Deuteron Production Research Articles

Deuteron production in ultrarelativistic heavy-ion collisions: A comparison of the coalescence and the minimum spanning tree procedure

The formation of deuterons in heavy-ion collisions at relativistic energies is investigated by employing two recently advanced models---the minimum spanning tree (MST) method and the coalescence model---by embedding them in the parton-hadron quantum molecular dynamics (PHQMD) and the ultrarelativistic quantum molecular dynamics (UrQMD) transport approaches. While the coalescence mechanism combines nucleons into deuterons at the kinetic freeze-out hypersurface, the MST identifies the clusters during the different stages of time evolution. We find that both clustering procedures give very similar results for the deuteron observables in the UrQMD as well as in the PHQMD environment. Moreover, the results agree well with the experimental data on deuteron production in Pb$+$Pb collisions at $\sqrt{{s}_{NN}}=8.8$ GeV (selected for the comparison of the methods and models in this study). A detailed investigation shows that the coordinate space distribution of the produced deuterons differs from that of the free nucleons and other hadrons. Thus, deuterons are not destroyed by additional rescattering.

Development of ECR ion source with high-temperature superconducting REBCO coils

A new High-Temperature Superconducting ECR (HTS-ECR) ion source is under development in Research Center for Nuclear Physics (RCNP), Osaka University. This ion source will be used for production of high intensity proton, deuteron and He ion beams. The HTS-ECR magnets are composed of three solenoid coils and a set of sextupole coils made of REBCO tapes, a high-temperature superconductor. The HTS-ECR ion source is designed to operate at frequency of 2.45 GHz and 10 GHz. Performance test of the HTS coils had been carried out at 31 K and 77 K. This HTS coil technology will be applied to development of a meter-size HTS coil system of a high intensity compact AVF cyclotron. This paper introduces the basic design of the HTS-ECR ion source. The performance test results showed that REBCO solenoids remain superconducting state with a current up to 400 A. Simulation results of the magnetic field and electromagnetic field distributions in a plasma chamber fulfilled the requirements of electron cyclotron resonance conditions at 2.45 GHz and 10 GHz. Simulation result of mirror ratios and electromagnetic field amplitudes are also presented in this paper.

Inclusive α production for the Li6+V51 system

Measurement of angular distributions and energy spectra of $\alpha$ and deuterons through breakup, transfer and incomplete fusion processes to dis-entangle their relative contributions and to investigate relative importance of breakup-fusion compared to transfer. Inclusive $\alpha$ production cross-sections have been measured for $^6$Li + $^{51}$V system near Coulomb barrier energies. Theoretical calculations for estimation of various reaction channels contributing to $\alpha$ production have been performed with finite range coupled reaction method using \textsc{FRESCO} code. The cross-sections from non-capture breakup (NCBU) ($\alpha$ + \textit{d}) and 1\textit{n}, 1\textit{p}, and 1\textit{d} transfer channels, compound nuclear decay channel and incomplete fusion (ICF) leading to $\alpha$ production were estimated to get the cumulative production cross-sections. Contributions from breakup, transfer and incomplete fusion channels could reproduce the integral direct $\alpha$ production cross-sections and their angular distributions quite well. The direct $\alpha$ production cross-sections are in agreement with other targets. The $\alpha$ production cross-sections are higher compared to the deuteron production. Kinematic analysis of the energy spectra of $\alpha$ particles and deuterons suggest that $\alpha$ particle spectra is dominated by breakp-fusion and deuteron spectra have contribution of breakup and transfer reactions. A systematic study of direct $\alpha$ production with various targets follow a universal behavior on average but noticeable differences are observed for different targets. A ratio of $\alpha$ and deuteron yields for a wide mass range of targets shows a saturation above barrier and an increasing production of $\alpha$ particles relative to deuteron around Coulomb barrier.

Production of light nuclei in small collision systems with ALICE

The energy densities reached in high-energy hadronic collisions at the LHC allow significant production of light (anti)nuclei. Their production yields have been measured as a function of pT and charged-particle multiplicity in different collision systems and at different center-of-mass energies by ALICE. One of the most interesting results obtained from such a large variety of experimental data is that the dominant production mechanism of light (anti)nuclei seems to depend solely on the event charged-particle multiplicity. Evidence for this comes from the continuous evolution of the deuteron15 to-proton and 3He-to-proton ratios with the event multiplicity across different collision systems and energies. The characterization of the light nuclei production mechanism is complemented by measurements of their production yields in jets and in the underlying event. In this paper, recent results on light nuclei production in small collision systems are shown and discussed in the context of the statistical hadronization and coalescence models. In addition, recent results on the deuteron production in jets and new preliminary results on its production in the underlying event measured in pp collisions at √S = 13 TeV are discussed.

Enhanced yield ratio of light nuclei in heavy ion collisions with a first-order chiral phase transition

Using a transport model that includes a first-order chiral phase transition between the partonic and the hadronic matter, we study the development of density fluctuations in the matter produced in heavy ion collisions as it undergoes the phase transition, and their time evolution in later hadronic stage of the collisions. Using the coalescence model to describe the production of deuterons and tritons from nucleons at the kinetic freeze out, we find that the yield ratio $ N_\text{t}N_\text{p}/ N_\text{d}^2$, where $N_\text{p}$, $N_\text{d}$, and $N_\text{t}$ are, respectively, the proton, deuteron, and triton numbers, is enhanced if the evolution trajectory of the produced matter in the QCD phase diagram passes through the spinodal region of a first-order chiral phase transition.

Deuteron production in relativistic heavy ion collisions via stochastic multiparticle reactions

We study the deuteron production via the deuteron pion and nucleon catalysis reactions, $\pi p n \leftrightarrow \pi d$ and $N p n \leftrightarrow N d$, by employing stochastic multi-particle reactions in the hadronic transport approach SMASH for the first time. This is an improvement compared to previous studies, which introduced an artificial fake resonance $d'$ to simulate these $3 \leftrightarrow 2$ reactions as a chain of $2\leftrightarrow 2$ reactions. The derivation of the stochastic criterion for multi-particle reactions is presented in a comprehensive fashion and its implementation is tested against an analytic expression for the scattering rate and the equilibrating particle yields in box calculations. We then study Au + Au collisions at $\sqrt{s_{\mathrm{NN}}} = 7.7$ GeV, where we find that multi-particle collisions substantially reduce the time required for deuterons to reach partial chemical equilibrium with nucleons. Subsequently, the final yield of $d$ is practically independent from the number of $d$ at particlization, confirming the results of previous studies. The mean transverse momentum and the integrated elliptic flow as a function of centrality are rather insensitive to the exact realization of the $2\leftrightarrow 3$ reactions.

Multiplicity scaling of light nuclei production in relativistic heavy-ion collisions

Using the nucleon coalescence model based on kinetic freeze-out nucleons from the 3D MUSIC+UrQMD and the 2D VISHNU hybrid model with a crossover equation of state, we study the multiplicity dependence of deuteron (d) and triton (t) production from central to peripheral Au+Au collisions at sNN= 7.7, 14.5, 19.6, 27, 39, 62.4 and 200 GeV and Pb+Pb at sNN=2.76 TeV, respectively. It is found that the ratio NtNp/Nd2 of the proton yield Np, deuteron yield Nd and triton yield Nt exhibits a scaling behavior in its multiplicity dependence, i.e., decreasing monotonically with increasing charged-particle multiplicity. A similar multiplicity scaling of this ratio is also found in the nucleon coalescence calculation based on kinetic freeze-out nucleons from a multiphase transport (AMPT) model. The scaling behavior of NtNp/Nd2 can be naturally explained by the interplay between the sizes of light nuclei and the nucleon emission source. We further argue that the multiplicity scaling of NtNp/Nd2 can be used to validate the production mechanism of light nuclei, and the collision energy dependence of this yield ratio can further serve as a baseline in the search for the QCD critical point in relativistic heavy-ion collisions.

Light Cluster Production in Central Symmetric Heavy-Ion Reactions from Fermi to Gev Energies

Correlations and clustering are of great importance in the study of the Nuclear Equation of State. Information on these items/aspects can be obtained using heavy-ion reactions which are described by dynamical theories. We propose a dataset that will be useful for improving the description of light cluster production in transport model approaches. The dataset combines published and new data and is presented in a form that allows direct comparison of the experiment with theoretical predictions. The dataset is ranging in bombarding energy from 32 to 1930 A MeV. In constructing this dataset, we put in evidence the existence of a change in the light cluster production mechanism that corresponds to a peak in deuteron production.

Effect of nuclear elastic scattering on the D(d,n)3He fusion reactivity induced by energetic protons observed in the large helical device

The enhancement of the fusion reaction rate coefficient induced by energetic protons, which is one of the typical nuclear elastic scattering (NES) effects, was observed in the large helical device (LHD) located at the National Institute for Fusion Science. An intense high purity hydrogen beam (the atomic ratio of the contained deuterium was less than 1 ppm) with ∼170 keV-energy and ∼10 MW-power was injected into a deuterium plasma with the electron temperature ∼9 keV and density ∼1019 m−3. After the hydrogen beam injection, the neutron generation rate by the D(d,n)3He fusion reaction immediately increased, and an increment of over one order of magnitude was observed, even though there was no meaningful ion temperature variation. The reasons for the increment in the neutron generation rate are discussed with reference to the Boltzmann–Fokker–Planck analysis along with LHD experimental data. It is concluded that the increment was induced by the production of energetic deuterons due to the NES of energetic protons.

The nature of X(3872) from high-multiplicity pp collisions

The structure of exotic resonances that do not trivially fit the usual quark model expectations has been a matter of intense scientific debate during the last two decades. A possible way of estimating the size of these states is to study their behavior when immersed in QCD matter. Recently, LHCb has measured the relative abundance of the exotic X(3872) over the ordinary psi (2S). We use the comover interaction model to study the yield of a compact X(3872). To confirm the reliability of the model in high-multiplicity pp collisions, we describe the suppression of excited over ground Upsilon states. With this at hand, we show that the size of the compact X(3872) would be slightly larger than that of the psi (2S). If the X(3872) is instead assumed to be a meson molecule of large size, we argue that its evolution in QCD matter should be described via a coalescence model, as suggested by data on deuteron production. We show that the predictions of this model for the X(3872) are in contrast with data.

Jet-associated deuteron production in pp collisions at [formula omitted] TeV

Deuteron production in high-energy collisions is sensitive to the space–time evolution of the collision system, and is typically described by a coalescence mechanism. For the first time, we present results on jet-associated deuteron production in pp collisions at s=13 TeV, providing an opportunity to test the established picture for deuteron production in events with a hard scattering. Using a trigger particle with high transverse-momentum (pT>5 GeV/c) as a proxy for the presence of a jet at midrapidity, we observe a measurable population of deuterons being produced around the jet proxy. The associated deuteron yield measured in a narrow angular range around the trigger particle differs by 2.4–4.8 standard deviations from the uncorrelated background. The data are described by PYTHIA model calculations featuring baryon coalescence.

Measurement of differential cross sections of neutron-induced deuteron production reactions on carbon from 25 to 52 MeV * *Supported by the National Natural Science Foundation of China (11775006) and the National Key R&D Program of China (2016YFA0401604)

The angle-differential cross sections of neutron-induced deuteron production from carbon were measured at six neutron energies from 25 to 52 MeV relative to those of n-p elastic scattering at the China Spallation Neutron Source (CSNS) Back-n white neutron source. By employing the Δ E-E telescopes of the Light-charged Particle Detector Array (LPDA) system at 15.1° to 55.0° in the laboratory system, ratios of the angle-differential cross sections of the 12C(n, xd) reactions to those of the n-p scattering were measured, and then, the angle-differential cross sections of the 12C(n, xd) reactions were obtained using the angle-differential cross sections of the n-p elastic scattering from the JENDL-4.0/HE-2015 library as the standard. The obtained results are compared with data from previous measurements, all of which are based on mono-energic neutrons, the evaluated data from the JENDL-4.0/ HE-2015 library and the ENDF-B/VIII.0 library, and those from theoretical calculations based on INCA code and Talys-1.9 code. Being the first white-neutron-source-based systematic measurement of the angle-differential cross sections of neutron-induced deuteron production reactions on carbon in several tens of MeV, the present work can provide a reference to the data library considering the lack of experimental data.

Deuteron production in AuAu collisions at sNN=7–200 GeV via pion catalysis

We study deuteron production using no-coalescence hydrodynamic + transport simulations of central AuAu collisions at $\sqrt{s_{NN}} = 7 - 200$ GeV. Deuterons are sampled thermally at the transition from hydrodynamics to transport, and interact in transport dominantly via $\pi p n \leftrightarrow \pi d$ reactions. The measured proton, Lambda, and deuteron transverse momentum spectra and yields are reproduced well for all collision energies considered. We further provide a possible explanation for the measured minimum in the energy dependence of the coalescence parameter, $B_2(\sqrt{s_{NN}})$ as well as for the difference between $B_2(d)$ for deuterons and that for anti-deuterons, $B_2(\bar{d})$.

Understanding the energy dependence of B_2 in heavy ion collisions: interplay of volume and space-momentum correlations

The deuteron coalescence parameter B_2 in proton+proton and nucleus+nucleus collisions in the energy range of sqrt{s_{NN}}= 900–7000 GeV for proton + proton and sqrt{s_{NN}}= 2–2760 GeV for nucleus + nucleus collisions is analyzed with the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) transport model, supplemented by an event-by-event phase space coalescence model for deuteron and anti-deuteron production. The results are compared to data by the E866, E877, PHENIX, STAR and ALICE experiments. The B_2 values are calculated from the final spectra of protons and deuterons. At lower energies, sqrt{s_{NN}}le 20 GeV, B_2 drops drastically with increasing energy. The calculations confirm that this is due to the increasing freeze-out volume reflected in B_2sim 1/V. At higher energies, sqrt{s_{NN}}ge 20 GeV, B_2 saturates at a constant level. This qualitative change and the vanishing of the volume suppression is shown to be due to the development of strong radial flow with increasing energy. The flow leads to strong space-momentum correlations which counteract the volume effect.

The São Paulo Potential and the 3He Breakup Reaction at 130 MeV on 93Nb and 197Au

Nuclear reactions induced by weakly bound nuclei often result in the emission of light particles as products of the projectile breakup. The incident particle is expected to fragment before reaching the interior of the target nuclei, a characteristic that tends to favor forward angular emission. Although the first models developed for such reactions were proposed many decades ago by Udagawa and Tamura, Ichimura, Austern, Vincent, and Kasano, and Hussein and McVoy, to this date most of the attention has been dedicated to the breakup of the deuteron and other very weakly bound systems, while more strongly bound projectiles have not been fully explored. Here, we describe the production of protons and deuterons from the breakup of 3He. The breakup of 3He on two heavy targets, 93Nb and 197Au, is analyzed in this study. However, the incoming energy involved is much larger than that of the standard phenomenological optical potentials available in the literature for the 3He entrance channel. We have overcome this difficulty by using the São Paulo potential and adjusting the nuclear diffusivity. The deuteron inclusive spectra were calculated at several angles and compared well with the experimental data. Theoretical proton emission predictions are also given for future reference, since no inclusive measurements were performed for the targets under study. One of our goals is to verify the description of deuteron emission from fast projectiles, for which many partial waves contribute to the scattering process.

Light Nuclei (d, t) Production in Au + Au Collisions at [formula omitted

In high-energy nuclear collisions, light nuclei can be regarded as a cluster of baryons and their yields are sensitive to the baryon density fluctuations. Thus, the production of light nuclei can be used to study the QCD phase transition, at which the baryon density fluctuation will be enhanced. A yield ratio of light nuclei, defined as N(t)×N(p)/N2(d), is predicted to be a sensitive observable to search for the 1st-order phase transition and/or QCD critical point in heavy-ion collisions. In this paper, we present the energy and centrality dependence of (anti)deuteron and triton production in Au+Au collisions at sNN=7.7,11.5,14.5,19.6,27,39,54.4,62.4,and200GeV measured by the STAR experiment at RHIC. We show beam-energy dependence for the coalescence parameter, B2(d) and B3(t), particle ratios, d/p, t/p, and t/d, and the yield ratio of N(t)×N(p)/N2(d). More importantly, non-monotonic energy dependence is observed for the yield ratio, N(t)×N(p)/N2(d), in 0-10% central Au+Au collisions with a peak around 20-30 GeV. Their physics implications on QCD critical point search and change of the equation of state will be discussed.

Constraining the production mechanism of light (anti-)nuclei in small systems with ALICE at the LHC: Parallel Session - Small systems III

The large samples of high-quality data collected at the LHC by the ALICE Collaboration allow for a systematic study of light (anti-)nuclei production in pp collisions at s=5,7and13TeV and in p–Pb collisions at sNN=5.02TeV. The excellent performance of the Inner Tracking System, Time-Projection Chamber and Time-Of-Flight detectors provide a clear identification and separation of primary produced light (anti-)nuclei from secondaries. The results on deuteron and 3He production as a function of multiplicity in pp and p–Pb collisions are shown. The goal is to study whether the production of (anti-)nuclei in small systems is better described by the coalescence model or by the statistical hadronisation model. The main observables for testing the production mechanisms are the coalescence parameter BA and the ratio between the transverse-momentum integrated yields of nuclei and protons, d/p, 3He/p and 3H/p. These observables are studied as a function of the event multiplicity and compared with the predictions of theoretical models.

Beam-energy dependence of the production of light nuclei in Au + Au collisions

We study the collision energy dependence of (anti-)deuteron and (anti-)triton production in the most central Au+Au collisions at $\sqrt{s_\mathrm{NN}}=$ 7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV, using the nucleon coalescence model. The needed phase-space distribution of nucleons at the kinetic freeze-out is generated from a new 3D hybrid dynamical model (\texttt{iEBE-MUSIC}) by using a smooth crossover equation of state (EoS) without a QCD critical point. Our model calculations predict that the coalescence parameters of (anti-)deuteron ($B_2(d)$ and $B_2(\bar{d})$) decrease monotonically as the collision energy increases, and the light nuclei yield ratio $N_t N_p/N_d^2$ remains approximately a constant with respect to the collision energy. These calculated observables fail to reproduce the non-monotonic behavior of the corresponding data from the STAR Collaboration. Without including any effects of the critical point in our model, our results serve as the baseline predictions for the yields of light nuclei in the search for the possible QCD critical points from the experimental beam energy scan of heavy ion collisions.

Production of energetic protons, deuterons, and neutrons up to 60 MeV via disruption of a current-carrying plasma column at 3 MA

Acceleration of ions to multi-MeV energies is investigated in various plasma devices to better understand processes in astrophysical plasmas and to develop efficient accelerators for a variety of applications. This paper reports the production of proton, deuteron, and electron beams in a z-pinch—a cylindrically symmetric plasma column that is compressed by its own magnetic field. For this work, the GIT-12 pulsed-power generator was used to drive a novel configuration of z-pinch that dramatically enhanced ion acceleration associated with disruption of the current by instabilities in the compressed plasma. During the disruption of 3 MA current, hydrogen ions were accelerated up to at least 50 MeV, which is almost a hundred-times the ion energy provided by the generator driving voltage of 0.6 MV. Under optimal conditions, the total numbers of hydrogen ions with energies above 20 and 50 MeV were 4 × 1013 and 1011, respectively. Accelerated deuterons produced one 20 ns (full width at half maximum) pulse of fast neutrons via D(d, n)3He and other nuclear reactions. A maximum neutron output of (1.0 ± 0.2) × 1012 neutrons/sr was observed downstream, i.e., in the anode to cathode direction. In this direction, the maximum neutron energy reached 58 ± 7 MeV. Both ion and neutron beams in our experiment reached an end-point energy of about 60 MeV, which is the highest value observed in pulsed-power devices. A localized peak voltage of ≳60 MV was driven by the inductive energy that was stored around the plasma column and that was extracted during a sub-nanosecond current drop. Considering the natural occurrence of current-carrying columns in laboratory and space plasmas, the current interruption observed in z-pinches could represent a more general physical process that contributes to the efficient conversion of magnetic energy into the energy of particle beams in various plasmas.

(Anti-)deuteron production in pp collisions at sqrt{s}=13 text {TeV}

The study of (anti-)deuteron production in pp collisions has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. In this paper the production of text {(anti-)deuterons} is studied as a function of the charged particle multiplicity in inelastic pp collisions at sqrt{s}=13 TeV using the ALICE experiment. Thanks to the large number of accumulated minimum bias events, it has been possible to measure (anti-)deuteron production in pp collisions up to the same charged particle multiplicity ({mathrm {d} N_{ch}/mathrm {d} eta } sim 26) as measured in p–Pb collisions at similar centre-of-mass energies. Within the uncertainties, the deuteron yield in pp collisions resembles the one in p–Pb interactions, suggesting a common formation mechanism behind the production of light nuclei in hadronic interactions. In this context the measurements are compared with the expectations of coalescence and statistical hadronisation models (SHM).