Particles

8 pages, 3634 KiB

Open AccessArticle

Design and Beam Dynamic Studies of an Injector for a Compact THz Coherent Radiation Source

by Siriwan Jummunt, Wanisa Promdee, Thakonwat Chanwattana, Nawin Junthong, Somjai Chunjarean and Supat Klinkhieo

Particles 2023, 6(2), 674-681; https://doi.org/10.3390/particles6020040 - 16 Jun 2023

Cited by 1 | Viewed by 1052

Abstract

An intense narrow-band terahertz (THz) radiation source has been designed to generate a broad tuning range of radiation frequencies between 0.5 THz and 5.0 THz. The THz radiation is produced when a short-bunch electron beam propagates through an undulator. To achieve high-power peak [...] Read more.

An intense narrow-band terahertz (THz) radiation source has been designed to generate a broad tuning range of radiation frequencies between 0.5 THz and 5.0 THz. The THz radiation is produced when a short-bunch electron beam propagates through an undulator. To achieve high-power peak radiation, the source requires high-brightness electron beams with low beam emittance and short bunch length. A proposed design for the photocathode RF gun used as the electron source is presented. The gun with high mode separation and high Q-factor can be achieved for producing a good beam quality. The beam dynamics of the injector have been preliminarily optimized using the software ASTRA and Elegant, investigating the impact of laser pulse shape on electron beam quality. The results of the beam dynamics studies are comprehensively discussed in this paper. Full article

(This article belongs to the Special Issue Generation and Application of High-Power Radiation Sources)

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10 pages, 2897 KiB

Open AccessArticle

Development of Type A Quadrupole Magnet for Siam Photon Source II

by Supachai Prawanta, Thongchai Leetha, Pariwat Singthong, Pajeeraphorn Numanoy, Apichai Kwankasem, Visitchai Sooksrimuang, Chaiyut Preecha, Supat Klinkiew and Prapaiwan Sunwong

Particles 2023, 6(2), 664-673; https://doi.org/10.3390/particles6020039 - 09 Jun 2023

Viewed by 1454

Abstract

A prototype of a type A quadrupole magnet has been designed and manufactured for the 3 GeV storage ring of Siam Photon Source II, the second synchrotron light source in Thailand. The required quadrupole gradient is 51 T/m with the magnet effective length [...] Read more.

A prototype of a type A quadrupole magnet has been designed and manufactured for the 3 GeV storage ring of Siam Photon Source II, the second synchrotron light source in Thailand. The required quadrupole gradient is 51 T/m with the magnet effective length being 162 mm. Magnet modeling and magnetic field calculation were performed using Radia and Opera-3D. The bore radius of the magnet is 16 mm. The magnet will be operated at the excitation of 5544 A-turns. A mechanical analysis of the magnet structure was performed in SOLIDWORKS and ANSYS, where the maximum deformation of 0.003 mm was found at the magnet poles, and the first-mode natural frequency was higher than 100 Hz. The magnet yoke is made of AISI 1006 low-carbon steel with a fabrication tolerance of ±0.020 mm. Magnet coils are water-cooled and made of high-purity copper. The temperature rise of the coils was below 3.0 °C at the maximum excitation of 6664 A-turns, which is 20% above the operating point. Magnetic field measurement was carried out using the Hall probe technique. The measured magnetic field and coil temperature of the prototype show good agreement with the calculations. Full article

(This article belongs to the Special Issue Generation and Application of High-Power Radiation Sources)

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17 pages, 437 KiB

Open AccessArticle

Density and Mass Function for Regular Rotating Electrically Charged Compact Objects Determined by Nonlinear Electrodynamics Minimally Coupled to Gravity

by Irina Dymnikova

Particles 2023, 6(2), 647-663; https://doi.org/10.3390/particles6020038 - 06 Jun 2023

Viewed by 778

Abstract

We address the question of the electromagneticdensity and the mass function for regular rotating electrically charged compact objects as determined by dynamical equations of nonlinear electrodynamics minimally coupled to gravity. The rotating electrically charged compact objects are described by axially symmetric geometry, in [...] Read more.

We address the question of the electromagneticdensity and the mass function for regular rotating electrically charged compact objects as determined by dynamical equations of nonlinear electrodynamics minimally coupled to gravity. The rotating electrically charged compact objects are described by axially symmetric geometry, in which their electromagnetic fields are governed by four source-free equations for two independent field components of the electromagnetic tensor

F_{μ ν}

, with two constraints on the integration functions. An additional condition of compatibility of four dynamical equations for two independent field functions imposes the constraint on the Lagrange derivative

L_{F} = d L / d F

, directly related to the electromagnetic density. As a result, the compatibility condition determines uniquely the generic form of the electromagnetic density and the mass function for regular rotating electrically charged compact objects. Full article

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9 pages, 2081 KiB

Open AccessArticle

The Particle-Tracking Simulation of a New Photocathode RF Gun in the Free-Electron Laser Facility, KU-FEL

by Yuhao Zhao, Heishun Zen and Hideaki Ohgaki

Particles 2023, 6(2), 638-646; https://doi.org/10.3390/particles6020037 - 06 Jun 2023

Viewed by 944

Abstract

A project is underway that aims to generate attosecond pulses via high-harmonic generation in rare gases, driven by extremely short and highly intense pulses from free-electron-laser oscillators. For this purpose, it has been planned that a new photocathode RF gun, dedicated to high-bunch-charge [...] Read more.

A project is underway that aims to generate attosecond pulses via high-harmonic generation in rare gases, driven by extremely short and highly intense pulses from free-electron-laser oscillators. For this purpose, it has been planned that a new photocathode RF gun, dedicated to high-bunch-charge operation, will be installed at the KU-FEL (Kyoto University Free Electron Laser) oscillator facility. In this study, RF guns with two different structures (1.6-cell and 1.4-cell) were compared, from the perspective of exploring the possibility of introducing bunch-interval modulation, which is important for achieving high extraction efficiency in the FEL oscillator. As a result, it was confirmed that the introduction of bunch-phase modulation would be possible only in the case of the 1.6-cell RF gun. After the structure of the RF gun was decided on, particle-tracking simulations were performed, to study the electron-beam parameters using the 1.6-cell RF gun and 1 nC bunch charge. The results showed that we could obtain the peak current of 1 kA without a large degradation of the other parameters. Full article

(This article belongs to the Special Issue Generation and Application of High-Power Radiation Sources)

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16 pages, 2302 KiB

Open AccessArticle

Toward the System Size Dependence of Anisotropic Flow in Heavy-Ion Collisions at

\sqrt{s_{N N}}

= 2–5 GeV

by Mikhail Mamaev and Arkadiy Taranenko

Particles 2023, 6(2), 622-637; https://doi.org/10.3390/particles6020036 - 02 Jun 2023

Viewed by 1141

Abstract

The study of the high-density equation of state (EOS) and the search for a possible phase transition in dense baryonic matter is the main goal of beam energy scan programs with relativistic heavy ions at energies

\sqrt{s_{N N}}

= 2–5 GeV. The [...] Read more.

The study of the high-density equation of state (EOS) and the search for a possible phase transition in dense baryonic matter is the main goal of beam energy scan programs with relativistic heavy ions at energies

\sqrt{s_{N N}}

= 2–5 GeV. The most stringent constraints currently available on the high-density EOS of symmetric nuclear matter come from the present measurements of directed (

v_{1}

) and elliptic flow (

v_{2}

) signals of protons in Au + Au collisions. In this energy range, the anisotropic flow is strongly affected by the presence of cold spectators due to the sizable passage time. The system size dependence of anisotropic flow may help to study the participant–spectator contribution and improve our knowledge of the EOS of symmetric nuclear matter. In this work, we discuss the layout of the upgraded BM@N experiment and the anticipated performance for differential anisotropic flow measurements of identified hadrons at Nuclotron energies:

\sqrt{s_{N N}}

= 2.3–3.5 GeV. Full article

(This article belongs to the Special Issue Selected Papers from "Physics Performance Studies at FAIR and NICA")

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11 pages, 426 KiB

Open AccessArticle

Testing the Paradigm of Nuclear Many-Body Theory

by Omar Benhar

Particles 2023, 6(2), 611-621; https://doi.org/10.3390/particles6020035 - 31 May 2023

Cited by 5 | Viewed by 1042

Abstract

Nuclear many-body theory is based on the tenet that nuclear systems can be accurately described as collections of point-like particles. This picture, while providing a remarkably accurate explanation of a wealth of measured properties of atomic nuclei, is bound to break down in [...] Read more.

Nuclear many-body theory is based on the tenet that nuclear systems can be accurately described as collections of point-like particles. This picture, while providing a remarkably accurate explanation of a wealth of measured properties of atomic nuclei, is bound to break down in the high-density regime, in which degrees of freedom other than protons and neutrons are expected to come into play. Valuable information on the validity of the description of dense nuclear matter in terms of nucleons, needed to firmly establish its limit of applicability, can be obtained from electron–nucleus scattering data at large momentum transfer and low energy transfer. The emergence of y-scaling in this kinematic region, unambiguously showing that the beam particles couple to high-momentum nucleons belonging to strongly correlated pairs, indicates that at densities as large as five times nuclear density—typical of the neutron star interior—nuclear matter largely behaves as a collection of nucleons. Full article

(This article belongs to the Special Issue 2022 Feature Papers by Particles’ Editorial Board Members)

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16 pages, 1272 KiB

Open AccessArticle

Parameters and Pulsation Constant of Cepheid

by Sergei V. Sinitsyn

Particles 2023, 6(2), 595-610; https://doi.org/10.3390/particles6020034 - 26 May 2023

Cited by 1 | Viewed by 1756

Abstract

The analysis of fifty empirical period-radius relations and forty-three empirical period-luminosity relations is performed for the Cepheids. It is found that most of these relations have significant systematic errors. A new metrological method is suggested to exclude these systematic errors using the new [...] Read more.

The analysis of fifty empirical period-radius relations and forty-three empirical period-luminosity relations is performed for the Cepheids. It is found that most of these relations have significant systematic errors. A new metrological method is suggested to exclude these systematic errors using the new empirical metrological relations and the empirical temperature scale of the various samples of the Cepheids. In this regard, the reliable relations between the mass, radius, effective surface temperature, luminosity, absolute magnitude on the one hand, and the pulsation period on the other hand, as well as the reliable dependence of the radius on the mass are determined for the Cepheids of types δ Cephei and δ Scuti from the Galaxy. These reliable relations permit us to accurately determine the empirical value of the pulsation constant for the Cepheids of both types for the first time. It is found that the pulsation constant very weakly depends on the pulsation period of the Cepheid, contrary to the known theoretical calculation. Hence, the Cepheids pulsate almost as a unified whole and homogeneous spherical body in wide ranges of a star’s mass and evolutionary state with an extremely inhomogeneous distribution of stellar substance over its volume. Therefore, it is first suggested that the pulsation of the Cepheid is, first of all, the pulsation of the almost unified whole and homogenous shell of its gravitational mass. This pulsation is triggered by well-known effects; for example, the local optical opacity of the stellar substance and overshooting, using the usual pulsation of the stellar substance. Full article

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15 pages, 3366 KiB

Open AccessReview

Mechanisms of Producing Primordial Black Holes and Their Evolution

by Maxim A. Krasnov and Valery V. Nikulin

Particles 2023, 6(2), 580-594; https://doi.org/10.3390/particles6020033 - 14 May 2023

Viewed by 1830

Abstract

Primordial black holes have become a highly intriguing and captivating field of study in cosmology due to their potential theoretical and observational significance. This review delves into a variety of mechanisms that could give rise to PBHs and explores various methods for examining [...] Read more.

Primordial black holes have become a highly intriguing and captivating field of study in cosmology due to their potential theoretical and observational significance. This review delves into a variety of mechanisms that could give rise to PBHs and explores various methods for examining their evolution through mass accretion. Full article

(This article belongs to the Special Issue Beyond the Standard Models in Particle Physics and Cosmology)

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12 pages, 1695 KiB

Open AccessArticle

Centrality Determination in Heavy-Ion Collisions Based on Monte-Carlo Sampling of Spectator Fragments

by Ilya Segal

Particles 2023, 6(2), 568-579; https://doi.org/10.3390/particles6020032 - 10 May 2023

Viewed by 1278

Abstract

The size and evolution of the matter created in a relativistic heavy-ion collision strongly depend on collision geometry, defined by centrality. Experimentally the centrality of collisions can be characterized by the measured multiplicities of the produced particles at midrapidity or by the energy [...] Read more.

The size and evolution of the matter created in a relativistic heavy-ion collision strongly depend on collision geometry, defined by centrality. Experimentally the centrality of collisions can be characterized by the measured multiplicities of the produced particles at midrapidity or by the energy measured in the forward rapidity region, which is sensitive to the spectator fragments. This serves as a proxy for the true collision centrality, as defined by the impact parameter in the models of collisions. In this work, the procedure for centrality determination based on Monte-Carlo sampling of spectator fragments has been proposed. The validity of the procedure has been checked using the fully reconstructed DCM-QGSM-SMM model events and published data from the NA61/SHINE experiment. Full article

(This article belongs to the Special Issue Selected Papers from "Physics Performance Studies at FAIR and NICA")

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12 pages, 1422 KiB

Open AccessArticle

The van der Waals Hexaquark Chemical Potential in Dense Stellar Matter

by Keith Andrew, Eric V. Steinfelds and Kristopher A. Andrew

Particles 2023, 6(2), 556-567; https://doi.org/10.3390/particles6020031 - 09 May 2023

Viewed by 1255

Abstract

We explore the chemical potential of a QCD-motivated van der Waals (VDW) phase change model for the six-quark color-singlet, strangeness S = −2 particle known as the hexaquark with quark content (uuddss). The hexaquark may have internal structure, indicated by short range correlations [...] Read more.

We explore the chemical potential of a QCD-motivated van der Waals (VDW) phase change model for the six-quark color-singlet, strangeness S = −2 particle known as the hexaquark with quark content (uuddss). The hexaquark may have internal structure, indicated by short range correlations that allow for non-color-singlet diquark and triquark configurations whose interactions will change the magnitude of the chemical potential. In the multicomponent VDW Equation of State (EoS), the quark-quark particle interaction terms are sensitive to the QCD color factor, causing the pairing of these terms to give different interaction strengths for their respective contributions to the chemical potential. This results in a critical temperature near 163 MeV for the color-singlet states and tens of MeV below this for various mixed diquark and triquark states. The VDW chemical potential is also sensitive to the number density, leading to chemical potential isotherms that exhibit spinodal extrema, which also depend upon the internal hexaquark configurations. These extrema determine regions of metastability for the mixed states near the critical point. We use this chemical potential with the chemical potential-modified TOV equations to investigate the properties of hexaquark formation in cold compact stellar cores in beta equilibrium. We find thresholds for hexaquark layers and changes in maximum mass values that are consistent with observations from high mass compact stellar objects such as PSR 09043 + 10 and GW 190814. In general, we find that the VDW-TOV model has an upper stability mass and radius bound for a chemical potential of 1340 MeV with a compactness of C~0.2. Full article

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10 pages, 1323 KiB

Open AccessArticle

Probing the Hot QCD Matter via Quarkonia at the Next-Generation Heavy-Ion Experiment at LHC

by Yuri Kharlov, Yeghishe Hambardzumyan and Antony Varlamov

Particles 2023, 6(2), 546-555; https://doi.org/10.3390/particles6020030 - 02 May 2023

Viewed by 1109

Abstract

Quarkonia represent one of the most valuable probes of the deconfined quark–gluon hot medium since the very first experimental studies with ultrarelativistic heavy-ion collisions. A significant step forward in characterizing the QCD matter via systematic studies of quarkonia production will be performed by [...] Read more.

Quarkonia represent one of the most valuable probes of the deconfined quark–gluon hot medium since the very first experimental studies with ultrarelativistic heavy-ion collisions. A significant step forward in characterizing the QCD matter via systematic studies of quarkonia production will be performed by the next-generation heavy-ion experiment ALICE 3, a successor of the ongoing ALICE experiment at the Large Hadron Collider. The new advanced detector of ALICE 3 will allow for exploring the production of S- and P-state quarkonia at high statistics, at low and moderate transverse momenta ranges. The performance of ALICE 3 for quarkonia measurements and the requirements for the detectors are discussed. Full article

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31 pages, 750 KiB

Open AccessReview

Several Topics on Transverse Momentum-Dependent Fragmentation Functions

by Kai-Bao Chen, Tianbo Liu, Yu-Kun Song and Shu-Yi Wei

Particles 2023, 6(2), 515-545; https://doi.org/10.3390/particles6020029 - 27 Apr 2023

Cited by 6 | Viewed by 1732

Abstract

The hadronization of a high-energy parton is described by fragmentation functions which are introduced through QCD factorizations. While the hadronization mechanism per se remains uknown, fragmentation functions can still be investigated qualitatively and quantitatively. The qualitative study mainly concentrates on extracting genuine features [...] Read more.

The hadronization of a high-energy parton is described by fragmentation functions which are introduced through QCD factorizations. While the hadronization mechanism per se remains uknown, fragmentation functions can still be investigated qualitatively and quantitatively. The qualitative study mainly concentrates on extracting genuine features based on the operator definition in quantum field theory. The quantitative research focuses on describing a variety of experimental data employing the fragmentation function given by the parameterizations or model calculations. With the foundation of the transverse-momentum-dependent factorization, the QCD evolution of leading twist transverse-momentum-dependent fragmentation functions has also been established. In addition, the universality of fragmentation functions has been proven, albeit model-dependently, so that it is possible to perform a global analysis of experimental data in different high-energy reactions. The collective efforts may eventually reveal important information hidden in the shadow of nonperturbative physics. This review covers the following topics: transverse-momentum-dependent factorization and the corresponding QCD evolution, spin-dependent fragmentation functions at leading and higher twists, several experimental measurements and corresponding phenomenological studies, and some model calculations. Full article

(This article belongs to the Special Issue Strong Interactions in the Standard Model: Massless Bosons to Compact Stars)

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18 pages, 1725 KiB

Open AccessArticle

Centrality Selection Effect on Elliptic Flow Measurements in Relativistic Heavy-Ion Collisions at NICA Energies

by Dim Idrisov, Petr Parfenov and Arkadiy Taranenko

Particles 2023, 6(2), 497-514; https://doi.org/10.3390/particles6020028 - 26 Apr 2023

Viewed by 1087

Abstract

The elliptic flow (

v_{2}

) of produced particles is one of the important observables sensitive to the transport properties of the strongly interacting matter created in relativistic heavy-ion collisions. Detailed differential measurements of

v_{2}

are also foreseen in the future [...] Read more.

The elliptic flow (

v_{2}

) of produced particles is one of the important observables sensitive to the transport properties of the strongly interacting matter created in relativistic heavy-ion collisions. Detailed differential measurements of

v_{2}

are also foreseen in the future Multi-Purpose Detector (MPD) experiment at the Nuclotron based Ion Collider fAcility (NICA) at collision energies

\sqrt{s_{N N}}

= 4–11 GeV. Elliptic flow strongly depends on collision geometry, defined by the impact parameter b. Usually b is an input to theoretical calculations and can be deduced from experimental observables in the final state using the centrality procedure. In this work, we investigate the influence of the choice of centrality procedure on the elliptic flow measurements at NICA energies. Full article

(This article belongs to the Special Issue Selected Papers from "Physics Performance Studies at FAIR and NICA")

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12 pages, 3201 KiB

Open AccessArticle

A Monte Carlo Study of Hyperon Production with the MPD and BM@N Experiments at NICA

by Alexander Zinchenko, Mikhail Kapishin, Viktar Kireyeu, Vadim Kolesnikov, Alexander Mudrokh, Dilyana Suvarieva, Veronika Vasendina and Dmitry Zinchenko

Particles 2023, 6(2), 485-496; https://doi.org/10.3390/particles6020027 - 18 Apr 2023

Viewed by 1048

Abstract

Study of the strangeness production in heavy-ion collisions is one of the most important parts of the physics program of the BM@N and MPD experiments at the NICA accelerator complex. With collision energies

\sqrt{s_{N N}}

of 2.3–3.3 GeV in the fixed target [...] Read more.

Study of the strangeness production in heavy-ion collisions is one of the most important parts of the physics program of the BM@N and MPD experiments at the NICA accelerator complex. With collision energies

\sqrt{s_{N N}}

of 2.3–3.3 GeV in the fixed target mode at BM@N and 4–11 GeV in the collider mode at MPD, the experiments will cover the region of the maximum net baryon density and provide high-statistics complementary data on different physics probes. In this paper, some results of Monte Carlo studies of hyperon production with the BM@N and MPD experiments are presented, demonstrating their performance for investigation of the objects with strangeness. Full article

(This article belongs to the Special Issue Selected Papers from "Physics Performance Studies at FAIR and NICA")

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15 pages, 6504 KiB

Open AccessArticle

Chaos in QCD? Gap Equations and Their Fractal Properties

by Thomas Klähn, Lee C. Loveridge and Mateusz Cierniak

Particles 2023, 6(2), 470-484; https://doi.org/10.3390/particles6020026 - 11 Apr 2023

Viewed by 1004

Abstract

In this study, we discuss how iterative solutions of QCD-inspired gap-equations at the finite chemical potential demonstrate domains of chaotic behavior as well as non-chaotic domains, which represent one or the other of the only two—usually distinct—positive mass gap solutions with broken or [...] Read more.

In this study, we discuss how iterative solutions of QCD-inspired gap-equations at the finite chemical potential demonstrate domains of chaotic behavior as well as non-chaotic domains, which represent one or the other of the only two—usually distinct—positive mass gap solutions with broken or restored chiral symmetry, respectively. In the iterative approach, gap solutions exist which exhibit restored chiral symmetry beyond a certain dynamical cut-off energy. A chirally broken, non-chaotic domain with no emergent mass poles and hence with no quasi-particle excitations exists below this energy cut-off. The transition domain between these two energy-separated domains is chaotic. As a result, the dispersion relation is that of quarks with restored chiral symmetry, cut at a dynamical energy scale, and determined by fractal structures. We argue that the chaotic origin of the infrared cut-off could hint at a chaotic nature of confinement and the deconfinement phase transition. Full article

(This article belongs to the Special Issue Strong Interactions in the Standard Model: Massless Bosons to Compact Stars)

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