Coulomb breakup of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">Li</mml:mi></mml:math>for nuclear astrophysics

A new Coulomb breakup experiment was performed for ${}^{7}\mathrm{Li}$ with an improved experimental technique and theoretical treatment. Energy spectra of $\ensuremath{\alpha}$ particles and tritons were examined to find the signature of post-Coulomb acceleration in the breakup of ${}^{7}\mathrm{Li}$ at ${E}_{\ensuremath{\alpha}t}=0.$ The data revealed the delayed nature of nonresonant breakup of astrophysical relevance that stems from quantum tunneling. Semiclassical discussions are presented of the lifetime of continuum states in ${}^{7}\mathrm{Li}$ and distortion of relative kinetic energies between $\ensuremath{\alpha}$ and t by post-Coulomb acceleration. Dynamical calculations of Coulomb breakup were performed by solving a time-dependent Schr\"odinger equation. A simple potential model of ${}^{7}\mathrm{Li}$ was employed. The dynamical calculations reasonably reproduced experimental cross sections for both resonant and nonresonant breakup with two key ingredients: higher order effects and mixture of $E1$ and $E2$ multipoles. Considering the dominant role of the first-order $E1$ nature in adiabatic Coulomb breakup, cross sections in the ${v}_{\ensuremath{\alpha}}&gt;~{v}_{t}$ branch at $7\ifmmode^\circ\else\textdegree\fi{}$--$15\ifmmode^\circ\else\textdegree\fi{}$ for ${}^{64}\mathrm{Zn}$ and ${}^{90}\mathrm{Zr}$ were used to deduce astrophysical S factors $S(E)$ for $t(\ensuremath{\alpha},\ensuremath{\gamma}{)}^{7}\mathrm{Li}.$ They exhibit a moderate energy dependence at small energies. The strongly energy-dependent $S(E)$ resulted from the previous Coulomb breakup experiment based on cross sections with ${v}_{\ensuremath{\alpha}}&lt;~{v}_{t};$ they are most likely Coulomb distorted and are revised in the present work.

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