FATIMA - A FAst TIMing Array for DESPEC

The objective of this project is to design a new modular high-efficiency FAst TIMing array designed for measuremnts at DESPEC. The ultra fast timing method using fast response scintillation detectors, is a well-established method to measure level lifetimes in the range from a few picoseconds to several nanoseconds [1]. Its main application is for the exotic nuclei populated in beta-decay and via de-excitation of microsecond isomers at DESPEC. High precision results can be obtained at the level of intensity as low as 1-5 particles/s for exotic nuclei.

Preliminary sketch of FATIMA

The complete FATIMA will consist of 48 detectors arranged around the DESPEC implantation point. We are planning to use the newly developped LaBr3 detectors, with optimized size and shape, optimized shielding and suitable photosensors. Fast timing measurements will be performed via triple beta-gamma-gamma coincidences for beta decays and via gamma-gamma coincidences for the long-lived isomeric states. For very weak sources important lifetime information will be obtained from double coincidence beta-gamma events. We expect to be able to measure lifetimes with precision down to 10 ps with the centroid shift method and reach half-lives values of 50 ps by the method of de-convolution of the slope. Moreover, we expect to perform measurements initially with beam intensities down to 10-20 particles/s at the implantation point. In some cases level lifetimes could be measured via double beta-gamma coincidences using the complete LaBr3(Ce) array for weak sources down to about 1 particle/s.

Preliminary sketch of FATIMA

[1] H. Mach, R.L. Gill, M. Moszynski, A method for picosecond lifetime measurements for neutron-rich nuclei, Nucl. Instrum. Methods A 280 (1989) 49-72.



Luis M Fraile
Grupo de Física Nuclear
Facultad de Físicas
Universidad Complutense
Avda. Complutense s/n
E-28040 Madrid SPAIN

PHONE: +34 91 394 4784