TY  - GEN
Y1  - 2012///
ID  - heidok13138
KW  - alpha decay 
KW  -  imaginary time method 
KW  -  multiphoton regime 
KW  -  strong field approximation 
KW  -  tunneling 
KW  -  semiclassical methods
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/13138/
AV  - public
A1  - Castañeda Cortés, Héctor Mauricio
N2  - Excited or short-lived nuclei often decay by emitting alpha particles that are assumed to be preformed inside the nucleus and confined in the nuclear potential well. In this picture, alpha decay refers to the tunneling of the alpha particle through the potential barrier. In this thesis we investigate for the first time how strong laser fields can assist the tunneling of the alpha particle and thus influence the nuclear decay. Generally speaking, laser-assisted alpha decay can be described as laser-assisted tunneling of a quasistationary state, i.e, a slowly decaying state. Our theoretical treatment is developed starting from the complex trajectory formulation of the well-known strong-field approximation  used to describe laser-induced ionization. We extend this formulation and develop a method to treat the decay of quasistationary states. The effect of both static and optical and x-ray monochromatic fields on the lifetimes and alpha-particle emission spectra are investigated for a number of alpha-emitting nuclei. We find that even at strong intensities, the laser-induced acceleration of the alpha decay is negligible, ranging from a relative modification in the decay rate of 10^-3 for static fields of electric field strengths of 10^15 V/m, to 10^-8 for strong optical fields with intensities of 10^22 W/cm^2, and to 10^-6 for strong x-ray fields with laser intensities around 10^24 W/cm^2. However, the effect of the external field is visible in the spectrum of emitted alpha particles, leading in the case of optical fields even to rescattering phenomena for intensities approaching 6*10^22 W/cm^2. The dynamics of the alpha particle in laser fields of intensities below the rescattering limit is investigated.
TI  - Laser assisted alpha decay
ER  -