Nuclear Physics Experiments Research Articles

Unambiguous Detection of High-Energy Vortex States via the Superkick Effect

Vortex states of photons, electrons, and other particles are freely propagating wave packets with helicoidal wave fronts winding around the axis of a phase vortex. A particle prepared in a vortex state carries a nonzero orbital angular momentum projection on the propagation direction, a quantum number that has never been exploited in experimental particle and nuclear physics. Low-energy vortex photons, electrons, neutrons, and helium atoms have been demonstrated in experiment and found numerous applications, and there exist proposals of boosting them to higher energies. However, verification that a high-energy particle is indeed in a vortex state will be a major challenge, since the low energy techniques become impractical at higher energies. Here, we propose a new diagnostic method based on the so-called superkick effect, which can unambiguously detect the presence of a phase vortex. A proof-of-principle experiment with vortex electrons can be done with existing technology, and its realization will also constitute the first observation of the superkick effect. Published by the American Physical Society 2024

Enhancing nondestructive mass identification via Fourier-transform fluorescence analysis

Single-ion mass identification is important for atomic and nuclear physics experiments on ions produced with low yields. Cooling the ion to ultralow temperatures through interaction with a laser-cooled ion will enhance the precision of the measurements. In this paper we present axial-common-mode frequency measurements of balanced and unbalanced Coulomb crystals from the Fourier transform of the fluorescence photons from a Doppler-cooling transition in calcium ions after probing the ion crystal with a five-radio-frequency comb. A single ion nondestructively detected can be used for identification, yielding a mass-resolving power m/ΔmFWHM≈310 from the axial common mode. This identification can be performed from a single measurement within times below 1 s. Published by the American Physical Society 2024

Spin decoherence and off-resonance behavior of radio-frequency-driven spin rotations in storage rings

High-frequency driven resonant spin rotators are routinely used as standard instruments in polarization experiments in particle and nuclear physics. Maintaining the continuous exact parametric spin resonance condition of the equality of the spin rotator and the spin precession frequency during operation is one of the challenges. We present a detailed analytical description of the effects of detuning the exact spin resonance on the precessing vertical and in-plane components of the polarization. An important part of the formalism presented here is the consideration of experimentally relevant spin decoherence effects. Within the developed formalism, we address the impact of feedback via pilot-bunch-based comagnetometry on continuous spin flips and on the related interpretation of charged-particle electric dipole moment searches using storage rings. We propose a spin-flip-based tomography of the longitudinal profile of polarization in a bunch, which is important for the evaluation of the polarization-dependent luminosity in collider experiments. We emphasize the potential importance of the previously unexplored phase of the horizontal polarization of the envelope as an indicator of the stability of radio-frequency-driven spin rotations in storage rings and as a testing ground for spin decoherence mechanisms. Published by the American Physical Society 2024

Data reduction for low energy nuclear physics experiments using data frames

Low energy nuclear physics experiments are transitioning towards fully digital data acquisition systems. Realizing the gains in flexibility afforded by these systems relies on equally flexible data reduction techniques. In this paper, methods utilizing data frames and in-memory techniques to work with data, including data from self-triggering, digital data acquisition systems, are discussed within the context of a Python package, sauce. It is shown that data frame operations can encompass common analysis needs and allow interactive data analysis. Two event building techniques, dubbed referenced and referenceless event building, are shown to provide a means to transform raw list mode data into correlated multi-detector events. These techniques are demonstrated in the analysis of two example data sets.

Codebase release 2.0 for sauce

Low energy nuclear physics experiments are transitioning towards fully digital data acquisition systems. Realizing the gains in flexibility afforded by these systems relies on equally flexible data reduction techniques. In this paper, methods utilizing data frames and in-memory techniques to work with data, including data from self-triggering, digital data acquisition systems, are discussed within the context of a Python package, sauce. It is shown that data frame operations can encompass common analysis needs and allow interactive data analysis. Two event building techniques, dubbed referenced and referenceless event building, are shown to provide a means to transform raw list mode data into correlated multi-detector events. These techniques are demonstrated in the analysis of two example data sets.

Development and commissioning of ion-optical elements for ion and antiproton beams with energies up to 5 keV

In nuclear and atomic physics experiments, charged ion beams often need to be guided from the ion production to the experimental site. In the PUMA experiment, an ion source beamline was developed, which can be operated with up to 5 keV beam energy at a base pressure of 10-9 mbar or better. In this technical report, a low-energy pulsed drift tube for beam energy modification, a hybrid einzel lens assembly for beam focusing and steering and an iris shutter assembly for separating beamline sections with different vacuum requirements are described with their design principles and performances.

New readout system of the FATIMA detectors based on Silicon Photomultipliers arrays

We present a new readout system based on large area Silicon Photomultipliers arrays coupled with cylindrical 1.5” × 2” LaBr3(Ce) FATIMA-type crystals. This readout achieves the fast-timing capabilities of such crystals coupled to the usual Photomultiplier Tubes. Energy calibration was measured with 137Cs and 152Eu standard radioactive sources, while the timing performances were investigated with a 60Co radioactive source. We benchmark our results against the corresponding results obtained with the fast R9779 Photomultiplier tubes and highlight the importance of achieving similar energy and timing performances for nuclear structure experiments. The FWHM energy resolution for the 1.5” × 2” LaBr3(Ce) crystal coupled with the SiPM and PMT was found to be 3.31(2)% and 3.85(1)%, respectively, for the 661.6 keV transition of the 137Cs source. The timing resolution was measured between a conical crystal known for its fast response and a cylindrical crystal coupled to a SiPM or PMT readout. We obtain values of FWHM = 230(1) ps and 232(1) ps, respectively, between the 1173.2–1332.5 keV transitions of the 60Co source. In addition, a temperature effect compensation circuit was developed to maintain a good stability of the gain during long measurements, typical for in-beam/off-beam experiments in nuclear physics.

Shedding light on dark sectors with gravitational waves

The nature of dark matter remains one of the greatest unsolved mysteries in elementary particle physics. It might well be that the dark matter particle belongs to a dark sector completely secluded or extremely weakly coupled to the visible sector. We demonstrate that gravitational waves arising from first-order phase transitions in the early Universe can be used to look for signatures of dark sector models connected to neutron physics. This introduces a new connection between gravitational-wave physics and nuclear physics experiments. Focusing on two particular extensions of the Standard Model with dark U(1) and SU(2) gauge groups constructed to address the neutron lifetime puzzle, we show how those signatures can be searched for in future gravitational-wave and astrometry experiments. Published by the American Physical Society 2024

Resource Letter: Synthesis of the elements in stars

This Resource Letter provides a guide to the literature on the field of nuclear astrophysics, and particularly the origin of the elements. Nuclear astrophysics is a multidisciplinary field that aims at understanding where everything we see around us comes from and how it came to be. Astronomical observations, astrophysics modeling, and nuclear physics experiment and theory come together to answer important questions like: Where and how are the elements created? How do stars evolve? What drives the different types of stellar explosions? What is left behind after the cataclysmic death of a star? This Resource Letter presents our current understanding of the origin of the various chemical elements, together with modern research and new developments in the field, with a particular focus on the measurement of nuclear properties for astrophysical applications.

Design and commissioning of a two-harmonic pre-buncher for extended bunch spacing at LEAF

The Low Energy Heavy Ion Accelerator Facility (LEAF) is a low-energy, high-intensity heavy-ion linear accelerator facility at Institute of Modern Physics (IMP) for multidiscipline research. The beam bunch repetition rate coincides with the LINAC frequency of 81.25 MHz, resulting in a 12.3 ns period. However, in the context of certain nuclear physics experiments, a longer bunch spacing is deemed essential for the precise detection of experimental products. To address this need, a strategy to extend the bunch spacing to 98 ns has been proposed by integrating a pre-buncher operating at a fundamental frequency of 10.156 MHz before the radio-frequency quadrupole (RFQ) in conjunction with a fast chopper in the medium energy beam transport (MEBT) system. The pre-buncher is a pivotal component in enabling a greater beam current at the target, surpassing the capability of employing a chopper alone. To enhance the bunching efficiency, the pre-buncher operates with two frequencies: the fundamental frequency of 10.156 MHz and its first sub-harmonic of 20.3125 MHz, each of which is produced by a coaxial resonator. This paper describes the design, manufacture, off-line testing, and beam commissioning of the pre-buncher.

Impact of dark energy on the structure of neutron stars: The vacuum case

The potential role of a cosmic vacuum dark component in the properties of neutron stars is investigated. It is assumed that the static, spherically symmetric distribution of matter within neutron stars is supported by two distinct components: ordinary matter and a vacuum fluid. For normal matter we use a set of state-of-the-art nuclear matter equations of state, each grounded in nuclear physics experiments. The vacuum energy component is inhomogeneously distributed within the star and obeys the standard equation of state (pv=−εv). This is characterized by an energy density fraction y=εm/(εm+εv), which we model as either a constant or radius-dependent. Our findings reveal that the inclusion of vacuum energy significantly affects the mass-radius relationships in neutron stars, influencing both the maximum achievable masses and the qualitative form of these relationships. Some constraints from current multimessenger observational data limiting the amount of vacuum energy within neutron stars are also discussed. Published by the American Physical Society 2024

Influence of beam content composition on testbeam studies of hadron calorimeters

Abstract Hadron calorimeters are one of the most important detectors in the contemporary nuclear and particle physics experiments. Their construction and verification process takes years in designing, testing and data analysis of prototypes. Crucial step for the prototypes are tests performed by exposing the detectors to charge particle beams. Here we study the impact of the different beam content composition to one of the main properties of the hadron calorimeters – their energy resolution. We implement a test detector - Metal Hadronic Calorimeter (MACA) in GEANT4 environment and we perform different simulations to study the influence to the main energy resolution parameters.

The Roles of Thomson and Rutherford in the Birth of Atomic Physics:The Interaction of Experiment and Theory

AbstractThe discovery of the electron in 1897 by J. J. Thomson meant that the atom was no longer the smallest unit of matter. This led to a set of responses both experimental and theoretical which consolidated a new branch of physics—atomic physics. What were the tools available at the time to address atomic physics and how were they deployed? The research begins with Thomson who sought to describe a structure of the atom that accommodates both mechanical and electromagnetic properties, but he had little experimental data to base it on. It was indeed an experimental finding which paved the way for the modern conception of the structure of the atom—Rutherford's scattering experiment. A complex relation between theory and experiment in a new domain of physics is uncovered. While the revolutionary discovery of the electron was the result of a classical propagation experiment, the discovery of the concentrated charge at the center of the atom was an outcome of a scattering experiment—a bombardment technique. This technique has turned out to be the hallmark of experimental atomic physics.

Experimental neutrino physics in a nuclear landscape.

There are profound connections between neutrino physics and nuclear experiments. Exceptionally precise measurements of single and double beta-decay spectra illuminate the scale and nature of neutrino mass and may finally answer the question of whether neutrinos are their own anti-matter counterparts. Neutrino-nucleus scattering underpins oscillation experiments and probes nuclear structure, neutrinos offer a rare vantage point into collapsing stars and nuclear fission reactors and techniques pioneered in neutrino nuclear physics experiments are advancing quantum sensing technologies. In this article, we review current and planned efforts at the intersection of neutrino and nuclear experiments. This article is part of the theme issue 'The liminal position of Nuclear Physics: from hadrons to neutron stars'.

PROJECT ON RESEARCH OF NUCLEAR dd-SYNTHESIS WITH POLARIZATION OF INITIAL PARTICLES AT LOW ENERGIES (PolFusion)

The nuclear dd-fusion reaction can proceed by three possible channels: 3H + 𝑝 (≈ 50%), 3He + 𝑛 (≈ 50%), 4He + (≈ 10−7%). Interest in dd-fusion has been aroused by both fundamental research and astrophysics and applied science, particularly in the field of fusion reactor development. In the 1970s at the Kurchatov Institute, the idea of studying the nuclear dd-fusion reaction using polarized deuteron beams was proposed. The development of this idea was continued in the PolFusion (Polarized Fusion) nuclear physics experiment, which aims to study the reaction of nuclear dd-synthesis with polarized source particles in the low energy region. The experiment is planned to measure the scattering asymmetries of dd-fusion reaction products in the final state at different mutual orientation of the spins of colliding deuterons in the energy range 10—100 keV. The authors will present an overview of the status of the experiment.

Design and beam dynamics validation of a spiral FFAG accelerator for CSNS-II

The fixed-field alternating gradient (FFAG) accelerator, with its compact structure and the combined advantages of high energy from synchrotrons and high beam intensity from cyclotrons, offers unparalleled benefits in accelerating protons, heavy ions, and short-lived particles such as muons and unstable nuclei. The China Spallation Neutron Source plans to establish an FFAG accelerator with a diameter of 20 meters at the end of the negative hydrogen linac for various purposes, including experiments in nuclear physics and medical applications. For this design, a scaling scheme using spiral magnets as the basic focusing structure is investigated to provide the proton beam with kinetic energy ranging from 300 MeV to 600 MeV. We present the design results for the scaling FFAG accelerator and discuss the optimization of the cell tune. A detailed beam dynamics verification and discussion of the proposed FFAG accelerator lattice are presented using the ray-tracing code Zgoubi, including off-axis optical characteristics, large amplitude transverse motion, and full-cycle longitudinal acceleration. The FFAG accelerator is demonstrated to provide a large transverse and longitudinal acceptance for the tracking beam in the designed lattice. A new simulation code based on Python for the study of FFAG accelerator beam dynamics has been developed, and the corresponding verification results are also presented.

Development of a phoswich detector utilizing bismuth germanate crystal scintillator and polyethylene naphthalate scintillation film

In this study, we present the development of a phoswich detector system employing a Bismuth Germanate (BGO) crystal scintillator in combination with a Polyethylene naphthalate (PEN) film plastic scintillator. Phoswich detectors can contribute to various applications, including radiation monitoring, medical imaging, and nuclear physics experiments, due to their ability to discriminate between different types of radiation. The thin PEN film is sensitive to α and β radiation, while the BGO scintillator exhibits good γ radiation detection efficiency. The incident radiation type and its energy can be determined by analyzing the difference in decay times between these two scintillators. This paper presents an analysis of the detector’s response to α, β, and γ radiation, and the particle tagging efficiencies are to be over 99.9%, 92%, and 99.8%, respectively.

Nuclear Physics in the Era of Quantum Computing and Quantum Machine Learning

AbstractIn this paper, the application of quantum simulations and quantum machine learning is explored to solve problems in low‐energy nuclear physics. The use of quantum computing to address nuclear physics problems is still in its infancy, and particularly, the application of quantum machine learning (QML) in the realm of low‐energy nuclear physics is almost nonexistent. Three specific examples are presented where the utilization of quantum computing and QML provides, or can potentially provide in the future, a computational advantage: i) determining the phase/shape in schematic nuclear models, ii) calculating the ground state energy of a nuclear shell model‐type Hamiltonian, and iii) identifying particles or determining trajectories in nuclear physics experiments.

Real-time charged track reconstruction for CLAS12

This paper presents the results of charged particle track reconstruction in CLAS12 using artificial intelligence. In our approach, we use machine learning algorithms to reconstruct tracks, including their momentum and direction, with high accuracy from raw hits of the CLAS12 drift chambers. The reconstruction is performed in real-time, with the rate of data acquisition, and allows for the identification of event topologies in real-time. This approach revolutionizes the Nuclear Physics experiments' data processing, allowing us to identify and categorize the experimental data on the fly, and will lead to a significant reduction in experiment data processing. It can also be used in streaming readout applications leading to more efficient data acquisition and post-processing.

Predictions for the Alpha Decay of Z = 127–138 Super Heavy Nuclei Using the CYE Model

In recent years, the synthesis and identification of Superheavy elements have been of a great interest in the area of both experimental and theoretical nuclear physics. Using the CYE model, the alpha decay, cluster decay, and spontaneous fission in the heavy and superheavy nuclei have been studied. In the current work, we will investigate the α decay and obtain cluster decay half lifetimes in the interval Z = 127–138 and the spontaneous fission half lifetimes using the two-sphere approximation and will compare the results with the other theoretical values and the semiempirical formula by Xu et al. We believe that the predicted decay half-lifetimes are valuable for future tests, because they are in a good agreement with other theoretical formalisms.