Clustering features of 14^{14}N nuclei in relativistic multifragmentation process

Progress in the study of the peripheral nuclear interactions in $^{14}N$ dissociation at $2.1A GeV$ in nuclear emulsion is outlined. The leading role of the multiple fragmentations in the most peripheral nucleus interactions is discussed. The production of unusual states, for which a regrouping of nucleons beyond the $\alpha$-particle clustering is needed, is identified for this channel.Comment: 6 pages, 4 figures, International Conference "Current Problems in Nuclear Physics and Atomic Energy" (NPAE-Kyiv2008), 9-15 June, 2008, Ukrain

Dissociation of relativistic nuclei in peripheral interactions in nuclear track emulsion

Possibilities of the nuclear emulsion technique for the study of the systems of several relativistic fragments produced in the peripheral interactions of relativistic nuclei are discussed. The interactions of the $^{10}$B and $^{9}$Be nuclei in emulsion are taken as an example to show the manifestation of the cluster degrees of freedom in relativistic fragmentation. For the case of the relativistic $^{9}$Be nucleus dissociation it is shown that exact angular measurements play a crucial role in the restoration of the excitation spectrum of the alpha particle fragments. The energy calibration of the angular measurements by the $^{9}$Be nucleus enables one to conclude reliably about the features of internal velocity distributions in more complicated systems of relativistic $\alpha$ particles.Comment: 7 pages, 10 figures, conference: NATO ARW & INTAS Summer School, Kurpaty, Yalta, Ukraine, September 10-17, 200

Unstable nuclei in dissociation of light stable and radioactive nuclei in nuclear track emulsion

A role of the unstable nuclei ${}^{6}$Be, ${}^{8}$Be and ${}^{9}$B in the dissociation of relativistic nuclei ${}^{7,9}$Be, ${}^{10}$B and ${}^{10,11}$C is under study on the basis of nuclear track emulsion exposed to secondary beams of the JINR Nuclotron. Contribution of the configuration ${}^{6}$Be + \mit{n} to the ${}^{7}$Be nucleus structure is 8 $\pm$ 1% which is near the value for the configuration ${}^{6}$Li + \mit{p}. Distributions over the opening angle of $\alpha$-particle pairs indicate to a simultaneous presence of virtual ${}^{8}$Be$_{g.s.}$ and ${}^{8}$Be$_{2^+}$ states in the ground states of the ${}^{9}$Be and ${}^{10}$C nuclei. The core ${}^{9}$B is manifested in the {${}^{10}$C} nucleus with a probability of 30 $\pm$ 4%. Selection of the ${}^{10}$C "white" stars accompanied by ${}^{8}$Be$_{g.s.}$ (${}^{9}$B) leads to appearance in the excitation energy distribution of 2$\alpha$2\mit{p} "quartets" of the distinct peak with a maximum at 4.1 $\pm$ 0.3 MeV. ${}^{8}$Be$_{g.s.}$ decays are presented in 24 $\pm$ 7% of 2He + 2H events of the ${}^{11}$C coherent dissociation and 27 $\pm$ 11% of the 3He ones. The channel ${}^{9}$B + H amounts 14 $\pm$ 3%. The ${}^{8}$Be$_{g.s.}$ nucleus is manifested in the coherent dissociation ${}^{10}$B $\to$ 2He + H with a probability of 25 $\pm$ 5% including 14 $\pm$ 3% of ${}^{9}$B decays. A probability ratio of the mirror channels ${}^{9}$B + \mit{n} and ${}^{9}$Be + \mit{p} is estimated to be 6 $\pm$ 1.Comment: To be published in Physics of Particles in Nuclei (in press

Secondary nuclear fragment beams for investigations of relativistic fragmentation of light radioactive nuclei using nuclear photoemulsion at Nuclotron

Slowly extracted relativistic beams of light nuclei and a beam transportation line net system constitute a good base for secondary nuclear beams forming at the LHE accelerator facility. A recent years activity in the field at the Laboratory is connected with a project on study light nuclei structure by means the emulsion technique [1,2]. The paper shortly summarizes results of the work

Manifestation of Jet Quenching in the Total Transverse Energy Distributions in the Nucleus-Nucleus Collisions

In the framework of the HIJING model global characteristics of nucleus- nucleus collisions are studied for a Large Hadron Collider energy scale. An interesting model prediction is the presence of a central bump over a pseudorapidity plateau of a total transverse energy distribution. The bump is induced by a jet quenching effect in a dense nuclear matter. It is shown that on a wide acceptance calorimeter with a pseudorapidity coverage -5 < \eta < 5 allow to obtain experimental confirmation of such an effect.Comment: 9 pages, 5 figure

Global Features of Nucleus-Nucleus Collisions in the Ultrarelativistic Domain

HIJING generator simulation of nucleus-nucleus collisions at ultrarelativistic energies are presented. Is shown, that the global characteristics of nucleus-nucleus collisions, such as of distribution of a charge multiplicity, total and electromagnetic transverse energy over pseudorapidity are rather sensitive to some predictions of formation models of high-exited nuclear medium, namely parton energy losses in dense nuclear matter. This losses results to appearance of a broad maximum in global variable distributions over pseudorapidity. The most profound of this effect occurs at central heavy ion collisions at LHC energy.Comment: 7 pages, 5 figure

Rapidity distribution of jet quenching: effects on global observables

We discuss modification in the rapidity distribution of the transverse energy flow as a signal of medium-induced partonic energy loss in ultrarelativistic heavy ion collisions. A scan of the global energy flow and jet rates in the wide rapidity region might provide the important information about the pseudo-rapidity size of a dense medium created in heavy ion collisions at the LHC

The Hoyle state in relativistic dissociation of light nuclei

In the context of the search for triples of relativistic $\alpha$-particles in the Hoyle state, the analysis of available data on the dissociation of the nuclei ${}^{12}$C, ${}^{16}$O and ${}^{22}$Ne in the nuclear emulsion was carried out. The Hoyle state is identified by the invariant mass calculated from pair angles of expansion in $\alpha$-triples in the approximation of the conservation of the momentum per nucleon of the parent nucleus. The contribution of the Hoyle state to the dissociation of ${}^{12}$C $\to$ 3$\alpha$ is 11\%. In the case of the coherent dissociation of ${}^{16}$O $\to$ 4$\alpha$ it reaches 22\% when the portion of the channel ${}^{16}$O $\to$ 2${}^{8}$Be is equal to 5\%.Comment: Submitted to Physics of Atomic Nucle

Clustering features of the 7^7Be nucleus in relativistic fragmentation

Charge topology of fragmentation of 1.2 A GeV $^7$Be nuclei in nuclear track emulsion is presented.The dissociation channels $^4$He + $^3$He, 2$^3$He+ n, $^4$He + 2$^1$H are considered in detail. It is established that the events $^6$Be + n amount about to 27 % in the channel $^4$He + 2$^1$H.Comment: 5 pages, 3 figures, conference: The 22nd European Conference on Few Body Problems in Physics, Krak\'ow, Poland, 9 - 13 September 201

Estimation of Collision Impact Parameter

We demonstrate that the nuclear collision geometry (i.e. impact parameter) can be determined with 1.5 fm accuracy in an event-by-event analysis by measuring the transverse energy flow in the pseudorapidity region $3 \le |\eta| \le 5$ with a minimal dependence on collision dynamics details at the LHC energy scale. Using the HIJING model we have illustrated our calculation by a simulation of events of nucleus-nucleus interactions at the c.m.s energy from 1 up to 5.5 TeV per nucleon and various type of nuclei