Reaction dynamics and hot nuclei formation 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>36</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Ar</mml:mi><mml:mrow><mml:msup><mml:mrow><mml:mo>+</mml:mo></mml:mrow><mml:mrow><mml:mn>98</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Mo</mml:mi></mml:math>reaction at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inlin

Santonocito, D.; Piattelli, P.; Blumenfeld, Y.; Suomijärvi, T.; Agodi, C.; Alamanos, N.; Alba, R.; Auger, F.; Bellia, G.; Chomaz, Ph.; Colonna, M.; Coniglione, R.; Zoppo, A. Del; Finocchiaro, P.; Frascaria, N.; Gillibert, A.; Faou, J.H. Le; Loukachine, K.; Maiolino, C.; Migneco, E.; Roynette, J.C.; Sapienza, P.; Scarpaci, J.A.

doi:10.1103/physrevc.66.044619

Cited by 18 publications

(10 citation statements)

References 53 publications

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“…Moreover, the use of a constant level density parameter instead of one varying with nuclear temperature even worsens the quality of the fit. Therefore in the present work, we confirm a suppression of the GDR γ emission for energies above E * ∼ 2 MeV/nucleon for A = 126, in reasonable agreement with the value of ∼2.5 MeV/nucleon extracted previously for nuclei with similar mass ( [45][46][47]. The same suppression was observed also for lighter nuclei, A = 60-70, at higher excitation energies (E * ∼ 5 MeV/nucleon) [16], denoting a mass dependence of the limiting excitation energy for the collective motion that is very similar to the mass dependence of the limiting temperature that nuclei can sustain [48].…”

Section: Gdr In the Charge Symmetric Reactionsupporting

confidence: 93%

Dynamical dipole mode in fusion reactions at 16 MeV/nucleon and beam energy dependence

Pierroutsakou¹,

Martin²,

Agodi³

et al. 2009

Phys. Rev. C

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High-energy γ rays and light charged particles from the 36Ar + 96Zr and 40Ar + 92Zr reactions at Elab = 16\ud and 15.1 MeV/nucleon, respectively, were measured in coincidence with evaporation residues by means of the\ud MEDEA multidetector array coupled to four parallel plate avalanche counters. The aim of this experiment was to\ud investigate the prompt γ radiation, emitted in the decay of the dynamical dipole mode, in the about 16 MeV/nucleon\ud energy range and to map its beam energy dependence, comparing the present results with our previous ones\ud obtained at lower energies. The studied reactions populate, through entrance channels having different charge\ud asymmetries, a compound nucleus in the region of Ce under the same conditions of excitation energy and spin.\ud Light charged particle energy spectra were used to pin down the average excitation energy and the average mass\ud of the system. By studying the γ -ray spectra of the charge symmetric reaction 40Ar + 92Zr, the statistical giant\ud dipole resonance (GDR) parameters and angular distribution were extracted, and a comparison of the linearized\ud 90◦γ -ray spectra of the two reactions revealed a 12% extra yield in the GDR energy region for the more charge\ud asymmetric system. The center-of-mass angular distribution data of this extra γ yield, compatible with a dipole\ud oscillating along the symmetry axis of the dinuclear system, support its dynamical nature. The experimental\ud findings are compared with theoretical predictions performed within a Boltzmann-Nordheim-Vlasov transport\ud model and based on a collective bremsstrahlung analysis of the entrance channel reaction dynamics.An interesting\ud sensitivity to the symmetry term of the equation of state and to in-medium effects on nucleon-nucleon (nn) cross\ud sections is finally discussed

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Section: Gdr In the Charge Symmetric Reactionsupporting

confidence: 93%

Dynamical dipole mode in fusion reactions at 16 MeV/nucleon and beam energy dependence

Pierroutsakou¹,

Martin²,

Agodi³

et al. 2009

Phys. Rev. C

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“…The velocity v int shows values close to half-beam velocity for all three reactions, similar to those extracted in the proton fits. Temperatures are slightly higher than those extracted in the proton fit but display a similar trend, as observed in previous studies [15,25], increasing from about 8 MeV for reactions at 17A MeV to 9 MeV for the reaction at 23A MeV. Multiplicity values increase from 0.5 in the 116 Sn + 12 C reaction at 17A MeV to 1.1 in the 116 Sn + 24 Mg reaction at 17A MeV, as shown in Table I.…”

Section: Reactionsupporting

confidence: 87%

“…A multiplicity value similar to the one extracted from 12 C reaction at the same beam energy was extracted in agreement with a scenario in which the emitted protons mainly come from the first chance nucleon-nucleon collisions [15,30,32]. The main features of the source lead to an interpretation in which, in a multiple-source picture, the intermediate source represents a way to mimic the pre-equilibrium emission.…”

Section: Reactionsupporting

confidence: 81%

“…The analysis of the evaporation residue velocity distribution shows a centroid shifted to lower velocities, and a width which is, in general, broader than expected from complete fusion, revealing a sizable contribution of incomplete fusion events [23][24][25]. The broadening of the velocity distribution width reflects the contribution due the different momentum transfers leading to systems with different masses and excitations energies [15,25,28]. In this experiment very asymmetric systems were used for which the excitationenergy distribution is expected to be narrow which allows for a better determination of its value.…”

Section: Excitation-energy Determinationmentioning

confidence: 85%

“…Details of the particle and γ -ray identification procedure and typical two-dimensional spectra can be found in Ref. [15]. The BaF 2 detectors were energy calibrated by using the 4.4 and 6.1 MeV γ rays emitted from AmBe and PuC sources.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Onset of quenching of the giant dipole resonance at high excitation energies

et al. 2014

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International audienceThe evolution of the giant dipole resonance (GDR) properties in nuclei of mass A=120 to 132 has been investigated in an excitation energy range between 150 and 270 MeV through the study of complete and nearly complete fusion reactions using Sn116 beams at 17A and 23A MeV from the cyclotron of the Laboratorio Nazionale del Sud impinging on C12 and Mg24 targets. γ rays and light charged particles were detected using the multi-element detector array MEDEA in coincidence with evaporation residues detected by using mass and charge identification spectrometry with telescope (MACISTE). Light-charged-particle energy spectra were analyzed within the framework of a multiple-source-emission scenario by using a fitting procedure to determine the amount of pre-equilibrium emission and deduce the excitation energies reached in the compound nuclei. A detailed analysis of the γ-ray spectra and their comparison with statistical model calculations is presented. Evidence of a quenching of the GDR gamma yield was found at 270 MeV excitation energy. The quenching effect becomes progressively more important with increasing excitation energy, as observed when the comparison is extended to data from the reaction Ar36+Mo96 at 37A MeV where hot nuclei were populated up to 430 MeV excitation energy. A coherent scenario emerges indicating the existence of a limiting excitation energy for the collective motion of about E∗/A=2.1 MeV for systems of mass A=105 to 111 while a slightly lower value was observed for nuclei of mass A∼132. The existence of a possible link between GDR disappearance and the liquid-gas phase transition is discussed

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Evolution of the giant dipole resonance properties with excitation energy

Santonocito¹,

Blumenfeld²

Dynamics and Thermodynamics With Nuclear Degrees of Freedom

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The studies of the evolution of the hot Giant Dipole Resonance (GDR) properties as a function of excitation energy are reviewed. The discussion will mainly focus on the A ∼ 100 − 120 mass region where a large amount of data concerning the width and the strength evolution with excitation energy are available. Models proposed to interpret the main features and trends of the experimental results will be presented and compared to the available data in order to extract a coherent scenario on the limits of the development of the collective motion in nuclei at high excitation energy. Experimental results on the GDR built in hot nuclei in the mass region A ∼ 60 − 70 will be also shown allowing to investigate the mass dependence of the main GDR features. The comparison between limiting temperatures for the collective motion and critical temperatures extracted from caloric curve studies will suggest a possible link between the disappearance of collective motion and the liquid-gas phase transition.

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Reaction dynamics and hot nuclei formation in the36Ar+98Moreaction at
D. Santonocito¹,
P. Piattelli²,
Y. Blumenfeld³
et al.

Cited by 18 publications

References 53 publications

Dynamical dipole mode in fusion reactions at 16 MeV/nucleon and beam energy dependence

Dynamical dipole mode in fusion reactions at 16 MeV/nucleon and beam energy dependence

Onset of quenching of the giant dipole resonance at high excitation energies

Evolution of the giant dipole resonance properties with excitation energy

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Reaction dynamics and hot nuclei formation in the36Ar+98Moreaction atD. Santonocito1, P. Piattelli2, Y. Blumenfeld3 et al.

Cited by 18 publications

References 53 publications

Dynamical dipole mode in fusion reactions at 16 MeV/nucleon and beam energy dependence

Dynamical dipole mode in fusion reactions at 16 MeV/nucleon and beam energy dependence

Onset of quenching of the giant dipole resonance at high excitation energies

Evolution of the giant dipole resonance properties with excitation energy

Contact Info

Product

Resources

About

Reaction dynamics and hot nuclei formation in the36Ar+98Moreaction at
D. Santonocito¹,
P. Piattelli²,
Y. Blumenfeld³
et al.