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Hybrid Hadronization of Jet Showers from $e^++e^-$ to $A+A$ with JETSCAPE
Authors:
Cameron Parker,
Aaron Angerami,
Ritu Arora,
Steffen Bass,
Shanshan Cao,
Yi Chen,
Raymond Ehlers,
Hannah Elfner,
Wenkai Fan,
Rainer J. Fries,
Charles Gale,
Yayun He,
Ulrich Heinz,
Barbara Jacak,
Peter Jacobs,
Sangyong Jeon,
Yi Ji,
Lauren Kasper,
Michael Kordell II,
Amit Kumar,
Joseph Latessa,
Yen-Jie Lee,
Roy Lemmon,
Dananjaya Liyanage,
Arthur Lopez
, et al. (26 additional authors not shown)
Abstract:
In this talk we review jet production in a large variety of collision systems using the JETSCAPE event generator and Hybrid Hadronization. Hybrid Hadronization combines quark recombination, applicable when distances between partons in phase space are small, and string fragmentation appropriate for dilute parton systems. It can therefore smoothly describe the transition from very dilute parton syst…
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In this talk we review jet production in a large variety of collision systems using the JETSCAPE event generator and Hybrid Hadronization. Hybrid Hadronization combines quark recombination, applicable when distances between partons in phase space are small, and string fragmentation appropriate for dilute parton systems. It can therefore smoothly describe the transition from very dilute parton systems like $e^++e^-$ to full $A+A$ collisions. We test this picture by using JETSCAPE to generate jets in various systems. Comparison to experimental data in $e^++e^-$ and $p+p$ collisions allows for a precise tuning of vacuum baseline parameters in JETSCAPE and Hybrid Hadronization. Proceeding to systems with jets embedded in a medium, we study in-medium hadronization for jet showers. We quantify the effects of an ambient medium, focusing in particular on the dependence on the collective flow and size of the medium. Our results clarify the effects we expect from in-medium hadronization of jets on observables like fragmentation functions, hadron chemistry and jet shape.
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Submitted 7 November, 2023; v1 submitted 31 October, 2023;
originally announced October 2023.
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A multistage framework for studying the evolution of jets and high-$p_T$ probes in small collision systems
Authors:
Abhijit Majumder,
Aaron Angerami,
Ritu Arora,
Steffen Bass,
Shanshan Cao,
Yi Chen,
Raymond Ehlers,
Hannah Elfner,
Wenkai Fan,
Rainer J. Fries,
Charles Gale,
Yayun He,
Ulrich Heinz,
Barbara Jacak,
Peter Jacobs,
Sangyong Jeon,
Yi Ji,
Lauren Kasper,
Michael Kordell II,
Amit Kumar,
Joseph Latessa,
Yen-Jie Lee,
Roy Lemmon,
Dananjaya Liyanage,
Arthur Lopez
, et al. (26 additional authors not shown)
Abstract:
Understanding the modification of jets and high-$p_T$ probes in small systems requires the integration of soft and hard physics. We present recent developments in extending the JETSCAPE framework to build an event generator, which includes correlations between soft and hard partons, to study jet observables in small systems. The multi-scale physics of the collision is separated into different stag…
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Understanding the modification of jets and high-$p_T$ probes in small systems requires the integration of soft and hard physics. We present recent developments in extending the JETSCAPE framework to build an event generator, which includes correlations between soft and hard partons, to study jet observables in small systems. The multi-scale physics of the collision is separated into different stages. Hard scatterings are first sampled at binary collision positions provided by the Glauber geometry. They are then propagated backward in space-time following an initial-state shower to obtain the initiating partons' energies and momenta before the collision. These energies and momenta are then subtracted from the incoming colliding nucleons for soft-particle production, modeled by the 3D-Glauber + hydrodynamics + hadronic transport framework. This new hybrid approach (X-SCAPE) includes non-trivial correlations between jet and soft particle productions in small systems. We calibrate this framework with the final state hadrons' $p_T$-spectra from low to high $p_T$ in $p$-$p$, and and then compare with the spectra in $p$-$Pb$ collisions from the LHC. We also present results for additional observables such as the distributions of event activity as a function of the hardest jet $p_T$ in forward and mid-rapidity for both $p$-$p$ and $p$-$Pb$ collisions.
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Submitted 1 November, 2023; v1 submitted 4 August, 2023;
originally announced August 2023.
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A new metric improving Bayesian calibration of a multistage approach studying hadron and inclusive jet suppression
Authors:
W. Fan,
G. Vujanovic,
S. A. Bass,
A. Angerami,
R. Arora,
S. Cao,
Y. Chen,
T. Dai,
L. Du,
R. Ehlers,
H. Elfner,
R. J. Fries,
C. Gale,
Y. He,
M. Heffernan,
U. Heinz,
B. V. Jacak,
P. M. Jacobs,
S. Jeon,
Y. Ji,
L. Kasper,
M. Kordell II,
A. Kumar,
J. Latessa,
Y. -J. Lee
, et al. (30 additional authors not shown)
Abstract:
We study parton energy-momentum exchange with the quark gluon plasma (QGP) within a multistage approach composed of in-medium DGLAP evolution at high virtuality, and (linearized) Boltzmann Transport formalism at lower virtuality. This multistage simulation is then calibrated in comparison with high $p_T$ charged hadrons, D-mesons, and the inclusive jet nuclear modification factors, using Bayesian…
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We study parton energy-momentum exchange with the quark gluon plasma (QGP) within a multistage approach composed of in-medium DGLAP evolution at high virtuality, and (linearized) Boltzmann Transport formalism at lower virtuality. This multistage simulation is then calibrated in comparison with high $p_T$ charged hadrons, D-mesons, and the inclusive jet nuclear modification factors, using Bayesian model-to-data comparison, to extract the virtuality-dependent transverse momentum broadening transport coefficient $\hat{q}$. To facilitate this undertaking, we develop a quantitative metric for validating the Bayesian workflow, which is used to analyze the sensitivity of various model parameters to individual observables. The usefulness of this new metric in improving Bayesian model emulation is shown to be highly beneficial for future such analyses.
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Submitted 27 October, 2023; v1 submitted 18 July, 2023;
originally announced July 2023.
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Multiscale evolution of heavy flavor in the QGP
Authors:
G. Vujanovic,
A. Angerami,
R. Arora,
S. A. Bass,
S. Cao,
Y. Chen,
T. Dai,
L. Du,
R. Ehlers,
H. Elfner,
W. Fan,
R. J. Fries,
C. Gale,
Y. He,
M. Heffernan,
U. Heinz,
B. V. Jacak,
P. M. Jacobs,
S. Jeon,
Y. Ji,
L. Kasper,
M. Kordell II,
A. Kumar,
J. Latessa,
Y. -J. Lee
, et al. (30 additional authors not shown)
Abstract:
Shower development dynamics for a jet traveling through the quark-gluon plasma (QGP) is a multiscale process, where the heavy flavor mass is an important scale. During the high virtuality portion of the jet evolution in the QGP, emission of gluons from a heavy flavor is modified owing to heavy quark mass. Medium-induced radiation of heavy flavor is sensitive to microscopic processes (e.g. diffusio…
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Shower development dynamics for a jet traveling through the quark-gluon plasma (QGP) is a multiscale process, where the heavy flavor mass is an important scale. During the high virtuality portion of the jet evolution in the QGP, emission of gluons from a heavy flavor is modified owing to heavy quark mass. Medium-induced radiation of heavy flavor is sensitive to microscopic processes (e.g. diffusion), whose virtuality dependence is phenomenologically explored in this study. In the lower virtuality part of shower evolution, i.e. when the mass is comparable to the virtuality of the parton, scattering and radiation processes of heavy quarks differ from light quarks. The effects of these mechanisms on shower development in heavy flavor tagged showers in the QGP is explored here. Furthermore, this multiscale study examines dynamical pair production of heavy flavor (via virtual gluon splittings) and their subsequent evolution in the QGP, which is not possible otherwise. A realistic event-by-event simulation is performed using the JETSCAPE framework. Energy-momentum exchange with the medium proceeds using a weak coupling recoil approach. Using leading hadron and open heavy flavor observables, differences in heavy versus light quark energy-loss mechanisms are explored, while the importance of heavy flavor pair production is highlighted along with future directions to study.
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Submitted 27 October, 2023; v1 submitted 18 July, 2023;
originally announced July 2023.
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Effects of multi-scale jet-medium interactions on jet substructures
Authors:
JETSCAPE Collaboration,
Y. Tachibana,
A. Angerami,
R. Arora,
S. A. Bass,
S. Cao,
Y. Chen,
T. Dai,
L. Du,
R. Ehlers,
H. Elfner,
W. Fan,
R. J. Fries,
C. Gale,
Y. He,
M. Heffernan,
U. Heinz,
B. V. Jacak,
P. M. Jacobs,
S. Jeon,
Y. Ji,
K. Kauder,
L. Kasper,
W. Ke,
M. Kelsey
, et al. (35 additional authors not shown)
Abstract:
We utilize event-by-event Monte Carlo simulations within the JETSCAPE framework to examine scale-dependent jet-medium interactions in heavy-ion collisions. The reduction in jet-medium interaction during the early high-virtuality stage, where the medium is resolved at a short distance scale, is emphasized as a key element in explaining multiple jet observables, particularly substructures, simultane…
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We utilize event-by-event Monte Carlo simulations within the JETSCAPE framework to examine scale-dependent jet-medium interactions in heavy-ion collisions. The reduction in jet-medium interaction during the early high-virtuality stage, where the medium is resolved at a short distance scale, is emphasized as a key element in explaining multiple jet observables, particularly substructures, simultaneously. By employing the MATTER+LBT setup, which incorporates this explicit reduction of medium effects at high virtuality, we investigate jet substructure observables, such as Soft Drop groomed observables. When contrasted with existing data, our findings spotlight the significant influence of the reduction at the early high-virtuality stages. Furthermore, we study the substructure of gamma-tagged jets, providing predictive insights for future experimental analyses. This broadens our understanding of the various contributing factors involved in modifying jet substructures.
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Submitted 16 July, 2023;
originally announced July 2023.
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Hard jet substructure in a multistage approach
Authors:
Y. Tachibana,
A. Kumar,
A. Majumder,
A. Angerami,
R. Arora,
S. A. Bass,
S. Cao,
Y. Chen,
T. Dai,
L. Du,
R. Ehlers,
H. Elfner,
W. Fan,
R. J. Fries,
C. Gale,
Y. He,
M. Heffernan,
U. Heinz,
B. V. Jacak,
P. M. Jacobs,
S. Jeon,
Y. Ji,
K. Kauder,
L. Kasper,
W. Ke
, et al. (34 additional authors not shown)
Abstract:
We present predictions and postdictions for a wide variety of hard jet-substructure observables using a multistage model within the JETSCAPE framework. The details of the multistage model and the various parameter choices are described in [A. Kumar et al., arXiv:2204.01163]. A novel feature of this model is the presence of two stages of jet modification: a high virtuality phase [modeled using the…
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We present predictions and postdictions for a wide variety of hard jet-substructure observables using a multistage model within the JETSCAPE framework. The details of the multistage model and the various parameter choices are described in [A. Kumar et al., arXiv:2204.01163]. A novel feature of this model is the presence of two stages of jet modification: a high virtuality phase [modeled using the modular all twist transverse-scattering elastic-drag and radiation model (MATTER)], where modified coherence effects diminish medium-induced radiation, and a lower virtuality phase [modeled using the linear Boltzmann transport model (LBT)], where parton splits are fully resolved by the medium as they endure multiple scattering induced energy loss. Energy-loss calculations are carried out on event-by-event viscous fluid dynamic backgrounds constrained by experimental data. The uniform and consistent descriptions of multiple experimental observables demonstrate the essential role of modified coherence effects and the multistage modeling of jet evolution. Using the best choice of parameters from [A. Kumar et al., arXiv:2204.01163], and with no further tuning, we present calculations for the medium modified jet fragmentation function, the groomed jet momentum fraction $z_g$ and angular separation $r_g$ distributions, as well as the nuclear modification factor of groomed jets. These calculations provide accurate descriptions of published data from experiments at the Large Hadron Collider. Furthermore, we provide predictions from the multistage model for future measurements at the BNL Relativistic Heavy Ion Collider.
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Submitted 16 October, 2024; v1 submitted 6 January, 2023;
originally announced January 2023.
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Comprehensive Study of Multi-scale Jet-medium Interaction
Authors:
Y. Tachibana,
A. Angerami,
R. Arora,
S. A. Bass,
S. Cao,
Y. Chen,
T. Dai,
L. Du,
R. Ehlers,
H. Elfner,
W. Fan,
R. J. Fries,
C. Gale,
Y. He,
M. Heffernan,
U. Heinz,
B. V. Jacak,
P. M. Jacobs,
S. Jeon,
Y. Ji,
L. Kasper,
W. Ke,
M. Kelsey,
M. Kordell II,
A. Kumar
, et al. (33 additional authors not shown)
Abstract:
We explore jet-medium interactions at various scales in high-energy heavy-ion collisions using the JETSCAPE framework. The physics of the multi-stage modeling and the coherence effect at high virtuality is discussed through the results of multiple jet and high-$p_{\mathrm{T}}$ particle observables, compared with experimental data. Furthermore, we investigate the jet-medium interaction involved in…
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We explore jet-medium interactions at various scales in high-energy heavy-ion collisions using the JETSCAPE framework. The physics of the multi-stage modeling and the coherence effect at high virtuality is discussed through the results of multiple jet and high-$p_{\mathrm{T}}$ particle observables, compared with experimental data. Furthermore, we investigate the jet-medium interaction involved in the hadronization process.
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Submitted 23 December, 2022;
originally announced December 2022.
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Bayesian analysis of QGP jet transport using multi-scale modeling applied to inclusive hadron and reconstructed jet data
Authors:
R. Ehlers,
A. Angerami,
R. Arora,
S. A. Bass,
S. Cao,
Y. Chen,
L. Du,
T. Dai,
H. Elfner,
W. Fan,
R. J. Fries,
C. Gale,
Y. He,
M. Heffernan,
U. Heinz,
B. V. Jacak,
P. M. Jacobs,
S. Jeon,
Y. Ji,
L. Kasper,
W. Ke,
M. Kelsey,
M. Kordell II,
A. Kumar,
J. Latessa
, et al. (33 additional authors not shown)
Abstract:
The JETSCAPE Collaboration reports a new determination of jet transport coefficients in the Quark-Gluon Plasma, using both reconstructed jet and hadron data measured at RHIC and the LHC. The JETSCAPE framework incorporates detailed modeling of the dynamical evolution of the QGP; a multi-stage theoretical approach to in-medium jet evolution and medium response; and Bayesian inference for quantitati…
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The JETSCAPE Collaboration reports a new determination of jet transport coefficients in the Quark-Gluon Plasma, using both reconstructed jet and hadron data measured at RHIC and the LHC. The JETSCAPE framework incorporates detailed modeling of the dynamical evolution of the QGP; a multi-stage theoretical approach to in-medium jet evolution and medium response; and Bayesian inference for quantitative comparison of model calculations and data. The multi-stage framework incorporates multiple models to cover a broad range in scale of the in-medium parton shower evolution, with dynamical choice of model that depends on the current virtuality or energy of the parton.
We will discuss the physics of the multi-stage modeling, and then present a new Bayesian analysis incorporating it. This analysis extends the recently published JETSCAPE determination of the jet transport parameter $\hat{q}$ that was based solely on inclusive hadron suppression data, by incorporating reconstructed jet measurements of quenching. We explore the functional dependence of jet transport coefficients on QGP temperature and jet energy and virtuality, and report the consistency and tensions found for current jet quenching modeling with hadron and reconstructed jet data over a wide range in kinematics and $\sqrt{s_{\text{NN}}}$. This analysis represents the next step in the program of comprehensive analysis of jet quenching phenomenology and its constraint of properties of the QGP.
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Submitted 16 August, 2022;
originally announced August 2022.
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Origin of Plutonium-244 in the Early Solar System
Authors:
Maria Lugaro,
Andrés Yagüe López,
Benjámin Soós,
Benoit Côté,
Mária Pető,
Nicole Vassh,
Benjamin Wehmeyer,
Marco Pignatari
Abstract:
We investigate the origin in the early Solar System of the short-lived radionuclide 244Pu (with a half life of 80 Myr) produced by the rapid (r) neutron-capture process. We consider two large sets of r-process nucleosynthesis models and analyse if the origin of 244Pu in the ESS is consistent with that of the other r and slow (s) neutron-capture process radioactive nuclei. Uncertainties on the r-pr…
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We investigate the origin in the early Solar System of the short-lived radionuclide 244Pu (with a half life of 80 Myr) produced by the rapid (r) neutron-capture process. We consider two large sets of r-process nucleosynthesis models and analyse if the origin of 244Pu in the ESS is consistent with that of the other r and slow (s) neutron-capture process radioactive nuclei. Uncertainties on the r-process models come from both the nuclear physics input and the astrophysical site. The former strongly affects the ratios of isotopes of close mass (129I/127I, 244Pu/238U, and 247Pu/235U). The 129I/247Cm ratio, instead, which involves isotopes of a very different mass, is much more variable than those listed above and is more affected by the physics of the astrophysical site. We consider possible scenarios for the evolution of the abundances of these radioactive nuclei in the galactic interstellar medium and verify under which scenarios and conditions solutions can be found for the origin of 244Pu that are consistent with the origin of the other isotopes. Solutions are generally found for all the possible different regimes controlled by the interval ($δ$) between additions from the source to the parcel of interstellar medium gas that ended up in the Solar System, relative to decay timescales. If r-process ejecta in interstellar medium are mixed within a relatively small area (leading to a long $δ$), we derive that the last event that explains the 129I and 247Cm abundances in the early Solar System can also account for the abundance of 244Pu. Due to its longer half life, however, 244Pu may have originated from a few events instead of one only. If r-process ejecta in interstellar medium are mixed within a relatively large area (leading to a short $δ$), we derive that the time elapsed from the formation of the molecular cloud to the formation of the Sun was 9-16 Myr.
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Submitted 3 August, 2022;
originally announced August 2022.
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Multi-scale evolution of charmed particles in a nuclear medium
Authors:
JETSCAPE collaboration,
W. Fan,
G. Vujanovic,
S. A. Bass,
A. Majumder,
A. Angerami,
R. Arora,
S. Cao,
Y. Chen,
T. Dai,
L. Du,
R. Ehlers,
H. Elfner,
R. J. Fries,
C. Gale,
Y. He,
M. Heffernan,
U. Heinz,
B. V. Jacak,
P. M. Jacobs,
S. Jeon,
Y. Ji,
K. Kauder,
L. Kasper,
W. Ke
, et al. (35 additional authors not shown)
Abstract:
Parton energy-momentum exchange with the quark gluon plasma (QGP) is a multi-scale problem. In this work, we calculate the interaction of charm quarks with the QGP within the higher twist formalism at high virtuality and high energy using the MATTER model, while the low virtuality and high energy portion is treated via a (linearized) Boltzmann Transport (LBT) formalism. Coherence effect that reduc…
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Parton energy-momentum exchange with the quark gluon plasma (QGP) is a multi-scale problem. In this work, we calculate the interaction of charm quarks with the QGP within the higher twist formalism at high virtuality and high energy using the MATTER model, while the low virtuality and high energy portion is treated via a (linearized) Boltzmann Transport (LBT) formalism. Coherence effect that reduces the medium-induced emission rate in the MATTER model is also taken into account. The interplay between these two formalisms is studied in detail and used to produce a good description of the D-meson and charged hadron nuclear modification factor RAA across multiple centralities. All calculations were carried out utilizing the JETSCAPE framework.
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Submitted 13 May, 2023; v1 submitted 1 August, 2022;
originally announced August 2022.
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Inclusive jet and hadron suppression in a multistage approach
Authors:
A. Kumar,
Y. Tachibana,
C. Sirimanna,
G. Vujanovic,
S. Cao,
A. Majumder,
Y. Chen,
L. Du,
R. Ehlers,
D. Everett,
W. Fan,
Y. He,
J. Mulligan,
C. Park,
A. Angerami,
R. Arora,
S. A. Bass,
T. Dai,
H. Elfner,
R. J. Fries,
C. Gale,
F. Garza,
M. Heffernan,
U. Heinz,
B. V. Jacak
, et al. (35 additional authors not shown)
Abstract:
We present a new study of jet interactions in the quark-gluon plasma created in high-energy heavy-ion collisions, using a multistage event generator within the JETSCAPE framework. We focus on medium-induced modifications in the rate of inclusive jets and high transverse momentum (high-$p_{\mathrm{T}}$) hadrons. Scattering-induced jet energy loss is calculated in two stages: A high virtuality stage…
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We present a new study of jet interactions in the quark-gluon plasma created in high-energy heavy-ion collisions, using a multistage event generator within the JETSCAPE framework. We focus on medium-induced modifications in the rate of inclusive jets and high transverse momentum (high-$p_{\mathrm{T}}$) hadrons. Scattering-induced jet energy loss is calculated in two stages: A high virtuality stage based on the MATTER model, in which scattering of highly virtual partons modifies the vacuum radiation pattern, and a second stage at lower jet virtuality based on the LBT model, in which leading partons gain and lose virtuality by scattering and radiation. Coherence effects that reduce the medium-induced emission rate in the MATTER phase are also included. The TRENTo model is used for initial conditions, and the (2+1)dimensional VISHNU model is used for viscous hydrodynamic evolution. Jet interactions with the medium are modeled via 2-to-2 scattering with Debye screened potentials, in which the recoiling partons are tracked, hadronized, and included in the jet clustering. Holes left in the medium are also tracked and subtracted to conserve transverse momentum. Calculations of the nuclear modification factor ($R_{\mathrm{AA}}$) for inclusive jets and high-$p_{\mathrm{T}}$ hadrons are compared to experimental measurements at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). Within this framework, we find that with one extra parameter which codifies the transition between stages of jet modification -- along with the typical parameters such as the coupling in the medium, the start and stop criteria etc. -- we can describe these data at all energies for central and semicentral collisions without a rescaling of the jet transport coefficient $\hat{q}$.
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Submitted 16 April, 2023; v1 submitted 3 April, 2022;
originally announced April 2022.
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Role of bulk viscosity in deuteron production in ultrarelativistic nuclear collisions
Authors:
D. Everett,
D. Oliinychenko,
M. Luzum,
J. -F. Paquet,
G. Vujanovic,
S. A. Bass,
L. Du,
C. Gale,
M. Heffernan,
U. Heinz,
L. Kasper,
W. Ke,
D. Liyanage,
A. Majumder,
A. Mankolli,
C. Shen,
D. Soeder,
J. Velkovska,
A. Angerami,
R. Arora,
S. Cao,
Y. Chen,
T. Dai,
R. Ehlers,
H. Elfner
, et al. (31 additional authors not shown)
Abstract:
We use a Bayesian-calibrated multistage viscous hydrodynamic model to explore deuteron yield, mean transverse momentum and flow observables in LHC Pb-Pb collisions. We explore theoretical uncertainty in the production of deuterons, including (i) the contribution of thermal deuterons, (ii) models for the subsequent formation of deuterons (hadronic transport vs coalescence) and (iii) the overall sen…
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We use a Bayesian-calibrated multistage viscous hydrodynamic model to explore deuteron yield, mean transverse momentum and flow observables in LHC Pb-Pb collisions. We explore theoretical uncertainty in the production of deuterons, including (i) the contribution of thermal deuterons, (ii) models for the subsequent formation of deuterons (hadronic transport vs coalescence) and (iii) the overall sensitivity of the results to the hydrodynamic model -- in particular to bulk viscosity, which is often neglected in studies of deuteron production. Using physical parameters set by a comparison to only light hadron observables, we find good agreement with measurements of the mean transverse momentum $\langle p_T \rangle$ and elliptic flow $v_2$ of deuterons; however, tension is observed with experimental data for the deuteron multiplicity in central collisions. The results are found to be sensitive to each of the mentioned theoretical uncertainties, with a particular sensitivity to bulk viscosity, indicating that the latter is an important ingredient for an accurate treatment of deuteron production.
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Submitted 15 March, 2022;
originally announced March 2022.
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The Radioactive Nuclei $^{\textbf{26}}$Al and $^{\textbf{60}}$Fe in the Cosmos and in the Solar System
Authors:
Roland Diehl,
Maria Lugaro,
Alexander Heger,
Andre Sieverding,
Xiaodong Tang,
KuoAng Li,
Ertao Li,
Carolyn L. Doherty,
Martin G. H. Krause,
Anton Wallner,
Nikos Prantzos,
Hannah E. Brinkman,
Jaqueline W. den Hartogh,
Benjamin Wehmeyer,
Andrés Yagüe López,
Moritz M. M. Pleintinger,
Projjval Banerjee,
Wei Wang
Abstract:
The cosmic evolution of the chemical elements from the Big Bang to the present time is driven by nuclear fusion reactions inside stars and stellar explosions. A cycle of matter recurrently re-processes metal-enriched stellar ejecta into the next generation of stars. The study of cosmic nucleosynthesis and of this matter cycle requires the understanding of the physics of nuclear reactions, of the c…
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The cosmic evolution of the chemical elements from the Big Bang to the present time is driven by nuclear fusion reactions inside stars and stellar explosions. A cycle of matter recurrently re-processes metal-enriched stellar ejecta into the next generation of stars. The study of cosmic nucleosynthesis and of this matter cycle requires the understanding of the physics of nuclear reactions, of the conditions at which the nuclear reactions are activated inside the stars and stellar explosions, of the stellar ejection mechanisms through winds and explosions, and of the transport of the ejecta towards the next cycle, from hot plasma to cold, star-forming gas. Due to the long timescales of stellar evolution, and because of the infrequent occurrence of stellar explosions, observational studies are challenging. Due to their radioactive lifetime of million years, the 26Al and 60Fe isotopes are suitable to characterise simultaneously the processes of nuclear fusion reactions and of interstellar transport. We describe and discuss the nuclear reactions involved in the production and destruction of 26Al and 60Fe, the key characteristics of the stellar sites of their nucleosynthesis and their interstellar journey after ejection from the nucleosynthesis sites. We connect the theoretical astrophysical aspects to the variety of astronomical messengers, from stardust and cosmic-ray composition measurements, through observation of gamma rays produced by radioactivity, to material deposited in deep-sea ocean crusts and to the inferred composition of the first solids that have formed in the Solar System. We show that considering measurements of the isotopic ratio of 26Al to 60Fe eliminate some of the unknowns when interpreting astronomical results, and discuss the lessons learned from these two isotopes on cosmic chemical evolution.
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Submitted 5 October, 2021; v1 submitted 17 September, 2021;
originally announced September 2021.
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Equilibrium constants of nuclear reactions in supernova explosions
Authors:
Jorge A. Muñoz,
Marcos A. García,
Jorge A. López
Abstract:
We study the change in internal rotational energy in the transformation of protons to neutrons in the \b{eta}-decay reactions that take place in the collapse of the iron core of massive stars that precede type II supernova explosions. We consider an ensemble of electrons, protons, neutrons and neutrinos undergoing \b{eta}-decay reactions, treat the protons and neutrons as triatomic rotors, evaluat…
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We study the change in internal rotational energy in the transformation of protons to neutrons in the \b{eta}-decay reactions that take place in the collapse of the iron core of massive stars that precede type II supernova explosions. We consider an ensemble of electrons, protons, neutrons and neutrinos undergoing \b{eta}-decay reactions, treat the protons and neutrons as triatomic rotors, evaluate the equilibrium constant to obtain the change in rotational energy during the proton-to-neutron transformation. We estimate such change for a variety of conditions, and compare to the energy released in a supernova explosion.
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Submitted 4 April, 2021;
originally announced April 2021.
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Properties of nuclear pastas
Authors:
Jorge A. Lopez,
Claudio O. Dorso,
Guillermo A. Frank
Abstract:
In this Review we study the nuclear pastas as they are expected to be formed in neutron star cores. We start with a study of the pastas formed in nuclear matter (composed of protons and neutrons), we follow with the role of the electron gas on the formation of pastas, and we then investigate the pastas in neutron star matter (nuclear matter embedded in an electron gas).
In this Review we study the nuclear pastas as they are expected to be formed in neutron star cores. We start with a study of the pastas formed in nuclear matter (composed of protons and neutrons), we follow with the role of the electron gas on the formation of pastas, and we then investigate the pastas in neutron star matter (nuclear matter embedded in an electron gas).
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Submitted 14 July, 2020;
originally announced July 2020.
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Symmetry energy in neutron star matter
Authors:
Claudio O. Dorso,
Guillermo A. Frank,
Jorge A. Lopez
Abstract:
We investigate the structure attained by neutron star matter with proton to neutron ratios ranging from x=0.1 to 0.5, densities in the range of 0.02 fm-3 to 0.085 fm-3, and temperatures T<4 MeV. In particular we study the pasta shapes and the phase changes previously observed in nuclear matter, as well as the behavior of the symmetry energy. We corroborate the existence of homogeneous to non-homog…
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We investigate the structure attained by neutron star matter with proton to neutron ratios ranging from x=0.1 to 0.5, densities in the range of 0.02 fm-3 to 0.085 fm-3, and temperatures T<4 MeV. In particular we study the pasta shapes and the phase changes previously observed in nuclear matter, as well as the behavior of the symmetry energy. We corroborate the existence of homogeneous to non-homogeneous phase transitions, and the different values of the symmetry energy at different densities and temperatures.
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Submitted 10 September, 2018;
originally announced September 2018.
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Phase transitions and symmetry energy in nuclear pasta
Authors:
C. O. Dorso,
G. A. Frank,
J. A. López
Abstract:
Cold and isospin-symmetric nuclear matter at sub-saturation densities is known to form the so-called pasta structures, which, in turn, are known to undergo peculiar phase transitions. Here we investigate if such pastas and their phase changes survive in isospin asymmetric nuclear matter, and whether the symmetry energy of such pasta configurations is connected to the isospin content, the morpholog…
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Cold and isospin-symmetric nuclear matter at sub-saturation densities is known to form the so-called pasta structures, which, in turn, are known to undergo peculiar phase transitions. Here we investigate if such pastas and their phase changes survive in isospin asymmetric nuclear matter, and whether the symmetry energy of such pasta configurations is connected to the isospin content, the morphology of the pasta and to the phase transitions. We find that indeed pastas are formed in isospin asymmetric systems with proton to neutron ratios of x=0.3, 0.4 and 0.5, densities in the range of 0.05 1/fm$^3$<$ρ$< 0.08 1/fm$^3$, and temperatures T<2 MeV. Using tools (such as the caloric curve, Lindemann coefficient, radial distribution function, Kolmogorov statistic, and Euler functional) on the composition of the pasta, determined the existence of homogeneous structures, tunnels, empty regions, cavities and transitions among these regions. The symmetry energy was observed to attain different values in the different phases showing its dependence on the morphology of the nuclear matter structure.
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Submitted 23 March, 2018;
originally announced March 2018.
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Isospin-asymmetric nuclear matter
Authors:
J. A. López,
E. Ramírez-Homs,
R. González,
R. Ravelo
Abstract:
This study uses classical molecular dynamics to simulate infinite nuclear matter and study the effect of isospin asymmetry on bulk properties such as energy per nucleon, pressure, saturation density, compressibility and symmetry energy. The simulations are performed on systems embedded in periodic boundary conditions with densities and temperatures in the ranges $ρ$=0.02 to 0.2 fm$^{-3}$ and T = 1…
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This study uses classical molecular dynamics to simulate infinite nuclear matter and study the effect of isospin asymmetry on bulk properties such as energy per nucleon, pressure, saturation density, compressibility and symmetry energy. The simulations are performed on systems embedded in periodic boundary conditions with densities and temperatures in the ranges $ρ$=0.02 to 0.2 fm$^{-3}$ and T = 1, 2, 3, 4 and 5 MeV, and with isospin content of $x=Z/A$=0.3, 0.4 and 0.5. The results indicate that symmetric and asymmetric matter are self-bound at some temperatures and exhibit phase transitions from a liquid phase to a liquid-gas mixture. The main effect of isospin asymmetry is found to be a reduction of the equilibrium densities, a softening of the compressibility and a disappearance of the liquid-gas phase transition. A procedure leading to the evaluation of the symmetry energy and its variation with the temperature was devised, implemented and compared to mean field theory results.
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Submitted 31 January, 2014; v1 submitted 24 November, 2013;
originally announced November 2013.
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Probing the statistical decay and alpha-clustering effects in 12c+12c and 14n+10b reactions
Authors:
Luca Morelli,
G. Baiocco,
M. D Agostino,
M. Bruno,
F. Gulminelli,
M. Cinausero,
M. Degerlier,
D. Fabris,
F. Gramegna,
T. Marchi,
S. Barlini,
M. Bini,
G. Casini,
N. Gelli,
A. Lopez,
G. Pasquali,
S. Piantelli,
S. Valdre'
Abstract:
An experimental campaign has been undertaken at INFN Laboratori Nazionali di Legnaro, Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. A first reaction 12C+12C at 7.9 AMeV beam energy has been measured, using the GARFIELD+Ring Counte…
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An experimental campaign has been undertaken at INFN Laboratori Nazionali di Legnaro, Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. A first reaction 12C+12C at 7.9 AMeV beam energy has been measured, using the GARFIELD+Ring Counter experimental setup. Fusion-evaporation events have been exclusively selected. The comparison to a dedicated Hauser-Feshbach calculation allows us to give constraints on the nuclear level density at high excitation energy for light systems ranging from C up to Mg. Out-of-equilibrium emission has been evidenced and attributed both to entrance channel effects favoured by the cluster nature of reaction partners and, in more dissipative events, to the persistence of cluster correlations well above the 24Mg threshold for 6 alphas decay. The 24Mg compound nucleus has been studied with a new measurement 14N + 10B at 5.7 AMeV. The comparison between the two datasets would allow us to further constrain the level density of light nuclei. Deviations from a statistical behaviour can be analyzed to get information on nuclear clustering.
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Submitted 2 September, 2013;
originally announced September 2013.
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Cold nuclear matter
Authors:
C. O. Dorso,
P. A. Giménez Molinelli,
J. I. Nichols,
J. A. López
Abstract:
The behavior of nuclear matter is studied at low densities and temperatures using classical molecular dynamics with three different sets of potentials with different compressibility. Nuclear matter is found to arrange in crystalline structures around the saturation density and in non-homogeneous (i.e. pasta-like) structures at lower densities. Similar results were obtained with a simple Lennard-Jo…
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The behavior of nuclear matter is studied at low densities and temperatures using classical molecular dynamics with three different sets of potentials with different compressibility. Nuclear matter is found to arrange in crystalline structures around the saturation density and in non-homogeneous (i.e. pasta-like) structures at lower densities. Similar results were obtained with a simple Lennard-Jones potential. Finite size effects are analysed and the existence of the non-homogeneous structures is shown to be inherent to the use of periodic boundary conditions and the finitude of the system. For large enough systems the non-homogeneous structures are limited to one sphere, one rod or one slab per simulation cell, which are shown to be minimal surface structures under cubic periodic boundary conditions at the corresponding volume fraction. The relevance of these findings to the simulations of neutron star and supernovae matter is discussed.
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Submitted 9 May, 2013; v1 submitted 23 November, 2012;
originally announced November 2012.
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Coulomb forces in neutron star crusts
Authors:
C. O. Dorso,
P. A. Giménez Molinelli,
J. A. López,
E. Ramírez-Homs
Abstract:
We study the role the proton-electron gas interaction has on the formation of nuclear structures in neutron star crusts. Using a classical molecular dynamics model we study isospin symmetric and asymmetric matter at subsaturation densities and low temperatures varying the Coulomb interaction strength. The effect of such variation is quantified on the fragment size multiplicity, the inter-particle…
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We study the role the proton-electron gas interaction has on the formation of nuclear structures in neutron star crusts. Using a classical molecular dynamics model we study isospin symmetric and asymmetric matter at subsaturation densities and low temperatures varying the Coulomb interaction strength. The effect of such variation is quantified on the fragment size multiplicity, the inter-particle distance, the isospin content of the clusters, the nucleon mobility and cluster persistence, and on the nuclear structure shapes. We find that the proton-electron Coulomb interaction distributes matter more evenly, disrupts the formation of larger objects, reduces the isospin content, modifies the nucleon average displacement, but does not affect the inter-nucleon distance in clusters . The nuclear structures are also found to change shapes by different degrees depending on their isospin content, temperature and density.
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Submitted 23 August, 2012;
originally announced August 2012.
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Topological characterization of neutron star crusts
Authors:
C. O. Dorso,
P. A. Giménez Molinelli,
J. A. López
Abstract:
Neutron star crusts are studied using a classical molecular dynamics model developed for heavy ion reactions. After the model is shown to produce a plethora of the so-called "pasta" shapes, a series of techniques borrowed from nuclear physics, condensed matter physics and topology are used to craft a method that can be used to characterize the shape of the pasta structures in an unequivocal way.
Neutron star crusts are studied using a classical molecular dynamics model developed for heavy ion reactions. After the model is shown to produce a plethora of the so-called "pasta" shapes, a series of techniques borrowed from nuclear physics, condensed matter physics and topology are used to craft a method that can be used to characterize the shape of the pasta structures in an unequivocal way.
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Submitted 23 August, 2012;
originally announced August 2012.
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From nuclei to nuclear pasta
Authors:
Claudio O. Dorso,
Pedro A. Giménez Molinelli,
Jorge A. López
Abstract:
To provide a practitioner's introduction to the study of the nuclear pasta, this article presents a brief review of the evolution of the methods used to study nucleon dynamics. This is followed with a more complete description of the extension of classical molecular dynamics (CMD) to infinite systems. The different techniques used to characterize the nuclear structure, such as cluster recognition…
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To provide a practitioner's introduction to the study of the nuclear pasta, this article presents a brief review of the evolution of the methods used to study nucleon dynamics. This is followed with a more complete description of the extension of classical molecular dynamics (CMD) to infinite systems. The different techniques used to characterize the nuclear structure, such as cluster recognition algorithms, radial correlation functions and the Minkowski functionals are presented. We reach full functionality of the extended CMD when the Coulomb interaction is introduced through two common methodologies and its effect on the structure is presented. We close the article with some final remarks.
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Submitted 4 November, 2011;
originally announced November 2011.
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Isoscaling and the nuclear EOS
Authors:
C. A. Dorso,
P. A. Giménez Molinelli,
J. A. López
Abstract:
Experiments with rare isotopes are shedding light on the role isospin plays in the equation of state (EoS) of nuclear matter, and isoscaling -an straight-forward comparison of reactions with different isospin- could deliver valuable information about it. In this work we test this assertion pragmatically by comparing molecular dynamics simulations of isoscaling reactions using different equations o…
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Experiments with rare isotopes are shedding light on the role isospin plays in the equation of state (EoS) of nuclear matter, and isoscaling -an straight-forward comparison of reactions with different isospin- could deliver valuable information about it. In this work we test this assertion pragmatically by comparing molecular dynamics simulations of isoscaling reactions using different equations of state and looking for changes in the isoscaling parameters; to explore the possibility of isoscaling carrying information from the hot-and-dense stage of the reaction, we perform our study in confined and expanding systems. Our results indicate that indeed isoscaling can help us learn about the nuclear EoS, but only in some range of excitation energies.
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Submitted 30 April, 2011;
originally announced May 2011.
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Isoscaling and the high Temperature limit
Authors:
C. O. Dorso,
C. M. Hernández,
J. A. López,
J. A. Muñoz
Abstract:
This study shows that isoscaling, usually studied in nuclear reactions, is a phenomenon common to all cases of fair sampling. Exact expressions for the yield ratio $R_{21}$ and approximate expressions for the isoscaling parameters $α$ and $β$ are obtained and compared to experimental results. It is concluded that nuclear isoscaling is bound to contain a component due to sampling and, thus, a wor…
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This study shows that isoscaling, usually studied in nuclear reactions, is a phenomenon common to all cases of fair sampling. Exact expressions for the yield ratio $R_{21}$ and approximate expressions for the isoscaling parameters $α$ and $β$ are obtained and compared to experimental results. It is concluded that nuclear isoscaling is bound to contain a component due to sampling and, thus, a words of caution is issued to those interested in extracting information about the nuclear equation of state from isoscaling.
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Submitted 23 August, 2008;
originally announced August 2008.
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Geometrical aspects of isoscaling
Authors:
A. Dávila,
C. Escudero,
J. A. López,
C. O. Dorso
Abstract:
The property of isoscaling in nuclear fragmentation is studied using a simple bond percolation model with ``isospin'' added as an extra degree of freedom. It is shown analytically, first, that isoscaling is expected to exist in such a simple model with the only assumption of fair sampling with homogeneous probabilities. Second, numerical percolations of hundreds of thousands of grids of differen…
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The property of isoscaling in nuclear fragmentation is studied using a simple bond percolation model with ``isospin'' added as an extra degree of freedom. It is shown analytically, first, that isoscaling is expected to exist in such a simple model with the only assumption of fair sampling with homogeneous probabilities. Second, numerical percolations of hundreds of thousands of grids of different sizes and with different $N$ to $Z$ ratios confirm this prediction with remarkable agreement. It is thus concluded that isoscaling emerges from the simple assumption of fair sampling with homogeneous probabilities, a requirement which, if put in the nomenclature of the minimum information theory, translates simply into the existence of equiprobable configurations in maximum entropy states.
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Submitted 12 April, 2005;
originally announced April 2005.
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Dynamical aspects of isoscaling
Authors:
C. O. Dorso,
C. R. Escudero,
M. Ison,
J. A. López
Abstract:
The origin and dynamical evolution of isoscaling was studied using classical molecular dynamics simulations of ${}^{40}$Ca + ${}^{40}$Ca, ${}^{48}$Ca + ${}^{48}$Ca, and ${}^{52}$Ca + ${}^{52}$Ca, at beam energies ranging from $20 \ MeV/A$ to $85 MeV/A$. The analysis included a study of the time evolution of this effect. Isoscaling was observed to exist in these reactions from the very early prim…
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The origin and dynamical evolution of isoscaling was studied using classical molecular dynamics simulations of ${}^{40}$Ca + ${}^{40}$Ca, ${}^{48}$Ca + ${}^{48}$Ca, and ${}^{52}$Ca + ${}^{52}$Ca, at beam energies ranging from $20 \ MeV/A$ to $85 MeV/A$. The analysis included a study of the time evolution of this effect. Isoscaling was observed to exist in these reactions from the very early primary isotope distributions (produced by highly {\it non-equilibrated} systems) all the way to asymptotic times. This indicates that isoscaling is independent of quantum effects and thermodynamical equilibrium. In summary, collision-produced isoscaling appears to be due more to the mere partitioning of the proton-neutron content of the participant nuclei, than to specific details of the reaction dynamics.
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Submitted 12 April, 2005;
originally announced April 2005.
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Entropy and Size in HIC
Authors:
A. Barrañón,
J. A. López,
J. Escamilla Roa
Abstract:
Distinct entropy definitions have been used to obtain an inverse correlation between the residual size and entropy for Heavy Ion Collisions. This explains the existence of several temperatures for different residual size bins, as reported elsewhere (Natowitz et. al., 2002). HIC collisions were simulated using binary interaction LATINO model where Pandharipande potential replicates internucleonic…
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Distinct entropy definitions have been used to obtain an inverse correlation between the residual size and entropy for Heavy Ion Collisions. This explains the existence of several temperatures for different residual size bins, as reported elsewhere (Natowitz et. al., 2002). HIC collisions were simulated using binary interaction LATINO model where Pandharipande potential replicates internucleonic interaction. System temperature is defined as the temperature obtained when Kinetic Gas Theory is applied to the nucleons in the participant region. Fragments are detected with an Early Cluster Recognition Algorithm that optimizes the partitions in energy space.
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Submitted 30 March, 2005;
originally announced March 2005.
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Dynamical study of spinodal decomposition in heavy ion collisions
Authors:
A. Barrañón,
J. A. López
Abstract:
Nuclei undergo a phase transition in nuclear reactions according to a caloric curve determined by the amount of entropy. Here, the generation of entropy is studied in relation to the size of the nuclear system.
Nuclei undergo a phase transition in nuclear reactions according to a caloric curve determined by the amount of entropy. Here, the generation of entropy is studied in relation to the size of the nuclear system.
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Submitted 30 March, 2005;
originally announced March 2005.
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A HIC Primitive Spinodal Decomposition Signature
Authors:
Armando Barrañón,
J. A. López
Abstract:
Evidence of a primitive spinodal decomposition has been obtained for central Ni+Ni Heavy Ion Collision, since higher order charge correlations show a peak when four fragments of size equal to 6 are produced with an excitation of 4.75 MeV. This can be considered as a signature of a primitive breakup in equal sized fragments with a privileged fragment size. This computational result confirms other…
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Evidence of a primitive spinodal decomposition has been obtained for central Ni+Ni Heavy Ion Collision, since higher order charge correlations show a peak when four fragments of size equal to 6 are produced with an excitation of 4.75 MeV. This can be considered as a signature of a primitive breakup in equal sized fragments with a privileged fragment size. This computational result confirms other experimental and theoretical evidences about spinodal decompostion in HIC.
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Submitted 29 March, 2005; v1 submitted 29 March, 2005;
originally announced March 2005.
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Relaxation, Emission Modes and Limit Temperatures in Ni+Ni HIC
Authors:
Armando Barrañón,
J. A. López,
C. Dorso
Abstract:
A dynamical stability analysis is performed for Ni+Ni central collision at intermediate energies, showing that in chemical, thermal and dynamical equilibriums are reached at an early stage of system evolution. This is obtained by computing the relaxation times of the quadrupole momentum, speed of sound and electric charge density of the system. This way, fragment emission modes at low and high e…
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A dynamical stability analysis is performed for Ni+Ni central collision at intermediate energies, showing that in chemical, thermal and dynamical equilibriums are reached at an early stage of system evolution. This is obtained by computing the relaxation times of the quadrupole momentum, speed of sound and electric charge density of the system. This way, fragment emission modes at low and high energies as well as the qualitative behavior of the limit temperatures are determined.
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Submitted 4 April, 2004;
originally announced April 2004.
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Size Effects in Heavy Ions Fragmentation
Authors:
A. Barrañón,
J. A. López,
C. O. Dorso
Abstract:
Rise-Plateau Caloric curves for different Heavy Ion collisions have been obtained, in the range of experimental observations. Limit temperature decreases when the residual size is increased, in agreement with recent theoretical analysis of experimental results reported by other Collaborations. Besides, promptly emitted particles influence on temperature plateau is shown. LATINO binary interactio…
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Rise-Plateau Caloric curves for different Heavy Ion collisions have been obtained, in the range of experimental observations. Limit temperature decreases when the residual size is increased, in agreement with recent theoretical analysis of experimental results reported by other Collaborations. Besides, promptly emitted particles influence on temperature plateau is shown. LATINO binary interaction semiclassical model is used to reproduce the inter-nucleonic forces via Pandharipande Potential and fragments are detected with an Early Cluster Recognition Algorithm.
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Submitted 1 January, 2003; v1 submitted 1 January, 2003;
originally announced January 2003.