The European Physical Journal D最新文献

{"title":"Laboratory constraint on the electric charge of the neutron and the neutrino","authors":"Savely G. Karshenboim","doi":"10.1140/epjd/s10053-025-00964-5","DOIUrl":"10.1140/epjd/s10053-025-00964-5","url":null,"abstract":"<p>We revisit constraints on the value of the electric charge of the neutron and the neutrinos as well as on the electric-charge proton–electron difference <span>(e_p+e_e)</span>. We consider phenomenological constraints based on laboratory study of the electrical neutrality of would-be neutral subatomic, atomic, and molecular species under assumption of the conservation of the electric charge in the <span>(beta )</span> decay that relates the values of <span>(e_p+e_e, e_n, e_nu )</span>. Some of constraints published previously utilized an additional assumption <span>(e_nu =0)</span>, which we do not. We dismiss a cosmological constraint at the level of <span>(10^{-35},e)</span> utilized by Particle Data Group (PDG) in their <i>Review of particle properties</i> Workman et al. (Particle Data Group) (Prog Theor Exp Phys 2022:083C01, 2022) as a controversial one which makes the laboratory constraints on <span>(e_nu )</span> dominant. The phenomenological constraints from the available data of laboratory experiments are obtained as <span>(e_p+e_e=(0.2pm 2.6)times 10^{-21},e)</span>, <span>(e_n=(-0.4pm 1.1)times 10^{-21},e)</span>, and <span>(e_nu =(0.6pm 3.2)times 10^{-21},e)</span>. The ones on <span>(e_p+e_e)</span> and <span>(e_n)</span> are at the same level as the related constraints of PDG but somewhat different because of releasing the value of <span>(e_nu )</span>. Our <span>(e_nu )</span> constraint is several orders of magnitude weaker than the controversial cosmological result dominated in the PDG constraint, but several orders of magnitude stronger than the other individual <span>(e_nu )</span> constraints considered by PDG. We also consider consistency of the phenomenological constraints and the Standard Model (SM). The SM ignores the mass term of the neutrinos and cannot describe the neutrino oscillations which makes it not a complete theory but a part of it. We demonstrate that the condition of the cancellation of the triangle anomalies within the complete theory does not disagree with the phenomenological constraints since different extensions of the SM may produce different additional contributions to the anomalies. A choice of the extension fixes the way how those contributions are organized. In particular, we consider a minimal extension of the SM, where leptons (<span>(nu ,e)</span>) are treated the same ways as quarks, which sets <span>(e_p+e_e=0)</span> and allows for numerical strengthening the constraint on <span>(e_n)</span> and <span>(e_nu )</span>, which is <span>(e_n=-e_nu =(-0.4pm 1.0)times 10^{-21},e)</span>.</p><p>Phenomenological constraint on the value of the electric charge of the neutrino</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-025-00964-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-energy proton beam generation via combined radiation pressure acceleration and laser wakefield acceleration in modulated plasma channels","authors":"Xin Chen,&nbsp;Lu Yang,&nbsp;Xiao-Nan Wang,&nbsp;Li Xiong,&nbsp;Peng-Fan Chen,&nbsp;Hai-Long Zhou,&nbsp;Xiao-Fei Lan,&nbsp;Yong-Sheng Huang,&nbsp;Yang-Fan He","doi":"10.1140/epjd/s10053-025-00977-0","DOIUrl":"10.1140/epjd/s10053-025-00977-0","url":null,"abstract":"<p>High-energy proton beams are essential for fundamental research and applied physics. The combined acceleration mechanism based on radiation pressure acceleration has made great progress in obtaining high-energy protons. However, Rayleigh–Taylor instability (RTI) is still a potential influencing factor that will limit the quality of high-energy proton beams. Different from the previous suppression and neglect of RTI, this paper introduces a parabolic density plasma channel to accelerate protons by virtue of the characteristics of RTI. Three-dimensional Particle-in-cell simulations reveal that this scheme achieves high-energy protons with cut-off energy of 39 <span>(textrm{GeV})</span>, total charge of 0.97 <span>(textrm{nC})</span>, and the emittance of 1.12 <span>(mathrm{{mm}};mathrm{{mrad}})</span> in both the <i>y</i> and <i>z</i> directions. There are locally distributed electrons in the parabolic density plasma channel, and the focusing field around them can effectively focus protons. Compared with the uniform density plasma channel, the parabolic density plasma channel can significantly improve the quality of the proton beam, which could offer significant guidance for the generation and application of high-energy proton beams.</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electromagnetic emission of a hollow needle to mesh negative corona and quasi-periodical spark discharge in the air","authors":"Stanislav Pekárek","doi":"10.1140/epjd/s10053-025-00975-2","DOIUrl":"10.1140/epjd/s10053-025-00975-2","url":null,"abstract":"<div><p>We investigated the emission of electromagnetic waves from the stainless-steel hollow needle to mesh corona and quasi-periodical spark discharge without and with airflow through the negative needle electrode in the frequency range below 500 MHz. We showed that there is no electromagnetic waves emission from the pulseless corona discharge. After the discharge transition to the quasi-periodical spark, high-amplitude current pulses correlate with the bursts of electromagnetic radiation. We demonstrated that the spectral distribution of emitted radiation is independent of the discharge voltage, current, and airflow through the needle electrode. We found that the highest peak of the power level of the electric component of emitted waves occurs at the frequency of 15.2 MHz, and the power level of emitted radiation as a function of frequency gradually decreases.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-025-00975-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of the Breit interaction on spin polarization of Auger electrons following electron-impact excitation of Be-like ions","authors":"Y. Li,&nbsp;Z. Q. Tian,&nbsp;J. Q. Wang,&nbsp;C. Z. Dong,&nbsp;S. Fritzsche,&nbsp;Z. W. Wu","doi":"10.1140/epjd/s10053-025-00980-5","DOIUrl":"10.1140/epjd/s10053-025-00980-5","url":null,"abstract":"<p>Spin polarization of Auger electrons emitted from nonradiative Auger decay <span>(1s2s^{2}2p_{1/2},J!=!1 !rightarrow ! 1s^{2}2s,J_{f}!=!1/2)</span> following inner-shell electron-impact excitation from the ground state of highly charged Be-like ions is studied by using the density-matrix theory and the relativistic distorted-wave theory. The question is raised: How does the Breit interaction affect spin polarization of the emitted Auger electrons? Generally, both alignment and intrinsic anisotropy parameters determine the anisotropy of the emitted electrons in this excitation–autoionization process. Here, we calculate and analyze intrinsic spin-polarization parameter for Be-like <span>(hbox {Mg}^{8+})</span>, <span>(hbox {Fe}^{22+})</span>, <span>(hbox {Mo}^{38+})</span>, <span>(hbox {Nd}^{56+})</span>, <span>(hbox {Au}^{75+})</span>, and <span>(hbox {U}^{88+})</span> ions to obtain spin polarization of the Auger electrons. It is found that the Breit interaction hardly contributes to the spin polarization for low-<i>Z</i> Be-like ions such as <span>(hbox {Mg}^{8+})</span>, even at high impact electron energies, whereas for medium- and high-<i>Z</i> ions the situation becomes fairly different. To be specific, the spin polarization becomes nearly zero and almost independent of the emission angle of the Auger electrons owing to the Breit interaction, which becomes more and more prominent with increasing nuclear charge. Moreover, the Breit interaction even changes the direction of the spin polarization vector for high-<i>Z</i> ions especially at low impact energies, for example, for <span>(hbox {U}^{88+})</span> ions at impact energies below the threefold excitation threshold.</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scattering of electron and positron by methane","authors":"M. Mousumi Khatun,&nbsp;A. K. Fazlul Haque,&nbsp;M. Alfaz Uddin","doi":"10.1140/epjd/s10053-025-00974-3","DOIUrl":"10.1140/epjd/s10053-025-00974-3","url":null,"abstract":"<p>This work provides a comprehensive theoretical investigation of <span>({e^-}-CH_4)</span> and <span>({e^+}-CH_4)</span> scattering systems over a wide range of projectile energies, from 1 eV to 1 MeV. The single scattering independent atom model (IAM) and the screening correction (IAMS), arising from a semi-classical analysis of atomic geometrical overlap, are used within the same framework for the present analysis. A broad spectrum of scattering observable quantities is calculated, such as differential, integrated elastic, momentum transfer, viscosity, inelastic, grand total and total ionization cross sections along with the Sherman function. For this spin-dependent and relativistic scattering study, the Dirac equation is solved using a complex optical potential model (OPM) by partial wave phase-shift analysis to generate the scattering cross-sections data. A satisfactory level of concordance is observed when our computed results are compared to both experimental data and other theoretical calculations available in the literature. The screening corrected independent atom model (IAMS) has been found to produce results with greater accuracy than the IAM.</p><p>Comparison of <img> scattering cross sections (a) DCS in units of <span>(a_0^2/sr)</span> at 90°scattering angle, (b) Sherman function S(θ) at 90°scattering angle, (c) TCS, (d) IECS, (e) TICS and (f) MTCS in units of <span>(a_0^2)</span>. </p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cold source of atomic hydrogen for loading large magnetic traps","authors":"Aleksei Semakin,&nbsp;Janne Ahokas,&nbsp;Otto Hanski,&nbsp;Slava Dvornichenko,&nbsp;Tom Kiilerich,&nbsp;François Nez,&nbsp;Pauline Yzombard,&nbsp;Valery Nesvizhevsky,&nbsp;Eberhard Widmann,&nbsp;Paolo Crivelli,&nbsp;Sergey Vasiliev","doi":"10.1140/epjd/s10053-025-00976-1","DOIUrl":"10.1140/epjd/s10053-025-00976-1","url":null,"abstract":"<p>We present a design and performance tests of an intense source of cold hydrogen atoms for loading large magnetic traps. Our source is based on a cryogenic dissociator of molecular hydrogen at 0.6 K followed by a series of thermal accommodators at 0.5, 0.2 and 0.13 K with inner surfaces covered by a superfluid helium film. All components are thermally anchored to corresponding stages of a dilution refrigerator. The source provides a continuous flux of <span>(7times 10^{13})</span> H atoms/s in a temperature range of 130–200 mK. We have successfully used the source for loading a large Ioffe–Pritchard magnetic trap recently built in our laboratory (Ahokas et al. in Rev Sci Instrum 93(2):023201, 2022). Calorimetric measurements of the atomic recombination heat allow reliable determination of the atomic flux and H gas density in the trap. We have tested the performance of the source and loading of H atoms into the trap at various configurations of the trapping field, reducing the magnetic barrier height to 75<span>(%)</span> and 50<span>(%)</span> of the nominal value of 0.8 T (0.54 K) as well as at the open configuration of the trap at its lower end, when the atoms are in contact with the trapping cell walls covered by a superfluid helium film. In the latter case, raising the trapping cell temperature to 200–250 mK, the low-field seeking atoms at densities exceeding 10<span>(^{11})</span> <span>(hbox {cm}^{-3})</span> can be stored for the time over 10<span>(^3)</span> s, sufficiently long for experiments on precision spectroscopy of cold H gas.</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-025-00976-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143707115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dielectronic recombination into high-n Rydberg shells","authors":"S. Fritzsche,&nbsp;H. K. Huang,&nbsp;Z.-K. Huang,&nbsp;S. Schippers,&nbsp;W. Q. Wen,&nbsp;Z. W. Wu","doi":"10.1140/epjd/s10053-025-00969-0","DOIUrl":"10.1140/epjd/s10053-025-00969-0","url":null,"abstract":"<p>The dielectronic recombination (DR) of multiply and highly charged ions often proceeds due to the capture of electrons into high-<i>n</i> Rydberg orbitals. The formation of these high-<i>n</i> resonances is relevant to the dynamics of low-temperature plasma and has been explored especially for the DR of initially lithium-like ions. Despite the great interest in low-temperature plasma rate coefficients for different ions, however, several difficulties have hampered the modeling of high-<i>n</i> resonances owing to their complex shell and fine structure, or merely the size of these ions in their doubly excited state. To improve the modeling of DR processes with high-<i>n</i> Rydberg orbitals, we here expand and illustrate the use of JAC, the Jena Atomic Calculator. In particular, we now support several empirical corrections in order to synthesize DR spectra for a wide range of positive ions. This expansion also prepares JAC for a new class of storage-ring experiments that aim for determining improved valence-shell excitations energies of (highly charged) beryllium- and other few-electron ions. To demonstrate this expansion of the JAC code, we here compute and discuss the low-lying DR resonances of initially beryllium-like Pt<span>(^{78+})</span> ions and compare the predicted spectra with previous measurements and computations. Beside this rather uninvolved example, the JAC toolbox is suitable for many other, if not most, multiply and highly charged ions across the periodic table.</p><p>Well-known difficulties and challenges in dealing with high-n dielectronic recombination (DR) computations</p>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-025-00969-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143707144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Muonium fine structure: theory update, tests of Lorentz violation, and experimental prospects","authors":"Philipp Blumer,&nbsp;Svenja Geissmann,&nbsp;Arnaldo J. Vargas,&nbsp;Gianluca Janka,&nbsp;Ben Ohayon,&nbsp;Paolo Crivelli","doi":"10.1140/epjd/s10053-025-00971-6","DOIUrl":"10.1140/epjd/s10053-025-00971-6","url":null,"abstract":"<div><p>We review the status of the QED calculations for the muonium <span>(2S_{1/2}-2P_{3/2})</span> energy interval and provide the updated theoretical value of 9874.357(1)<span>({,{textrm{MHz}},})</span>. Additionally, we present a model for probing Lorentz-violating coefficients within the Standard Model Extension framework using the fine structure measurement in the presence and absence of a weak external magnetic field, enabling novel tests of CPT and Lorentz symmetry. Using Monte Carlo simulations, we estimate that a precision of <span>(sim {10,mathrm{text {k}text {Hz}}})</span> on the isolated <span>(2S_{1/2}, F=1 - 2P_{3/2}, F=1)</span> transition could be achievable employing Ramsey’s separate oscillatory fields (SOF) technique. Collecting the required statistics will become feasible with the upcoming High-Intensity Muon Beam (HiMB) at the Paul Scherrer Institute (PSI) in Switzerland. These advancements will enable precise tests of radiative QED corrections and nuclear self-energy contributions, while also providing tests of new physics and sensitivity to unconstrained coefficients for Lorentz violation within the Standard Model Extension framework.</p></div>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-025-00971-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143707114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Ar microplasma irradiation on surface, structural and field emission properties of brass","authors":"Asad Ali,&nbsp;Mahreen Akram,&nbsp;Shazia Bashir,&nbsp;Khaliq Mahmood,&nbsp;Shahzad Naseem,&nbsp;Saqib Jamil,&nbsp;Aiman Saif Ullah,&nbsp;Abdul Wahid,&nbsp;Rana Muhammad Ayub,&nbsp;Shoaib Akmal","doi":"10.1140/epjd/s10053-025-00973-4","DOIUrl":"10.1140/epjd/s10053-025-00973-4","url":null,"abstract":"<div><p>Ar microplasma irradiation is used to induce morphological, structural, electrical and field emission modifications of brass for different treatment times. The ablation depth evaluated by optical microscopy analysis gradually increases and then decreases with the increase of treatment time. Scanning Electron Microscope (SEM) analysis reveals the generation of microscale holes, blisters and fibrous structures which are explained on the basis of collisional/thermal sputtering, diffusion and bursting of gaseous bubbles. X-Ray Diffraction (XRD) analysis reveals absence of new compositional phase however, variation in peak intensities, crystallite size, dislocation line density, and stress/ strain is observed. The potential of microplasma treated brass to be used as field emission cathode is evident from significantly improved field emission parameters. The correlation of field emission parameters with the structural density, work function and electrical conductivity measurements suggests geometrical field enhancement, increased number of emission sites and enhanced charge transport properties offered by the grown structures.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div><p>The graphical abstract showing (a) schematic view of microplasma set up (b) Optical micrograph of treated Brass surface for the exposure time of 10 minutes showing fibrous morphology (c) High resolution SEM image of treated Brass surface for the exposure time of 10 minutes and (d) Correlation of structural density with corresponding maximum current density Jmax</p></div>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143698532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Precision measurements of muonium and muonic helium hyperfine structure at J-PARC","authors":"Patrick Strasser,&nbsp;Mitsushi Abe,&nbsp;Kanta Asai,&nbsp;Seiso Fukumura,&nbsp;Mahiro Fushihara,&nbsp;Yu Goto,&nbsp;Takashi Ino,&nbsp;Ryoto Iwai,&nbsp;Sohtaro Kanda,&nbsp;Shiori Kawamura,&nbsp;Masaaki Kitaguchi,&nbsp;Shoichiro Nishimura,&nbsp;Takayuki Oku,&nbsp;Takuya Okudaira,&nbsp;Adam Powell,&nbsp;Ken-ichi Sasaki,&nbsp;Hirohiko M. Shimizu,&nbsp;Koichiro Shimomura,&nbsp;Hiroki Tada,&nbsp;Hiroyuki A. Torii,&nbsp;Takashi Yamanaka,&nbsp;Takayuki Yamazaki,&nbsp;(MuSEUM Collaboration)","doi":"10.1140/epjd/s10053-025-00959-2","DOIUrl":"10.1140/epjd/s10053-025-00959-2","url":null,"abstract":"<div><p>At the J-PARC Muon Science Facility (MUSE), the MuSEUM collaboration is now performing new precision measurements of the ground state hyperfine structure (HFS) of both muonium and muonic helium atoms. High-precision measurements of the muonium ground-state HFS are recognized as one of the most sensitive tools for testing bound-state quantum electrodynamics theory to precisely probe the standard model and determine fundamental constants of the positive muon magnetic moment and mass. The same technique can also be employed to measure muonic helium HFS, obtain the negative muon magnetic moment and mass, and test and improve the theory of the three-body atomic system. Measurements at zero magnetic field have already yielded more accurate results than previous experiments for both muonium and muonic helium atoms. High-field measurements are now ready to start collecting data using the world’s most intense pulsed muon beam at the MUSE H-line. We aim to improve the precision of previous measurements ten times for muonium and a hundred times or more for muonic helium. We review all the key developments for these new measurements, focusing on the high-field experiment, and report the latest results and prospects.</p></div>","PeriodicalId":789,"journal":{"name":"The European Physical Journal D","volume":"79 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjd/s10053-025-00959-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}