Total Charged Multiplicity Research Articles

Oxidation State Localized Orbitals: A Method for Assigning Oxidation States Using Optimally Fragment-Localized Orbitals and a Fragment Orbital Localization Index.

Oxidation states represent the ionic distribution of charge in a molecule and are significant in tracking redox reactions and understanding chemical bonding. While effective algorithms already exist based on formal Lewis structures as well as using localized orbitals, they exhibit differences in challenging cases where effects such as redox noninnocence are at play. Given a density functional theory (DFT) calculation with chosen total charge and spin multiplicity, this work reports a new approach to obtaining fragment-localized orbitals that is termed oxidation state localized orbitals (OSLO), together with an algorithm for assigning the oxidation state using the OSLOs and an associated fragment orbital localization index (FOLI). Evaluating the FOLI requires fragment populations, and for this purpose a new version of the intrinsic atomic orbital (IAO) scheme is introduced in which the IAOs are evaluated using a reference minimal basis formed from on-the-fly superposition of atomic density (IAO-AutoSAD) calculations in the target basis set and at the target level of theory. The OSLO algorithm is applied to a range of challenging cases including high valent metal oxide complexes, redox noninnocent NO and dithiolate transition metal complexes, a range of carbene-containing TM complexes, and other examples including the potentially inverted ligand field in [Cu(CF3)4]-. Across this range of cases, OSLO produces generally satisfactory results. Furthermore, in borderline cases, the OSLOs and associated FOLI values provide direct evidence of the emergence of covalent interactions between fragments that nicely complements existing approaches.

Effects of impact parameter filters on observables in heavy-ion collisions at INDRA energies

The collision centrality (or the impact parameter b) in heavy-ion experiments is inferred from final state observables, however, usually b is an input to theoretical calculations. The effects of different methods used for the centrality selection (i.e. total charged multiplicity Mch, total transverse kinetic energy of light charged particles , and the ratio of transverse-to-longitudinal kinetic energy ERAT) on the nuclear stopping and the collective flow are studied in Xe+Sn collisions at INDRA energies (/nucleon). The study is conducted within the framework of the ultra-relativistic quantum molecular dynamics (UrQMD) model. It is found that the nuclear stopping power RE obtained from events binning with ERAT is larger than the experimental data as well as the results obtained using Mch and . At Ebeam = 50 MeV/nucleon, the elliptic flow from events selected with different methods spreads widely, especially for more central collisions. The elliptic flow from events sorted by ERAT is weakly dependent on the collision centrality. The difference in elliptic flow at mid-rapidity among different centrality filters steadily decreases with increasing beam energy and impact parameter. At 150 MeV/nucleon, the differences in directed and elliptic flows arising from different centrality filters vanish.

Leading cluster approach to simulations of hadron collisions with GHOST generator

The model HDPM of CORSIKA has been updated and developed on the base of the recent measurements by ALICE, CMS, TOTEM, LHCb, LHCf... The new model, GHOST, involving a four-source production reproduces correctly the pseudo-rapidity distributions of charged secondaries and has been tested with the data in the mid and forward rapidity region, especially in the complex case of TOTEM, and also with the recent measurements of CMS, up to $ \sqrt s = 13\,{\rm{TeV}} $ (9.0 1016 eV in laboratory system). Special calculations have been devoted to the semi-inclusive data playing an important role in the cosmic ray simulation (fluctuations in earliest collisions, individual cascades measured at high altitude with high energy emulsion chambers). Taking into account the violation of KNO scaling, the negative binomial distribution (NegBin-expressed in terms of scaled elements) $ z = {n \mathord{\left/ {\vphantom {n {\bar {n}}}} \right. \kern-\nulldelimiterspace} {\bar {n}}} $ (n is the number of charged secondaries) has been used pointing out a possible asymptotic behaviour of total charged multiplicities at primary energies exceeding 40 TeV (8.5 1017 eV). Thus, larger reduction of the energies devoted to the leading cluster and very large multiplicity of secondary particles could suggest for EAS generated by primary protons a larger production of muons and a shower maximum at higher altitude.

Chou-Yang Model for Forward-Backward Multiplicity Correlations at 7 TeV using Generalized Multiplicity Distribution.

The basis of the Chou-Yang model is made up of a stochastic and non-stochastic distribution and has been successful in describing forward-backward multiplicities.[1] This project examines data drawn from CERN’s 7 TeV run where we revist the Chou-Yang model’s components. It also approaches phenomenological descriptions for cluster sizes from forward-backward multiplicaity correlation strength by the E735 collaboration.[6] For the stochastic binomial component, it examines the variance of the charge asymmetry parameter z with regards to fixed total charged multiplicities n. The fitting of the Generalized Multiplicity distribution along with the linear least square fitting of the forward backward multiplicity is analysed. The parameters for the Generalized Multiplicity Distribution is presented along with an investigation on the cluster size r.[3] This serves as an extention to the work done by W.Y Wang’sWeighted GMD model at7TeV, however the nonweighted GMD model is used here.[7]

Dopamine and Caffeine Encapsulation within Boron Nitride (14,0) Nanotubes: Classical Molecular Dynamics and First Principles Calculations.

Classical molecular dynamics (MD) and density functional theory (DFT) calculations are developed to investigate the dopamine and caffeine encapsulation within boron nitride (BN) nanotubes (NT) with (14,0) chirality. Classical MD studies are done at canonical and isobaric-isothermal conditions at 298 K and 1 bar in explicit water. Results reveal that both molecules are attracted by the nanotube; however, only dopamine is able to enter the nanotube, whereas caffeine moves in its vicinity, suggesting that both species can be transported: the first by encapsulation and the second by drag. Findings are analyzed using the dielectric behavior, pair correlation functions, diffusion of the species, and energy contributions. The DFT calculations are performed according to the BLYP approach and applying the atomic base of the divided valence 6-31g(d) orbitals. The geometry optimization uses the minimum-energy criterion, accounting for the total charge neutrality and multiplicity of 1. Adsorption energies in the dopamine encapsulation indicate physisorption, which induces the highly occupied molecular orbital-lower unoccupied molecular orbital gap reduction yielding a semiconductor behavior. The charge redistribution polarizes the BNNT/dopamine and BNNT/caffeine structures. The work function decrease and the chemical potential values suggest the proper transport properties in these systems, which may allow their use in nanobiomedicine.

Multiple production up to √s = 13 TeV with the generator GHOST adapted to cosmic ray simulation

The model HDPM of CORSIKA has been updated and developed on the base of the recent measurements by LHCb, CMS, TOTEM... The new model GHOST involving a 4-source production reproduces correctly the pseudorapidity distributions of charged secondaries and has been testified with the data in the mid and forward rapidity region, especially in the complex case of TOTEM and also with the recent measurements of CMS up to FX2 (9.2 · 1016 eV). Special calculations have been devoted to the semi-inclusive data playing an important role in the cosmic ray simulation (fluctuations in the earliest collisions, individual cascades and remarkable events). Taking into account the violation of KNO scaling, the negative binomial distribution has been used pointing out an asymptotic behaviour of total charged multiplicities at primary energies exceeding 40 TeV (7 · 1017 eV). The interpretation of the most recent measurements suggests for EAS generated by primary protons a larger production of muons and a cascade maximum at higher altitude than previously assumed.

Multiple production up to √s = 13 TeV with the generator GHOST adapted to cosmic ray simulation

The model HDPM of CORSIKA has been updated and developed on the base of the recent measurements by LHCb, CMS, TOTEM... The new model GHOST involving a 4-source production reproduces correctly the pseudorapidity distributions of charged secondaries and has been testified with the data in the mid and forward rapidity region, especially in the complex case of TOTEM and also with the recent measurements of CMS up to FX2 (9.2 · 10 16 eV). Special calculations have been devoted to the semi-inclusive data playing an important role in the cosmic ray simulation (fluctuations in the earliest collisions, individual cascades and remarkable events). Taking into account the violation of KNO scaling, the negative binomial distribution has been used pointing out an asymptotic behaviour of total charged multiplicities at primary energies exceeding 40 TeV (7 · 10 17 eV). The interpretation of the most recent measurements suggests for EAS generated by primary protons a larger production of muons and a cascade maximum at higher altitude than previously assumed.

Multiplicity fluctuations in heavy-ion collisions using canonical and grand-canonical ensemble

We report the higher order cumulants and their ratios for baryon, charge and strangeness multiplicity in canonical and grand-canonical ensembles in ideal thermal model including all the resonances. When the number of conserved quanta is small, an explicit treatment of these conserved charges is required, which leads to a canonical description of the system and the fluctuations are significantly different from the grand canonical ensemble. Cumulant ratios of total charge and net-charge multiplicity as a function of collision energies are also compared in grand canonical ensemble.

Strangeness production and long-range correlations in pp collisions in string fusion approach

The effects of string fusion on the correlations in strange particles production in proton-proton collisions at high energy are studied in the framework of a Monte Carlo string-parton model. The model is based on the strings formation in elementary dipole-dipole collisions. The hardness of the elementary interaction is defined by a transverse size of the colliding dipoles. The interaction between strings is realized in the accordance with the string fusion model prescriptions by the introduction of the lattice in the impact parameter plane and taking into account the finite rapidity length of strings. The particles species differentiation is implemented according to Schwinger mechanism. The parameters of the model are fixed with the experimental data on total inelastic cross section and charged multiplicity. In the framework of the model the long-range correlation functions with an accounting of strangeness have been studied. A new intensive event-by-event observable has been proposed, which characterizes the fraction of strange particles in the event. The predictions on the correlations between strangeness, multiplicity and mean transverse momentum are obtained for pp collisions at 7 TeV.

Holographic pomeron and entropy

In dipole-dipole scattering at large rapidity $\ensuremath{\chi}=\mathrm{ln}(s/{s}_{0})$, the induced instanton on the string world sheet carries entropy ${\mathbf{S}}_{k}=2({\ensuremath{\alpha}}_{\mathbf{P}k}\ensuremath{-}1)\ensuremath{\chi}$, with ${\ensuremath{\alpha}}_{\mathbf{P}k}\ensuremath{-}1$ the Pomeron intercept for a dipole source of N-ality $k$. We argue that this entropy is released promptly over a time ${t}_{R}\ensuremath{\approx}({\mathbf{b}}_{\ensuremath{\perp}}/\ensuremath{\chi}{)}^{3}/(4{\ensuremath{\alpha}}^{\ensuremath{'}})$, with ${\ensuremath{\alpha}}^{\ensuremath{'}}/2$ the Pomeron slope and ${\mathbf{b}}_{\ensuremath{\perp}}$ the impact parameter. This stringy entropy may explain the $3/2$ jump in the total charged multiplicities at about ten participants reported over a wide range of collider energies by PHOBOS. We predict the charged multiplicities in $pp$, $pA$ and central $AA$ collisions at LHC.

Coherent particle production and multiplicities in three-jet-events of Z0 annihilations

The particle production in hadronic three-jet events from Z-decays is studied with data from the DELPHI-experiment. The topology dependence of the multiplicity produced with large angles to the event plane is compared with a LO prediction revealing a 1/ N c -suppressed destructive gluon interference. The topology dependence of the total charged event multiplicity is compared with a MLLA prediction. A parameter fit to the data results in a precise measurement of the colour factor ratio C A / C F = 2.261 ± 0.014(stat.) ± 0.036(syst.) ± 0.052(theor.) ± 0.041(clus.). The multiplicity of two-gluon systems is extracted from the measured multiplicities over a wide range of energy scale, allowing for studies of the ratio of the multiplicities of q- and gg-systems and the ratio of the derivatives of the multiplicities w.r.t. energy.

Two-stage multifragmentation of1AGeV Kr, La, and Au

Multifragmentation in fully reconstructed events from 1A GeV Kr and La collisions with C has been studied. Results are compared with similar data for 1A GeV Au+C. The emitted charged particles and fragments are identified with emission from either a prompt first stage or a second stage in which the remnant resulting from the first stage breaks up. The nuclear charge, mass, and excitation energy distributions of the remnant are determined. The total charged multiplicity, as well as those of the first and second stages are obtained. Freeze-out temperatures and thermal excitation energy permit the determination of the caloric curve. The fragment charge distribution as well as the IMF multiplicity distribution and those of individual fragments are obtained. The various results are examined as to the extent of universal behavior when scaled for varying system size. Comparisons are made with intranuclear cascade and statistical multifragmentation model calculations.Received 23 February 2000DOI:https://doi.org/10.1103/PhysRevC.62.024616©2000 American Physical Society

Measurement of the charged multiplicities in b, c and light quark events from Z0 decays

Average charged multiplicities have been measured separately in b, c and light quark ( u, d, s) events from Z 0 decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of b and light quark events, and reconstructed charmed mesons were used to select c quark events. We measured the charged multiplicities: n uds = 20.21 ± 0.10( stat.) ± 0.22( syst.) , n c = 21.28 ± 0.46( stat.) −0.36 +0.41 syst.) and n b = 23.14 ± 0.10( stat.) −0.37 +0.38( syst.) , from which we derived the differences between the total average charged multiplicities of c or b quark events and light quark events: Δ n c = 1.07 ± 0.47( stat.) −0.30 +0.36( syst.) and Δ n b = 2.93 ± 0.14( stat.) −0.29 +0.30( syst.) . We compared these measurements with those at lower center-of-mass energies and with perturbative QCD predictions. These combined results are in agreement with the QCD expectations and disfavor the hypothesis of flavor-independent fragmentation.

Some characteristics of produced particles in16O-emulsion collisions at different relativistic energies

The charged-particle multiplicities produced in inelastic interactions of16O ions at 3.7 and 60A GeV with emulsion nuclei are investigated and compared with theoretical predictions. Results from the interaction with CNO and AgBr target nuclei are analysed in terms of negative binomial (NB) distribution. Data from other nucleus-emulsion collision experiments have been used to fit an empirically proposed relationship for the average value of total charged multiplicity as a function of the geometrically determined number of interacting nucleons.

Dynamics of the Multifragmentation of 1AGeV Gold on Carbon

An exclusive study of the interaction of 1A GeV Au with C shows a separability into two stages: a prompt stage involving emission of most Z=1 and some Z=2 particles and a second stage involving the decay of an equilibrated remnant, which typically undergoes multifragmentation. The mean mass, charge, excitation energy, and the initial temperature Ti of the remnant have been determined as a function of the total charge multiplicity, m, as has the freeze-out temperature Tf. Both Ti and Tf increase linearly with m and their values at the critical point have been determined. Tf rises monotonically with excitation energy as expected for a continuous phase transition.Received 15 March 1996DOI:https://doi.org/10.1103/PhysRevLett.77.235©1996 American Physical Society

Individual fragment yields and determination of the critical exponent σ

We have studied the yield of individual fragments formed in the projectile fragmentation of gold nuclei at 1 AGeV incident on a carbon target as a function of the total charge multiplicity. The yields of fragments of different nuclear charge peak at different multiplicities. We show that this behavior can be used to determine the critical exponent σ. We obtain σ = 0.68±0.05, consistent with the liquid-gas value.

Reducibility and a new entropic term in multifragment charge distributions.

The charge distributions and their dependence on fragment multiplicity have been studied for the multifragmentation of 30 MeV/nucleon Xe1Au, Cu. For both targets, the charge distributions are approximately independent of the fragment multiplicity n. However, a residual systematic dependence on n is detectable at the largest values of the total charge multiplicity Nc . Such n dependence obeys a simple scaling law and suggests the presence of an entropic term possibly related to the mechanism of multifragmentation. Thermal scaling between the different bins of Nc seems to occur. PACS number~s!: 25.70.Pq In the multifragmentation of Ar1Au at 110 MeV/nucleon @1# the fragment multiplicity distribution Pn , at any given event transverse energy Et5(Eisin 2 qi , was shown to be reducible to an elementary one-fragment emission probability p by means of the well known binomial equation. It was also noticed that the logarithm of the extracted p depends linearly on 1/AEt ~Arrhenius plot!. These empirical observations were confirmed at other energies and for other systems @2#. Binomial reducibility permits the reconstruction of the probability of an n-fragment event in terms of a binomial combination of a fixed one-fragment probability, and suggests that the fragments are emitted independently with constant probability p. The linearity of the Arrhenius plots in turn suggests that the probability p has a Boltzmann-like thermal dependence:

ALCOR: a dynamical model for hadronization

Hadron multiplicities are calculated in the framework of the algebraic coalescence rehadronization model (ALCOR), which counts for redistribution of quarks into hadrons for relativistic heavy-ion collisions. Dynamical in-medium suppression of the light to heavy quark coalescence factors and the influence of Bjorken flow on the final hadronic composition are incorporated in the model. A comparison is made with the CERN SPS NA35 (S+S) heavy-ion experiment where the total total quark number is fitted to the total charge multiplicity and predictions for NA49 (Pb+Pb) is presented.

Study of pre-scission evaporation for [formula omitted] at 10.6 MeV/u using 3π-phoswich detector system

We measured the pre-scission multiplicity of charged particle for the system of 84Kr + 27Al at 10.6 MeV/u. The charge multiplicity of pre-scission is about 80 % of the total charge multiplicity, which is about ten times as large as that calculated by a statistical model code (GEMINI). To reproduce the pre-scission multiplicity it is essential to introduce a fission delay time of the order of 10 −20 sec. It makes, however, the significant suppression of the binary fragment cross sections. To reproduce both cross section of binary fragments and pre-scission particle multiplicity simultaneously with the code, the pre-scission particles should not be emitted at the pre-saddle point, but between the saddle and scission points. The another explanation is that the composite system is formed between the saddle and scission points.

Energy dependence of multifragmentation in 84Kr+197Au collisions.

The relationship between observed intermediate mass fragment and total charged particle multiplicities has been measured for [sup 84]Kr + [sup 197]Au collisions at energies between [ital E]/[ital A]=35 and 400 MeV. Fragment multiplicities are greatest for central or near-central collisions. For these collisions, fragment production increases up to [ital E]/[ital A][approx]100 MeV, and then decreases at higher energies.