Elastic scattering of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mi mathvariant="normal">Li</mml:mi><mml:mprescripts /><mml:none /><mml:mn>7</mml:mn></mml:mmultiscripts><mml:mo>+</mml:mo><mml:mmultiscripts><mml:mi mathvariant="normal">Si</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>28</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math>at near-barrier energies

Pakou, A.; Alamanos, N.; Doukelis, G.; Gillibert, A.; Kalyva, G.; Kokkoris, M.; Kossionides, S.; Lagoyannis, A.; Musumarra, A.; Papachristodoulou, C.; Patronis, N.; Perdikakis, G.; Pierroutsakou, D.; Pollacco, E. C.; Rusek, K.

doi:10.1103/physrevc.69.054602

Cited by 108 publications

(101 citation statements)

References 30 publications

(44 reference statements)

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“…The reason may probably be due to the competition between the attractive polarization potential due to the bound excited state of 7 Li [28] and the repulsive breakup polarization potential [29]. The BTA has also been observed is some neutron and proton radioactive halo nuclei such as, 6 He with 209 Bi [30] and 8 B with 58 Ni [24,31].…”

mentioning

confidence: 96%

“…This new phenomenon has been termed the breakup threshold anomaly (BTA) [3]. Based on their measured transfer cross section much higher than the breakup cross section at the near barrier energy for the 6,7 Li + 28 Si system, Pakou et al [4][5][6][7][8] argue that transfer channels can also be important at low energies for some weakly bound systems, and therefore those channels may be the main reason for the nondecreasing of the imaginary potential at near barrier energies. The BTA has been investigated in a large number of nuclear systems involving weakly bound projectiles with a variety of medium and large mass targets, for instance 9…”

mentioning

confidence: 99%

“…A simultaneous analysis of elastic scattering, fusion, and total reaction cross sections for the weakly bound systems 6,7 Li + 28 Si at energies close to the Coulomb barrier is performed by optical model calculations. The nuclear polarization potential U is split into volume part U F , which accounts for fusion reactions and a surface part U DR , responsible for direct reactions.…”

mentioning

confidence: 99%

“…Based on their measured transfer cross section much higher than the breakup cross section at the near barrier energy for the 6,7 Li + 28 Si system, Pakou et al [4][5][6][7][8] argue that transfer channels can also be important at low energies for some weakly bound systems, and therefore those channels may be the main reason for the nondecreasing of the imaginary potential at near barrier energies. The BTA has been investigated in a large number of nuclear systems involving weakly bound projectiles with a variety of medium and large mass targets, for instance 9 Be with 27 Al [9], with 64 Zn [10][11][12][13], with 144 Sm [14,15] and with 208 Pb, 209 Bi [16,17]; 6 Li and 7 Li with targets 208 Pb [3,18], 27 Al [19][20][21], 144 Sm [22], 58,64 Ni [23,24], 59 Co [25], 90 Zr [26], 138 Ba [11,27,28], 28 Si [6]. Although the BTA is observed in all systems involving 6 Li, for 7 Li its presence is observed for some systems but not for others.…”

mentioning

confidence: 99%

“…The BTA has been investigated in a large number of nuclear systems involving weakly bound projectiles with a variety of medium and large mass targets, for instance 9 Be with 27 Al [9], with 64 Zn [10][11][12][13], with 144 Sm [14,15] and with 208 Pb, 209 Bi [16,17]; 6 Li and 7 Li with targets 208 Pb [3,18], 27 Al [19][20][21], 144 Sm [22], 58,64 Ni [23,24], 59 Co [25], 90 Zr [26], 138 Ba [11,27,28], 28 Si [6]. Although the BTA is observed in all systems involving 6 Li, for 7 Li its presence is observed for some systems but not for others. The reason may probably be due to the competition between the attractive polarization potential due to the bound excited state of 7 Li [28] and the repulsive breakup polarization potential [29].…”

mentioning

confidence: 99%

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Optical model calculations on the threshold anomaly for theLi6+<

2010

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A simultaneous analysis of elastic scattering, fusion, and total reaction cross sections for the weakly bound systems 6,7 Li + 28 Si at energies close to the Coulomb barrier is performed by optical model calculations. The nuclear polarization potential U is split into volume part U F , which accounts for fusion reactions and a surface part U DR , responsible for direct reactions. The parameters of the Woods-Saxon potentials are determined by a χ 2 analysis of the data. The presence of the threshold anomaly or the breakup threshold anomaly is investigated from the energy dependence of both the fusion and direct reaction parts of the polarization potential.For some time it has been known that reactions with heavy systems present the so-called threshold anomaly (TA), i.e., the real and imaginary parts of the optical potential obtained from elastic scattering fits around the Coulomb barrier, and show a distinctive energy dependent behavior. The imaginary potential drops sharply as the energy decreases toward the barrier energy, while the real potential strength shows a strong localized peak around the barrier. At higher energies both potentials are almost energy independent [1]. This energy behavior of the optical potential is understood in terms of the strong coupling between the elastic scattering channel to other reaction channels that produce an attractive polarization potential. The absolute value of this attractive real polarization potential increases the strength of the already attractive nuclear potential which, in turn, lowers the fusion barrier and consequently produces an enhancement of the fusion cross sections at energies below the Coulomb barrier. This energy dependence of the real potential is expressed frequently bywhere V 0 is the real nuclear potential at high energies and V (E) the polarization potential. The decrease of the imaginary potential W (E) of the optical potential as the collision energy approaches the barrier is due to the closing of reaction channels. It is also well known that the energy dependence between the real and imaginary polarization potentials are connected by the dispersion relation expressed by the principal integral value [2],It is then clear that any strong change in W (E) must be accompanied by a localized strong variation in V (E). In the case where weakly bound projectiles are involved, many studies reveal that the situation is quite different. Due to the weak binding energy of the nucleus, strong couplings between breakup and elastic channels at energies below the Coulomb barrier may arise. In such a situation, the imaginary part W (E) of the optical potential cannot sharply decrease, as it does for tightly bound nuclei, since it must account for the appreciable breakup cross-section yields observed at energies below the barrier. Accordingly, the real part of the polarization potential V (E) does not contribute to an increase in the strength of the nuclear potential, but instead has a repulsive characteristic. This new phenomenon has been termed the breakup threshold...

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