Investigation of the Tilted Foils Technique (TFT) to polarize radioactive beams.
by
Christophe Sotty(Katholieke Universiteit Leuven (BE))
→
Europe/Zurich
26-1-022 (CERN)
26-1-022
CERN
Description
The control of the spin population of nuclei is of great interest to probe the nuclear structure. Nuclear spin-polarized Radioactive Isotope Beams (RIBs) represent a powerful tool to study the nuclear structure and electromagnetic properties of materials with beta-NMR (Nuclear Magnetic Resonance) and gamma-ray spectroscopy. As example of experimental methods using oriented beams, one can cite the Time Differential Perturbed Angular Distribution (TDPAD) used to measure the magnetic dipole and electric quadrupole moments of microsecond isomeric states.
The possibility to obtain nuclear spin-polarized ensembles has already been investigated for many decades with different methods, e.g. the Low Temperature Nuclear Orientation (LTNO). Concerning specifically the polarization of RIBs, two main techniques are used nowadays: the optical pumping employed in ISOL facilities, and the projectile-fragmentation reaction method used at the In-Flight facilities. The optical pumping technique is not suitable for any RIBs far from stability and any chemical elements. The projectile-fragmentation can produce polarization only in a specific beam energy range.
The tilted foils technique offers the possibility to use short lived radioactive beams by polarizing the nuclei in-flight. Already investigated in the past, new interests for this technique arose since the recent use of RIBs far from the beta-stability valley.
One proposed to investigate the possibility to nuclear spin-polarize RIBs using the specific Tilted Foils Technique (TFT) at the CERN-ISOLDE facility. The nuclear polarization project at CERN started many year ago with the High Voltage Platform (HV Platform); The polarization project can be separated in three different parts. The first part, corresponding to the present work, consists to study the impact of the different parameters of the TFT used to obtain a high degree of polarization. In order to measure the spin polarization, the beta-NMR technique has been employed. The second part consists to investigate the effect of polarized beams in reactions. The last part consists to investigate the possibility to post-accelerate polarized beam keeping a high degree of polarization.
