Emulsion Nuclei Research Articles

Highlights of Unstable States in Relativistic Dissociation of Light Nuclei in Nuclear Emulsion

Highlights of Unstable States in Relativistic Dissociation of Light Nuclei in Nuclear Emulsion

Utilize azimuthal correlation to examine the collective flow influence caused by the reaction between $$^{84}$$Kr nuclei and emulsion nuclei at 1 A GeV

Utilize azimuthal correlation to examine the collective flow influence caused by the reaction between $$^{84}$$Kr nuclei and emulsion nuclei at 1 A GeV

Emission characteristics of the slowest target protons produced in the interaction of $$^{84}Kr$$ nuclei with emulsion nuclei at 1 A GeV

Emission characteristics of the slowest target protons produced in the interaction of $$^{84}Kr$$ nuclei with emulsion nuclei at 1 A GeV

Multiplicity correlation of fast target protons and projectile fragments for the events produced in the interaction of 84Kr nuclei with emulsion nuclei at 1 A GeV

It has become obvious that one crucial aspect in understanding high energy nuclear reactions is the fragmentation of colliding nuclei. The nuclear emulsion is a 4[Formula: see text] detector that makes it simple to identify and quantify the charges of projectile fragments. In this work, we study the multiplicity distribution and angle distributions of single, double charge projectile fragments, fast target protons (gray particle) as well as their correlation for the events produced in the interactions of [Formula: see text] with emulsion nuclei at 1[Formula: see text]A[Formula: see text]GeV. We also study the target-dependent angle distribution of gray particles. The results are compared with other experimental data as per availability. This analysis shows that multiplicity distributions have a remarkable link between the projectile and target fragmentation processes.

Deciphering 𝚵− capture events in light emulsion nuclei

Abstract. We recently showed that all five KEK and J-PARC uniquely assigned two-body Ξ- + AZ → A′ΛZ′ + A′′ΛZ′′ capture events in CNO light emulsion nuclei are consistent with Coulomb-assisted 1pΞ¯ nuclear states in a ξ-nuclear potential of nuclear-matter depth Vξ ≳ 20 MeV [1]. Here we argue that the recently reported 14N capture events named KINKA and IRRAWADDY are more likely Ξ1p0 - 14C nuclear states [2] than Ξ1s--14 N states, the latter assignment implying considerably smaller values of Vξ.

Studies of angular distribution of the grey particles in 16O-emulsion collision at 3.7A GeV

By means of [Formula: see text] emulsion track detectors, we report the characteristics of the experimental angular distributions of the fast target protons (grey particles) emitted in interactions of [Formula: see text]O with emulsion nuclei at 3.7A[Formula: see text]GeV. Grey tracks in nuclear emulsion corresponding protons with kinetic energy in the ranges [Formula: see text][Formula: see text]MeV. The angular distributions are compared with those resulting from interactions of other projectiles ([Formula: see text]C, [Formula: see text]Ne and [Formula: see text]Si) at nearly the same incident energy. These angular distributions are studied at different target sizes ([Formula: see text]-values) and at various projectile spectator charges ([Formula: see text]-values) in the framework of the modified Maxwell– Boltzmann statistical model. The nuclear limiting fragmentation hypothesis is shown to be fulfilled for these target protons angular distributions which are found to be independent of the target size and centrality of collisions. Also, the size of the projectile is found to be ineffective at Dubna energies. The angular distributions of all groups of events possess peaks positioned at [Formula: see text]. The calculated statistical moments of the distributions along with skewness and kurtosis are investigated in addition to the forward-backward asymmetry ratio [Formula: see text] for the different groups of events.

Studies of fast protons produced in the reactions of 16O Nuclei incident on emulsion nuclei at 3.7A GeV

• The grey particle multiplicity characteristics, reflects the role of the limiting fragmentation hypothesis. • It is found that the multiplicity distribution of grey particle is independent of the projectile energy or its size. • The multiplicity distribution P(Ng) of the emitted g-particles fit well with the Gauss distribution function, which is both symmetric and platykurtic behavior. Both values of Skewness (S) and Kurtasis (K) are less than zero. • The experimental data shows that the selectivity of N h particle multiplicity as an indication of the impact parameter of nuclear interaction is better than the choice of charged projectile spectator nucleons Q in each event. We report the experimental data of the fast target protons produced in the reaction of 16 O-Em at 3.7A GeV. The emission mechanism of the fast target protons (grey particles with kinetic energy in the range of 26 – 400 MeV) is investigated in terms of multiplicity characteristics. Our experimental data is compared with the corresponding data from the interactions of 12 C, 22 Ne and 28 Si projectiles at nearly the same incident energy. It is found that the multiplicity distribution is independent of the projectile energy or its size. The interaction events were classified in two ways. First, according to the degree of their centrality, depending on the number of the nucleons remaining as spectators Q (stripping nucleons) from the projectile. The second way, the interactions are classified according to the target size (N h – parameter). At various groups of events, the higher moments of the multiplicity distributions were calculated statistically. The experimental data shows that the selectivity of N h particle multiplicity as an indication of the impact parameter of nuclear interaction is better than the choice of charged projectile spectator nucleons Q in each event.

Interaction of <sup>28</sup>Si with Emulsion Nuclei at 4.5 AGeV/c in View of Thermo-Statistical Approach

In this work, we study some changes of nuclear matter in the interactions of 28S with emulsion nuclei at 4.5 AGeV/c. From the experimental quantities investigated using Tsallis’ statistics, we deduced the temperature, entropy density and non-equilibrium factor of the nuclear medium. These obtained parameters were used to reveal variations in the nuclear matter at the stated interaction energy. The results that came up from this study were compared with their corresponding results obtained from other heavy ion collision experiments at wide energy range.

Ξ-nuclear constraints from 𝚵−emulsion capture events

All five KEK and J-PARC two-body Ξ−+AZ →A′ΛZ’ +A″ΛZ” capture events in light emulsion nuclei, including KISO and IBUKI in14N, are consistent with Coulombassisted 1pΞ−nuclear states. The underlying Ξ-nuclear potential is strongly attractive, with nuclear-matter depthVΞlarger than 20 MeV. The recent14N capture events KINKA and IRRAWADDY assigned by J-PARC E07 to 1sΞ−nuclear states, and implying considerably shallowerVΞ, have also another interpretation as 1pΞ0nuclear states.

An Enhancement of Formation of Unstable 8Be Nucleus with the Growth of α-Particle Multiplicity in Fragmentation of Relativistic Nuclei

In this paper, the correlation between the formation of the unstable $^{8}$Be nucleus and accompanying $\alpha$ particles in the fragmentation of relativistic $^{16}$O, $^{22}$Ne, $^{28}$Si, and $^{197}$Au nuclei in a nuclear track emulsion is investigated. The $^{8}$Be decays are identified in a wide energy range by invariant masses calculated from 2$\alpha$-pair opening angles. The adopted approximations are verified by data on fragmentation of $^{16}$O nuclei in a hydrogen bubble chamber in a magnetic field. An increase in the $^{8}$Be contribution to the dissociation with the growth of $\alpha$-particle multiplicity is found.

Study of Angular Distribution and KNO Scaling in the Collisions of 28Si with Emulsion Nuclei at 14.6A GeV

An attempt has been made to study the angular characteristics of heavy ion collision at high energy in the interactions of 28Si nuclei using with nuclear emulsion. The KNO scaling behavior in terms of the multiplicity distribution has been studied. A simplest universal function has been used to represent the present experimental data.

ОСОБЕННОСТИ РАСПРЕДЕЛЕНИЯ СОБЫТИЙ ПО МНОЖЕСТВЕННОСТИ ВТОРИЧНЫХ ЧАСТИЦ В ЗАВИСИМОСТИ ОТ ЭНЕРГИИ СТОЛКНОВЕНИЯ И АССИМЕТРИЧНОСТИ СТАЛКИВАЮЩИХСЯ РЕЛЯТИВИСТСКИХ ЯДЕР

To search for signals of the phase transition of matter from the hadronic state to the quark­gluon plasma, interactions with extreme characteristics are studied. The study of the dependence of the av­erage multiplicity on the projectile energy for sulfur and silicon nuclei with energies of 3.7 AGeV, 14 AGeV, and 200 AGeV has been carried out. Experimental data on inelastic interactions with the nuclei of the NIKFI BR­2 emulsion obtained at the SPS at CERN and at the Synchrophasotron at JINR. To take into account fluctuations in the initial conditions of the nucleus­nucleus interaction, the events were divided into central and peripheral ones. A comparative analysis of the average multiplicity with heavy and light nuclei of the photographic emulsion is presented. The multiplicity increase factor has an almost linear increase in energy (on the logarithmic axis) for all events, except for the central interactions of sulfur nuclei with heavy emulsion nuclei at 200 AGeV. These events are explosive events, which give a flux of secondary particles in a narrow range of average pseudo­rapidity and significantly shifted towards low values <η>. The analysis of events of complete destruction of the projectile nucleus is presented. Such events are considered as events in which the most favorable conditions are created for the formation of a quark­gluon plasma.

Constraints on Ξ− nuclear interactions from capture events in emulsion

Five Ξ−p→ΛΛ two-body capture events in 12C and 14N emulsion nuclei, in which a pair of single-Λ hypernuclei is formed and identified by their weak decay, have been observed in (K−,K+) emulsion exposures at KEK and J-PARC. Applying a Ξ−-nucleus optical potential methodology to study atomic and nuclear transitions, we confirm that these capture events occur from Coulomb assisted 1pΞ− nuclear states. Long-range ΞN shell-model correlations are found essential to achieve consistency between the 12C and 14N events. The resulting Ξ-nuclear interaction is strongly attractive, with Ξ potential depth in nuclear matter VΞ≳20 MeV. Implications to multi-strangeness features of dense matter are outlined.

Correlation in formation of 8Be nuclei and α-particles in fragmentation of relativistic nuclei

In the events of peripheral dissociation of relativistic nuclei in the nuclear track emulsion, it is possible to study the emerging ensembles of He and H nuclei, including those from decays of unstable 8Be and 9B nuclei, as well as the Hoyle state. These extremely short-lived states are identified by invariant masses calculated from the angles in 2α-pairs, 2αp- and 3α-triplets in the approximation of conservation of momentum per nucleon of the primary nucleus. In the same approach, it is possible to search for more complex states. This paper explores the correlation between the formation of 8Be nuclei and the multiplicity of accompanying α-particles in the dissociation of relativistic 16O, 22Ne, 28Si, and 197Au nuclei. On the above basis, estimates of this correlation are presented for the unstable 9B nucleus and the Hoyle state. The enhancement in the 8Be contribution to dissociation with the α-particle multiplicity has been found. Decays of 9B nuclei and Hoyle states follow the same trend.

Emission characteristics of target black fragments in 16O-Emulsion collisions at 3.7AGeV

As a function of collision centrality, the multiplicity and angular distributions for the slowest target fragments (black particles) emitted in interactions of 16O ions with emulsion nuclei at 3.7[Formula: see text]A[Formula: see text]GeV were investigated. The multiplicity distribution is unaffected by the projectile’s energy or mass. At different impact parameters, the higher moments of multiplicity distributions of black particles were measured. The calculated values of the scaled variance (variance divided by the mean) show that the emission of slower target fragments at high energies is not a statistically independent process in all cases. At various projectile spectators, the angular distributions of the emitted black particles were investigated. The obtained data were compared to the statistical model’s predictions to describe the process responsible for producing secondary particles.

Characteristics of the grey particles emission at relativistic energy

The theme of present analysis is to focus on the emission characteristics of grey particles emitted in 4π angle, forward hemisphere angle (θ < 90°) (FHS) and backward hemisphere angle (θ ≥ 90°) (BHS). We have studied the average multiplicity variation of grey particles for the events emitted from the reaction of projectiles with CNO and AgBr target nuclei of nuclear emulsion. We have also investigated the emission probability of grey particles with projectile mass in between the range of 1 and 207. In this analysis we have observed that the emission probability of grey particles is higher in forward hemisphere angle as compared to backward hemisphere angle. We have also observed that the average multiplicity of grey particles is independent on the projectile mass and incident energy.

Unstable states in dissociation of relativistic nuclei

The invariant mass method is used to identify the $^8$Be and $^9$B nuclei and Hoyle state formed in dissociation of relativistic nuclei in a nuclear track emulsion. It is shown that to identify these extremely short-lived states in the case of the isotopes $^9$Be, $^{10}$B, $^{10}$C, $^{11}$C, $^{12}$C, and $^{16}$O, it is sufficient to determine the invariant mass as a function of the angles in pairs and triples of He and H fragments in the approximation of the conservation of momentum per nucleon of the parent nucleus. According to the criteria established in this way, the contribution of these three unstable states was evaluated in the relativistic fragmentation of the $^{28}$Si and $^{197}$Au nuclei.

Characteristics of the projectile and target fragments produced in 84Kr36 — emulsion interaction at 1GeV per nucleon

In the present analysis, we have focused on the emission characteristics of the projectile and target fragments produced from the interaction of [Formula: see text]Kr with nuclear emulsion at 1 A GeV. We have studied the variation of the fragmentation parameter for singly charged [Formula: see text], doubly charged [Formula: see text], lower multiple-charged [Formula: see text]–[Formula: see text], medium multiple-charged [Formula: see text]–[Formula: see text] and higher multiple-charged [Formula: see text], projectile fragments with respect to mass of the projectile and found that they are showing the different behaviors for different projectile fragments. We have also studied the emission behavior of shower particles, with respect to the black and gray particles. The present studies show that the production of shower particles strongly depends on the incident kinetic energy of the projectile and also depending on the interaction of the different types of target nuclei of nuclear emulsion.

The multiplicity characteristics of7Li-Em interactions as a function of noninteracting projectile nucleons

In this work, the interactions of7Li nuclei with emulsion at 3 A GeV/c were studied. Multiplicity of the charged secondary particles as well as the charge of the outgoing projectile fragments were measured, while correlations among them are discussed. The values of the total charge of the noninteracting projectile nucleons and the average number of interacting projectile nucleons are estimated. The dependence of the secondary particles on the number of heavily-ionized tracks is analyzed. The results show that interactions of7Li nuclei with emulsion nuclei exhibit a number of regularities, which had been noted in experiments with lighter nuclei. The absorption of relativistic particles, while increasing the degree of target destruction, is observed. The average multiplicities of the secondary charged particles depend on the impact parameter, as their values increase, while decreasing the impact parameter. The number of secondary charged particles in the heavy-ion interactions depends on the degree of disintegration of the target nuclei. This dependence is not observed in the case of the interaction of hadron with emulsion. The experimental data of the interaction of7Li are systematically compared with the other interactions at different energies. The results agree with the corresponding results at nearly the same energy.

A Study of Pseudo-Central Collision Events Observed in Pion-Nucleus Interactions

The present study is based on the interactions caused by 340-GeV negative pions with emulsion nuclei. The main aim of this paper is to investigate some aspects of central collision events. Thus, the events in which the total number of charged shower particles is greater than or equal to twenty eight (Ns geq 28) were chosen for the analysis. They are not exactly central collision events, but may be considered as pseudo-central collision events. The angular characteristics of relativistic charged secondaries have been studied in terms of pseudo-rapidity, and bimodality is found to be absent in the distributions. The mean pseudo-rapidity seems to be independent of grey and heavy particle multiplicities, which indicates its independence with number of collisions. Finally, the correlation between different particle multiplicities in this paper is discussed.