.
The partnerships presentation of the experimental technique utilizing muonic atoms is expected to lead to a terrific leap forward in the research study of QED confirmation under strong electrical fields.
Details of the research study were released online (27 April 2023 Japan time) prior to publication in the scientific journal Physical Review Letters ( 27 April 2023 Japan time).
Background
The effects of QED are more pronounced in environments with strong electrical fields, but theoretical computations become harder in this case. A strong electric field environment is extremely important for QED verification.
For many years, experiments using highly charged ions (HCIs), which are atoms removed of multiple electrons, have actually been performed as a method to understand a strong electric field environment. The electric field felt by the bound electrons in HCIs becomes stronger as the atomic number becomes bigger, and the shielding effect is suppressed by the removing of numerous electrons.
HCI research using big accelerators is still strongly pursued. Even for HCIs with big atomic numbers, the result of the limited size of the nucleus can not be neglected. It has been explained that this impact is not specifically understood, and hence the precision of QED verification, which compares experimental outcomes with theory, is considerably jeopardized.
Research Study Methodology and Results
To verify QED under strong electric fields in a various method than with HCIs, global research study groups have actually concentrated on “unique atoms,” in which a negatively charged particle is bound to the nucleus instead of the electron. Among the variety of unique atoms, muonic atoms are composed of negative muons (elementary particles about 200 times much heavier than electrons) and nuclei. Unfavorable muons can nowadays be drawn out as beams from big accelerators.
Muonic atoms are defined by the extremely close distance of the unfavorable muon to the nucleus, with the orbital radius of a bound muon being around 1/200th that of a bound electron. As a result, the electric field felt by the muon has to do with 40,000 times stronger than the electric field felt by a bound electron of the very same quantum level in an HCI, leading to a huge QED effect.
In addition, by utilizing unfavorable muons, which inhabit high angular momentum quantum levels with little overlap with the nucleus, it is possible to carry out experiments in which the impact of the finite size of the nucleus is mostly reduced. By precisely determining the energy of muonic characteristic X-rays discharged when muonic atoms are deexcited from a particular level to lower levels, QED can be verified under a strong electric field (Figure 1).
Conceptual diagram showing muonic atoms and quantum electrodynamic (QED) results. The presence of atoms or molecules in the vicinity of the muonic atoms might cause quick electron transfer and alters the energy of the muonic characteristic X-rays. The option is to utilize water down gas targets with a little number density (low pressure), however the number of produced muonic atoms and the resulting intensity of muonic characteristic X-rays are decreased.
The international research group conducted experiments at the Japan Proton Accelerator Research Complex (J-PARC) in Tokai-mura, Ibaraki, where the worlds most extreme low-velocity muon beam is readily available. In order to identify the energy with adequate accuracy even with low-intensity muonic characteristic X-rays, the experiment was carried out with a superconducting shift edge sensing unit (TES) microcalorimeter, which is a high-resolution and extremely effective X-ray detector.
Utilizing unusual gas neon (10Ne) atoms as the target, they have actually achieved an energy resolution that is one order of magnitude higher than that of conventional semiconductor detectors (FWHM: 5.2 eV) under water down conditions of 0.1 atm and effectively measured the muonic particular X-rays (Figure 2). The peaks shown are mainly due to the overlap of muonic particular X-rays from 6 different shifts, and the energy of the muonic characteristic X-rays was determined to a high precision of 0.002% by evaluating contributions from each of them.
Reliance of muonic particular X-ray energy on neon gas pressure and comparison with the latest theoretical calculation. The energy of muonic characteristic X-rays is outlined against the pressure of the neon gas target. No pressure-dependent energy variation was observed within speculative error, showing that the muon-neon atoms remained in a separated environment. The accurate muonic characteristic X-ray energy measurements remain in outstanding arrangement with the arise from the newest theoretical calculations. Credit: Okumura et al
. They duplicated the measurements while changing the pressure of the neon gas target (Figure 3) and verified that the energy of the muonic X-rays is constant within experimental error despite the pressure of the neon gas target. Thus, it can be concluded that the muonic neon atoms remained in an isolated environment.
Dependence of muonic characteristic X-ray energy on neon gas pressure and contrast with the latest theoretical computation. The energy of muonic particular X-rays is outlined against the pressure of the neon gas target. No pressure-dependent energy variation was observed within speculative mistake, showing that the muon-neon atoms were in a separated environment. The precise muonic characteristic X-ray energy measurements remain in exceptional agreement with the results from the most recent theoretical estimations. Credit: Okumura et al
. They compared the current theoretical computations with the speculative results and verified that they concurred within the speculative mistake. We succeeded in verifying the result of vacuum polarization under a strong electric field with an exceptionally high accuracy of 5.8%. This is comparable to the accuracy of strong-field QED using the multiply charged uranium ion U91+, which is the most precise observation to date.
Reference: “Proof-of-Principle Experiment for Testing Strong-Field Quantum Electrodynamics with Exotic Atoms: High Precision X-Ray Spectroscopy of Muonic Neon” by T. Okumura et al., 27 April 2023, Physical Review Letters.DOI: 10.1103/ PhysRevLett.130.173001.
Conceptual diagram revealing muonic atoms and quantum electrodynamic (QED) impacts. Credit: RIKEN
A worldwide team of scientists, including members from the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), has been successful in a proof-of-principle experiment to confirm strong-field quantum electrodynamics within exotic atoms, according to a current research study published in Physical Review Letters. This feat was achieved through high-precision measurement of the energy spectrum of muonic characteristic X-rays, that are produced from muonic atoms utilizing an advanced X-ray detector.
This effective experiment marks an essential advancement in the verification of crucial physical laws in the context of strong electrical fields, a world yet to be artificially generated by people. The highly accurate and reliable technique for figuring out X-ray energy, showed using innovative quantum technology in this study, is expected to be applied throughout different research locations, such as non-destructive elemental analysis approaches using muonic atoms.
It has always been an imagine researchers to find physical laws. They have been discovered or proposed to discuss observed phenomena that can not be comprehended by existing theories.
Amongst the range of unique atoms, muonic atoms are made up of negative muons (elementary particles about 200 times heavier than electrons) and nuclei. Conceptual diagram showing muonic atoms and quantum electrodynamic (QED) results. Therefore, muonic atoms are a promising speculative target for strong-field QED verification. The existence of atoms or molecules in the vicinity of the muonic atoms might trigger quick electron transfer and alters the energy of the muonic particular X-rays. The solution is to utilize water down gas targets with a small number density (low pressure), but the number of produced muonic atoms and the resulting intensity of muonic characteristic X-rays are reduced.
