Figure 1. Conceptual diagram showing muonic atoms and quantum electrodynamic (QED) impacts. A worldwide team of scientists has actually successfully carried out a proof-of-principle experiment to validate strong-field quantum electrodynamics with unique atoms. The experiment involved the use of high-precision measurements of the energy spectrum of muonic characteristic X-rays emitted from muonic atoms utilizing a state-of-the-art X-ray detector. Credit: RIKEN
Scientists have actually effectively conducted an experiment to confirm strong-field quantum electrodynamics with exotic atoms, using a state-of-the-art X-ray detector for high-precision measurements of muonic characteristic X-rays. This breakthrough paves the method for confirming fundamental physical laws under strong electric fields and advancing numerous research fields.
The groups results are a substantial action toward verifying essential physical laws under strong electrical fields, which humankind has actually not yet had the ability to develop synthetically. The extremely effective and precise X-ray energy decision method utilizing cutting edge quantum innovation showed in this research is expected to be used to numerous research fields, such as non-destructive essential analysis techniques utilizing muonic atoms [6]
Muonic particular X-rayWhen a negative muon bound to a nucleus deexcites from a greater energy orbital to a lower energy orbital, the excess energy is emitted as X-rays. These X-rays have particular energies depending upon the atom and are called muonic particular X-rays.
Muonic atom, unfavorable muonMuons are among the elementary particles and are the second generation of charged leptons in the Standard Model. There are positively or negatively charged muons, all with 1/2 spin and a typical life time of 2.2 split seconds. Negative muons decay into electrons, muon neutrinos, and antielectron neutrinos through weak interactions. Unfavorable muons are about 200 times heavier than electrons. Given that unfavorable muons have the same unfavorable charge as electrons, they behave as “heavy electrons” bound to a positively charged nucleus, like electrons. An atom composed of an unfavorable muon and a nucleus is called a muonic atom. A muonic atom ultimately decomposes due to the lifetime of the negative muon or due to the capture of the unfavorable muon by the nucleus.
When a product absorbs X-rays, superconducting Transition Edge Microcalorimeter (TES) A microcalorimeter is a detector that figures out the X-ray energy by the temperature level increase. The Superconducting Transition Edge Microcalorimeter determines the temperature level modification due to X-ray absorption utilizing the steep modification in electrical resistance near the superconductivity-normal conduction stage transition. TES represents Transition-Edge Sensor.
Quantum electrodynamics (QED) QED is a field theory that concerns electromagnetic interactions in between charged particles as being triggered by the exchange of photons and has been successful in explaining a range of phenomena that can not be understood by relativistic quantum mechanics.
Exotic atomsAtoms formed by changing the nucleus and electrons that make up an atom with other charged particles (positrons, muons, antiprotons, pions, etc) are called unique atoms. The combination of charge and mass of the particles that comprise an exotic atom is extremely various from that of nuclei and electrons, so exotic atoms act in an unique manner in which regular atoms do not.
Non-destructive essential analysis technique using muon atomsAs a non-destructive elemental analysis technique for unknown samples, the measurement of electronic particular X-rays emitted when a sample is irradiated with high-energy X-rays or electron beams has actually been commonly utilized. The electronic characteristic X-rays emitted from light components such as carbon and hydrogen have low energy, making it challenging to carry out essential analysis with adequate accuracy. Recently, a non-destructive elemental analysis technique utilizing muonic characteristic X-rays, which are given off when a sample product is irradiated with a negative muon beam, has been established. Given that muonic characteristic X-rays generally have greater energy than electronic particular X-rays, this method has an extremely high level of sensitivity to light elements. The muon-based elemental analysis approach has been used for the analysis of samples restored from the asteroid “Ryugu,” and its usefulness has been demonstrated.
J-PARC (Japan Proton Accelerator Research Complex) J-PARC is an accelerator facility situated in Tokai-mura, Ibaraki, where innovative research in different fields, such as particle and atomic physics, materials, and life sciences, is performed using the worlds most intense proton beams. The Muon Science Experimental Facility MUSE remains in the Materials and Life Science Experimental Facility (MLF) at J-PARC.
Bound muons in muonic atoms are continuously taking in and producing virtual photons, and the energy change due to this procedure is called self-energy. It is understood that the effect of vacuum polarization is particularly considerable in quantum electrodynamic effects on muonic atoms, and in the case of muonic neon atoms, the impact of vacuum polarization is more than 1,000 times bigger than the self-energy.
Transition energyAccording to quantum mechanics, electrons and muons bound to nuclei occupy discrete orbits, with their energy also being discretized (quantized). When a particle shifts from a higher energy orbital to a lower energy orbital is called the transition energy, the extra energy produced. In most cases, the transition energy is discharged as electromagnetic waves (light or X-rays).
Protecting effectIn an atom with several electrons, the impact is that the Coulomb force between the electrons and the nucleus appears to be minimized due to the charge of the remaining electrons.
Half-widthThis shows the width at half the value of an observation. The smaller this value is, the higher the resolution of the observation and the more exact the peak position can be measured.
Schwinger limitAccording to quantum electrodynamics, in extremely strong electrical fields surpassing an electrical field strength of 1.32 x 1018 V/m, the electromagnetic field exhibits nonlinear effects. This limiting electric field is called the Schwinger limitation after the physicist Julian Schwinger.
The experiment involved the use of high-precision measurements of the energy spectrum of muonic characteristic X-rays emitted from muonic atoms utilizing an advanced X-ray detector. By specifically measuring the energy of muonic characteristic X-rays discharged when muonic atoms are deexcited from a specific level to lower levels, QED can be verified under a strong electrical field (Figure 2).
The existence of atoms or molecules in the vicinity of the muonic atoms may cause rapid electron transfer and changes the energy of the muonic particular X-rays. The peaks shown are mainly due to the overlap of muonic characteristic X-rays from 6 various shifts, and the energy of the muonic particular X-rays was determined to a high precision of 0.002% by evaluating contributions from each of them.
It is known that the effect of vacuum polarization is especially significant in quantum electrodynamic impacts on muonic atoms, and in the case of muonic neon atoms, the result of vacuum polarization is more than 1,000 times larger than the self-energy.
International Collaboration Group.
The experiment was conducted at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), which is collectively operated by the Japan Atomic Energy Agency (JAEA) and the High Energy Accelerator Research Organization (KEK). The High Energy Accelerator Research Organization (KEK) Institute for Materials Structure Science established and ran the low-velocity negative muon beam and played an important function in the installation of experimental equipment, while the Kavli Institute for the Physics and Mathematics of the University of Tokyo, Osaka University, JAEA, Tokyo Metropolitan University, Rikkyo University, Kastler Brossel Laboratory in France, Tohoku University, and JAXA joined the advancement of experimental devices and measurement systems, and the acquisition and analysis of speculative data.
Research study Support.
This research study was moneyed by the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Scientific Research on Innovative Areas (Research Area Proposal Type), “Toward news frontiers: Encounter and synergy of state-of-the-art astronomical detectors and unique quantum beams (PI: Tadayuki Takahashi),” “Precise verification of molecular and atomic physics by unfavorable muon beam and its application to astrophysical observations (PI: Toshiyuki Azuma),” Grant-in-Aid for Scientific Research (A), “Clarification of Thorium-229 nuclear isomer structure: brand-new development of high accuracy clock science (PI: Tadaaki Isobe),” Grant-in-Aid for Scientific Research (A), “Innovation of atomic and molecular characteristics research study utilizing superconductive molecular detectors (PI: Shinji Okada),” Grant-in-Aid for Challenging Research (Pioneering), “Development of cryogenic Compton cam for high precision x-ray polarization spectroscopy (PI: Shinya Yamada), “Grant-in-Aid for Young Scientists, “Chemical responses of unfavorable ions in space environments probed by innovative neutral molecular detectors (PI: Takuma Okumura),” and Grant-in-Aid for Transformative Research Areas (A) (Publicly Offered Research), “Development of next-generation neutral molecular detection system for astrochemical reactions (PI: Takuma Okumura), and the RIKEN Pioneering Projects moneyed by RIKEN.
It has constantly been an imagine scientists to find physical laws. They have been discovered or proposed to describe observed phenomena that can not be understood by existing theories. Oftentimes, the discovery of new physics requires the advancement of new speculative methods and enhanced precision of measurements. The most precisely checked theory of physical laws is Quantum ElectroDynamics (QED), which describes the tiny interactions between charged particles and light. Researchers are continuously pressing the limits of how far QED accurately describes our physical truth.
The TES detector was initially developed for area X-ray observation. Takahashis present project at Kavli IPMU has been to carry out extraordinary cross-disciplinary research using this detector. His team consists of Kavli IPMU Project Assistant Professor Shin ichiro Takeda, Project Researcher Miho Katsuragawa, and at-the-time college student Kairi Mine, who took part in the muon experiments.
The collaborations demonstration of the speculative strategy using muonic atoms is anticipated to result in a terrific leap forward in the study of QED confirmation under strong electric fields.
Details of the study were published just recently in the scientific journal Physical Review Letters.
Background
The results of QED are more pronounced in environments with strong electric fields, however theoretical computations end up being more tough in this case. For many years, experiments utilizing highly charged ions (HCIs), which are atoms stripped of several electrons, have actually been performed as a technique to recognize a strong electric field environment. HCI research using big accelerators is still strongly pursued.
Research Study Methodology and Results
To confirm QED under strong electrical fields in a different way than with HCIs, worldwide research groups have actually focused on “exotic 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 (primary particles about 200 times much heavier than electrons) and nuclei. Unfavorable muons can nowadays be extracted as beams from big accelerators. Muonic atoms are identified by the exceptionally close proximity of the unfavorable muon to the nucleus, with the orbital radius of a bound muon being approximately 1/200th that of a bound electron. As an outcome, 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 same quantum level in an HCI, resulting in a big QED impact. In addition, by utilizing unfavorable muons, which occupy high angular momentum quantum levels with little overlap with the nucleus, it is possible to carry out experiments in which the result of the finite size of the nucleus is largely reduced. By precisely determining the energy of muonic characteristic X-rays emitted when muonic atoms are deexcited from a particular level to lower levels, QED can be verified under a strong electrical field (Figure 2).
Figure 2. Conceptual diagram showing muonic atoms and quantum electrodynamic (QED) results. In a muonic atom, the negative muon (-) is bound to the nucleus and orbits around it. According to quantum electrodynamics, the bound unfavorable muon continues its orbital movement while repeatedly producing and absorbing virtual photons (self-energy: SE ). In addition, there is an electrostatic attraction in between the neon nucleus (Ne10+) and the unfavorable muon, and the photons propagating through this interaction continually repeat the development and annihilation of virtual electron-positron (e ±) sets (vacuum polarization: VP ). In this research study, we exactly measured the energy of muonic characteristic X-rays emitted when the unfavorable muon deexcites to a lower state. Credit: Okumura et al
. Thus, muonic atoms are an appealing experimental target for strong-field QED confirmation. However, there are numerous problems to overcome. The biggest is that a variety of muonic atoms need to be prepared in an isolated environment. The presence of atoms or particles in the area of the muonic atoms may cause rapid electron transfer and alters the energy of the muonic particular X-rays. The solution is to use dilute gas targets with a small number density (low pressure), however the variety of produced muonic atoms and the resulting strength of muonic particular X-rays are reduced. The worldwide research study group carried out experiments at the Japan Proton Accelerator Research Complex (J-PARC) in Tokai-mura, Ibaraki, where the worlds most intense low-velocity muon beam is available. In order to figure out the energy with sufficient accuracy even with low-intensity muonic particular X-rays, the experiment was performed with a superconducting transition edge sensing unit (TES) microcalorimeter, which is a highly effective and high-resolution X-ray detector.
Utilizing uncommon gas neon (10Ne) atoms as the target, they have accomplished an energy resolution that is one order of magnitude greater than that of traditional semiconductor detectors (FWHM [11]: 5.2 eV) under water down conditions of 0.1 atm and successfully measured the muonic characteristic X-rays (Figure 3). The peaks shown are generally due to the overlap of muonic particular X-rays from six various transitions, and the energy of the muonic particular X-rays was figured out to a high precision of 0.002% by analyzing contributions from each of them.
Spectrum of released muonic particular X-rays emitted from muonic neon atoms.( a) Muonic particular X-rays released from muonic neon atoms appearing around 6300 eV at a neon gas target pressure of 0.1 atm. They duplicated the measurements while altering the pressure of the neon gas target (Figure 4) and confirmed that the energy of the muonic X-rays is continuous within experimental mistake regardless of the pressure of the neon gas target.
Dependence of muonic characteristic X-ray energy on neon gas pressure and contrast with the newest theoretical calculation. The energy of muonic characteristic X-rays is outlined against the pressure of the neon gas target. The energy of muonic particular X-rays is outlined versus the pressure of the neon gas target.
Referral: “Proof-of-Principle Experiment for Testing Strong-Field Quantum Electrodynamics with Exotic Atoms: High Precision X-ray Spectroscopy of Muonic Neon” by Takuma Okumura, Toshiyuki Azuma, Douglas A. Bennett, I-Huan Chiu, William B. Doriese, Malcolm S. Durkin, Joseph W. Fowler, Johnathon D. Gard, Tadashi Hashimoto, Ryota Hayakawa, Gene C. Hilton, Yuto Ichinohe, Paul Indelicato, Tadaaki Isobe, Sohtaro Kanda, Miho Katsuragawa, Naritoshi Kawamura, Yasushi Kino, Kairi Mine, Yasuhiro Miyake, Kelsey M. Morgan, Kazuhiko Ninomiya, Hirofumi Noda, Galen C. ONeil, Shinji Okada, Kenichi Okutsu, Nancy Paul, Carl D. Reintsema, Dan R. Schmidt, Koichiro Shimomura, Patrick Strasser, Hirotaka Suda, Daniel S. Swetz, Tadayuki Takahashi, Shinichiro Takeda, Satoshi Takeshita, Motonobu Tampo, Hideyuki Tatsuno, Yasuhiro Ueno, Joel N. Ullom, Shin Watanabe and Shinya Yamada, 27 April 2023, Physical Review Letters.DOI: 10.1103/ PhysRevLett.130.173001.
Supplementary Explanations.