ترغب بنشر مسار تعليمي؟ اضغط هنا

Yield scaling, size hierarchy and fluctuations of observables in fragmentation of excited heavy nuclei

97   0   0.0 ( 0 )
 نشر من قبل Nicolas Le Neindre
 تاريخ النشر 2007
  مجال البحث
والبحث باللغة English
 تأليف N. Le Neindre




اسأل ChatGPT حول البحث

Multifragmentation properties measured with INDRA are studied for single sources produced in Xe+Sn reactions in the incident energy range 32-50 A MeV and quasiprojectiles from Au+Au collisions at 80 A MeV. A comparison for both types of sources is presented concerning Fisher scaling, Zipf law, fragment size and fluctuation observables. A Fisher scaling is observed for all the data. The pseudo-critical energies extracted from the Fisher scaling are consistent between Xe+Sn central collisions and Au quasi-projectiles. In the latter case it also corresponds to the energy region at which fluctuations are maximal. The critical energies deduced from the Zipf analysis are higher than those from the Fisher analysis.

قيم البحث

اقرأ أيضاً

An effective Finite-Size Scaling (FSS) of moment products from recent STAR measurements of the variance $sigma$, skewness $S$ and kurtosis $kappa$ of net-proton multiplicity distributions, are reported for a broad range of collision centralities in A u+Au ($sqrt{s_{NN}}= 7.7 - 200$ GeV) collisions. The products $Ssigma $ and $kappa sigma^2 $, which are directly related to the hgher-order baryon number susceptibility ratios $chi^{(3)}_B/chi^{(2)}_B$ and $chi^{(4)}_B/chi^{(2)}_B$, show scaling patterns consistent with earlier indications for a second order phase transition at a critical end point (CEP) in the plane of temperature vs. baryon chemical potential ($T,mu_B$) of the QCD phase diagram. The resulting scaling functions validate the earlier estimates of $T^{text{cep}} sim 165$ MeV and $mu_B^{text{cep}} sim 95$ MeV for the location of the CEP, and the critical exponents used to assign its 3D Ising model universality class.
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 $^{8}$Be and $^{9}$B nuclei, as well as the Hoyl e state. These extremely short-lived states are identified by invariant masses calculated from the angles in 2$alpha$-pairs, 2$alpha p$- and 3$alpha$-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 $^{8}$Be nuclei and the multiplicity of accompanying $alpha$-particles in the dissociation of relativistic $^{16}$O, $^{22}$Ne, $^{28}$Si, and $^{197}$Au nuclei. On the above basis, estimates of this correlation are presented for the unstable $^{9}$B nucleus and the Hoyle state. The enhancement in the $^{8}$Be contribution to dissociation with the $alpha$-particle multiplicity has been found. Decays of $^{9}$B nuclei and Hoyle states follow the same trend.
68 - A. Obertelli , A. Gade , D. Bazin 2006
Fragmentation reactions with intermediate-energy heavy-ion beams exhibit a wide range of reaction mechanisms, ranging from direct reactions to statistical processes. We examine this transition by measuring the relative population of excited states in several sd-shell nuclei produced by fragmentation with the number of removed nucleons ranging from two to sixteen. The two-nucleon removal is consistent with a non-dissipative process whereas the removal of more than five nucleons appears to be mainly statistical.
Experimental results on peripheral fragmentation of relativistic $^{11}$B nuclei are presented. In the experiment the emulsions exposured to $^{11}$B beam with momentum 2.75 A GeV/c at the JINR Nuclotron are used. The relative probability of various fragmentation channels for nucleus breakups (class A) and more violent peripheral interactions (class B) have been determined. For classes under investigations the sum of the fragment charges in narrow forward cone is equal to the projectile charge, but in the events of class A there are no secondary particles and in the events of class B there are. In both classes the main channels is $^{11}$B$to$2He+X: 62% and 50%, corresponding. The main channel $^{11}$B$to$2(Z$_{fr}$=2)+(Z$_{fr}$=1) was investigated in details. Momentum measurements of single-charged fragments have been done to determine number of p, d and t in the channel. This way it was found that the ratio N$_{p}$ : N$_{d}$ : N$_{t}$ is about 1:1:1 for $^{11}$B nuclei dissociation and about 15:5:1 for peripheral interactions of $^{11}$B nuclei.
In the present paper, experimental observations of the multifragmentation processes of light relativistic nuclei carried out by means of emulsions are reviewed. Events of the type of white stars in which the dissociation of relativistic nuclei is not accompanied by the production of mesons and the target-nucleus fragments are considered. A distinctive feature of the charge topology in the dissociation of the Ne, Mg, Si, and S nuclei is an almost total suppression of the binary splitting of nuclei to fragments with charges higher than 2. The growth of the nuclear fragmentation degree is revealed in an increase in the multiplicity of singly and doubly charged fragments with decreasing charge of the non-excited part of the fragmenting nucleus. The processes of dissociation of stable Li, Be, B, C, N, and O isotopes to charged fragments were used to study special features of the formation of systems consisting of the lightest $alpha$, d, and t nuclei. Clustering in form of the $^3$He nucleus can be detected in white stars via the dissociation of neutron-deficient Be, B, C, and N isotopes.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا