Phys. Part. Nucl. Lett.

This paper presents a design of a calibration system for the Light Readout System of the prototype modular Liquid Argon Time-Projection Chamber (LArTPC) of the Near Detector of the Deep Underground Neutrino Experiment (DUNE). The calibration system and its components have been tested at the Joint Institute for Nuclear Research (JINR) and during the prototype LArTPC trials conducted at the University of Bern, Switzerland. The results demonstrate that the system fulfills its intended functionality, allowing for the calibration of the photodetectors in the light-readout system of the LArTPC and the study of its temporal characteristics.

Phys. Part. Nucl. Lett.

One way to increase the sensitivity of the precision laser inclinometer (PLI) is to change over from the photovoltaic mode to the reverse-biased photodiode mode. This allows a broader linear range and an improved signal-to-noise ratio. Additionally, this approach enables the use of lower resolution ADCs (14–16 bit instead of 24 bit), which significantly reduces the cost of the device. A study of the Hamamatsu S12915-1010R/66R, Thorlabs FDS-100, and Hamamatsu S3204-08 photodiodes is conducted to determine their linear range of operation in the photovoltaic and photodiode modes. The noise level of the CPLI readout channels is measured using closed photodiodes, and two modes of operation of the photodiodes in the CPLI on the signal channels are investigated. The research results indicate the possibility of using this mode of operation of photodiodes in the CPLI.

Phys.Part.Nucl.Lett.

JINR in collaboration with the St. Petersburg-based Efremov Institute of Electrophysical Apparatus (NIIEFA) is developing a superconducting isochronous cyclotron MSC230, which is intended to conduct research in radiobiology and to develop proton flash radiotherapy techniques. In relation to this, formation of a high-intensity proton beam with the energy selectable in a range of 120–230 MeV, a dose rate of 50–100 Gy/s, and homogeneous in cross section with a diameter of 13–15 cm at the new accelerator is explored. Results of modeling by the Monte Carlo method and measurements of the depth-dose distributions of a proton beam, the energy spectrum of which is modified to obtain an extended homogeneous plateau at the end of the range (spread-out Bragg peak), are presented. This is achieved by using so-called ridge filters. A method for design and manufacturing ridge filters using a 3D printer that can change the length of the plateau in a fairly wide range of values by rotating it relative to the beam axis is presented. The results of the study lend a hope that two sets, each consisting of 5–6 such filters, will be able to span the entire required range of the Bragg peak plateau, and for all values of the selected energy.

Nucl. Instrum. Meth. A

The “muon-to-electron conversion” (Mu2e) experiment at Fermilab will search for the Charged Lepton Flavour Violating neutrino-less coherent conversion of a muon into an electron in the field of an aluminum nucleus. The observation of this process would be the unambiguous evidence of physics beyond the Standard Model. The detector has been designed as a state-of-the-art crystal calorimeter and employs 1348 pure Cesium Iodide (CsI) crystals readout by UV-extended silicon photosensors and fast front-end and digitization electronics. A design consisting of two identical annular matrices (named “disks”) positioned at the relative distance of 70 cm, downstream the aluminum target along the muon beamline, satisfies the Mu2e physics requirements. The hostile Mu2e operational conditions, in terms of radiation levels (total ionizing dose of 90 krad and a neutron fluence of $5x10^{12}n/c{m}^2@1MeVeq\left(Si\right)/y$), magnetic field intensity (1 T) and vacuum level ($10^{-4}$ Torr) have posed tight constraints on the design of the detector mechanical structures and materials choice. The support structure of the two 674 crystal matrices employs two aluminum hollow rings and parts made of open-cell vacuum-compatible carbon fiber. The photosensors and service front-end electronics for each crystal are assembled in a unique mechanical unit inserted in a machined copper holder. The 674 units are supported by a machined plate made of vacuum-compatible plastic material. The plate also integrates the cooling system made of a network of copper lines flowing a low temperature radiation-hard fluid and placed in thermal contact with the copper holders. The data acquisition electronics is hosted in aluminum custom crates positioned on the external lateral surface of the two disks. The crates also integrate the electronics cooling system.

Pisma Zh.Eksp.Teor.Fiz.

First results on the polarization of $\Lambda $ hyperons inclusively produced on 26.5-GeV/c${{K}^{ - }}$ and ${{\pi }^{ - }}$ beams are presented. The measurements were carried out using the SPASCHARM setup at the U-70 accelerator facility (Protvino, Russia) on nuclear targets in 2021 and 2022. The polarization of an $\Lambda $ hyperon on the ${{\pi }^{ - }}$ beam does not exceed several percent in most of the studied kinematic region. The data obtained on the ${{K}^{ - }}$-meson beam exhibit a significant positive polarization at large values of the Feynman variable x$_{F}$ and transverse momentum p$_{T}$ measured for the first time on nuclei.

JINST

The CERN LHC provided proton and heavy ion collisions duringits Run 2 operation period from 2015 to 2018. Proton-protoncollisions reached a peak instantaneous luminosity of2.1× 10$^{34}$ cm$^{-2}$s$^{-1}$, twice the initialdesign value, at √(s)=13 TeV. The CMS experimentrecords a subset of the collisions for further processing as part ofits online selection of data for physics analyses, using a two-leveltrigger system: the Level-1 trigger, implemented in custom-designedelectronics, and the high-level trigger, a streamlined version ofthe offline reconstruction software running on a large computerfarm. This paper presents the performance of the CMS high-leveltrigger system during LHC Run 2 for physics objects, such asleptons, jets, and missing transverse momentum, which meet the broadneeds of the CMS physics program and the challenge of the evolvingLHC and detector conditions. Sophisticated algorithms that wereoriginally used in offline reconstruction were deployedonline. Highlights include a machine-learning b tagging algorithmand a reconstruction algorithm for tau leptons that decayhadronically.

Nucl. Instrum. Meth. A

The calorimeter of the Mu2e experiment is being assembled, with all production components completed and tested, apart from the digital electronics that is still underway. The mechanical structure is fully built, with a complete integration and test of all the analog sensors and electronics. We summarize construction and assembly phases, Quality Control tests, calibration procedures and first tests performed in the assembly area, as well as the installation and commissioning plans of the final disks in the Mu2e hall.

Phys.Part.Nucl.

The review describes the results of experiments based on quite different and independent approaches to solving the problem of interaction of muons with nuclei. Different paths of muon capture by nuclei and subsequent paths of secondary processes are considered: radiationless capture followed by nuclear fission, excitation of the nucleus with the escape of particles (neutrons and charged ones), and excitation of nuclear levels with the escape of gamma quanta. The experimental data require refinement, in particular with respect to the spectroscopy of fission fragments, the spectroscopy of secondary particles, and statistical accuracy. All of the experimental methods described rely on interpretation within theoretical models. Improvement in each of these parts will mutually stimulate refinements or new paths in subsequent research. The article is addressed to young aspiring physicists interested in muon physics and looking for new phenomena of interactions of elementary particles with nuclei and atoms, and solutions to emerging problems using modern experimental methods.

Eur. Phys. J. C

The CMS detector, including its muon system, has been operating at the CERN LHC in increasingly challenging conditions for about 15 years. The muon detector was designed to provide excellent triggering and track reconstruction for muons produced in proton–proton collisons at an instantaneous luminosity ($\mathcal {L}$) of $1 \times 10^{34}$ cm$^{-2}$s$^{-1}$. During the Run 2 data-taking period (2015–2018), the LHC achieved an instantaneous luminosity of twice its design value, resulting in larger background rates and making the efficient detection of muons more difficult. While some backgrounds result from natural radioactivity, cosmic rays, and interactions of the circulating protons with residual gas in the beam pipe, the dominant source of background hits in the muon system arises from proton–proton interactions themselves. Charged hadrons leaving the calorimeters produce energy deposits in the muon chambers. In addition, high-energy particles interacting in the hadron calorimeter and forward shielding elements generate thermal neutrons, which leak out of the calorimeter and shielding structures, filling the CMS cavern. We describe the method used to measure the background rates in the various muon subsystems. These rates, in conjunction with simulations, can be used to estimate the expected backgrounds in the High-Luminosity LHC. This machine will run for at least 10 years starting in 2029 reaching an instantaneous luminosity of $\mathcal {L} = 5 \times \text {10}^\text {34}\,\text {cm}^\text {-2}\,\text {s}^\text {-1}$ and increasing ultimately to $\mathcal {L} = 7.5 \times \text {10}^\text {34}\,\text {cm}^\text {-2}\,\text {s}^\text {-1}$. These background estimates have been a key ingredient for the planning and design of the muon detector upgrade.

Phys. Rev. D

By analyzing $e^+e^-$ annihilation data corresponding to an integrated luminosity of 7.93 fb$^{-1}$, collected at the center-of-mass energy of 3.773 GeV with the BESIII detector, we search for the semileptonic decays $D^0\to K^-\eta e^+\nu_e$, $D^+\to K_S^0 \eta e^+\nu_e$ and $D^+\to \eta\eta e^+\nu_e$ for the first time. We present evidence for $D^0\to K^-\eta e^+\nu_e$ with a significance of $3.3\sigma$. The branching fraction of $D^0\to K^-\eta e^+\nu_e$ is measured to be $(0.84_{-0.34}^{+0.29}\pm0.22)\times 10^{-4}$. Here, the first uncertainties are statistical and the second ones are systematic. No significant signals are observed for the decays $D^+\to K_S^0 \eta e^+\nu_e$ and $D^+\to \eta\eta e^+\nu_e$ and we set the upper limits on their branching fractions.

Phys.Rev.D

In this work the Coulomb effects (Coulomb correlations) in $\pi^+\pi^-$ pairs produced in p + Ni collisions at 24 GeV/$c$, are studied using experimental $\pi^+\pi^-$ pair distributions in $Q$, the relative momentum in the pair center of mass system (c.m.s), and its projections $Q_L$ (longitudinal component) and $Q_t$ (transverse component) relative to the pair direction in the laboratory system (l.s.). The $Q$, $Q_L$, and $Q_t$ distributions of the {\sl Coulomb pairs} in the c.m.s. have been simulated assuming they are described by the phase space modified by the known point-like Coulomb correlation function $A_C(Q)$, corrected for small effects due to the nonpoint-like pair production and the strong two-pion interaction. The same distributions of {\sl non-Coulomb pairs} have been simulated according to the phase space, but without $A_C(Q)$. It is shown that the number of {\sl Coulomb pairs} in all $Q_t$ intervals, including the small $Q_t$ (small opening angles $\theta$ in the l.s.) is calculated with the theoretical precision better than 2%. The comparison of the simulated and experimental numbers of {\sl Coulomb pairs} at small $Q_t$ allows us to check and correct the detection efficiency for the pairs with small $\theta$ (0.06 mrad and smaller). It is shown that {\sl Coulomb pairs} can be used as a new physical tool to check and correct the quality of the simulated events. The special property of the {\sl Coulomb pairs} is the possibility of checking and correcting the detection efficiency, especially for the pairs with small opening angles.

AIP Conf. Proc.

An overview of the MONUMENT experimental programme is given, as well as some additional possibilities not yet fully explored in the study of the ordinary muon capture process. The importance of studying partial capture rates, angular correlations in the process, and the hyperfine K-series splitting of mesorengenic radiation is highlighted. The possibility of astrophysical appli-cations is pointed out, given the similarity between the muon capture process and the scattering of intermediate-energy neutrinos from supernova explosions at the nucleus.

Eur. Phys. J. C

The BESIII experiment has been operating since 2009 and has received several upgrades, to study the $\tau $-charm physics utilizing the BEPCII accelerator. The BEPCII is a double-ring multi-bunch collider with a luminosity of $1 \times 10^{33} \, {\text {cm}}^{-2} \, {\text {s}}^{-1}$ optimized at a center-of-mass (cms) energy of $2 \times 1.89$ GeV. The rich physics topics, long lifetime and the large volume of data present challenges to offline data processing. This paper describes the design and implementation of the offline software system to meet the requirements and challenges of BESIII, including offline software architecture, geometry management, database management, event data model and tag-based analysis.

PTEP

We performed a measurement of the inclusive missing-mass spectrum of the |$^{12}$|C|$(K^-, K^+)$| reaction at an incident beam momentum of 1.8 GeV/c. This measurement was carried out by using the Superconducting Kaon Spectrometer (SKS) and the K1.8 beamline spectrometer at the Hadron Experimental Facility in J-PARC. From the missing-mass of the |$^{12}$|C|$(K^-, K^+)$| reaction, the binding energy of a |$\Xi ^-$| hyperon in a core |$^{11}$|B nucleus, |$B_{\Xi ^-}$|⁠, can be calculated. Our experimental setup yielded a good energy resolution of 8.2 MeV (full width at half maximum), which allowed us to observe significant enhancements in the proximity of the |$^{12}_{\Xi }$|Be production threshold region. In order to extract information from the missing-mass spectrum, we employed several fitting parameters assumptions. A good agreement with the spectrum shape was obtained by adding two Gaussian functions, with the constant experimental resolution for the |$\Xi$|-hypernuclear states, to the background distribution. The peak positions were obtained to be |$B_{\Xi ^-} = 8.9 \pm 1.4$| (stat.) |$^{+3.8}_{-3.1}$| (syst.) MeV and |$B_{\Xi ^-} = -2.4 \pm 1.3$| (stat.) |$^{+2.8}_{-1.2}$| (syst.) MeV. Another model assumption, one Breit–Wigner function with |$B_{\Xi ^-} = -2.7 \pm 2.2$| (stat.) |$^{+0.5}_{-0.7}$| (syst.) MeV and |$\Gamma = 4.1 \pm 2.1$| (stat.) |$^{+1.2}_{-0.7}$| (syst.) MeV, also yielded a similar |$\chi ^2$| value.

Universe

Ground-based observations of Very High Energy (VHE) gamma rays from extreme astrophysical sources are significantly influenced by atmospheric conditions. This is due to the atmosphere being an integral part of the detector when utilizing Imaging Atmospheric Cherenkov Telescopes (IACTs). Clouds and dust particles diminish atmospheric transmission of Cherenkov light, thereby impacting the reconstruction of the air showers and consequently the reconstructed gamma-ray spectra. Precise measurements of atmospheric transmission above Cherenkov observatories play a pivotal role in the accuracy of the analysed data, among which the corrections of the reconstructed energies and fluxes of incoming gamma rays, and in establishing observation strategies for different types of gamma-ray emitting sources. The Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes and the Cherenkov Telescope Array Observatory (CTAO), both located on the Observatorio del Roque de los Muchachos (ORM), La Palma, Canary Islands, use different sets of auxiliary instruments for real-time characterisation of the atmosphere. In this paper, historical data taken by MAGIC LIDAR (LIght Detection And Ranging) and CTAO FRAM (F/Photometric Robotic Telescope) are presented. From the atmospheric aerosol transmission profiles measured by the MAGIC LIDAR and CTAO FRAM aerosol optical depth maps, we obtain the characterisation of the clouds above the ORM at La Palma needed for data correction and optimal observation scheduling.

Phys. Rev. D

Using a data sample of $e^+e^-$ collisions corresponding to an integrated luminosity of 7.93 $\rm fb^{-1}$ collected with the BESIII detector at the center-of-mass energy 3.773~GeV, we perform the first amplitude analysis of the decay $D^{+} \to K_{S}^{0} K_{S}^{0} \pi^{+}$. The absolute branching fraction of $D^{+} \to K_{S}^{0}K_{S}^{0} \pi^{+}$ is measured to be $(2.97 \pm 0.09_{\rm stat.} \pm 0.05_{\rm syst.})\times10^{-3}$. The dominant intermediate process is $D^{+} \to K_{S}^{0}K^{*}(892)^{+}$, whose branching fraction is determined to be $(8.72 \pm 0.28_{\rm stat.} \pm 0.15_{\rm syst.}) \times 10^{-3}$, including all the $K^*(892)^+$ decays.

Phys.Atom.Nucl.

The production of polarized $J/\psi$ mesons at the NICA (Nuclotron based Ion Collider fAcility) energy of $\sqrt{s}=27$ GeV is studied on the basis of the generalized parton model in the leading order of perturbative QCD. The hadronization of a $c\bar{c}$ quark pair to a $J/\psi$ meson is described within the model of nonrelativistic QCD. Nonperturbative model parameters are determined on the basis of a comparison with available experimental data on the production of prompt $J/\psi$ mesons at the energies of $\sqrt{s}=19.4$ GeV (NA3) and $\sqrt{s}=200$ GeV (PHENIX).

JHEP

Using $e^+e^-$ collision data collected by the BESIII detector at BEPCII corresponding to an integrated luminosity of 30 $\rm fb^{-1}$, we measure Born cross sections and effective form factors for the process $e^+e^-\to\Xi^0\bar{\Xi}^0$ at forty-five center-of-mass energies between 3.51 and 4.95 GeV. The dressed cross section is fitted, assuming a power-law function plus a charmonium(-like) state, i.e., $\psi(3770)$, $\psi(4040)$, $\psi(4160)$, $\psi(4230)$, $\psi(4360)$, $\psi(4415)$ or $\psi(4660)$. No significant charmonium(-like) state decaying into $\Xi^0\bar\Xi^0$ is observed. Upper limits at the 90% confidence level on the product of the branching fraction and the electronic partial width are provided for each decay. In addition, ratios of the Born cross sections and the effective form factors for $e^+e^-\to\Xi^0\bar{\Xi}^0$ and $e^+e^-\to\Xi^-\bar{\Xi}^+$ are also presented to test isospin symmetry and the vector meson dominance model.

Bull.Russ.Acad.Sci.Phys.

Spectra of deuterons and tritons are measured upon the absorption of stopped π$^{−}$ mesons on a live target (an analog of a $^{28}$Si target). It is shown this technique allows the identification of direct pathways for the formation of deuterons and tritons. The share of these particles in the total yields is ~30%.

Phys. Part. Nucl.

MPDRoot is an off-line software framework for simulation, reconstruction, and physical analysis of the simulated or experimental data for MPD experiment at NICA collider. The experiment is projected to run for a few decades and to obtain ~10$^{8}$ events of heavy ion collisions, collecting the data for physics analysis at the 100 PB scale. For overall experiment success it is imperative to have state of the art data analysis software, which integrates best of available latest technologies, while adhering to time-proven, most effective development methodologies. In this paper, we introduce the MPD Data Lab—the technological integration of Acceptance Test Driven Development and Rapid Development concepts into the MPDRoot framework. At the beginning, we standardized the existing codebase by designing and writing API. This was a necessary step to be able to plug-in the external diagnostic software entities and to make the in-depth comparison of different realizations of the reconstruction modules possible. The logic of the diagnostics is encapsulated into the separate controller—the QA Engine, while its visualization is provided by JupyterLab framework. We show how full integration of MPDRoot’s libraries into JupyterLab enables to use the power of rapid development provided by JupyterLab technology to enhance productivity by fast prototyping of MPDRoot’s algorithms. The combination of these technologies together with the existing development environment form a software complex, providing means to accomplish the long term strategic objectives—competent software development with reliable quality control and algorithm innovation.

Phys. Part. Nucl.

We report on newest results in ${{k}_{{\text{T}}}}$-factorization approach for $ep$-processes. We describe HERA data on longitudinal structure function measurements as well as on associated prompt photon and jet photoproduction. The calculations include first application of the new LLM-2022 transverse momentum dependent gluon distribution developed by the authors. The study includes also the first implementation of parton showers for photoproduction processes in ${{k}_{{\text{T}}}}$-factorization. The data are described well with the simulations. The $ep$-processes are included to the new version of Monte-Carlo generator pegasus.

Phys.Part.Nucl.

A review on the gluon transverse momentum dependent distribution (TMD) and its application to the analysis of the $ep$ DIS at the HERA energies, hard and soft $pp$ processes at LHC energies and mid-rapidity is presented.

Phys.Part.Nucl.

Further development of the approach to the study of relativistic nuclear interactions in the space of four-dimensional velocities using the similarity principle is reported. In essence, the approach is modified by including quark–gluon dynamics in hadron generation during nucleus–nucleus interactions in the central rapidity region. Inclusive spectra of pions and kaons produced in pp and nucleus–nucleus, collisions are studied as a function of their transverse momentum p$_{T}$ in the central rapidity region calculated within the modified approach based on the assumption of similarity of inclusive hadron spectra. A satisfactory description is given of the NA61/SHINE data for the yield ratios K$^{+}$/π$^{+}$ and K$^{−}$/π$^{−}$ as a function of $\sqrt s $ in pp and BeBe collisions. Calculations of antiparticle-to-particle yield ratios (${{\bar {p}} \mathord{\left/ {\vphantom {{\bar {p}} p}} \right. \kern-0em} p}$, ${{\bar {d}} \mathord{\left/ {\vphantom {{\bar {d}} d}} \right. \kern-0em} d}$, ${{{{{\overline {{\text{He}}} }}^{3}}} \mathord{\left/ {\vphantom {{{{{\overline {{\text{He}}} }}^{3}}} {{\text{H}}{{{\text{e}}}^{3}}}}} \right. \kern-0em} {{\text{H}}{{{\text{e}}}^{3}}}}$) in proton–proton and nucleus–nucleus reactions are presented.

Nucl.Instrum.Meth.A

The Mu2e experiment at Fermilab will search for the neutrino-less coherent conversion of a muon into an electron in the field of a nucleus. Mu2e detectors comprise a straw tracker, an electromagnetic calorimeter and a veto for cosmic rays. The calorimeter employs 1348 Cesium Iodide crystals readout by silicon photo-multipliers and fast front-end, and digitization electronics. The digitization board is named DiRAC (Digitizer ReAdout Controller) and 140 cards are needed for the readout of the full calorimeter. The DiRACs are hosted in crates located on the external surface of calorimeter disks, inside the detector solenoid cryostat and must sustain very high radiation and magnetic field so it was necessary to fully qualify it. Several version of prototypes were validated for operation in a high-vacuum (10⁻⁴ Torr) and under a 1T magnetic field. An extensive radiation hardness qualification campaign, carried out with photons, 14 MeV neutron beams, and 200 MeV protons, certified the DiRAC design to sustain doses up to 12 krad, neutron fluences up to $\sim 10^{11}1{\mathrm{MeV\; n}}_{eq}/{\mathrm{cm}}^2$, and very low occurrences of single-event effects. The qualification campaigns and quality assurance procedures will be reviewed.

Phys.Part.Nucl.Lett.

This paper describes the results of applying an evolutionary algorithm to optimize the hyperparameters of a neural network (NN) solving the problem of separating the rare Higgs boson birth process in association with a single top quark $pp \to tH(H \to bb)$ from the main background processes $pp \to tt,ttH,tZbq$.