Observation of Thermodynamical Properties in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>162</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Dy</mml:mi></mml:math>,<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mrow><mml:mn>166</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Er</mml:mi></mml:math>, and<mml:math xmlns:m

Melby, E.; Bergholt, L.; Guttormsen, M.; Hjorth‐Jensen, M.; Ingebretsen, F.; Messelt, S.; Rekstad, J.; Schiller, A.; Siem, S.; Ødegård, S. W.

doi:10.1103/physrevlett.83.3150

Cited by 99 publications

(124 citation statements)

References 12 publications

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“…4 ǫ ⋆ ≈ (ǫ AA +Q)−ǫ coll −ǫ preeq −ǫ rot , where: (i) the reaction Q-value and ǫ rot are of the order ∼1A MeV and have opposite signs, and (ii) the radial flow energy, ǫ coll , and the pre-equilibrium component, ǫ preeq , represent ∼3A MeV for a symmetric system at these energies [1][2][3]. 5 Note however that both, ALADIN and EOS, collaborations have updated slightly upwards their original curves (shown in Fig. 3) to account for several corrections in T (sequential feedings) and ǫ ⋆ (collective radial flow energy), see e.g.…”

Section: Caloric Curvementioning

confidence: 99%

Thermal bremsstrahlung photons probing the nuclear caloric curve

et al. 2002

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Hard-photon (E γ > 30 MeV) emission from second-chance nucleon-nucleon Bremsstrahlung collisions in intermediate energy heavy-ion reactions is studied employing a realistic thermal model. Photon spectra and yields measured in several nucleus-nucleus reactions are consistent with an emission from hot nuclear systems with temperatures T ≈ 4 -7 MeV. The corresponding caloric curve in the region of excitation energies ǫ ⋆ ≈ 3A -8A MeV shows lower values of T than those expected for a Fermi fluid.

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Section: Caloric Curvementioning

confidence: 99%

Thermal bremsstrahlung photons probing the nuclear caloric curve

et al. 2002

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“…One method, which is limited to the particle bound excitation energy region, involves the measurement of continuum γ-ray spectra following inelastic scattering and transfer reactions [11]. Both NLD and γ-ray strength function are inputs to the analysis of the spectra.…”

mentioning

confidence: 99%

Measurement of the Damping of the Nuclear Shell Effect in the Doubly MagicPb208Region

et al. 2013

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The damping of the nuclear shell effect with excitation energy has been measured through an analysis of the neutron spectra following the triton transfer in the 7 Li induced reaction on 205 Tl.The measured neutron spectra demonstrate the expected large shell correction energy for the nuclei in the vicinity of doubly magic 208 Pb and a small value around 184 W. A quantitative extraction of the allowed values of the damping parameter γ, along with those for the asymptotic nuclear level density parameterã, has been made for the first time. The shell effect is a cornerstone of the mean field theory describing finite fermionic systems. The shell structure in atoms decides the chemical properties of the corresponding elements. In nuclear physics the spin orbit coupling, in addition, plays a dominant role in deciding the shell closures and the associated magic numbers of protons and neutrons. The nuclei having such numbers of neutrons and protons have an extra stability with respect to that expected from the average behaviour described by the liquid drop model (LDM). Many important nuclear phenomena such as the occurrence of super heavy elements [1,2], fission isomers [3,4], super-deformed nuclei [5] and new magic numbers in exotic nuclei [6,7] are the consequences of the shell effect. The shell effect also affects another fundamental property of the nucleus viz. the nuclear level density (NLD). The NLD is an indispensable input to the statistical calculation of compound nuclear decay and thus an important physical quantity for many practical applications, such as the calculations of reaction rates relevant to nuclear astrophysics, nuclear reactors and spallation neutron sources.The NLD was first calculated by Bethe using a noninteracting Fermi gas model, without shell effects, arriving at its leading dependence on excitation energy (E X ) and angular momentum (J) [8,9]. The generic behaviour with respect to E X is described by e 2 √ aE X . Here 'a' is the NLD parameter which is related to the single particle density at the Fermi energy. Direct measurements of the NLD are based on the study of slow neutron resonances, which are mainly s-and p-wave, and are extrapolated to higher J values to estimate the angular momentum summed or total NLD. The total NLD inferred from such a measurement shows that on the average the level density parameter a increases linearly with the mass number (A) of the nucleus as a ≈A/8 MeV −1 . However, there is a significant departure from this liquid drop value at shell closures. This departure is the largest for the doubly magic nucleus 208 Pb, where a (at E X ∼7 MeV) is as low as A/26 MeV −1 . This shell effect on the NLD parameter is expected to damp with excitation energy so that a approaches its liquid drop value at E X ∼ 40 MeV [10]. It is important to make measurements on the damping of the shell effect over a wide E X range. To our knowledge, no such measurement has been reported.Experimental information on the damping of the shell effect can be obtained by measuring the E X dependence...

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“…In the associated extensive ensemble, the bimodality condition is also equivalent to the requirement of a convexity anomaly in the thermodynamic potential. The first experimental evidences of such a phenomenon have been reported recently in different fields: the melting of sodium clusters [6],the fragmentation of hydrogen clusters [8], the pairing in nuclei [9] and nuclear multifragmentation [7,87,88]. However, much more experimental and theoretical studies are now expected to progress in this new field of phase transitions in finite systems.…”

Section: Resultsmentioning

confidence: 99%

“…This may be the case of non saturating forces such as the gravitational [2,3,4,5] or the Coulombic forces. The system may be too small, as in the case of clusters and nuclei [6,7,8,9]. The physics of finite systems is even more complicated since often they are not only small but also open and transient.…”

Section: Introduction: Unusual Mesoscopic Worldsmentioning

confidence: 99%

Phase Transitions in Finite Systems using Information Theory

Chomaz

Gulminelli²

2008

AIP Conference Proceedings

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Abstract. In this paper, we present the issues we consider as essential as far as the statistical mechanics of finite systems is concerned. In particular, we emphasis our present understanding of phase transitions in the framework of information theory. Information theory provides a thermodynamically-consistent treatment of finite, open, transient and expanding systems which are difficult problems in approaches using standard statistical ensembles.As an example, we analyze is the problem of boundary conditions, which in the framework of information theory must also be treated statistically. We recall that out of the thermodynamical limit the different ensembles are not equivalent and in particular they may lead to dramatically different equation of states, in the region of a first order phase transition. We recall the recent progresses achieved in the understanding of first-order phase transition in finite systems: the equivalence between the Yang-Lee theorem and the occurrence of bimodalities in the intensive ensemble and the presence of inverted curvatures of the thermodynamic potential of the associated extensive ensemble. We come back to the concept of order parameters and to the role of constraints on order parameters in order to predict the expected signature of first-order phase transition: in absence of any constraint (intensive ensemble) bimobality of the event distribution is expected while an inverted curvature of the thermodynamic potential is expected at a fixe value of the order parameter (extensive ensemble) in between the phases (coexistence zone). We stress that this discussion is not restricted to the possible occurrence of negative specific heat, but can also include negative compressibility's and negative susceptibilities, and in fact any curvature anomaly of the thermodynamic potential.

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Observation of Thermodynamical Properties in the162Dy,166Er, and

Cited by 99 publications

References 12 publications

Thermal bremsstrahlung photons probing the nuclear caloric curve

Thermal bremsstrahlung photons probing the nuclear caloric curve

Measurement of the Damping of the Nuclear Shell Effect in the Doubly MagicPb208Region

Phase Transitions in Finite Systems using Information Theory

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