Narrow Results

The correlations between the multiplicities of secondary charged particles emitted in collisions of 3 A GeV/c⁷Li with emulsion have been studied. The dependence of the correlation strength on the mass number of the projectile has been analyzed. Moreover, the dependence of the average multiplicities of shower particle emitted in the forward and backward hemispheres on the number of target fragments has been investigated. The study of the number of backward slow protons (black and grey particles) indicates that, while the number of backward particles is a good factor representing the purely target fragments, the number of backward grey particles can be considered an accurate experimental factor for the impact parameter dependence of the collision.

The characteristics of the interactions of 4.5A GeV/c²⁸Si nuclei with emulsion have been investigated. The method of separating interactions into those with hydrogen, light and heavy target nuclei has been discussed. The multiplicity distribution, average multiplicities, multiplicity correlation and the angular distributions of the secondary particles emitted in ²⁸Si-emulsion are calculated according to the Modified Fritiof Model and compared with the experimental data and with other available data for p, ¹²C, ²⁴Mg at the same energy. It has been found that the modified Fritiof model can describe the multiplicity characteristics of the different emitted particles in the above-mentioned interaction with different target groups. The comparison of the experimental data with the modified Fritiof model shows no clear preference for the case of the light target while it seems to be nearer to the experimental data in the case of the heavy target and the emulsion

A systematic study and statistically significant results of the different types of correlations, for angles, rapidity and rapidity intervals, between various charged secondary particles and projectile fragments produced in the inelastic interactions of ²⁴Mg with emulsion at 4.5A GeV/c have been investigated. All types of particles are found to be emitted asymmetrically in the azimuthal plane. This asymmetry increases with decreasing the impact parameter. The two-particle correlation function is found to be positive except in the extreme projectile fragmentation region. It has also been observed that the particles belonging to the different kinematical regions of the nucleus-nucleus interactions (intergroup correlation) have a tendency to be emitted from opposite sides of the azimuthal plane. The azimuthal angle correlations for pairs of charged secondary particles are also studied.

The experimental results of multiplicity distributions of grey and relativistic shower particles emitted in the interactions of ²⁸Si and ¹²C ions at 4.5 A GeV/c with nuclear emulsion are reported. The study of the multiplicity distributions of relativistic shower particles and medium energy target-associated protons produced in heavy-ion collisions seems to observe the semi-inclusive KNO scaling. A simplified universal function has been used to represent the experimental data.

Nakamura and Kudo proposed a scaling form for charged particle pseudorapidity distributions on the basis of scaling in the mean hypothesis. This scaling form was tested primarily for hadron–hadron interaction data. But no attempt was made to verify this for hadron–nucleus interaction which offers unique opportunity to learn about the space–time structure of a strongly interacting process. In view of this we report an analysis of p–AgBr interaction data at 400 GeV/c and 200 GeV/c, π^-–AgBr interaction data at 200 GeV/c and 350 GeV/c to test its (Nakamura–Kudo scaling) validity in hadron–nucleus interaction. In all cases the data show a remarkable agreement with the scaling behavior of Nakamura and Kudo.

The present paper deals with the interactions of ²²Ne and ²⁸Si nuclei at (4.1–4.5)A GeV/c with emulsion. Some characteristics of the compound multiplicity n_c given by the sum of the number of shower particles n_s and grey particles n_g have been investigated. The present experimental data are compared with the corresponding ones calculated according to modified cascade evaporation model (MCEM). The results reveal that the compound multiplicity distributions for these two reactions are consistent with the corresponding ones of MCEM data. It can also be seen that the peak of these distributions shifts towards a higher value of n_c with increasing projectile mass. It may further be seen that the compound multiplicity distributions becomes broader with increasing target size and its width increases with the size of the projectile nucleus. In addition, it has been found that the MCEM can describe the compound multiplicity characteristics of the different projectile, target and the correlation between different emitted particles. The values of average compound multiplicity increase with increasing mass of the projectile. Furthermore, it is observed that while the value of 〈n_c〉 depends on the mass number of the projectile A_p and the target mass number A_t, the value of the ratio 〈n_c〉/D(n_c) seems to be independent of A_p and A_t. The impact parameter is found to affect the shape of the compound multiplicity distribution. Finally, the dependence of the average compound multiplicity on the numbers of grey and black particles, and the sum of them, is obvious. The values of the slope have been found to be independent of the projectile nucleus.

In the present paper, some results on the correlations of the nucleus–nucleus interactions, at high energy, between different particle multiplicities are reported. The correlations between the multiplicities of the different charged particles emitted in the interactions of ²²Ne and ²⁸Si nuclei with emulsion at (4.1–4.5)A GeV/c have been studied. The correlations of the compound multiplicity n_c, defined as the sum of both numbers of the shower particles n_s and grey particles n_g, have been investigated. The experimental data have been compared with the corresponding theoretical ones, calculated according to the modified cascade evaporation model (MCEM). An agreement has already been fairly obtained between the experimental values and the calculated ones. The dependence of the average compound multiplicity, on the numbers of shower, grey, black and heavy particles is obvious and the values of the slope have been found to be independent of the projectile nucleus. On the other hand, the variation of the average shower, grey, black and heavy particles is found to increase linearly with the compound particles. A strong correlation has been observed between the number of produced shower particles and the number of compound particles. Moreover, the value of the average compound multiplicity is found to increase with the increase of the projectile mass. Finally, an attempt has also been made to study the scaling of the compound multiplicity distribution showing that the compound multiplicity distribution is nearly consistent with the KNO scaling behavior.

The experimental results on the multiplicity and probability distribution of the emitted charged pions $(N_{\pi })$ in the interactions of ${}^{84}$Kr${}_{36}$ projectile at around 1GeV per nucleon with nuclear emulsion targets are reported. In this work, we have employed a wounded nucleon model (WNM) to calculate the total number of wounded nucleons $(W)$ and the total number of interactions $(\nu )$. The dependence of average multiplicities of produced relativistic charged particles on the calculated wounded nucleons and total interactions are investigated. The obtained results revealed that the average multiplicity of $〈N_{\pi }〉$ is dependent on the projectile and target mass number. The calculated values of the total number of wounded nucleons and the total numbers of interactions show a strong dependence on the mass of the colliding nuclei. The emission rate of the mean multiplicity of $〈N_s〉$ and $〈N_{\pi }〉$ linearly increases with increasing the total number of wounded nucleons and interactions.

In this work, the interactions of ⁷Li 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 of ⁷Li 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 of ⁷Li are systematically compared with the other interactions at different energies. The results agree with the corresponding results at nearly the same energy.

This paper deals with the interactions of ${}^{12}$C-nucleus with the nuclear emulsion at 4.5AGeV/c, focused on distributions of multiplicity and the variation of the average multiplicities for secondary charged particles (black, gray, shower, and heavy particles) for the events released from these interactions. These averages have been calculated based on a model of modified cascade evaporation. A comparison has been made between the average multiplicities of the charged secondary particles produced from ${}^{12}$C and others from projectiles that interact with the nuclear emulsion at different energies, this comparison of ${}^{12}$C with other projectiles shows the fluctuations of the values of the average shower with gray for ${}^{16}$O and ${}^{28}$Si interactions occurring somewhat faster. The average number of shower, gray particles increases with the increasing mass number of the projectile Ap, except for black particles, which are nearly constant. The correlations of the average multiplicities for the different charged secondary particles are discussed. There is strong linear dependence in the correlations of average particles of shower, compound, and heavy on gray particles. The results of experimental and theoretical data were also verified with recent analysis data and new observations and were found to be consistent. Moreover, the results indicate that the residual target nucleus may have reached a temperature and constant excitation energy at a certain value for shower particles. The excess amount of energy at higher values of shower particles may be pumped into the system, and this energy may be expended during a transition of phase in the target nucleus system. The theoretical calculation results show good agreement with experimental data.

The OPERA experiment (Oscillation Project with Emulsion tRacking Apparatus) has been designed to confirm the neutrino oscillation hypothesis by direct observation of the tau neutrino appearance coming out of a (almost) pure muon neutrino beam. The beam is extracted from the SPS at CERN towards the Gran Sasso Underground Laboratory, the location of OPERA, 730km afar. In order to detect the leptonic tau decays, the vertex detector needs a spatial resolution of the order of micrometers. Nuclear emulsion films are the only detector materials capable of fulfilling this tight condition. In addition, emulsion scanning techniques have been significantly improved during the last recent neutrino experiments. This article is going to review the status of the detector, the neutrino beam properties, the first results from the 2008 run and the neutrino event analyses putting special emphasis on the emulsion detection technique.

The OPERA experiment aims at the direct confirmation of the leading oscillation mechanism in the atmospheric sector looking for the appearance of ν_τ in an almost pure ν_μ beam (the CERN CNGS beam). In five years of physics run the experiment collected 17.97 × 10¹⁹ p.o.t. The detection of τS produced in ν_τ CC interactions and of their decays is accomplished exploiting the high spatial resolution of nuclear emulsions. Furthermore OPERA has good capabilities in detecting electron neutrino interactions, setting limits on the ν_μ → ν_ℯ oscillation channel. In this talk the status of the analysis will be presented together with updated results on both oscillation channels.

Cosmic ray muon radiography is a novel technique for imaging the internal structure of volcanoes. It exploits the capability of high energy muons from cosmic-rays to penetrate large thicknesses of rock, in order to obtain a density map of volcanic edifices and trying to guess informations on the variation in the rock density distribution, like those expected from dense lava conduits, or low density magma supply paths. Nuclear emulsions are tracking detectors well suited to be employed in this context since they have an excellent angular resolution (few mrad), they are cheap, compact and robust, easily transportable on a mountain, able to work in harsh environments, and do not require power supply. The main drawback in the usage of such passive detectors is the time consuming procedure of data acquisition since a large detector area (of the order of 1 m²) is needed to collect a sufficient statistics of muons. In the last decade, the development of faster automatic scanning systems made it possible to overcome this difficulty. The first successful result in the field of muon radiography with nuclear emulsions was obtained by a Japanese group that observed in 2007 the conduit structure of the active Mt. Asama volcano. Since 2010, other volcanoes have been explored with the same technique: Mt. Unzen in Japan in 2010, Stromboli volcano in Italy in 2011, and Mt. Teide in Tenerife in 2012. An overview of the Stromboli emulsion detector design will be given, followed by the preliminary results obtained. Next plans for future projects will be also considered.

Nuclear emulsion was used to search for double-Λ hypernuclei for a half century. We have nine events showing sequential decay of two units of Λ hyperon in nucleus, however our knowledge of Λ-Λ interaction is still poor, so far. Based on knowhow given by the past emulsion experiments, the E07 experiment at J-PARC is expected to present the events in ~10² and ~10³ with Hybrid-emulsion and Overall-scanning method, respectively.

The OPERA experiment aims at providing a direct proof of the ν_μ → ν_τ oscillations by observing ν_τ CC interactions in an high purity ν_μ accelerator beam, the CNGS (CERN Neutrinos to Gran Sasso). The beam exposure started in 2008 and ended in 2012. Events recorded in the Emulsion Cloud Chamber detectors, made of lead plates and nuclear emulsions, are being analysed since 2008. In the last period, a large amount of data has been extracted additionally, leading to the validation of the 4th ν_τ candidate event. This new result brings the observation of the oscillation with a significance exceeding 4 sigma.