Fusion reactions: Successes and limitations of a one-dimensional description

Bass, R.

doi:10.1007/3-540-09965-4_23

Cited by 51 publications

(19 citation statements)

References 15 publications

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“…We assume that evaporation always selects the "cheaper" species (i.e., protons if C p < C n , neutrons otherwise). In the following, C is calculated from tabulated nucleon separation energies [18] and the Bass prescription [19,20] for the Coulomb barrier. Under this assumption, removal of the "expensive" nuclear species (e.g., protons from 132 Sn and neutrons from 104 Sn) can never occur by evaporation; therefore, it must take place during the cascade stage, and little excitation energy must be available at the beginning of evaporation, otherwise, the competing nuclear species will be evaporated.…”

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confidence: 99%

Evaporation-cost dependence in heavy-ion fragmentation

Audirac¹,

Obertelli²,

Doornenbal³

et al. 2013

Phys. Rev. C

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Inclusive multineutron and multiproton removal cross sections from 112 Sn and 104 Sn at relativistic energies have been measured. The data show two distinct regimes of the reaction process that depend on the nucleon evaporation cost of the final nucleus. This behavior is universal by regarding the mass or asymmetry of the initial system or target composition. A state-of-the-art cascade and deexcitation model reproduces the observed trend but systematically fails in reproducing cross sections for the removal of the more bound nucleon species. The fragmentation of a many-body bound system from the fast collision with an extra particle is a generic problem in areas as different as atomic physics through electron-induced ionization [1], nuclear physics through the nuclear fragmentation in spallation targets [2], or astrophysics through the ejection of rocks from gravitational rings after asteroid collisions [3]. This complex process depends a priori on the two-body interaction cross section, the geometry of the system, and the binding of its individual constituents. This multiparticle removal probability is challenging to predict to a high precision since it also depends on processes, such as the re-interaction of scattered components and the release of dissipation energy by statistical emission of particles, e.g., the ionization of atoms by energetic electrons is impacted by the Auger effect. Models for nuclear fragmentation have been numerous [4]. At kinetic energies larger than 100 MeV/nucleon, it is possible to accurately reproduce experimental fragmentation cross sections by modeling the reaction in two steps: intranuclear cascade (INC) followed by statistical deexcitation of the remnant nucleus [2]. Fragmentation results from the interplay of both processes [5]. In the case of one-nucleon removal, the proton-neutron asymmetry has recently demonstrated important limits of our treatment of direct reactions [6,7], and the role of evaporation in weakly bound nuclei has been questioned for deeply bound nucleon removal [8]. In this Rapid Communication, we present new fragmentation data from stable and unstable Sn isotopes at incident energies of ∼165 MeV/nucleon. We characterize these data by the difference in emission cost between the removed species and the other one, C = C removed − C other , where C n = S n is the neutron-evaporation cost, C p = S p + V c is the proton-evaporation cost, S n(p) is the neutron (proton) separation energy, and V c is the Coulomb barrier. We show that the ejection of identical nucleons presents two universal regimes that depend on the sign of C.Fast 104 Sn and 112 Sn beams at 155 and 173 MeV/nucleon, respectively, have been produced at the RIBF facility, operated conjointly by the RIKEN Nishina Center and the CNS of the University of Tokyo, by fragmentation of a 124 Xe primary beam of 0.5 e μA onto a 0.555 g/cm 2 9 Be production target. The secondary cocktail beams were composed of 104 Sn ( 112 Sn) at 25% (77%) purity. The achieved intensity of 104 Sn was 350 pps. Secondary targets w...

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confidence: 99%

Evaporation-cost dependence in heavy-ion fragmentation

Audirac¹,

Obertelli²,

Doornenbal³

et al. 2013

Phys. Rev. C

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“…They show for the 1n channel a maximum at (122) MeV and a halfwidth of about 5 MeV. The maxima are slightly below the fusion barriers calculated by using the Bass potential [9]. The excitation energy of 12 MeV corresponds to the energy of the maximum of the 1n-channel.…”

Section: Fig 1 -The Decay Chain Ofmentioning

confidence: 96%

Heavy clusters in cold nuclear rearrangements in fusion and fission

Armbruster

1997

Nuov Cim A

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Summary. -The experimental evidence for the appearance of cluster aspects in the dynamics of large rearrangement processes, as fusion and fission, is presented. Clusters in the sense as used in the following are strongly bound, doubly magic neutron rich nuclei as Phys., 51 (1988) 57). I will discuss experiments concerning the stability of clusters to intrinsic excitation energy in fusion and fission (ARMBRUSTER P., Lect. Notes Phys., 158 (1982) 1), and the manifestation of clusters in the fusion entrance channel (ARMBRUSTER P., J. Phys. Soc. Jpn., 58 (1989) 232). The importance of compactness of the clustering system seems to be equally decisive in fission and fusion. Finally, I will cover the importance of clusters for the production of SHEs. 1. -Where are we in the production of the superheavy elements ?Since 1981 six superheavy elements with deformed nuclei were discovered at GSI, Darmstadt. The first three elements bohrium (Bh), hassium (Hs) and meitnerium (Mt) were produced in the eighties [1-3], whereas we synthesized the last three recently after all parts of our experimental equipment were improved and the effective luminosity

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“…However, larger deviations between the models occur for rare TP, i.e. very heavy ones (A~P > 20) and "exotic" isotopes with an extreme lV/Z ratio (3He, llLi, etc. ).…”

Section: Common Parametrizationmentioning

confidence: 98%