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Quantum phase transitions in mesoscopic systems are studied. It is shown that the main features of phase transitions, defined for infinite number of particles, N--> infinity, persist even for moderate N approximately 10. A Landau analysis of first order transitions is done and a "critical" exponent at the spinodal point is defined. Two order parameters are… (More)
We present a simple method for discerning the evolution from vibrational to rotational structure in nuclei as a function of spin. The prescription is applied to the yrast cascades in the A approximately 110 region and a clear transition from vibrational to rotational motion is found.
It is shown that (152)Sm and other N = 90 isotones are the first empirical manifestation of the newly predicted analytic description of nuclei at the critical point of a vibrator to axial rotor phase transition.
New sideband partners of the yrast bands built on the pi(h11/2)nu(h11/2) configuration were identified in 55Cs, 57La, and 61Pm N = 75 isotones of 134Pr. These bands form with 134Pr unique doublet-band systematics suggesting a common basis. Aplanar solutions of 3D tilted axis cranking calculations for triaxial shapes define left- and right-handed chiral… (More)
We report on a gamma-ray coincidence analysis using a mixed array of hyperpure germanium and cerium-doped lanthanum tri-bromide (LaBr3:Ce) scintillation detectors to study nuclear electromagnetic transition rates in the pico-to-nanosecond time regime in 33,34P and 33S following fusion-evaporation reactions between an 18O beam and an isotopically enriched… (More)
Nuclei below the Z = 50 magic shell gap with A∼100 show a wide variety of structural phenomena. These include excellent examples of vibrational collectivity at low-spins, which give way to more rotational-like excitations with increasing angular momentum. In this paper we present recent results from an experiment performed at Yale to study the yrast… (More)
The aim of this paper is to discuss and compare several architectural possibilities for implementing a simulator for (ultra) sound propagation in a controlled environment (e.g. using specified obstacles and signal sources). Although initially such sound propagation simulators were designed to assist the design of robotic "ears" of autonomous agents trying… (More)
The B(E2;0(+)-->2+) values for the first 2+ excited states of neutron-rich 132,134,136Te have been measured using Coulomb excitation of radioactive ion beams. The B(E2) values obtained for 132,134Te are in excellent agreement with expectations based on the systematics of heavy stable Te isotopes, while that for 136Te is unexpectedly small. These results are… (More)
Recently, a set of nine nonmagic nuclei with anomalous values of the B(E2) ratio B 4/2 ≡ B(E2; 4 + 1 → 2 + 1)/B(E2; 2 + 1 → 0 + 1) < 1 were identified. Such values are outside the range allowed by current collective models. In the present work, the B(E2; 4 + 1 → 2 + 1) values for two of these nuclei, 98 Ru and 180 Pt, were re-measured to determine if the… (More)
Shape/phase transitions in atomic nuclei have first been discovered in the framework of the Interacting Boson Approximation (IBA) model. Critical point symmetries appropriate for nuclei at the transition points have been introduced as special solutions of the Bohr Hamiltonian, stirring the introduction of additional new solutions describing wide ranges of… (More)