Speaker
Dr
Takehiko Saito
(GSI)
Description
Nuclear spectroscopy with heavy ion beams and fixed nuclear targets has recently become a powerful tool to study sub-atomic nuclei with strangeness. The first HypHI experiment at GSI has demonstrated the feasibility of the method by reconstructing invariant masses and decay vertexes with $^6$Li beams at 2 $A$ GeV bombarding a graphite target, and formation and mesonic $\pi ^-$ decay of light hypernuclei have been successfully observed. The results have revealed a significantly short lifetime of hypertriton. Furthermore, it has also revealed indications of signals in the d+$\pi ^-$ and t+$\pi ^-$ invariant mass distributions, that may indicate a possibility of a weakly bound state with a lambda hyperon together with two neutrons. These subjects are recently under debate.
The accuracy and the statistics of the developed method for the hypernuclear spectroscopy with heavy ion beams should yet be improved. The method also has to be further developed with different detection techniques and beams at higher energies. A new experimental project to study hypernuclei has been proposed at GSI, and it will introduce the WASA central detector, which is currently at COSY in Juelich and under transportation to GSI, for pion measurement combined with the high resolution fragment separator, FRS, for measuring decay residues. The project has been already approved and experiments with WASA+FRS will be performed in coming years. The project will be continued with the Super-FRS at FAIR. Another new development at higher energies is in progress for the future heavy ion accelerator facility in China, High Intensity heavy ion Accelerator Facility, HIAF. It will open a possibility to study double-strangeness hypernuclei with heavy ion beams and fixed targets. The HIAF will also enable hypernuclei spectroscopy with its fragment separator with a similar fashion of the experiment with WASA+FRS at GSI. These new projects at GSI/FAIR and HIAF will be discussed.
Primary author
Dr
Takehiko Saito
(GSI)
