16O Interactions Research Articles

Pre-Equilibrium Clustering in Production of Spectator Fragments in Collisions of Relativistic Nuclei

An algorithm of pre-equilibrium clustering of spectator matter based on the construction of the minimum spanning tree (MST) is presented. The algorithm was implemented in the Abrasion-Ablation Monte Carlo for Colliders (AAMCC) model designed to study the characteristics of spectator matter in collisions of relativistic nuclei. Due to accounting for the pre-equilibrium clusters in modelling 208Pb–208Pb collisions at the LHC, the agreement of simulation results with experimental data on the average multiplicities of spectator nucleons was improved. The results of the AAMCC-MST were compared with experimental data on the interactions of 197Au nuclei in nuclear photoemulsion. Comparison of the yields of spectator nuclei calculated for 16O–16O collisions with the yields measured in interactions of 16O with light nuclei of photoemulsion made it possible to estimate the effect of MST-clustering in small nuclear systems.

Application of ion beam analysis for the characterization of SiC- and DLC-thin films

Three series of protective coatings (thickness ca. 200-300 nm) were prepared on the surface of Ti-Al-V alloy (TA6V): silicon carbide (SiC) films produced by ion sputtering (I), silicon carbide films and subjected to Dynamic Ion Mixing (DIM) during the deposition procedure (II) and Diamond Like Carbon (DLC) films produced by ion beam deposition (III). The chemical composition (Si, C and O) of the films was determined using ion beam analysis techniques. The silicon, carbon and oxygen depth distribution was determined by proton Rutherford backscattering spectrometry (p-RBS) and using the resonances at 4.265 and 3.035 MeV of the 12C(α,α)12C and 16O(α,α)16O interactions respectively. The ratio of Si:C was found to be close to the stoichiometric one. The corrosion resistance of the coated samples was tested under strong aggressive conditions (5M HCl at 50 oC). The investigation following the corrosion attack showed that the thickness of the films remained practically unchanged. Only slight diffusion and dissolution effects were observed indicating the good quality of the produced thin films.

Justification of Landau Hydrodynamic-Tube model in central relativistic heavy-ion collisions

The statistical event-by-event analysis of inelastic interactions of 16O and 32S nuclei in emulsion at 60 A GeV/c and 200 A GeV/c reveals the existence of groups of high multiplicity events belonging to very central nuclear interactions with Gaussian pseudorapidity distributions for produced particles as suggested by the original hydrodynamic-tube model. Characteristics of these events are presented. The experimental observations are interpreted as a result of quark-gluon plasma formation in the course of central nuclear interactions.

Multisource Evidence for Final State Hadrons in 3.7A GeV 16O–Nucleus Interactions

In 3.7A GeV 16O interactions with emulsion nuclei, the shower particle multiplicity characteristics are investigated. Data are presented in terms of the number of emitted particles in both forward and backward angular zones. The dependence on the target size and emission direction is presented. The target separation of events depends on Glauber's multiple scattering theory approaches. A decay mechanism seems to be a characteristic of the backward production. This production may be during the de–excitation of the excited target nucleus, regarding the nuclear limiting fragmentation hypothesis. The forward emitted particle is due to a creation system. The target size is an effective parameter as well as the projectile size in this system, considering the geometrical concept regarded in the nuclear fireball concept. The data are simulated in the framework of the modified FRITIOF model. The multisource thermal model can predict source numbers responsible for particle production.

Observed side feeding in incomplete fusion dynamics in 16O + 160Gd reaction at energy ∼5.6 MeV/A: Spin distribution measurements

Spin distributions of various residues populated via complete fusion (CF) and incomplete fusion (ICF) reactions in the interaction of 16O with 160Gd at the projectile energy Eproj∼5.6 MeV/A have been studied. The experimentally measured spin distributions of the residues associated with the ICF reactions are found to be distinctly different from those populated via the CF reactions. An attempt has been made to extract the side-feeding pattern from the spin distributions of CF and ICF reaction products. It has been observed that the CF products are strongly fed over a broad spin range. But, no side-feeding takes place in the low observed spins as low partial waves are strongly hindered in the fast α-emission channels (associated with ICF) in the forward direction. It has also been observed that the mean input angular momentum for direct α-emitting (ICF) channels is relatively higher than evaporation α-emitting (CF) channels, and it increases with direct α-multiplicity in forward direction.

A graphics processor-based intranuclear cascade and evaporation simulation

Monte Carlo simulations of the transport of protons in human tissue have been deployed on graphics processing units (GPUs) with impressive results. To provide a more complete treatment of non-elastic nuclear interactions in these simulations, we developed a fast intranuclear cascade-evaporation simulation for the GPU. This can be used to model non-elastic proton collisions on any therapeutically relevant nuclei at incident energies between 20 and 250 MeV. Predictions are in good agreement with Geant4.9.6p2. It takes approximately 2 s to calculate 1×106 200 MeV proton–16O interactions on a NVIDIA GTX680 GPU. A speed-up factor of ∼20 relative to one Intel i7-3820 core processor thread was achieved.

Nuclear diffraction dissociation of 16O, 22Ne, 28Si, 32S, 56Fe at 1–3.7 A GeV in nuclear emulsion

In this paper, we discuss various aspects of the nuclear diffraction dissociation interactions of 16O, 22Ne, 28Si, 32S, 56Fe nuclei accelerated at the Dubna–JINR Synchrophasotron and Nuclotron in the energy range 1–3.7 A GeV. We use criteria which separate electromagnetic dissociation events among the nuclear collisions. We describe their topology and study their characteristic parameters, relative rates of nuclear fragmentation, average multiplicities and the angular distributions of fragments as a function of the energy and of the nature of the primary nuclei. Nuclear emulsions were used for this purpose, which allowed the detection of all projectile and target fragments.

Characteristics of the total disintegration events of emulsion heavy target nuclei caused by O16 and 28Si nuclei at high energies

The present paper deals with the interactions of 16O and 28Si nuclei with emulsion heavy target nuclei (silver (Ag) and bromine (Br)) at 4.5A GeV/c. The results have been analyzed to identify interesting characteristics of the total disintegration (TD) events produced in these interactions. Events having a number of heavily ionizing particles Nh ≥ 28 have been selected in this study. The integral multiplicity distributions for the disintegrated particles from the target nuclei have been used to separate the inelastic interactions with the free hydrogen (H), the light (CNO), and the heavy (AgBr) nuclei. The average multiplicities of the different secondary particles emitted in these interactions have been compared with the corresponding ones of different projectiles nearly at the same momentum. The average multiplicity of the grey particles is found to increase with the mass of the projectile, while the average multiplicity of the black particles is found to decrease with increasing mass of the projectile; this result agrees with the prediction of the fireball model. Also, the dependence of the shower, grey, and black particles produced in the TD events on the mass of the projectile has been studied. Moreover, the dependence of the probability of the TD for the projectile mass as well as the target fragments has also been discussed. The results show that the multiplicity distributions of the shower, grey, and black particles present a Gaussian distribution. Finally, the linear dependence of the grey and compound multiplicities on the black, heavy, and shower particles has also been observed.

A study of the energy dependence for the multiplicity of shower particles produced in a 16O–emulsion interaction in the framework of the Coulomb-modified Glauber model

The total reaction cross sections for the interaction of 16O with emulsion nuclei (16O–Em) at energies: 0.2, 2.1, 3.6, 14.6, 60.0, and 200.0A GeV have been calculated in the framework of the Coulomb-modified Glauber model. A similar calculation in case of proton–emulsion (p–Em) interactions is carried out at the same energies. For both types of interactions, the corresponding projectile and target participants beside the corresponding binary collisions have been calculated for the same energies. Then the averages of these quantities have been obtained. These averages have been used in the calculations of the corresponding average multiplicity of the shower particles (s-particles) in the case of the 16O–Em interaction. The agreement between the calculated total reaction cross sections and the corresponding experimental data is quite good. Also, a good agreement between the calculated average multiplicities of the shower particles and the corresponding experimental data has been obtained.PACS Nos.: 24.10.Cn, 24.10.Ht, 25.60.Dz

Excitation functions of evaporation residues in the interaction of 16O with 103Rh at incident energies up to 400 MeV

The excitation functions for production of 48 residues in the interaction of 16O with 103Rh have been measured at incident energies varying from about 40 to 400MeV. Their analysis shows that many competing reaction mechanism contribute to the formation of these residues including complete fusion, break-up-fusion reactions and 16O inelastic scattering. The cross-sections of most of these mechanisms are obtained by independent measurements of the spectra of intermediate-mass fragments observed in the interaction of 16O on 93Nb. The agreement between measured and calculated excitation functions is satisfactory in most of the cases.

Characterization and corrosion stability of SiC coatings using ion beam analysis techniques

Thin SiC films (thickness ca. 200–300 nm) were prepared by ion sputtering on the surface of Ti–Al–V alloy (TA6V) at room temperature and at 750 °C. Part of the films was additionally subjected to dynamic ion mixing (DIM) during the deposition procedure. The coated samples were electrochemically treated in 0.9% NaCl (37 °C) in order to investigate their pitting corrosion resistance. The determination of the silicon, carbon and oxygen depth distribution before and after the corrosion attack was performed by proton Rutherford backscattering spectrometry (p-RBS) and by using the resonances at 4.265 and 3.035 MeV of the 12C(α, α) 12C and 16O(α, α) 16O interactions, respectively. The ratio of Si:C was found to be close to the stoichiometric one. The coatings prepared at room temperature exhibited remarkable resistance to pitting corrosion. The surface morphology of the samples was also investigated by scanning electron microscopy (SEM/EDS).

Erratum to: “Study of backward, forward shower and grey particles production from the interactions of 16O with emulsion nuclei at 4.5 A GeV/c” [Chaos, Solitons and Fractals 18 (2003) 155–124

Erratum to: “Study of backward, forward shower and grey particles production from the interactions of 16O with emulsion nuclei at 4.5 A GeV/c” [Chaos, Solitons and Fractals 18 (2003) 155–124

Emission of intermediate-mass fragments in the interaction of 16O with 59Co, 93Nb and 197Au

In this paper we study the emission of 8Begs, B and N fragments in the interaction of 16O ions with 59Co, 93Nb and 197Au at incident energies varying from 6 to 25 MeV/nucleon. The spectra of these fragments, as well as those of C fragments studied in a previous paper, are dominated at forward angles by a component originating from break-up of 16O. At the higher incident energies break-up occurs after quite a sizeable projectile energy loss. Another mechanism which dominates at large emission angles, favours the emission of low-energy fragments and is attributed to the coalescence of nucleons during the cascade of nucleon-nucleon interactions by means of which the excited nuclei produced in the primary two-ion interaction thermalize.

Study of backward, forward shower and grey particles production from the interactions of 16O with emulsion nuclei at 4.5 A GeV/c

This paper presents the results of the study of interaction of the relativistic 16O nucleus with the momentum 4.5 A GeV/c with the photo emulsion. The average multiplicities of the different emitted hadrons (shower and grey) in the forward (FHS) and backward (BHS) hemisphere, compared with other data from the interaction of 1P, 4He, 6Li, 12C, 22Ne and 28Si at nearly the same momentum, have been studied as a function of projectile mass number, the number of interacting projectile nucleons, impact parameter and number of shower particles emitted in the backward hemisphere. The multiplicity distribution of the shower particles emitted in the forward and backward hemisphere directions using the KNO representation are represented and described by an exponential form for BHS shower particles. Another objective of this paper is to examine whether the mechanism of particle production in the BHS is significantly different from the operating in the production of particles in the FHS which can help to solve some questions connected with the role of collective phenomena in the backward emission of particles from the nuclear targets.

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.

Study of the energy flow in sulphur-and oxygen-nucleus collisions at 60 and 200 GeV/nucleon

We report on a systematic study of midrapidity transverse energy production and forward energy flow in interactions of16O and32S projectiles with S, Cu, Ag and Au targets at 60 and 200 GeV/nucleon. The variation of the shape of theET distributions with target and projectile mass can be understood from collision geometry. AverageET values determined for central collisions show an increasing stopping power for heavier target nuclei. A higher relative stopping is observed at 60 GeV/nucleon than at 200 GeV/nucleon. Bjorken estimates of the energy density reach approximately 3 GeV/fm3 in highET events at 200 GeV/nucleon with16O and32S projectiles. The systematics of the data and the shapes ofET and pseudorapidity distributions are well described by the Lund model Fritiof.

An emulsion study of 16O and 32S interactions at 200 GeV per nucleon selected by transverse energy

Interactions of 16O and 32S at 200 GeV per nucleon in emulsion and in emulsion-tungsten chamber targets were tagged by transverse energy and multiplicity triggers in the HELIOS apparatus at CERN. As a first sample, 375 events, covering a wide range of transverse energies, were located and studied in emulsion. Results are reported in this paper. The angular distribution has been measured, event by event, with a wide pseudorapidity coverage, both in emulsion and in the HELIOS calorimeters. The total charged multiplicity and the transverse energy per charged particle have been obtained as a function of the transverse energy and of the pseudorapidity. The measured distributions are compared with the predictions of the Dual Parton Model, as coded in the IRIS generator. Assuming that 59% of the E T is transported by charged particles, and estimating the energy density by a full transparency picture, a comparison with cosmic-ray data has also been attempted.

Inelastic electron-nucleus interactions at 5 GeV detected by ARGUS

Beam-gas events taken with the ARGUS detector at thee + e −-storage ring DORIS-II have been used to study interactions ofe ± at 5 GeV with light nuclei mainly16O. The selection ofe ± 16O events is discussed. The spectra of secondary protons and charged pions are found to be similar to those of hA interactions in accordance with the nuclear scaling. Measurements of like-particle (p p andπ π) correlations at small relative momenta were used to determine the radius of particle emission region ine ± 16O interactions. This radius proved to be equal within errors to the radius of particle emission region in hC interactions. No any narrow diproton resonance has been observed in the mass region from 1.9 to 2.2 GeV.

On the production of helium fragments in ultra-relativistic heavy-ion collisions

Partial production cross sections of projectile alpha fragments produced in high-energy interactions of 16O and 32S at 200 GeV/n and 16O at 60 GeV/n in emulsion are studied. Evidence of multiplicity scaling of such produced fragments is presented in the energy range 2–200 GeV/n for various projectiles.

Study of the energy flow in16O-nucleus collisions at 60 and 200 GeV/nucleon

We report a systematic study of mid-rapidityET production and forward energy flow in the interaction of16O projectiles on Al, Cu, Ag and Au at 60 and 200 GeV/nucleon. First results onET production with32S projectiles are presented.