Showing 1–50 of 70 results for author: Ruiz, R

Probing the electroweak structure of nuclei with rare atoms and molecules

Authors: Silviu-Marian Udrescu, Antoine Belley, Jason D. Holt, Gilad Perez, Ronald F. Garcia Ruiz

Abstract: Precision experiments of atoms and molecules have become a powerful probe of the electroweak structure of atomic nuclei and of physics beyond the Standard Model. We review how the interaction between a nucleus and its surrounding bound electrons can be exploited to precisely measure the electromagnetic, parity-violating, and CP-violating properties of nuclei and their fundamental constituents. We… ▽ More Precision experiments of atoms and molecules have become a powerful probe of the electroweak structure of atomic nuclei and of physics beyond the Standard Model. We review how the interaction between a nucleus and its surrounding bound electrons can be exploited to precisely measure the electromagnetic, parity-violating, and CP-violating properties of nuclei and their fundamental constituents. We focus on rare, unstable isotopes, surveying the experimental techniques and facilities developed in recent years that have extended these measurements to the most exotic regions of the nuclear chart. Recent advances in the precision control and interrogation of single molecules, together with direct laser excitation of nuclear transitions, are opening new frontiers in nuclear and particle physics. At the same time, progress in nuclear theory, machine learning, and high-performance computing is strengthening the connection between our microscopic description of nature and laboratory observables. In many cases, the precision with which nuclear and particle physics properties can be extracted is now limited not by experiment, but by the molecular, atomic, or nuclear theory required to interpret the measurements. This challenge presents a major opportunity for combined theoretical and experimental advances that will enable future discoveries. △ Less

Submitted 18 August, 2026; originally announced August 2026.

Comments: 74 pages, 24 figures

Laser spectroscopy illuminates the $N=32$ shell closure

Authors: Tim E. Lellinger, Liss V. Rodriguez, Patrick Muller, Osama Ahmad, Mark L. Bissell, Klaus Blaum, Emily Burbach, Bradley Cheal, Till Fabritz, Ronald F. Garcia Ruiz, Matthias Heinz, Jack Hughes, Phillip Imgram, Kristian Konig, Yinshen Liu, Bernhard Maass, Edward N. Matthews, Takayuki Miyagi, Witold Nazarewicz, Rainer Neugart, Gerda Neyens, Lukas Nies, Wilfried Nortershauser, Julian Palmes, Peter Plattner , et al. (7 additional authors not shown)

Abstract: Atomic nuclei are strongly correlated quantum many-body systems, and how their shell structure evolves with increasing neutron excess remains a central open question in nuclear physics. Calcium isotopes are an ideal testing ground: alongside the traditional magic numbers $N=20,28$, new shell closures have been proposed at $N=32,34$ ($^{52,54}\mathrm{Ca}$). While the charge radius rises rapidly tow… ▽ More Atomic nuclei are strongly correlated quantum many-body systems, and how their shell structure evolves with increasing neutron excess remains a central open question in nuclear physics. Calcium isotopes are an ideal testing ground: alongside the traditional magic numbers $N=20,28$, new shell closures have been proposed at $N=32,34$ ($^{52,54}\mathrm{Ca}$). While the charge radius rises rapidly towards $N=32$, further moments and radii in the isotopic chain have remained inaccessible due to the low production yield of a few ions per second. Here we apply a highly sensitive collinear laser spectroscopy technique, which reveals a strikingly simple behaviour: adding one neutron to $^{52}\mathrm{Ca}$ yields a pure single-particle magnetic dipole moment in $^{53}\mathrm{Ca}$, while the charge-radius slope towards $^{54}\mathrm{Ca}$ exceeds that towards $^{52}\mathrm{Ca}$. This provides strong evidence for a robust $N=32$ shell closure and stringently constrains nuclear structure models. △ Less

Submitted 11 August, 2026; originally announced August 2026.

Design and Performance of a Heated Gas Injector for Producing Cold Molecular Beams

Authors: Avneesh Verma, Jack Mango, Shungo Fukaya, Arian Jadbabaie, Sepehr Ebadi, Ronald F. Garcia Ruiz, John M. Doyle

Abstract: We realize an injector device that supplies warm gas directly into a cryogenic environment. This injector has several advantageous features, including robustness, rigidity, simple installation, and excellent thermal isolation between a hot ($\sim$300 K) copper fill line and a cold ($<$3 K) cryogenic buffer gas cell. Less than 200 mW heat load on the cell is observed in realistic conditions of a mo… ▽ More We realize an injector device that supplies warm gas directly into a cryogenic environment. This injector has several advantageous features, including robustness, rigidity, simple installation, and excellent thermal isolation between a hot ($\sim$300 K) copper fill line and a cold ($<$3 K) cryogenic buffer gas cell. Less than 200 mW heat load on the cell is observed in realistic conditions of a molecular precision measurement experiment. A polyamide-imide (PAI) tube is the essential design feature. The fill line is epoxied to one end of the tube while the other end of the tube is connected to the cell via a slip-fit onto a brass nipple, realizing a complete vacuum-tight seal. PAI contracts on the brass nipple when cooled, forming a cryogenic leak-tight seal. The injector is easily (de-)mountable and rigid, with no significant displacement of the fill line relative to the cell observed during cooldown to 4 K. We characterize injector performance by flowing into the cell $\text{SF}_6$ through the hot fill line and cold $\text{He}$ buffer gas through a separate cryogenic fill line while laser ablating a barium-containing target. This produces cold BaF free radicals, detected using absorption spectroscopy. This injector design will be employed to laser cool radium-containing molecules, such as $\text{RaF}$ and $\text{RaOH}$, where leak-tight delivery of $\text{SF}_6$ and $\text{H}_2\text{O}$ reagents into a cryogenic buffer gas cell is required for scientific and safety reasons. These molecules are of particular interest for the study of symmetry-violating nuclear properties and searches for physics beyond the Standard Model. △ Less

Submitted 16 June, 2026; originally announced June 2026.

Comments: 12 pages, 10 figures

Non-destructive cavity readout of molecules for precision measurements

Authors: Alejandro Salas-Estrada, Silviu-Marian Udrescu, Geoffrey Zheng, Qian Wang, Arian Jadbabaie, Vladan Vuletić, David DeMille, Ronald F. Garcia Ruiz, Edwin Pedrozo-Peñafiel

Abstract: We propose a non-destructive method to measure the population of molecules in a selected rotational-hyperfine state by coupling them to a high-finesse optical cavity. In contrast to traditional techniques, our approach enables fast (less than 1 ms) repeated measurements with reduced heating and losses, and with precision below the standard quantum limit. The method is particularly advantageous for… ▽ More We propose a non-destructive method to measure the population of molecules in a selected rotational-hyperfine state by coupling them to a high-finesse optical cavity. In contrast to traditional techniques, our approach enables fast (less than 1 ms) repeated measurements with reduced heating and losses, and with precision below the standard quantum limit. The method is particularly advantageous for radioactive molecules, systems of high interest for symmetry violation searches, for which production and sample size are limited, and repeated interrogation is essential for improved sensitivity. △ Less

Submitted 1 June, 2026; originally announced June 2026.

Comments: 16 pages, 7 figures

Radioactive Molecules as Laboratories of Fundamental Physics

Authors: A. Jadbabaie, S. Ebadi, R. F. Garcia Ruiz, N. R. Hutzler, A. M. Jayich, J. T. Singh

Abstract: Radioactive molecules provide a powerful new platform in the search for new physics at energy scales complementary to high-energy particle colliders. By combining enhancements from nuclear properties with the sensitivity and control offered by molecular structure, experiments with radioactive molecules offer great reach in the search for new physics beyond the Standard Model. Rapid progress in thi… ▽ More Radioactive molecules provide a powerful new platform in the search for new physics at energy scales complementary to high-energy particle colliders. By combining enhancements from nuclear properties with the sensitivity and control offered by molecular structure, experiments with radioactive molecules offer great reach in the search for new physics beyond the Standard Model. Rapid progress in this field is being driven by advances in the production and control of radioactive molecules, alongside the development of new experimental tools and theoretical techniques. In this Perspective, we discuss the current status and future prospects of this rapidly developing, interdisciplinary field at the intersection of nuclear physics, atomic and molecular physics, and particle physics. △ Less

Submitted 23 June, 2026; v1 submitted 12 May, 2026; originally announced May 2026.

Comments: Published in $\textit{Nature Reviews Physics}$ (2026), see http://www.nature.com/articles/s42254-026-00950-9 . 28 pages, 5 figures

Journal ref: Nat Rev Phys (2026)

Energies and lifetimes of the 9p and 10p excited states in atomic francium

Authors: P. Lassègues, A. Ajayakumar, M. Athanasakis-Kaklamanakis, O. Ahmad, M. Au, J. Berbalk, D. Bettaney, B. van den Borne, A. Chakraborty, T. E. Cocolios, M. Duggan, C. Fajardo, K. T. Flanagan, R. F. Garcia Ruiz, R. de Groote, D. Gonzalez-Acevedo, A. Kastberg, A. Koszorús, L. Lalanne, K. M. Lynch, D. T. McLeroy, A. McGlone, G. Neyens, L. Nies, L. Quanjel , et al. (7 additional authors not shown)

Abstract: We present the first measurement of 9p 2P1/2,3/2 and 10p 2P1/2,3/2 excited levels absolute wavenumbers and radiative lifetime in francium. We used the Collinear Resonance Ionization Spectroscopy (CRIS) technique, applied on a beam of 221Fr atoms. Prior to this work, no experimental data existed for francium p-states with n > 8. The results provide a precision experimental test of relativistic coup… ▽ More We present the first measurement of 9p 2P1/2,3/2 and 10p 2P1/2,3/2 excited levels absolute wavenumbers and radiative lifetime in francium. We used the Collinear Resonance Ionization Spectroscopy (CRIS) technique, applied on a beam of 221Fr atoms. Prior to this work, no experimental data existed for francium p-states with n > 8. The results provide a precision experimental test of relativistic coupled-cluster theory for the heaviest alkali, showing good agreement for lifetimes and relative excitation energies, despite a residual global offset in absolute energies. △ Less

Submitted 12 May, 2026; v1 submitted 14 April, 2026; originally announced April 2026.

Towards Collinear Laser Spectroscopy of Radioactive Molecules Utilizing In-trap Produced Molecular Ion Beam

Authors: W. C. Mei, S. J. Chen, X. F. Yang, J. H. Lv, D. Y. Chen, H. R. Hu, Y. F. Guo, Z. Yan, Y. P. Jing, C. Zhang, Y. P. Lin, T. X. Gao, X. Shen, S. W. Bai, R. F. Garcia Ruiz, J. Yang, Y. L. Ye

Abstract: Molecules containing short-lived isotopes, namely radioactive molecules, are among the most promising candidates for probing new physics beyond the Standard Model, although their production and spectroscopic measurements remain technically challenging. Here, we demonstrate an integrated methodology that combines formation of molecular ion beams in a radiofrequency quadrupole cooler-buncher with co… ▽ More Molecules containing short-lived isotopes, namely radioactive molecules, are among the most promising candidates for probing new physics beyond the Standard Model, although their production and spectroscopic measurements remain technically challenging. Here, we demonstrate an integrated methodology that combines formation of molecular ion beams in a radiofrequency quadrupole cooler-buncher with collinear laser spectroscopy. As a proof-of-principle experiment, we successfully produce molecular ions such as $\rm BaF^+$ and $\rm YbF^+$ via in-trap ion-molecule reactions and perform high-resolution laser spectroscopy of the target molecule $\rm ^{138}BaF$. Vibrational and rotational structures of $\rm ^{138}BaF$ across different electronic states are obtained using resonance-enhanced multiphoton ionization schemes, confirming the feasibility of the proposed methodology. This work establishes a practical route for future formation and spectroscopic studies of short-lived radioactive molecules, such as those containing $\rm ^{225}Ra$, at radioactive ion beam facilities. △ Less

Submitted 16 March, 2026; originally announced March 2026.

Extreme Ultraviolet Spectroscopy of Highly Charged Lu and Yb Ions for Nuclear Charge Radius Determination

Authors: Hunter Staiger, Endre Takacs, Steven A. Blundell, Naoki Kimura, Hiroyuki A. Sakaue, Ronald F. Garcia Ruiz, Witold Nazarewicz, Paul-Gerhard Reinhard, Chowdhury A. Faiyaz, Chihiro Suzuki, Dipti, István Angeli, Yuri Ralchenko, Izumi Murakami, Daiji Kato, Yuki Nagai, Ryuji Takaoka, Yoshiki Miya, Nobuyuki Nakamura

Abstract: We report a high-precision determination of the natural-abundance-averaged nuclear charge-radius difference between Yb and Lu using extreme ultraviolet (EUV) spectroscopy of highly charged ions (HCIs). By measuring the $D_1$ transition energies in Na- and Mg-like charge states of Lu and Yb confined in the Tokyo electron-beam ion trap, we extract meV-level energy shifts that are directly sensitive… ▽ More We report a high-precision determination of the natural-abundance-averaged nuclear charge-radius difference between Yb and Lu using extreme ultraviolet (EUV) spectroscopy of highly charged ions (HCIs). By measuring the $D_1$ transition energies in Na- and Mg-like charge states of Lu and Yb confined in the Tokyo electron-beam ion trap, we extract meV-level energy shifts that are directly sensitive to nuclear-size effects. Transition-energy differences obtained from these spectra are compared with state-of-the-art relativistic many-body perturbation theory, including a new treatment of Mg-like ions. We develop a generalized framework to propagate uncertainties arising from nuclear deformation and surface diffuseness and evaluate corresponding nuclear-sensitivity coefficients. Combining Na- and Mg-like results yields mutually consistent radius differences, demonstrating the robustness of both the experimental calibration and the theoretical predictions. To determine absolute isotopic radii, we perform a generalized least-squares optimization incorporating our HCI constraints together with optical-isotope-shift data and muonic-atom results. This analysis establishes that the $^{175}$Lu charge radius is smaller than that of $^{174}$Yb, restoring the expected odd-even staggering across the $N=94$ isotonic chain. Our recommended value, $R(^{175}\text{Lu}) = 5.291(11)$ fm, reduces the uncertainty of the Lu radius by a factor of three compared with the previous electron-scattering result and resolves a long-standing anomaly in rare-earth nuclear systematics. This work demonstrates that EUV spectroscopy of HCIs provides a powerful and broadly applicable method for precision nuclear-structure studies in heavy, deformed nuclei. The techniques developed here enable future investigations of isotonic and isoelectronic sequences, including radioactive nuclides and higher-$Z$ systems. △ Less

Submitted 25 November, 2025; originally announced November 2025.

Comments: 16 pages, 7 figures

Puzzling Isotonic Odd-Even Staggering of Charge Radii in Deformed Rare Earth Nuclei

Authors: Endre Takacs, Hunter Staiger, Steven A. Blundell, Naoki Kimura, Hiroyuki A. Sakaue, Ronald F. Garcia Ruiz, Witold Nazarewicz, Paul-Gerhard Reinhard, Chowdhury A. Faiyaz, Chihiro Suzuki, Dipti, István Angeli, Yuri Ralchenko, Izumi Murakami, Daiji Kato, Yuki Nagai, Ryuji Takaoka, Yoshiki Miya, Nobuyuki Nakamura

Abstract: The nuclear charge radius is a fundamental observable that encodes key aspects of nuclear structure, deformation, and pairing. Isotonic (constant neutron number) systematics in the deformed rare-earth region have long suggested that odd-$Z$ nuclei are more compact than their even-$Z$ neighbors - except for Lu, whose recommended radius appeared anomalously large relative to Yb and Hf. We report a h… ▽ More The nuclear charge radius is a fundamental observable that encodes key aspects of nuclear structure, deformation, and pairing. Isotonic (constant neutron number) systematics in the deformed rare-earth region have long suggested that odd-$Z$ nuclei are more compact than their even-$Z$ neighbors - except for Lu, whose recommended radius appeared anomalously large relative to Yb and Hf. We report a high-precision determination of the natural-abundance-averaged Lu-Yb charge-radius difference using extreme-ultraviolet spectroscopy of highly charged Na-like and Mg-like ions, supported by high-accuracy relativistic atomic-structure calculations - a recently introduced method with the unique ability to measure inter-element charge radius differences. Combined with muonic-atom and optical isotope-shift data, our result resolves the longstanding Lu inversion anomaly and reestablishes a pronounced odd-even staggering along the $N=94$ isotonic chain. The magnitude of this staggering is unexpectedly large, far exceeding that observed in semi-magic nuclei and in deformed isotopic sequences. State-of-the-art nuclear density functional theory calculations, including quantified uncertainties, fail to reproduce this enhancement, possibly indicating missing structural effects in current models. Our work demonstrates the power of highly charged ions for precise, element-crossing charge-radius measurements and provides stringent new constraints for future theoretical and experimental studies of nuclear-size systematics. △ Less

Submitted 27 November, 2025; v1 submitted 24 November, 2025; originally announced November 2025.

Comments: 7 pages, 3 figures - added arXiv link to companion paper (arXiv:2511.20537)

Deep Learning Framework for Enhanced Neutrino Reconstruction of Single-line Events in the ANTARES Telescope

Authors: A. Albert, S. Alves, M. André, M. Ardid, S. Ardid, J. -J. Aubert, J. Aublin, B. Baret, S. Basa, Y. Becherini, B. Belhorma, F. Benfenati, V. Bertin, S. Biagi, J. Boumaaza, M. Bouta, M. C. Bouwhuis, H. Brânzaş, R. Bruijn, J. Brunner, J. Busto, B. Caiffi, D. Calvo, S. Campion, A. Capone , et al. (115 additional authors not shown)

Abstract: We present the $N$-fit algorithm designed to improve the reconstruction of neutrino events detected by a single line of the ANTARES underwater telescope, usually associated with low energy neutrino events ($\sim$ 100 GeV). $N$-Fit is a neural network model that relies on deep learning and combines several advanced techniques in machine learning --deep convolutional layers, mixture density output l… ▽ More We present the $N$-fit algorithm designed to improve the reconstruction of neutrino events detected by a single line of the ANTARES underwater telescope, usually associated with low energy neutrino events ($\sim$ 100 GeV). $N$-Fit is a neural network model that relies on deep learning and combines several advanced techniques in machine learning --deep convolutional layers, mixture density output layers, and transfer learning. This framework divides the reconstruction process into two dedicated branches for each neutrino event topology --tracks and showers-- composed of sub-models for spatial estimation --direction and position-- and energy inference, which later on are combined for event classification. Regarding the direction of single-line events, the $N$-Fit algorithm significantly refines the estimation of the zenithal angle, and delivers reliable azimuthal angle predictions that were previously unattainable with traditional $χ^2$-fit methods. Improving on energy estimation of single-line events is a tall order; $N$-Fit benefits from transfer learning to efficiently integrate key characteristics, such as the estimation of the closest distance from the event to the detector. $N$-Fit also takes advantage from transfer learning in event topology classification by freezing convolutional layers of the pretrained branches. Tests on Monte Carlo simulations and data demonstrate a significant reduction in mean and median absolute errors across all reconstructed parameters. The improvements achieved by $N$-Fit highlight its potential for advancing multimessenger astrophysics and enhancing our ability to probe fundamental physics beyond the Standard Model using single-line events from ANTARES data. △ Less

Submitted 20 November, 2025; originally announced November 2025.

Commissioning the Resonance Ionization Spectroscopy Experiment at FRIB

Authors: A. J. Brinson, B. J. Rickey, J. M. Allmond, A. Dockery, A. Fernandez Chiu, R. F. Garcia Ruiz, T. J. Gray, J. Karthein, T. T. King, K. Minamisono, A. Ortiz-Cortes, S. V. Pineda, M. Reponen, B. C. Rasco, S. M. Udrescu, A. R. Vernon, S. G. Wilkins

Abstract: This manuscript reports on the commissioning of the Resonance Ionization Spectroscopy Experiment (RISE) at the BECOLA facility at FRIB. The new instrument implements the collinear resonance ionization spectroscopy technique for sensitive measurements of isotope shifts and hyperfine structure of short-lived isotopes produced at FRIB. The existing BECOLA beamline was extended to integrate an electro… ▽ More This manuscript reports on the commissioning of the Resonance Ionization Spectroscopy Experiment (RISE) at the BECOLA facility at FRIB. The new instrument implements the collinear resonance ionization spectroscopy technique for sensitive measurements of isotope shifts and hyperfine structure of short-lived isotopes produced at FRIB. The existing BECOLA beamline was extended to integrate an electrostatic ion-beam bender and an ion detector at ultra-high vacuum. An injection-seeded Ti:Sapphire laser and a multi-harmonic pulsed Nd:YAG laser were installed to perform resonant excitation and selective ionization. Commissioning tests were performed to demonstrate the capabilities of the new instrument by measuring the hyperfine structure of stable $^{27}$Al produced in an offline ion source. The RISE instrument is ready and operational for future studies of short-lived isotopes at FRIB. △ Less

Submitted 17 February, 2026; v1 submitted 11 November, 2025; originally announced November 2025.

Beam-tracing and profile evolution for localised beams in inhomogeneous plasmas

Authors: Lewin B. S. Marsh, Felix I. Parra, Valerian H. Hall-Chen, Juan Ruiz Ruiz

Abstract: We derive the beam tracing and profile evolution for the propagation of any localised beam with arbitrary profile through an inhomogeneous cold plasma. We recover standard Gaussian beam-tracing, with an additional PDE describing the evolution of the beam's profile as it propagates through the plasma. We then solve for generic families of solutions to the PDE using ladder operators, which can be ch… ▽ More We derive the beam tracing and profile evolution for the propagation of any localised beam with arbitrary profile through an inhomogeneous cold plasma. We recover standard Gaussian beam-tracing, with an additional PDE describing the evolution of the beam's profile as it propagates through the plasma. We then solve for generic families of solutions to the PDE using ladder operators, which can be chosen to reduce to Gauss-Hermite beams in homogeneous media. We importantly obtain an exact expression for the resulting beam profile, demonstrating that Hermite modes will generally evolve into a superposition of different modes during propagation through inhomogeneous plasmas, contrary to prior work on the subject. Importantly, this approach facilitates future analysis of the diagnostic signal received from arbitrary beams. △ Less

Submitted 20 December, 2025; v1 submitted 9 November, 2025; originally announced November 2025.

Comments: Preprint. Intended for journal submission

MuCol Milestone Report No. 7: Consolidated Parameters

Authors: Rebecca Taylor, Antoine Chancé, Dario Augusto Giove, Natalia Milas, Roberto Losito, Donatella Lucchesi, Chris Rogers, Lucio Rossi, Daniel Schulte, Carlotta Accettura, Simon Adrian, Rohit Agarwal, Claudia Ahdida, Chiara Aime, Avni Aksoy, Gian Luigi Alberghi, Simon Albright, Siobhan Alden, Luca Alfonso, Muhammad Ali, Anna Rita Altamura, Nicola Amapane, Kathleen Amm, David Amorim, Paolo Andreetto , et al. (437 additional authors not shown)

Abstract: This document is comprised of a collection of consolidated parameters for the key parts of the muon collider. These consolidated parameters follow on from the October 2024 Preliminary Parameters Report. Attention has been given to a high-level consistent set of baseline parameters throughout all systems of the complex, following a 10 TeV center-of-mass design. Additional details of the designs con… ▽ More This document is comprised of a collection of consolidated parameters for the key parts of the muon collider. These consolidated parameters follow on from the October 2024 Preliminary Parameters Report. Attention has been given to a high-level consistent set of baseline parameters throughout all systems of the complex, following a 10 TeV center-of-mass design. Additional details of the designs contributing to this baseline design are featured in the appendix. Likewise, explorative variations from this baseline set can be found in the appendix. The data is collected from a collaborative spreadsheet and transferred to overleaf. △ Less

Submitted 31 October, 2025; originally announced October 2025.

Are arXiv submissions on Wednesday better cited? Introducing Big Data methods in undergraduate courses on scientific computing

Authors: Stéphane Delorme, Leon Mach, Hubert Paszkiewicz, Richard Ruiz

Abstract: Extracting information from big data sets, both real and simulated, is a modern hallmark of the physical sciences. In practice, students face barriers to learning ``Big Data'' methods in undergraduate physics and astronomy curricula. As an attempt to alleviate some of these challenges, we present a simple, farm-to-table data analysis pipeline that can collect, process, and plot data from the 800k… ▽ More Extracting information from big data sets, both real and simulated, is a modern hallmark of the physical sciences. In practice, students face barriers to learning ``Big Data'' methods in undergraduate physics and astronomy curricula. As an attempt to alleviate some of these challenges, we present a simple, farm-to-table data analysis pipeline that can collect, process, and plot data from the 800k entries common to the arXiv preprint repository and the bibliographical database inSpireHEP. The pipeline employs contemporary research practices and can be implemented using open-sourced Python libraries common to undergraduate courses on Scientific Computing. To support the use such pipelines in classroom contexts, we make public an example implementation, authored by two undergraduate physics students, that runs on off-the-shelf laptops. For advanced students, we discuss applications of the pipeline, including for online DAQ monitoring and commercialization. △ Less

Submitted 11 September, 2025; originally announced September 2025.

Comments: 10 pages, 8 figures, 2 tables, 1 listing, project available at https://gitlab.cern.ch/riruiz/public-projects/-/tree/master/BibAPI/

Report number: IFJPAN-IV-2025-14, COMETA-2025-30

Laser spectroscopy and CP-violation sensitivity of actinium monofluoride

Authors: M. Athanasakis-Kaklamanakis, M. Au, A. Kyuberis, C. Zülch, K. Gaul, H. Wibowo, L. Skripnikov, L. Lalanne, J. R. Reilly, A. Koszorús, S. Bara, J. Ballof, R. Berger, C. Bernerd, A. Borschevsky, A. A. Breier, K. Chrysalidis, T. E. Cocolios, R. P. de Groote, A. Dorne, J. Dobaczewski, C. M. Fajardo Zambrano, K. T. Flanagan, S. Franchoo, J. D. Johnson , et al. (17 additional authors not shown)

Abstract: The apparent invariance of the strong nuclear force under combined charge conjugation and parity (CP) remains an open question in modern physics. Precision experiments with heavy atoms and molecules can provide stringent constraints on CP violation via searches for effects due to permanent electric dipole moments and other CP-odd properties in leptons, hadrons, and nuclei. Radioactive molecules ha… ▽ More The apparent invariance of the strong nuclear force under combined charge conjugation and parity (CP) remains an open question in modern physics. Precision experiments with heavy atoms and molecules can provide stringent constraints on CP violation via searches for effects due to permanent electric dipole moments and other CP-odd properties in leptons, hadrons, and nuclei. Radioactive molecules have been proposed as highly sensitive probes for such searches, but experiments with most such molecules have so far been beyond technical reach. Here we report the first production and spectroscopic study of a gas-phase actinium molecule, $^{227}$AcF. We observe the predicted strongest electronic transition from the ground state, which is necessary for efficient readout in searches of symmetry-violating interactions. Furthermore, we perform electronic- and nuclear-structure calculations for $^{227}$AcF to determine its sensitivity to various CP-violating parameters, and find that a realistic, near-term experiment with a precision of 1 mHz would improve current constraints on the CP-violating parameter hyperspace by three orders of magnitude. Our results thus highlight the potential of $^{227}$AcF for exceptionally sensitive searches of CP violation. △ Less

Submitted 7 July, 2025; originally announced July 2025.

Comments: Submitted

Journal ref: Nature 648 (2025) 562

Reduction in nuclear size and quadrupole deformation of high-spin isomers of 127,129In

Authors: A. R. Vernon, C. L. Binnersley, R. F. Garcia Ruiz, K. M. Lynch, T. Miyagi, J. Billowes, M. L. Bissell, T. E. Cocolios, J. P. Delaroche, J. Dobaczewski, M. Dupuis, K. T. Flanagan, W. Gins, M. Girod, G. Georgiev, R. P. de Groote, J. D. Holt, J. Hustings, Á. Koszorús, D. Leimbach, J. Libert, W. Nazarewicz, G. Neyens, N. Pillet, P. -G. Reinhard , et al. (7 additional authors not shown)

Abstract: We employed laser spectroscopy of atomic transitions to measure the nuclear charge radii and electromagnetic properties of the high-spin isomeric states in neutron-rich indium isotopes (Z = 49) near the closed proton and neutron shells at Z = 50 and N = 82. Our data reveal a reduction in the nuclear charge radius and intrinsic quadrupole moment when protons and neutrons are fully aligned in 129In(… ▽ More We employed laser spectroscopy of atomic transitions to measure the nuclear charge radii and electromagnetic properties of the high-spin isomeric states in neutron-rich indium isotopes (Z = 49) near the closed proton and neutron shells at Z = 50 and N = 82. Our data reveal a reduction in the nuclear charge radius and intrinsic quadrupole moment when protons and neutrons are fully aligned in 129In(N = 80), to form the high spin isomer. Such a reduction is not observed in 127In(N = 78), where more complex configurations can be formed by the existence of four neutron-holes. These observations are not consistently described by nuclear theory. △ Less

Submitted 20 May, 2025; originally announced May 2025.

Comments: Accepted in Physical Review Letters

The Muon Collider

Authors: Carlotta Accettura, Simon Adrian, Rohit Agarwal, Claudia Ahdida, Chiara Aime', Avni Aksoy, Gian Luigi Alberghi, Siobhan Alden, Luca Alfonso, Muhammad Ali, Anna Rita Altamura, Nicola Amapane, Kathleen Amm, David Amorim, Paolo Andreetto, Fabio Anulli, Ludovica Aperio Bella, Rob Appleby, Artur Apresyan, Pouya Asadi, Mohammed Attia Mahmoud, Bernhard Auchmann, John Back, Anthony Badea, Kyu Jung Bae , et al. (433 additional authors not shown)

Abstract: Muons offer a unique opportunity to build a compact high-energy electroweak collider at the 10 TeV scale. A Muon Collider enables direct access to the underlying simplicity of the Standard Model and unparalleled reach beyond it. It will be a paradigm-shifting tool for particle physics representing the first collider to combine the high-energy reach of a proton collider and the high precision of an… ▽ More Muons offer a unique opportunity to build a compact high-energy electroweak collider at the 10 TeV scale. A Muon Collider enables direct access to the underlying simplicity of the Standard Model and unparalleled reach beyond it. It will be a paradigm-shifting tool for particle physics representing the first collider to combine the high-energy reach of a proton collider and the high precision of an electron-positron collider, yielding a physics potential significantly greater than the sum of its individual parts. A high-energy muon collider is the natural next step in the exploration of fundamental physics after the HL-LHC and a natural complement to a future low-energy Higgs factory. Such a facility would significantly broaden the scope of particle colliders, engaging the many frontiers of the high energy community. The last European Strategy for Particle Physics Update and later the Particle Physics Project Prioritisation Panel in the US requested a study of the muon collider, which is being carried on by the International Muon Collider Collaboration. In this comprehensive document we present the physics case, the state of the work on accelerator design and technology, and propose an R\&D project that can make the muon collider a reality. △ Less

Submitted 30 April, 2025; originally announced April 2025.

Comments: 406 pages, supplementary report to the European Strategy for Particle Physics - 2026 update

Conceptual study on using Doppler backscattering to measure magnetic pitch angle in tokamak plasmas

Authors: AK Yeoh, VH Hall-Chen, QT Pratt, BS Victor, J Damba, TL Rhodes, NA Crocker, KR Fong, JC Hillesheim, FI Parra, J Ruiz Ruiz

Abstract: We introduce a new approach to measure the magnetic pitch angle profile in tokamak plasmas with Doppler backscattering (DBS), a technique traditionally used for measuring flows and density fluctuations. The DBS signal is maximised when its probe beam's wavevector is perpendicular to the magnetic field at the cutoff location, independent of the density fluctuations. Hence, if one could isolate this… ▽ More We introduce a new approach to measure the magnetic pitch angle profile in tokamak plasmas with Doppler backscattering (DBS), a technique traditionally used for measuring flows and density fluctuations. The DBS signal is maximised when its probe beam's wavevector is perpendicular to the magnetic field at the cutoff location, independent of the density fluctuations. Hence, if one could isolate this effect, DBS would then yield information about the magnetic pitch angle. By varying the toroidal launch angle, the DBS beam reaches cutoff with different angles with respect to the magnetic field, but with other properties remaining similar. Hence, the toroidal launch angle which gives maximum backscattered power is thus that which is matched to the pitch angle at the cutoff location, enabling inference of the magnetic pitch angle. We performed systematic scans of the DBS toroidal launch angle for repeated DIII-D tokamak discharges. Experimental DBS data from this scan were analysed and combined with Gaussian beam-tracing simulations using the Scotty code. The pitch-angle inferred from DBS is consistent with that from magnetics-only and motional-Stark-effect-constrained (MSE) equilibrium reconstruction in the edge. In the core, the pitch angles from DBS and magnetics-only reconstructions differ by one to two degrees, while simultaneous MSE measurements were not available. The uncertainty in these measurements was under a degree; we show that this uncertainty is primarily due to the error in toroidal steering, the number of toroidally separated measurements, and shot-to-shot repeatability. We find that the error of pitch-angle measurements can be reduced by optimising the poloidal launch angle and initial beam properties. △ Less

Submitted 18 December, 2025; v1 submitted 26 February, 2025; originally announced February 2025.

A simple method for deriving the birdcage coil magnetic field with experimental validation at 4 T, 7 T and 15.2 T

Authors: A. Villareal, J. Lazovic, S. E. Solis-Najera, R. Martin, R. Ruiz, L. Medina, A. O. Rodriguez

Abstract: Magnetic resonance imaging and spectroscopy rely on the magnetic fields generated by radiofrequency volume coils to acquire high-quality data. Consequently, a comprehensive understanding of electromagnetic field behavior in RF volume coils is essential for optimizing imaging techniques and designing advanced coils. This study introduces a theoretical model for the magnetic field generated by a bir… ▽ More Magnetic resonance imaging and spectroscopy rely on the magnetic fields generated by radiofrequency volume coils to acquire high-quality data. Consequently, a comprehensive understanding of electromagnetic field behavior in RF volume coils is essential for optimizing imaging techniques and designing advanced coils. This study introduces a theoretical model for the magnetic field generated by a birdcage coil, based on a spherical geometry approach. To validate the proposed model, phantom images were acquired at different resonant frequencies, and the magnetic field produced by the RF coil was compared with experimental data. The results demonstrate the accuracy and effectiveness of the theoretical model, offering valuable insights into the behavior of electromagnetic fields in RF coils. This study provides a promising framework for further analysis and development of RF coil design, with significant implications for advancing both MRI and spectroscopy technologies. △ Less

Submitted 22 January, 2025; originally announced January 2025.

MuCol Milestone Report No. 5: Preliminary Parameters

Authors: Carlotta Accettura, Simon Adrian, Rohit Agarwal, Claudia Ahdida, Chiara Aimé, Avni Aksoy, Gian Luigi Alberghi, Siobhan Alden, Luca Alfonso, Nicola Amapane, David Amorim, Paolo Andreetto, Fabio Anulli, Rob Appleby, Artur Apresyan, Pouya Asadi, Mohammed Attia Mahmoud, Bernhard Auchmann, John Back, Anthony Badea, Kyu Jung Bae, E. J. Bahng, Lorenzo Balconi, Fabrice Balli, Laura Bandiera , et al. (369 additional authors not shown)

Abstract: This document is comprised of a collection of updated preliminary parameters for the key parts of the muon collider. The updated preliminary parameters follow on from the October 2023 Tentative Parameters Report. Particular attention has been given to regions of the facility that are believed to hold greater technical uncertainty in their design and that have a strong impact on the cost and power… ▽ More This document is comprised of a collection of updated preliminary parameters for the key parts of the muon collider. The updated preliminary parameters follow on from the October 2023 Tentative Parameters Report. Particular attention has been given to regions of the facility that are believed to hold greater technical uncertainty in their design and that have a strong impact on the cost and power consumption of the facility. The data is collected from a collaborative spreadsheet and transferred to overleaf. △ Less

Submitted 5 November, 2024; originally announced November 2024.

Binding energies, charge radii, spins and moments: odd-odd Ag isotopes and discovery of a new isomer

Authors: B. van den Borne, M. Stryjczyk, R. P. de Groote, A. Kankainen, D. A. Nesterenko, L. Al Ayoubi, P. Ascher, O. Beliuskina, M. L. Bissell, J. Bonnard, P. Campbell, L. Canete, B. Cheal, C. Delafosse, A. de Roubin, C. S. Devlin, T. Eronen, R. F. Garcia Ruiz, S. Geldhof, M. Gerbaux, W. Gins, S. Grévy, M. Hukkanen, A. Husson, P. Imgram , et al. (11 additional authors not shown)

Abstract: We report on the masses and hyperfine structure of ground and isomeric states in $^{114,116,118,120}$Ag isotopes, measured with the phase-imaging ion-cyclotron-resonance technique (PI-ICR) with the JYFLTRAP mass spectrometer and the collinear laser spectroscopy beamline at the Ion Guide Isotope Separator On-Line (IGISOL) facility, Jyväskylä, Finland. We measured the masses and excitation energies,… ▽ More We report on the masses and hyperfine structure of ground and isomeric states in $^{114,116,118,120}$Ag isotopes, measured with the phase-imaging ion-cyclotron-resonance technique (PI-ICR) with the JYFLTRAP mass spectrometer and the collinear laser spectroscopy beamline at the Ion Guide Isotope Separator On-Line (IGISOL) facility, Jyväskylä, Finland. We measured the masses and excitation energies, electromagnetic moments, and charge radii, and firmly established the nuclear spins of the long-lived states. A new isomer was discovered in $^{118}$Ag and the half-lives of $^{118}$Ag long-lived states were reevaluated. We unambiguously pinned down the level ordering of all long-lived states, placing the inversion of the $I = 0^-$ and $I = 4^+$ states at $A = 118$ $(N = 71)$. Lastly, we compared the electromagnetic moments of each state to empirical single-particle moments to identify the dominant configuration where possible. △ Less

Submitted 5 December, 2024; v1 submitted 21 October, 2024; originally announced October 2024.

Comments: 11 pages paper (excl. references) + 3 pages of supplementary material

Journal ref: Phys. Rev. C 111, 014329 (2025)

Ionization potential of radium monofluoride

Authors: S. G. Wilkins, H. A. Perrett, S. M. Udrescu, A. A. Kyuberis, L. F. Pašteka, M. Au, I. Belošević, R. Berger, C. L. Binnersley, M. L. Bissell, A. Borschevsky, A. A. Breier, A. J. Brinson, K. Chrysalidis, T. E. Cocolios, B. S. Cooper, R. P. de Groote, A. Dorne, E. Eliav, R. W. Field, K. T. Flanagan, S. Franchoo, R. F. Garcia Ruiz, K. Gaul, S. Geldhof , et al. (21 additional authors not shown)

Abstract: The ionization potential (IP) of radium monofluoride (RaF) was measured to be 4.969(2)[10] eV, revealing a relativistic enhancement in the series of alkaline earth monofluorides. The results are in agreement with a relativistic coupled-cluster prediction of 4.969[7] eV, incorporating up to quantum electrodynamics corrections. Using the same computational methodology, an improved calculation for th… ▽ More The ionization potential (IP) of radium monofluoride (RaF) was measured to be 4.969(2)[10] eV, revealing a relativistic enhancement in the series of alkaline earth monofluorides. The results are in agreement with a relativistic coupled-cluster prediction of 4.969[7] eV, incorporating up to quantum electrodynamics corrections. Using the same computational methodology, an improved calculation for the dissociation energy ($D_{0}$) of 5.54[5] eV is presented. This confirms that radium monofluoride joins the small group of diatomic molecules for which $D_{0}>\mathrm{IP}$, paving the way for precision control and interrogation of its Rydberg states. △ Less

Submitted 21 October, 2024; v1 submitted 26 August, 2024; originally announced August 2024.

Beam focusing and consequences for Doppler Backscattering measurements

Authors: Juan Ruiz Ruiz, Felix I. Parra, Valerian H. Hall-Chen, Nathan Belrhali, Carine Giroud, Jon C. Hillesheim, Nicolas A. Lopez, JET contributors

Abstract: The phenomenon of beam focusing of microwaves in a plasma near a turning-point caustic is discussed in the context of the analytical solution to the Gaussian beam-tracing equations in the 2D linear-layer problem. The location of maximum beam focusing and the beam width at that location are studied in terms of the beam initial conditions. The analytic solution is used to study the effect of this fo… ▽ More The phenomenon of beam focusing of microwaves in a plasma near a turning-point caustic is discussed in the context of the analytical solution to the Gaussian beam-tracing equations in the 2D linear-layer problem. The location of maximum beam focusing and the beam width at that location are studied in terms of the beam initial conditions. The analytic solution is used to study the effect of this focusing on Doppler backscattering (DBS). We find that the filter function that characterises the scattering intensity contributions along the beam path through the plasma is inversely proportional to the beam width, predicting enhanced scattering contributions from the beam focusing region. We show that the DBS signal enhancement for small incident angles between the beam path and the density gradient is due to beam focusing and not due to forward scattering. The analytic beam model is used to predict the measurement of the $k_y$ density-fluctuation wavenumber power spectrum via DBS, showing that the spectral exponent of the turbulent, intermediate-to-high $k_y$ density-fluctuation spectrum might be quantitatively measurable via DBS, but not the spectral peak corresponding to the driving scale of the turbulent cascade. △ Less

Submitted 23 August, 2024; originally announced August 2024.

Recent advancements in atomic many-body methods for high-precision studies of isotope shifts

Authors: B. K. Sahoo, S. Blundell, A. V. Oleynichenko, R. F. Garcia Ruiz, L. V. Skripnikov, B. Ohayon

Abstract: The development of atomic many-body methods, capable of incorporating electron correlation effects accurately, is required for isotope shift (IS) studies. In combination with precise measurements, such calculations help to extract nuclear charge radii differences, and to probe for signatures of physics beyond the Standard Model of particle physics. We review here a few recently-developed methods i… ▽ More The development of atomic many-body methods, capable of incorporating electron correlation effects accurately, is required for isotope shift (IS) studies. In combination with precise measurements, such calculations help to extract nuclear charge radii differences, and to probe for signatures of physics beyond the Standard Model of particle physics. We review here a few recently-developed methods in the relativistic many-body perturbation theory (RMBPT) and relativistic coupled-cluster (RCC) theory frameworks for calculations of IS factors in the highly charged ions (HCIs), and neutral or singly-charged ions, respectively. The results are presented for a wide range of atomic systems in order to demonstrate the interplay between quantum electrodynamics (QED) and electron correlation effects. In view of this, we start our discussions with the RMBPT calculations for a few HCIs by rigorously treating QED effects; then we outline methods to calculate IS factors in the one-valence atomic systems using two formulations of the RCC approach. Then we present calculations for two valence atomic systems, by employing the Fock-space RCC methods. For completeness, we briefly discuss theoretical input required for the upcoming experiments, their possibilities to probe nuclear properties and implications to fundamental physics studies. △ Less

Submitted 19 August, 2024; originally announced August 2024.

Comments: Topical Review Preprint for J. Phys. B, Comments and Suggestions are welcome!

Interim report for the International Muon Collider Collaboration (IMCC)

Authors: C. Accettura, S. Adrian, R. Agarwal, C. Ahdida, C. Aimé, A. Aksoy, G. L. Alberghi, S. Alden, N. Amapane, D. Amorim, P. Andreetto, F. Anulli, R. Appleby, A. Apresyan, P. Asadi, M. Attia Mahmoud, B. Auchmann, J. Back, A. Badea, K. J. Bae, E. J. Bahng, L. Balconi, F. Balli, L. Bandiera, C. Barbagallo , et al. (362 additional authors not shown)

Abstract: The International Muon Collider Collaboration (IMCC) [1] was established in 2020 following the recommendations of the European Strategy for Particle Physics (ESPP) and the implementation of the European Strategy for Particle Physics-Accelerator R&D Roadmap by the Laboratory Directors Group [2], hereinafter referred to as the the European LDG roadmap. The Muon Collider Study (MuC) covers the accele… ▽ More The International Muon Collider Collaboration (IMCC) [1] was established in 2020 following the recommendations of the European Strategy for Particle Physics (ESPP) and the implementation of the European Strategy for Particle Physics-Accelerator R&D Roadmap by the Laboratory Directors Group [2], hereinafter referred to as the the European LDG roadmap. The Muon Collider Study (MuC) covers the accelerator complex, detectors and physics for a future muon collider. In 2023, European Commission support was obtained for a design study of a muon collider (MuCol) [3]. This project started on 1st March 2023, with work-packages aligned with the overall muon collider studies. In preparation of and during the 2021-22 U.S. Snowmass process, the muon collider project parameters, technical studies and physics performance studies were performed and presented in great detail. Recently, the P5 panel [4] in the U.S. recommended a muon collider R&D, proposed to join the IMCC and envisages that the U.S. should prepare to host a muon collider, calling this their "muon shot". In the past, the U.S. Muon Accelerator Programme (MAP) [5] has been instrumental in studies of concepts and technologies for a muon collider. △ Less

Submitted 28 January, 2025; v1 submitted 17 July, 2024; originally announced July 2024.

Comments: This document summarises the International Muon Collider Collaboration (IMCC) progress and status of the Muon Collider R&D programme

Measurement of zero-frequency fluctuations generated by coupling between Alfven modes in the JET tokamak

Authors: Juan Ruiz Ruiz, Jeronimo Garcia, Michael Barnes, Mykola Dreval, Carine Giroud, Valerian H. Hall-Chen, Michael R. Hardman, Jon C. Hillesheim, Yevgen Kazakov, Samuele Mazzi, Felix I. Parra, Bhavin S. Patel, Alexander A. Schekochihin, Ziga Stancar, the JET Contributors, the EUROfusion Tokamak Exploitation Team

Abstract: We report the first experimental detection of a zero-frequency fluctuation that is pumped by an Alfvèn mode in a magnetically confined plasma. Core-localized bidirectional Alfvèn modes of frequency inside the toroidicity-induced gap (and its harmonics) exhibit three-wave coupling interactions with a zero-frequency fluctuation. The observation of the zero-frequency fluctuation is consistent with th… ▽ More We report the first experimental detection of a zero-frequency fluctuation that is pumped by an Alfvèn mode in a magnetically confined plasma. Core-localized bidirectional Alfvèn modes of frequency inside the toroidicity-induced gap (and its harmonics) exhibit three-wave coupling interactions with a zero-frequency fluctuation. The observation of the zero-frequency fluctuation is consistent with theoretical and numerical predictions of zonal modes pumped by Alfvén modes, and is correlated with an increase in the deep core ion temperature, temperature gradient, and confinement factor $H_{89,P}$. Despite the energetic particle transport induced by the Alfvèn eigenmodes, the generation of a zero-frequency fluctuation that can suppress the turbulence leads to an overall improvement of confinement. △ Less

Submitted 21 January, 2025; v1 submitted 1 July, 2024; originally announced July 2024.

Acoustic Positioning for Deep Sea Neutrino Telescopes with a System of Piezo Sensors Integrated into Glass Spheres

Authors: A. Albert, S. Alves, M. André, M. Ardid, S. Ardid, J. -J. Aubert, J. Aublin, B. Baret, S. Basa, Y. Becherini, B. Belhorma, M. Bendahman, F. Benfenati, V. Bertin, S. Biagi, J. Boumaaza, M. Bouta, M. C. Bouwhuis, H. Brânzaş, R. Bruijn, J. Brunner, J. Busto, B. Caiffi, D. Calvo, S. Campion , et al. (115 additional authors not shown)

Abstract: Position calibration in the deep sea is typically done by means of acoustic multilateration using three or more acoustic emitters installed at known positions. Rather than using hydrophones as receivers that are exposed to the ambient pressure, the sound signals can be coupled to piezo ceramics glued to the inside of existing containers for electronics or measuring instruments of a deep sea infras… ▽ More Position calibration in the deep sea is typically done by means of acoustic multilateration using three or more acoustic emitters installed at known positions. Rather than using hydrophones as receivers that are exposed to the ambient pressure, the sound signals can be coupled to piezo ceramics glued to the inside of existing containers for electronics or measuring instruments of a deep sea infrastructure. The ANTARES neutrino telescope operated from 2006 until 2022 in the Mediterranean Sea at a depth exceeding 2000m. It comprised nearly 900 glass spheres with 432mm diameter and 15mm thickness, equipped with photomultiplier tubes to detect Cherenkov light from tracks of charged elementary particles. In an experimental setup within ANTARES, piezo sensors have been glued to the inside of such - otherwise empty - glass spheres. These sensors recorded signals from acoustic emitters with frequencies from 46545 to 60235Hz. Two waves propagating through the glass sphere are found as a result of the excitation by the waves in the water. These can be qualitatively associated with symmetric and asymmetric Lamb-like waves of zeroth order: a fast (early) one with $v_e \approx 5$mm/$μ$s and a slow (late) one with $v_\ell \approx 2$mm/$μ$s. Taking these findings into account improves the accuracy of the position calibration. The results can be transferred to the KM3NeT neutrino telescope, currently under construction at multiple sites in the Mediterranean Sea, for which the concept of piezo sensors glued to the inside of glass spheres has been adapted for monitoring the positions of the photomultiplier tubes. △ Less

Submitted 7 January, 2025; v1 submitted 12 May, 2024; originally announced May 2024.

Comments: Published by "Experimental Astronomy"

Journal ref: Exp Astron 59, 6 (2025)

Parity and time-reversal symmetry violation in diatomic molecules: LaO, LaS and LuO

Authors: Yuly Chamorro, Victor Flambaum, Ronald F. Garcia Ruiz, Anastasia Borschevsky, Lukáš F. Pašteka

Abstract: The violation of parity (P) and time-reversal (T) symmetry is enhanced in the LaS, LaO and LuO molecules due to the existence of states of opposite parity with small energy differences and the presence of heavy nuclei. We calculate the molecular enhancement for the P, T-violating electron electric dipole moment ($W_{\mathrm{d}}$), scalar-pseudoscalar nucleon-electron interaction ($W_{\mathrm{s}}$)… ▽ More The violation of parity (P) and time-reversal (T) symmetry is enhanced in the LaS, LaO and LuO molecules due to the existence of states of opposite parity with small energy differences and the presence of heavy nuclei. We calculate the molecular enhancement for the P, T-violating electron electric dipole moment ($W_{\mathrm{d}}$), scalar-pseudoscalar nucleon-electron interaction ($W_{\mathrm{s}}$), nuclear magnetic quadrupole moment ($W_{\mathrm{M}}$), and for the nuclear spin-dependent P-violating anapole moment ($W_{\mathrm{A}}$). We use the relativistic 4-components coupled cluster method and perform a systematic study to estimate the associated uncertainties in our approach. We find that the individual contribution of each computational parameter to the total uncertainty in a system is approximately the same for all the calculated enhancement factors, summing up to a total uncertainty of $\sim7$\%. We discuss the energy shifts and matrix elements associated with the calculated molecular enhancement factors and relate them to higher-energy P- and P, T- violating interactions. △ Less

Submitted 30 April, 2024; originally announced April 2024.

Gyrokinetic investigation of toroidal Alfven eigenmode (TAE) turbulence

Authors: Ajay C. J., Ben McMillan, Arkaprava Bokshi, Alessandro di Siena, M. J. Pueschel, Juan Ruiz Ruiz

Abstract: Toroidal Alfvén eigenmodes (TAEs) can transport fusion-born energetic particles out of the plasma volume, thereby decreasing plasma self-heating efficiency and possibly damaging reactor walls. Therefore, understanding TAE destabilisation and identifying saturation mechanisms is crucial to achieving burning plasma. While TAEs have been studies extensively in the past using kinetic-MHD codes, here a… ▽ More Toroidal Alfvén eigenmodes (TAEs) can transport fusion-born energetic particles out of the plasma volume, thereby decreasing plasma self-heating efficiency and possibly damaging reactor walls. Therefore, understanding TAE destabilisation and identifying saturation mechanisms is crucial to achieving burning plasma. While TAEs have been studies extensively in the past using kinetic-MHD codes, here a fully gyrokinetic study is employed which allows for additional physics. In the case studied, the primary drive mechanism is identified as the resonance between the magnetic drifts and the TAE, and this is seen to be disrupted by equilibrium flow shear which can stabilize the mode by rotating it in the the poloidal plane. It is found that zonal flows do not play a significant role in the saturation of these TAEs, and there are no saturation mechanisms present in the local gyrokinetic picture that are able to saturate the mode at physically relevant transport levels in the case of TAE-only turbulence. Instead, we confirm that the global profile flattening of fast-ion density is the key saturation mechanism. The nonlinear excitation of TAE travelling along the electron diamagnetic direction and its beating with the ion diamagnetic TAE, resulting in large amplitude oscillations that may help detect TAEs more easily in tokamaks, is also reported. △ Less

Submitted 29 April, 2024; originally announced April 2024.

Journal ref: AIP Advances 1 July 2024; 14 (7): 075120

Isotope-shift factors with quantum electrodynamics effects for many-electron systems: A study of the nuclear charge radius of $^{26m}$Al

Authors: Leonid V. Skripnikov, Sergey D. Prosnyak, Aleksei V. Malyshev, Michail Athanasakis-Kaklamanakis, Alex Jose Brinson, Kei Minamisono, Fabian C. Pastrana Cruz, Jordan Ray Reilly, Brooke J. Rickey, Ronald. F. Garcia Ruiz

Abstract: A method for calculating the field shift contribution to isotope shifts in many-electron atoms, incorporating quantum electrodynamics (QED) effects, is introduced. We also implement the model QED approach to incorporate QED contribution to the nuclear recoil effect at the high-order correlation effects treatment level. The proposed computational scheme is used to revise the value of the root-mean-… ▽ More A method for calculating the field shift contribution to isotope shifts in many-electron atoms, incorporating quantum electrodynamics (QED) effects, is introduced. We also implement the model QED approach to incorporate QED contribution to the nuclear recoil effect at the high-order correlation effects treatment level. The proposed computational scheme is used to revise the value of the root-mean-square (rms) nuclear charge radius of the isomer of aluminium-26, $^{26m}$Al. This radius is important for the global analysis of the $V_{ud}$ element of the Cabibbo-Kobayashi-Maskawa matrix. The difference in mean-square nuclear charge radii of $^{27}$Al and $^{26m}$Al, obtained by combining the calculated atomic factors with recently measured isotope shift (IS) of the $3s^23p~^2P_{3/2} \to 3s^24s~^2S_{1/2}$ transition in Al, is $0.443(44)(19)~{\rm fm}^2$, where the first and second uncertainties are experimental and theoretical ones, respectively. The latter is reduced by a factor of 4 with respect to the previous study. Using this value and the known value of the rms charge radius of $^{27}$Al, the resultant value $R_c(^{26m}$Al) = 3.132(10)~fm is obtained. With the improved accuracy of the calculated IS factors the error in $R_c(^{26m}$Al) is now dominated by the experimental uncertainty. Similar revision of rms charge radii is made for the $^{28}$Al, $^{29}$Al, $^{30}$Al, $^{31}$Al and $^{32}$Al isotopes using existing IS measurements. Additionally, atomic factors are computed for the $3s^23p~^2P_{3/2} \to 3s^24s~^2S_{1/2}$, $3s^23p~^2P_{1/2} \to 3s^25s~^2S_{1/2}$ and $3s^23p~^2P_{3/2} \to 3s^25s~^2S_{1/2}$ transitions in Al, which can be used in future experimental studies. △ Less

Submitted 19 July, 2024; v1 submitted 20 April, 2024; originally announced April 2024.

Journal ref: Phys. Rev. A 110, 012807 (2024)

Radiative lifetime of the A 2Π1/2 state in RaF with relevance to laser cooling

Authors: M. Athanasakis-Kaklamanakis, S. G. Wilkins, P. Lassègues, L. Lalanne, J. R. Reilly, O. Ahmad, M. Au, S. W. Bai, J. Berbalk, C. Bernerd, A. Borschevsky, A. A. Breier, K. Chrysalidis, T. E. Cocolios, R. P. de Groote, C. M. Fajardo-Zambrano, K. T. Flanagan, S. Franchoo, R. F. Garcia Ruiz, D. Hanstorp, R. Heinke, P. Imgram, A. Koszorús, A. A. Kyuberis, J. Lim , et al. (16 additional authors not shown)

Abstract: The radiative lifetime of the $A$ $^2 Π_{1/2}$ (v=0) state in radium monofluoride (RaF) is measured to be 35(1) ns. The lifetime of this state and the related decay rate $Γ= 2.86(8) \times 10^7$ $s^{-1}$ are of relevance to the laser cooling of RaF via the optically closed $A$ $^2 Π_{1/2} \leftarrow X$ $^2Σ_{1/2}$ transition, which makes the molecule a promising probe to search for new physics. Ra… ▽ More The radiative lifetime of the $A$ $^2 Π_{1/2}$ (v=0) state in radium monofluoride (RaF) is measured to be 35(1) ns. The lifetime of this state and the related decay rate $Γ= 2.86(8) \times 10^7$ $s^{-1}$ are of relevance to the laser cooling of RaF via the optically closed $A$ $^2 Π_{1/2} \leftarrow X$ $^2Σ_{1/2}$ transition, which makes the molecule a promising probe to search for new physics. RaF is found to have a comparable photon-scattering rate to homoelectronic laser-coolable molecules. Thanks to its highly diagonal Franck-Condon matrix, it is expected to scatter an order of magnitude more photons than other molecules when using just 3 cooling lasers, before it decays to a dark state. The lifetime measurement in RaF is benchmarked by measuring the lifetime of the $8P_{3/2}$ state in Fr to be 83(3) ns, in agreement with literature. △ Less

Submitted 6 June, 2024; v1 submitted 14 March, 2024; originally announced March 2024.

Comments: Accepted as a Letter in Physical Review A; 8 pages of main text, 5 pages of supplemental material

Stopping mass-selected alkaline-earth metal monofluoride beams of high energy via formation of unusually stable anions

Authors: Konstantin Gaul, Ronald F. Garcia Ruiz, Robert Berger

Abstract: Direct laser-coolability and a comparatively simple electronic structure render alkaline-earth metal monofluoride molecules versatile laboratories for precision tests of fundamental physics. In this theoretical work, a route for efficient stopping and cooling of high-energy hot beams of mass-selected alkaline-earth metal monofluorides via their anions is explored to facilitate subsequent precision… ▽ More Direct laser-coolability and a comparatively simple electronic structure render alkaline-earth metal monofluoride molecules versatile laboratories for precision tests of fundamental physics. In this theoretical work, a route for efficient stopping and cooling of high-energy hot beams of mass-selected alkaline-earth metal monofluorides via their anions is explored to facilitate subsequent precision experiments with trapped molecules. It is shown that these molecular anions possess an unusually strong chemical bond and that RaF$^-$ features properties favourable for efficient pre-cooling, indicating the applicability of direct laser-cooling of the anion. △ Less

Submitted 14 May, 2024; v1 submitted 14 March, 2024; originally announced March 2024.

Comments: 7 pages, 4 figures, 1 table, supplementary material; minor corrections on the text, updated acknowledgements and references

Observation of the distribution of nuclear magnetization in a molecule

Authors: S. G. Wilkins, S. M. Udrescu, M. Athanasakis-Kaklamanakis, R. F. Garcia Ruiz, M. Au, I. Belošević, R. Berger, M. L. Bissell, A. A. Breier, A. J. Brinson, K. Chrysalidis, T. E. Cocolios, R. P. de Groote, A. Dorne, K. T. Flanagan, S. Franchoo, K. Gaul, S. Geldhof, T. F. Giesen, D. Hanstorp, R. Heinke, T. Isaev, Á. Koszorús, S. Kujanpää, L. Lalanne , et al. (11 additional authors not shown)

Abstract: Rapid progress in the experimental control and interrogation of molecules, combined with developments in precise calculations of their structure, are enabling new opportunities in the investigation of nuclear and particle physics phenomena. Molecules containing heavy, octupole-deformed nuclei such as radium are of particular interest for such studies, offering an enhanced sensitivity to the proper… ▽ More Rapid progress in the experimental control and interrogation of molecules, combined with developments in precise calculations of their structure, are enabling new opportunities in the investigation of nuclear and particle physics phenomena. Molecules containing heavy, octupole-deformed nuclei such as radium are of particular interest for such studies, offering an enhanced sensitivity to the properties of fundamental particles and interactions. Here, we report precision laser spectroscopy measurements and theoretical calculations of the structure of the radioactive radium monofluoride molecule, $^{225}$Ra$^{19}$F. Our results allow fine details of the short-range electron-nucleus interaction to be revealed, indicating the high sensitivity of this molecule to the distribution of magnetization, currently a poorly constrained nuclear property, within the radium nucleus. These results provide a direct and stringent test of the description of the electronic wavefunction inside the nuclear volume, highlighting the suitability of these molecules to investigate subatomic phenomena. △ Less

Submitted 23 October, 2025; v1 submitted 7 November, 2023; originally announced November 2023.

Journal ref: Science 390(6771):386-389 (2025)

Electromagnetic Properties of Indium Isotopes Elucidate the Doubly Magic Character of $^{100}$Sn

Authors: J. Karthein, C. M. Ricketts, R. F. Garcia Ruiz, J. Billowes, C. L. Binnersley, T. E. Cocolios, J. Dobaczewski, G. J. Farooq-Smith, K. T. Flanagan, G. Georgiev, W. Gins, R. P. de Groote, F. P. Gustafsson, J. D. Holt, A. Kanellakopoulos, Á. Koszorús, D. Leimbach, K. M. Lynch, T. Miyagi, W. Nazarewicz, G. Neyens, P. -G. Reinhard, B. K. Sahoo, A. R. Vernon, S. G. Wilkins , et al. (2 additional authors not shown)

Abstract: Our understanding of nuclear properties in the vicinity of $^{100}$Sn, suggested to be the heaviest doubly magic nucleus with equal numbers of protons (Z=50) and neutrons (N=50), has been a long-standing challenge for experimental and theoretical nuclear physics. Contradictory experimental evidence exists on the role of nuclear collectivity in this region of the nuclear chart. Using precision lase… ▽ More Our understanding of nuclear properties in the vicinity of $^{100}$Sn, suggested to be the heaviest doubly magic nucleus with equal numbers of protons (Z=50) and neutrons (N=50), has been a long-standing challenge for experimental and theoretical nuclear physics. Contradictory experimental evidence exists on the role of nuclear collectivity in this region of the nuclear chart. Using precision laser spectroscopy, we measured the ground-state electromagnetic moments of indium (Z=49) isotopes approaching the N=50 neutron number down to 101In, and nuclear charge radii of 101-131In spanning almost the complete range between the two major neutron closed-shells at N=50 and N=82. Our results for both nuclear charge radii and quadrupole moments reveal striking parabolic trends as a function of the neutron number, with a clear reduction toward these two neutron closed-shells, thus supporting a doubly magic character of $^{100}$Sn. Two complementary nuclear many-body frameworks, density functional theory and ab initio methods, elucidate our findings. A detailed comparison with our experimental results exposes deficiencies of nuclear models, establishing a benchmark for future theoretical developments. △ Less

Submitted 30 September, 2024; v1 submitted 23 October, 2023; originally announced October 2023.

Comments: 12 pages, 6 figures, 4 tables; text-identical to Nature Physics article (2024)

Journal ref: Nature Physics 20 (2024) 1719

Electroweak Nuclear Properties from Single Molecular Ions in a Penning Trap

Authors: Jonas Karthein, Silviu-Marian Udrescu, Scott B. Moroch, Ivana Belosevic, Klaus Blaum, Anastasia Borschevsky, Yuly Chamorro, David DeMille, Jens Dilling, Ronald F. Garcia Ruiz, Nick R. Hutzler, Lukáš F. Pašteka, Ryan Ringle

Abstract: We present a novel technique to probe electroweak nuclear properties by measuring parity violation (PV) in single molecular ions in a Penning trap. The trap's strong magnetic field Zeeman shifts opposite-parity rotational and hyperfine molecular states into near degeneracy. The weak interaction-induced mixing between these degenerate states can be larger than in atoms by more than twelve orders of… ▽ More We present a novel technique to probe electroweak nuclear properties by measuring parity violation (PV) in single molecular ions in a Penning trap. The trap's strong magnetic field Zeeman shifts opposite-parity rotational and hyperfine molecular states into near degeneracy. The weak interaction-induced mixing between these degenerate states can be larger than in atoms by more than twelve orders of magnitude, thereby vastly amplifying PV effects. The single molecule sensitivity would be suitable for applications to nuclei across the nuclear chart, including rare and unstable nuclei. △ Less

Submitted 17 October, 2023; originally announced October 2023.

Comments: 8 pages, 3 figures, 1 table

Journal ref: Phys. Rev. Lett. 133, 033003 (2024)

Stable Deuterium-Tritium burning plasmas with improved confinement in the presence of energetic-ion instabilities

Authors: Jeronimo Garcia, Yevgen Kazakov, Rui Coelho, Mykola Dreval, Elena de la Luna, Emilia R. Solano, Ziga Stancar, Jacobo Varela, Matteo Baruzzo, Emily Belli, Phillip J. Bonofiglo, Jeff Candy, Costanza F. Maggi, Joelle Mailloux, Samuele Mazzi, Jef Ongena, Michal Poradzinski, Juan R. Ruiz, Sergei Sharapov, David Zarzoso, JET contributors

Abstract: Providing stable and clean energy sources is a necessity for the increasing demands of humanity. Energy produced by fusion reactions, in particular in tokamaks, is a promising path towards that goal. However, there is little experience with plasmas under conditions close to those expected in future fusion reactors, because it requires the fusion of Deuterium (D) and Tritium (T), while most of the… ▽ More Providing stable and clean energy sources is a necessity for the increasing demands of humanity. Energy produced by fusion reactions, in particular in tokamaks, is a promising path towards that goal. However, there is little experience with plasmas under conditions close to those expected in future fusion reactors, because it requires the fusion of Deuterium (D) and Tritium (T), while most of the experiments are currently performed in pure D. After more than 20 years, the Joint European Torus (JET) has carried out new D-T experiments with the aim of exploring the unique characteristics of burning D-T plasmas, such as the presence of highly energetic ions. A new stable, high confinement and impurity-free D-T regime, with strong reduction of energy losses with respect to D, has been found. Multiscale physics mechanisms critically determine the thermal confinement and the fusion power yield. These crucial achievements importantly contribute to the establishment of fusion energy generation as an alternative to fossil fuels. △ Less

Submitted 17 January, 2024; v1 submitted 21 September, 2023; originally announced September 2023.

Accurate theoretical determination of the ionization potentials of CaF, SrF, and BaF

Authors: A. A. Kyuberis, L. F. Pasteka, E. Eliav, H. Perrett, A. Sunaga, S. M. Udrescu, S. G. Wilkins, R. F. Garcia Ruiz, A. Borschevsky

Abstract: We present a comprehensive theoretical study of the ionization potentials of the MF (M= Ca, Sr, Ba) molecules using the state-of-the-art relativistic coupled cluster approach with single, double, and perturbative triple excitations (CCSD(T)). We have further corrected our results for the higher order excitations (up to full triples) and the QED self energy and vacuum polarisation contributions. We… ▽ More We present a comprehensive theoretical study of the ionization potentials of the MF (M= Ca, Sr, Ba) molecules using the state-of-the-art relativistic coupled cluster approach with single, double, and perturbative triple excitations (CCSD(T)). We have further corrected our results for the higher order excitations (up to full triples) and the QED self energy and vacuum polarisation contributions. We have performed an extensive investigation of the effect of the various computational parameters on the calculated ionisation potentials, which allowed us to assign realistic uncertainties on our predictions. For CaF and BaF, where precise experiments are available, our predictions are in excellent agreement with the measured values. In case of SrF, we provide a new accurate prediction of the ionisation potential that deviates from the available experimental data, motivating further experimental investigations. △ Less

Submitted 4 September, 2023; originally announced September 2023.

Comments: 7 pages, before paper submission (references will be added additionally)

Pinning down electron correlations in RaF via spectroscopy of excited states and high-accuracy relativistic quantum chemistry

Authors: M. Athanasakis-Kaklamanakis, S. G. Wilkins, L. V. Skripnikov, A. Koszorús, A. A. Breier, O. Ahmad, M. Au, S. W. Bai, I. Belošević, J. Berbalk, R. Berger, C. Bernerd, M. L. Bissell, A. Borschevsky, A. Brinson, K. Chrysalidis, T. E. Cocolios, R. P. de Groote, A. Dorne, C. M. Fajardo-Zambrano, R. W. Field, K. T. Flanagan, S. Franchoo, R. F. Garcia Ruiz, K. Gaul , et al. (31 additional authors not shown)

Abstract: We report the spectroscopy of the 14 lowest excited electronic states in the radioactive molecule radium monofluoride (RaF). The observed excitation energies are compared with fully relativistic state-of-the-art Fock-space coupled cluster (FS-RCC) calculations, which achieve an agreement of >=99.64% (within ~12 meV) with experiment for all states. Guided by theory, a firm assignment of the angular… ▽ More We report the spectroscopy of the 14 lowest excited electronic states in the radioactive molecule radium monofluoride (RaF). The observed excitation energies are compared with fully relativistic state-of-the-art Fock-space coupled cluster (FS-RCC) calculations, which achieve an agreement of >=99.64% (within ~12 meV) with experiment for all states. Guided by theory, a firm assignment of the angular momentum and term symbol is made for 10 states and a tentative assignment for 4 states. The role of high-order electron correlation and quantum electrodynamics effects in the excitation energy of excited states is studied, found to be important for all states. Establishing the simultaneous accuracy and precision of calculations is an important step for research at the intersection of particle, nuclear, and chemical physics, including searches of physics beyond the Standard Model, for which RaF is a promising probe. △ Less

Submitted 20 December, 2024; v1 submitted 28 August, 2023; originally announced August 2023.

Comments: Significant changes compared to previous version with additional experimental data. Accepted for publication under a different title

Precision Spectroscopy of Fast, Hot Exotic Isotopes Using Machine Learning Assisted Event-by-Event Doppler Correction

Authors: Silviu-Marian Udrescu, Diego Alejandro Torres, Ronald Fernando Garcia Ruiz

Abstract: We propose an experimental scheme for performing sensitive, high-precision laser spectroscopy studies on fast exotic isotopes. By inducing a step-wise resonant ionization of the atoms travelling inside an electric field and subsequently detecting the ion and the corresponding electron, time- and position-sensitive measurements of the resulting particles can be performed. Using a Mixture Density Ne… ▽ More We propose an experimental scheme for performing sensitive, high-precision laser spectroscopy studies on fast exotic isotopes. By inducing a step-wise resonant ionization of the atoms travelling inside an electric field and subsequently detecting the ion and the corresponding electron, time- and position-sensitive measurements of the resulting particles can be performed. Using a Mixture Density Network (MDN), we can leverage this information to predict the initial energy of individual atoms and thus apply a Doppler correction of the observed transition frequencies on an event-by-event basis. We conduct numerical simulations of the proposed experimental scheme and show that kHz-level uncertainties can be achieved for ion beams produced at extreme temperatures ($> 10^8$ K), with energy spreads as large as $10$ keV and non-uniform velocity distributions. The ability to perform in-flight spectroscopy, directly on highly energetic beams, offers unique opportunities to studying short-lived isotopes with lifetimes in the millisecond range and below, produced in low quantities, in hot and highly contaminated environments, without the need for cooling techniques. Such species are of marked interest for nuclear structure, astrophysics, and new physics searches. △ Less

Submitted 25 April, 2023; originally announced April 2023.

Journal ref: Phys. Rev. Research 6, 013128, 31 January 2024

Voltage scanning and technical upgrades at the Collinear Resonance Ionization Spectroscopy experiment

Authors: Michail Athanasakis-Kaklamanakis, Jordan R. Reilly, Agota Koszorus, Shane G. Wilkins, Louis Lalanne, Sarina Geldhof, Miranda Nichols, Quanjun Wang, Bram van den Borne, David Chorlton, Thomas E. Cocolios, Kieran T. Flanagan, Ronald F. Garcia Ruiz, Ruben de Groote, Dag Hanstorp, Gerda Neyens, Andrew J. Smith, Adam R. Vernon, Xiaofei F. Yang

Abstract: To optimize the performance of the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at CERN-ISOLDE, technical upgrades are continuously introduced, aiming to enhance its sensitivity, precision, stability, and efficiency. Recently, a voltage-scanning setup was developed and commissioned at CRIS, which improved the scanning speed by a factor of three as compared to the current laser-fre… ▽ More To optimize the performance of the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at CERN-ISOLDE, technical upgrades are continuously introduced, aiming to enhance its sensitivity, precision, stability, and efficiency. Recently, a voltage-scanning setup was developed and commissioned at CRIS, which improved the scanning speed by a factor of three as compared to the current laser-frequency scanning approach. This leads to faster measurements of the hyperfine structure for systems with high yields (more than a few thousand ions per second). Additionally, several beamline sections have been redesigned and manufactured, including a new field-ionization unit, a sharper electrostatic bend, and improved ion optics. The beamline upgrades are expected to yield an improvement of at least a factor of 5 in the signal-to-noise ratio by suppressing the non-resonant laser ions and providing time-of-flight separation between the resonant ions and the collisional background. Overall, the presented developments will further improve the selectivity, sensitivity, and efficiency of the CRIS technique. △ Less

Submitted 20 March, 2023; originally announced March 2023.

Comments: 10 pages. Under review at NIM B as part of the proceedings of EMIS 2022 at RAON, South Korea

Towards a Muon Collider

Authors: Carlotta Accettura, Dean Adams, Rohit Agarwal, Claudia Ahdida, Chiara Aimè, Nicola Amapane, David Amorim, Paolo Andreetto, Fabio Anulli, Robert Appleby, Artur Apresyan, Aram Apyan, Sergey Arsenyev, Pouya Asadi, Mohammed Attia Mahmoud, Aleksandr Azatov, John Back, Lorenzo Balconi, Laura Bandiera, Roger Barlow, Nazar Bartosik, Emanuela Barzi, Fabian Batsch, Matteo Bauce, J. Scott Berg , et al. (272 additional authors not shown)

Abstract: A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders desi… ▽ More A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work. △ Less

Submitted 27 November, 2023; v1 submitted 15 March, 2023; originally announced March 2023.

Comments: 118 pages, 103 figures

Opportunities for Fundamental Physics Research with Radioactive Molecules

Authors: Gordon Arrowsmith-Kron, Michail Athanasakis-Kaklamanakis, Mia Au, Jochen Ballof, Robert Berger, Anastasia Borschevsky, Alexander A. Breier, Fritz Buchinger, Dmitry Budker, Luke Caldwell, Christopher Charles, Nike Dattani, Ruben P. de Groote, David DeMille, Timo Dickel, Jacek Dobaczewski, Christoph E. Düllmann, Ephraim Eliav, Jon Engel, Mingyu Fan, Victor Flambaum, Kieran T. Flanagan, Alyssa Gaiser, Ronald Garcia Ruiz, Konstantin Gaul , et al. (37 additional authors not shown)

Abstract: Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas of fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances in the ability to create, cool, and control complex molecules down to the quantum level, along with recent and upcoming advances in radioactive species production at seve… ▽ More Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas of fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances in the ability to create, cool, and control complex molecules down to the quantum level, along with recent and upcoming advances in radioactive species production at several facilities around the world, create a compelling opportunity to coordinate and combine these efforts to bring precision measurement and control to molecules containing extreme nuclei. In this manuscript, we review the scientific case for studying radioactive molecules, discuss recent atomic, molecular, nuclear, astrophysical, and chemical advances which provide the foundation for their study, describe the facilities where these species are and will be produced, and provide an outlook for the future of this nascent field. △ Less

Submitted 4 February, 2023; originally announced February 2023.

Journal ref: Rep. Prog. Phys. 87 084301 (2024)

Ab initio in-medium similarity renormalization group for open-shell atomic systems

Authors: G. Tenkila, V. Chand, T. Miyagi, H. Patel, S. R. Stroberg, R. F. Garcia Ruiz, J. D. Holt

Abstract: Precise theoretical calculations of open-shell atomic systems are critical for extracting fundamental physics parameters from precision experiments. Here we present proof-of-principle calculations illustrating the effectiveness of the valence-space formulation of the ab initio in-medium similarity renormalization group, widely used in nuclear theory, as a new ab initio method for atomic systems. W… ▽ More Precise theoretical calculations of open-shell atomic systems are critical for extracting fundamental physics parameters from precision experiments. Here we present proof-of-principle calculations illustrating the effectiveness of the valence-space formulation of the ab initio in-medium similarity renormalization group, widely used in nuclear theory, as a new ab initio method for atomic systems. We adapt this approach to study properties of closed- and open-shell many-electron systems from helium to calcium. Ground-state energies, excitation spectra, and ionization energies are obtained for selected atoms, and reasonable agreement is found with benchmark coupled-cluster and many-body perturbation theory calculations, where available. △ Less

Submitted 15 December, 2022; originally announced December 2022.

Comments: 6 pages, 8 figures

Effect of mismatch on Doppler backscattering in MAST and MAST-U plasmas

Authors: Valerian H. Hall-Chen, Felix I. Parra, Jon C. Hillesheim, Juan Ruiz Ruiz, Neal A. Crocker, Peng Shi, Hong Son Chu, Simon J. Freethy, Lucy A. Kogan, William A. Peebles, Quinn T. Pratt, Terry L. Rhodes, Kevin Ronald, Rory Scannell, David C. Speirs, Stephen Storment, Jonathan Trisno

Abstract: The Doppler backscattering (DBS) diagnostic, also referred to as Doppler reflectometry, measures turbulent density fluctuations of intermediate length scales. However, when the beam's wavevector is not properly aligned perpendicular to the magnetic field, the backscattered power is attenuated. In previous work, we used beam tracing and reciprocity to derive this mismatch attenuation quantitatively… ▽ More The Doppler backscattering (DBS) diagnostic, also referred to as Doppler reflectometry, measures turbulent density fluctuations of intermediate length scales. However, when the beam's wavevector is not properly aligned perpendicular to the magnetic field, the backscattered power is attenuated. In previous work, we used beam tracing and reciprocity to derive this mismatch attenuation quantitatively. In this paper, we applied our model, in the small but finite mismatch limit, to a several new cases. We compared our predictions with multiple O-mode channels for the first time. We then identified a $\sim 3^{\circ}$ error in the MAST Q-band's quasioptics, showing that our model is useful for commissioning DBS diagnostics. For both O- and X-mode, we compared experimental data with our model's predictions at multiple times during the shots, unlike our previous work, where only a single time was analysed. Finally, we analysed other contributions to the backscattered signal, evaluating how much they affect our measurements of mismatch attenuation, giving comparisons with data from both MAST and MAST-U. This paper's detailed study systematically validates and demonstrates the usefulness of our model for quantitatively interpreting DBS data from spherical tokamaks. △ Less

Submitted 5 June, 2024; v1 submitted 30 November, 2022; originally announced November 2022.

Modelling of transient interference phenomena in collinear laser spectroscopy

Authors: Jovan Jovanovic, Ronald Fernando Garcia Ruiz

Abstract: Collinear laser spectroscopy of fast atomic beams has been established as one of the main tools to perform precision experiments with atoms containing short-lived nuclei. Although highly sensitive, the spectral resolution of these techniques is typically limited to several MHz. Here, we study the use of transient interference phenomena to potentially improve the experimental resolution. Previous a… ▽ More Collinear laser spectroscopy of fast atomic beams has been established as one of the main tools to perform precision experiments with atoms containing short-lived nuclei. Although highly sensitive, the spectral resolution of these techniques is typically limited to several MHz. Here, we study the use of transient interference phenomena to potentially improve the experimental resolution. Previous attempts to implement Ramsey-type measurements with fast beams were limited by the lack of understanding of the observed line shapes. By using a simple model, we provide a satisfactory description of the previously observed line shapes, and propose alternative experimental schemes to improve the resolution in fast ion-beam experiments. △ Less

Submitted 7 November, 2022; originally announced November 2022.

Comments: 7 pages without references, 8 figures

Validating and optimising mismatch tolerance of Doppler backscattering measurements with the beam model

Authors: Valerian H. Hall-Chen, Julius Damba, Felix I. Parra, Quinn T. Pratt, Clive A. Michael, Shi Peng, Terry L. Rhodes, Neal A. Crocker, Jon C. Hillesheim, Rongjie Hong, Shikang Ni, William A. Peebles, Ching Eng Png, Juan Ruiz Ruiz

Abstract: We use the beam model of Doppler backscattering (DBS), which was previously derived from beam tracing and the reciprocity theorem, to shed light on mismatch attenuation. This attenuation of the backscattered signal occurs when the wavevector of the probe beam's electric field is not in the plane perpendicular to the magnetic field. Correcting for this effect is important for determining the amplit… ▽ More We use the beam model of Doppler backscattering (DBS), which was previously derived from beam tracing and the reciprocity theorem, to shed light on mismatch attenuation. This attenuation of the backscattered signal occurs when the wavevector of the probe beam's electric field is not in the plane perpendicular to the magnetic field. Correcting for this effect is important for determining the amplitude of the actual density fluctuations. Previous preliminary comparisons between the model and Mega-Ampere Spherical Tokamak (MAST) plasmas were promising. In this work, we quantitatively account for this effect on DIII-D, a conventional tokamak. We compare the predicted and measured mismatch attenuation in various DIII-D, MAST, and MAST-U plasmas, showing that the beam model is applicable in a wide variety of situations. Finally, we performed a preliminary parameter sweep and found that the mismatch tolerance can be improved by optimising the probe beam's width and curvature at launch. This is potentially a design consideration for new DBS systems. △ Less

Submitted 30 September, 2022; originally announced September 2022.

New linear stability parameter to describe low-$β$ electromagnetic microinstabilities driven by passing electrons in axisymmetric toroidal geometry

Authors: M. R. Hardman, F. I. Parra, B. S. Patel, C. M. Roach, J. Ruiz Ruiz, M. Barnes, D. Dickinson, W. Dorland, J. F. Parisi, D. St-Onge, H. Wilson

Abstract: In magnetic confinement fusion devices, the ratio of the plasma pressure to the magnetic field energy, $β$, can become sufficiently large that electromagnetic microinstabilities become unstable, driving turbulence that distorts or reconnects the equilibrium magnetic field. In this paper, a theory is proposed for electromagnetic, electron-driven linear instabilities that have current layers localis… ▽ More In magnetic confinement fusion devices, the ratio of the plasma pressure to the magnetic field energy, $β$, can become sufficiently large that electromagnetic microinstabilities become unstable, driving turbulence that distorts or reconnects the equilibrium magnetic field. In this paper, a theory is proposed for electromagnetic, electron-driven linear instabilities that have current layers localised to mode-rational surfaces and binormal wavelengths comparable to the ion gyroradius. The model retains axisymmetric toroidal geometry with arbitrary shaping, and consists of orbit-averaged equations for the mode-rational surface layer, with a ballooning space kinetic matching condition for passing electrons. The matching condition connects the current layer to the large scale electromagnetic fluctuations, and is derived in the limit that $β$ is comparable to the square root of the electron-to-ion-mass ratio. Electromagnetic fluctuations only enter through the matching condition, allowing for the identification of an effective $β$ that includes the effects of equilibrium flux surface shaping. The scaling predictions made by the asymptotic theory are tested with comparisons to results from linear simulations of micro-tearing and electrostatic microinstabilities in MAST discharge #6252, showing excellent agreement. In particular, it is demonstrated that the effective $β$ can explain the dependence of the local micro-tearing mode (MTM) growth rate on the ballooning parameter $θ_0$ -- possibly providing a route to optimise local flux surfaces for reduced MTM-driven transport. △ Less

Submitted 22 February, 2023; v1 submitted 22 August, 2022; originally announced August 2022.

Comments: 29 pages, 14 figures

Spectroscopic Neutron Imaging for Resolving Hydrogen Dynamics Changes in Battery Electrolytes

Authors: E. R. Carreón Ruiz, J. Lee, J. I. Márquez Damián, M. Strobl, G. Burca, R. Woracek, M. Cochet, M. -O. Ebert, L. Höltschi, P. M. Kadletz, A. S. Tremsin, E. Winter, M. Zlobinski, L. Gubler, P. Boillat

Abstract: We present spectroscopic neutron imaging (SNI), a bridge between imaging and scattering techniques, for the analysis of hydrogenated molecules in lithium-ion cells. The scattering information of CHn-based organic solvents and electrolytes was mapped in two-dimensional space by investigating the wavelength-dependent property of hydrogen atoms through time-of-flight imaging. Our investigation demons… ▽ More We present spectroscopic neutron imaging (SNI), a bridge between imaging and scattering techniques, for the analysis of hydrogenated molecules in lithium-ion cells. The scattering information of CHn-based organic solvents and electrolytes was mapped in two-dimensional space by investigating the wavelength-dependent property of hydrogen atoms through time-of-flight imaging. Our investigation demonstrates a novel approach to detect physical and chemical changes in hydrogenated liquids, which extends, but not limits, the use of SNI to relevant applications in electrochemical devices, e.g., the study of electrolytes in Li-ion batteries. △ Less

Submitted 18 July, 2022; originally announced July 2022.

Cool molecular highly charged ions for precision tests of fundamental physics

Authors: Carsten Zülch, Konstantin Gaul, Steffen M. Giesen, Ronald F. Garcia Ruiz, Robert Berger

Abstract: Molecules and atomic highly charged ions provide powerful low-energy probes of the fundamental laws of physics: Polar molecules possess internal fields suitable to enhance fundamental symmetry violation by several orders of magnitudes, whereas atoms in high charge states can feature large relativistic effects and compressed level structures, ideally posed for high sensitivity to variations of fund… ▽ More Molecules and atomic highly charged ions provide powerful low-energy probes of the fundamental laws of physics: Polar molecules possess internal fields suitable to enhance fundamental symmetry violation by several orders of magnitudes, whereas atoms in high charge states can feature large relativistic effects and compressed level structures, ideally posed for high sensitivity to variations of fundamental constants. Polar, highly charged molecules could benefit from both: large internal fields and large relativistic effects. However, a high charge dramatically weakens chemical bonding and drives systems to the edge of Coulomb explosion. Herein, we propose multiply-charged polar molecules, that contain actinides, as promising candidates for precision tests of physics beyond the standard model. Explicitly, we predict PaF$^{3+}$ to be thermodynamically stable, coolable and well-suited for precision spectroscopy. The proposed class of compounds, especially with short-lived actinide isotopes from the territory of pear-shaped nuclei, has potential to advance our understanding of molecules under extreme conditions, to provide a window into unknown properties of atomic nuclei, and to boost developments in molecular precision spectroscopy in various areas, such as optical clocks and searches for new physics. △ Less

Submitted 19 March, 2022; originally announced March 2022.

Comments: 18 pages, 3 figures, 6 tables

Snowmass 2021: Quantum Sensors for HEP Science -- Interferometers, Mechanics, Traps, and Clocks

Authors: Oliver Buchmueller, Daniel Carney, Thomas Cecil, John Ellis, R. F. Garcia Ruiz, Andrew A. Geraci, David Hanneke, Jason Hogan, Nicholas R. Hutzler, Andrew Jayich, Shimon Kolkowitz, Gavin W. Morley, Holger Muller, Zachary Pagel, Christian Panda, Marianna S. Safronova

Abstract: A wide range of quantum sensing technologies are rapidly being integrated into the experimental portfolio of the high energy physics community. Here we focus on sensing with atomic interferometers; mechanical devices read out with optical or microwave fields; precision spectroscopic methods with atomic, nuclear, and molecular systems; and trapped atoms and ions. We give a variety of detection targ… ▽ More A wide range of quantum sensing technologies are rapidly being integrated into the experimental portfolio of the high energy physics community. Here we focus on sensing with atomic interferometers; mechanical devices read out with optical or microwave fields; precision spectroscopic methods with atomic, nuclear, and molecular systems; and trapped atoms and ions. We give a variety of detection targets relevant to particle physics for which these systems are uniquely poised to contribute. This includes experiments at the precision frontier like measurements of the electron dipole moment and electromagnetic fine structure constant and searches for fifth forces and modifications of Newton's law of gravity at micron-to-millimeter scales. It also includes experiments relevant to the cosmic frontier, especially searches for gravitional waves and a wide variety of dark matter candidates spanning heavy, WIMP-scale, light, and ultra-light mass ranges. We emphasize here the need for more developments both in sensor technology and integration into the broader particle physics community. △ Less

Submitted 14 September, 2022; v1 submitted 14 March, 2022; originally announced March 2022.

Comments: contribution to Snowmass 2021 18 pages, 3 figures; updated author list and references, fixed typos