LVII. <i>The ranges of the α particles from various radioactive substances and a relation between range and period of transformation</i>

Via the world-line instanton method, we study electron-positron pair creation by a strong (but sub-critical) electric field of the profile E/ cosh 2 (kx) superimposed by a weaker pulse E / cosh 2 (ωt). If the temporal Keldysh parameter γ ω = mω/(qE) exceeds a threshold value γ crit ω which depends on the spatial Keldysh parameter γ k = mk/(qE), we find a drastic enhancement of the pair creation probability -reporting on what we believe to be the first analytic non-perturbative result for the interplay between temporal and spatial field dependences E(t, x) in the Sauter-Schwinger effect. Finally, we speculate whether an analogous effect (drastic enhancement of tunneling probability) could occur in other scenarios such as stimulated nuclear decay, for example.

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“…To leading order in E α /m α , we reproduce the well known Geiger-Nuttall law [78] ln(P ) ∝ −S ∝ − Z √ E α . (7.5)…”

Section: Jhep02(2016)164mentioning

confidence: 83%

Dynamically assisted Sauter-Schwinger effect in inhomogeneous electric fields

Schneider

Schützhold

2016

J. High Energ. Phys.

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“…Geiger and Nuttal [14] were the first who proposed a semiempirical law connecting the α-decay half-life and its Q-value. Now, a large number of α-decays are observed from medium mass to superheavy nuclei, and several attempts have been made to give a universal formula [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

New semiempirical formula for exotic cluster decay

et al. 2004

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A new semiempirical formula, with only three parameters, is proposed for cluster decay half-lives. The parameters of the formula are obtained by making a least squares fit to the available experimental data. The calculated half-lives are compared with an earlier proposed model-independent scaling law. Also, the calculated results of this formula are compared with the recent results of the preformed cluster model for 12 C and 14 C emissions from different deformed and superdeformed Nd and Gd parents. The results are in good agreement with experiments as well as other models. 23.90.+w,25.85.Ca,23.60.+e

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“…The Q α value is essentially important for penetration [24,25,26,27]. It is known that if experimental Q α values are used for the α decay between ground states, Gamow's treatment [1] describes qualitatively well the penetration of the α particle through the Coulomb barrier, even though the α-particle is assumed to be "a particle" in the nucleus.…”

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confidence: 99%

αdecay and proton-neutron correlations

Kaneko

Hasegawa

2003

Phys. Rev. C

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We study the influence of proton-neutron (p-n) correlations on α-decay width. It is shown from the analysis of alpha Q values that the p-n correlations increase the penetration of the α particle through the Coulomb barrier in the treatment following Gamow's formalism, and enlarges the total α-decay width significantly. In particular, the isoscalar p-n interactions play an essential role in enlarging the α-decay width. The so-called "alpha-condensate" in Z ≥ 84 isotopes are related to the strong p-n correlations. PACS numbers: 23.60,+e, 21.60.Cs, The α decay has long been known as a typical decay phenomenon in nuclear physics [1]. Various microscopic approaches to estimating the formation amplitude of the α cluster have been proposed [2,3,4,5]. The calculations [6,7,8] showed that J = 0 proton-proton (pp) and neutron-neutron (n-n) pairing correlations cause substantial α-cluster formation on nuclear surface. This suggests that the BCS approach with a pairing force offers a promising tool to describe the α decay. Protonneutron (p-n) correlations are also significantly important for the α-decay process in a nucleus [9,10]. The effect of the p-n correlations on the α-formation amplitude was studied by a generalization of the BCS approach including the p-n interactions [11], though it was shown that the enhancement of the formation amplitude due to the p-n interactions is small. The authors of Ref. [12] pointed out that continuum part of nuclear spectra plays an important role in formation of α cluster. On the other hand, a shell model approach including α-cluster-model terms [13] gave a good agreement with the experimental decay width of the α particle from the nucleus 212 Po. It is also interesting to investigate the effect of deformation on the α-decay width. According to Ref. [12], the contribution of deformation improves theoretical values for deformed nuclei such as 244 Pu .The p-n interactions are expected to become strong in N ≈ Z nuclei because valence protons and neutrons in the same orbits have large overlaps of wavefunctions [14]. In fact, this can be seen in peculiar behavior of the binding energy at N = Z. The double differences of binding energies are good indicators to evaluate the p-n interactions [15,16]. We have recently studied [17] various aspects of the p-n interactions in terms of the double differences of binding energies, using the extended P + QQ force model [18]. The concrete evaluation confirmed that the p-n correlations become very strong in the N ≈ Z nuclei. It was shown in Ref. [19] that the isoscalar (T = 0) p-n pairing force persists over a wide range of N > Z nuclei. One of the double differences of binding energies was also discussed as a measure of α-particle superfluidity in nuclei [20,21]. (We abbreviate the α-like correlated four nucleons in a nucleus to "α-particle" in italic letters. The "α-particle" is not a free α particle but a correlated unit in a nucleus.) We expect that the p-n correlations must play an important role in the barrier penetration of the α decay.Experimenta...

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LVII. The ranges of the α particles from various radioactive substances and a relation between range and period of transformation

Cited by 350 publications

References 11 publications

Dynamically assisted Sauter-Schwinger effect in inhomogeneous electric fields

Dynamically assisted Sauter-Schwinger effect in inhomogeneous electric fields

New semiempirical formula for exotic cluster decay

αdecay and proton-neutron correlations

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