The flattening phase transition in systems of trapped ions

2009 ◽  
Vol 87 (10) ◽  
pp. 1425-1435 ◽  
Author(s):  
Taunia L. L. Closson ◽  
Marc R. Roussel

When the anisotropy of a harmonic ion trap is increased, the ions eventually collapse into a two-dimensional structure consisting of concentric shells of ions. This collapse generally behaves like a second-order phase transition. A graph of the critical value of the anisotropy parameter vs. the number of ions displays substructure closely related to the inner-shell configurations of the clusters. The critical exponent for the order parameter of this phase transition (maximum extent in the z direction) was found computationally to have the value β = 1/2. A second critical exponent related to displacements perpendicular to the z axis was found to have the value δ = 1. Using these estimates of the critical exponents, we derive an equation that relates the amplitudes of the displacements of the ions parallel to the x–y plane to the amplitudes along the z axis during the flattening process.

1977 ◽  
Vol 32 (1) ◽  
pp. 33-39
Author(s):  
Fred Fischer

Abstract A solid elastic skin on a liquid surface aquires a periodic ripple formation when a compressive strain surpasses a critical value. From a calculation the ripple wavelength is found to be proportional to the 3/4th power of the skin thickness. This instability can be described as a kind of second order phase transition, where a relative amplitude of the ripple wave is the order parameter. In addition, when the skin area is abruptly compressed the ripple wavelength depends on the magnitude of the compressive strain. Examples for skin rippling with wavelengths between 10 μm and 100 m are discussed.


2009 ◽  
Vol 23 (09) ◽  
pp. 2253-2259 ◽  
Author(s):  
M. KURT ◽  
H. YURTSEVEN

The critical behavior of the specific heat is studied in s-triazine ( C 3 N 3 H 3). Using the experimental data for the CP, the temperature dependence of the specific heat is analyzed according to a power-law formula and the values of the critical exponent for CP are extracted in the vicinity of the transition temperature (TC=198.07 K ). It is indicated that s-triazine undergoes a weakly first order (quasi-continuous) or second order phase transition.


2010 ◽  
Vol 88 (9) ◽  
pp. 651-656 ◽  
Author(s):  
Dipak Ghosh ◽  
Argha Deb ◽  
Ruma Saha ◽  
Rupa Das

The target excitation dependence of the degree of multifractality and critical exponent of pions produced for the 16O-AgBr interaction at 60 AGeV has been investigated. To study target excitation dependence, the data for the produced pions were distributed into three sets, depending on the number of grey tracks (ng). The different sets correspond to the different degrees of target excitation. The probability G-moments were used for the analysis in pseudorapidity space. The analysis reveals that the produced particle density distribution possesses multifractal structure for all degrees of target excitation (0 ≤ ng ≤ 3, 4 ≤ ng ≤ 7, and ng ≥ 8). The distribution Levy index and the phase transition critical exponent are calculated. The study indicates the non-thermal phase transition, but it does not show evidence for the second-order phase transition.


2017 ◽  
Vol 31 (11) ◽  
pp. 1750073 ◽  
Author(s):  
Dorílson S. Cambui ◽  
Tarras Iliass

In this paper, we used a self-propelled particle model to study the transition between phases of collective behavior observed in animal aggregates. In these systems, transitions occur when individuals shift from one collective state to another. We investigated transitions induced by both the speed and the noise. Statistical quantities that characterize the phase transition driven by noise, such as order parameter, the Binder cumulant and the susceptibility were analyzed, and we used the finite-size scaling theory to estimate the critical exponent ratios [Formula: see text] and [Formula: see text].


2011 ◽  
Vol 26 (18) ◽  
pp. 3035-3050 ◽  
Author(s):  
SONIA KABANA ◽  
PETER MINKOWSKI

The hypothesis is investigated, that the thermal structure of QCD phases at and near zero chemical potentials is determined by long range coherence, inducing the gauge boson pair condensate, and its thermal extension, representing a fundamental order parameter. A consistent model for thermal behavior including interactions is derived in which the condensate does not produce any latent heat as it vanishes at the critical temperature inducing a second-order phase transition with respect to energy density neglecting eventual numerically small critical exponents. Localization and delocalization of color fields are thus separated by a unique critical temperature.


2003 ◽  
Vol 17 (04n06) ◽  
pp. 614-620 ◽  
Author(s):  
G. SANGIOVANNI ◽  
M. CAPONE ◽  
S. CAPRARA

We review and extend a previous study1 on the symmetry of the superconducting state, stimulated by recent tunneling and Andreev reflection measurements giving robust evidences for the existence of a dx2-y2 + idxy order parameter in the overdoped regime of two different cuprates. Looking for a possible second-order phase transition from a standard dx2-y2 to a mixed and time reversal breaking state, we confirm the results of our previous analysis on La 2-x Sr x CuO 4. In the case of Y 1-y Ca y Ba 2 Cu 3 O 7-x as well, among all the allowed symmetries, the dx2 - y2 + idxy is the most favored one and the unconventional state is likely to occur in a small dome of the phase diagram located in the optimal-overdoped region and at very low temperatures.


2007 ◽  
Vol 310 (2) ◽  
pp. 1410-1412
Author(s):  
F. Ye ◽  
Y.W. Rodriguez ◽  
D.P. Belanger ◽  
J.A. Fernandez-Baca

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