Quantum tunnelling of a complex system: effects of a finite size and intrinsic structure

Flambaum, V. V.; Zelevinsky, V. G.

doi:10.1088/0954-3899/31/5/006

Cited by 17 publications

(18 citation statements)

References 12 publications

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“…In the standard scenario for the primordial nucleosynthesis (see Fig. 14) the unstable weakly bound nuclei (such as 6,8 He, 8,9,11 Li and so on) are intensively produced via (n, γ ) reactions with subsequent β decay to the stable nuclei (see, e.g., Ref. [43] and references therein).…”

Section: Astrophysical Aspectsmentioning

confidence: 99%

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Sub-barrier fusion of neutron-rich nuclei and its astrophysical consequences

2007

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Near-barrier fusion of neutron-rich nuclei was studied within the semiempirical channel coupling model for intermediate neutron rearrangement and within the time-dependent three-body Schrödinger equation. The possibility of neutron transfer with positive Q values considerably increases the barrier penetrability. A huge enhancement of deep sub-barrier fusion probability was found for light neutron-rich weakly bound nuclei (such as 6 He). This may be quite important for astrophysical primordial and supernova nucleosynthesis.

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Section: Astrophysical Aspectsmentioning

confidence: 99%

“…Also great efforts have been devoted to studying near-barrier fusion of light weakly bound nuclei [2][3][4][5][6][7]. Unusual effects are expected here both from the halo structure of these nuclei and from the specific tunneling mechanism of the composed weekly bound system that is of general interest for quantum theory [8].…”

Section: Introductionmentioning

confidence: 99%

Sub-barrier fusion of neutron-rich nuclei and its astrophysical consequences

2007

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“…An attractive feature of the 2p-emission is that two protons are emitted spontaneously from the ground state of unbound nuclei, and thus they are expected to carry information on the pairing correlations inside nuclei, including the diproton correlation [32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Role of diproton correlation in two-proton-emission decay of theBe6nucleus

2014

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We discuss a role of diproton correlation in two-proton emission from the ground state of a proton-rich nucleus, 6 Be. Assuming the three-body structure of α + p + p configuration, we develop a time-dependent approach, in which the two-proton emission is described as a time-evolution of a three-body metastable state. With this method, the dynamics of the two-proton emission can be intuitively discussed by monitoring the time-dependence of the two-particle density distribution. With a model Hamiltonian which well reproduces the experimental two-proton decay width, we show that a strongly correlated diproton emission is a dominant process in the early stage of the two-proton emission. When the diproton correlation is absent, the sequential two-proton emission competes with the diproton emission, and the decay width is underestimated. These results suggest that the two-proton emission decays provide a good opportunity to probe the diproton correlation in proton-rich nuclei beyond the proton drip-line.

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“…[2], "Although a number of theoretical works have studied tunneling phenomena in various situations, quantum tunneling of a composite particle, in which the particle itself has an internal structure, has yet to be clarified." There are experimental data [3,4] indicating that at low energies the penetration probability for loosely bound systems, such as the deuteron, can noticeably exceed the conventional estimates.The problems of tunneling and reflection of a composite particle were discussed recently with the help of various models [5,6,7,8,9,10,11]. It was stressed that new, usually ignored, effects are important for nuclear fusion and fission, nucleosynthesis in stars, molecular processes, transport phenomena in semiconductors and superconductors, both in quasi-one-dimensional and three-dimensional systems.…”

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confidence: 99%

Tunneling of a composite particle: effects of intrinsic structure

Bertulani

Flambaum

Zelevinsky

2007

J. Phys. G: Nucl. Part. Phys.

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We consider simple models of tunneling of an object with intrinsic degrees of freedom. This important problem was not extensively studied until now, in spite of numerous applications in various areas of physics and astrophysics. We show possibilities of enhancement for the probability of tunneling due to the presence of intrinsic degrees of freedom split by weak external fields or by polarizability of the slow composite object.Quantum tunneling is a subject of constantly renewed interest, both experimentally and theoretically. The standard textbook approach describes the tunneling process for a point-like particle in an external static potential. Chemical and nuclear subbarrier reactions [1], especially in astrophysical conditions, as a rule, involve complex objects with their intrinsic degrees of freedom. As stated in Ref. [2], "Although a number of theoretical works have studied tunneling phenomena in various situations, quantum tunneling of a composite particle, in which the particle itself has an internal structure, has yet to be clarified." There are experimental data [3,4] indicating that at low energies the penetration probability for loosely bound systems, such as the deuteron, can noticeably exceed the conventional estimates.The problems of tunneling and reflection of a composite particle were discussed recently with the help of various models [5,6,7,8,9,10,11]. It was stressed that new, usually ignored, effects are important for nuclear fusion and fission, nucleosynthesis in stars, molecular processes, transport phenomena in semiconductors and superconductors, both in quasi-one-dimensional and three-dimensional systems. The resonant tunneling associated with the intrinsic excitation, finite size effects, polarizability of tunneling objects, evanescent modes near the barrier, real [12,13] and virtual [14] radiation processes are the examples of interesting new physics. Below we consider simple models which illustrate how "hidden" degrees of freedom can show up in the process of tunneling leading to a considerable enhancement of the probability of this process.Let the tunneling particle possess two degenerate intrinsic states and the incident wave comes to the barrier in a pure state "up" (it is convenient to use the spin-1/2 language with respect to the z-representation). We assume one-dimensional motion with the simplest rectangular potential barrier of height U 0 located at 0 < x < a. At low energy E ≪ U 0 , when the imaginary action κ 0 a = [2m(U 0 − E)] 1/2 a is very large, the transmission coefficient T 0 ∝ exp(−2κ 0 a) is exponentially small. This probability can be exponentially enhanced by a weak "magnetic" field applied in the area of the barrier. We assume that the interaction of this field with the particle is −hσ x , where h is proportional to the transverse magnetic field.Indeed, this field creates the "down" spin component and splits the states inside the barrier according to the value of σ x . In the z-representation the regions x ≤ 0 and x ≥ a acquire the down component in the reflected a...

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Quantum tunnelling of a complex system: effects of a finite size and intrinsic structure

Cited by 17 publications

References 12 publications

Sub-barrier fusion of neutron-rich nuclei and its astrophysical consequences

Sub-barrier fusion of neutron-rich nuclei and its astrophysical consequences

Role of diproton correlation in two-proton-emission decay of theBe6nucleus

Tunneling of a composite particle: effects of intrinsic structure

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