The lifetimes of excited quantum states in the atomic nucleus give extremely important information about nuclear structure and the shape of the nucleus. This project description covers three measurement methods that together span the nuclear lifetime range from about 100 femtoseconds to many nanoseconds.
Students can select from the following themes:
(i) The Doppler broadened line shape method is based on a detailed analysis of gamma-ray line shapes that are affected by changing Doppler shifts as the decaying nucleus slows down in a solid target. This project will develop analysis methods and address reasons why some measurements by this technique disagree with other methods.
(ii) The recoil distance (or plunger) method is based on measuring the number of decays that occur in flight as an excited nucleus moves at known velocity over a known distance. The flight distance (hence flight time) is adjusted to map out the decay curve. We have new apparatus for this purpose based on a piezo-motor that will be commissioned in this project.
(iii) Direct measurements of the time between the population of a nuclear state and its decay are being developed using a new scintillator materials and digital data acquisition to enable improved measurements through sophisticated digital signal processing (computation and programming).
The outcome of the project will include the commissioning of new equipment, new methods, and enhanced lifetime measurement capability for nuclear structure studies. Students will gain accelerator-based laboratory experience and develop skills in building scientific instruments, scientific programming, digital data acquisition and data analysis.