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Thermal Bremsstrahlung probing nuclear multifragmentation in nucleus-nucleus collisions around the Fermi energy

Abstract : The thermodynamical properties of nuclear matter at moderate temperatures and densities, in the vicinity of the predicted nuclear liquid-gas phase transition, are studied using as experimental probe the hard-photons (E_gamma > 30 MeV) emitted in nucleus-nucleus collisions. Photon and charged-particle production in four different heavy-ion reactions (36Ar+197Au, 107Ag, 58Ni, 12C at 60A MeV) is measured exclusively and inclusively coupling the TAPS photon spectrometer with two charged-particle and intermediate-mass-fragment detectors covering nearly 4pi.

We confirm that bremsstrahlung emission in first-chance (off-equilibrium) proton-neutron collisions (pn gamma) is the dominant origin of hard photons. We also firmly establish the existence of a thermal radiation component emitted in second-chance proton-neutron collisions. This thermal bremsstrahlung emission takes place in semi-central and central nucleus-nucleus reactions involving heavy targets. We exploit this observation i) to demonstrate that thermal equilibrium is reached during the reaction, ii) to establish a new thermometer of nuclear matter based on bremsstrahlung photons, iii) to derive the thermodynamical properties of the excited nuclear sources and, in particular, to establish a ``caloric curve" (temperature versus excitation energy) and iv) to assess the time-scales of the nuclear break-up process.
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https://tel.archives-ouvertes.fr/tel-00202019
Contributor : David d'Enterria <>
Submitted on : Thursday, January 3, 2008 - 9:09:38 PM
Last modification on : Thursday, February 1, 2018 - 1:34:18 AM
Long-term archiving on: : Tuesday, April 13, 2010 - 4:11:22 PM

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  • HAL Id : tel-00202019, version 1

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D. d'Enterria. Thermal Bremsstrahlung probing nuclear multifragmentation in nucleus-nucleus collisions around the Fermi energy. Nuclear Theory [nucl-th]. Université de Caen, 2000. English. ⟨tel-00202019⟩

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