Picosecond lifetime measurements using Recoil Distance Doppler Shift method (an opportunity at FIPPS ?)

Orateur : Joa LJUNGVALL (CSNSM Orsay)

The atomic nucleus is a complex multi-body system where two fermion species interact via the in-medium nuclear force. Despite this simple pattern emerges, and excitation’s in nuclei can be described in the context of a nuclear shell-model or in macroscopic models where the nucleus is treated as a two-fluid system. Our understanding of the atomic nucleus is today at the "precision" level we are probing small terms in nuclear interaction. Because of this contemporary experimental nuclear-structure physics is concentrated either on exotic nuclei or on observables more sensitive to details in the nuclear wave function -e.g. electromagnetic transition strengths. A privileged method to measure lifetimes in the picosecond range is the Recoil Distance Doppler Shift method. Here the Doppler Shift of a ray, together with the possibility of changing the velocity of the emitting nuclei as a function of time is, used to measure the lifetime of the -ray emitting state. I will give a short introduction to the method and show some examples how the information given by such measurements helps to improve our understanding of the nucleus. Finally I will give a personal view on the possibilities to perform such measurements at the FIPP Spectrometer, focusing mainly on technical challenges.

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