Study of Exotic Nuclei at FLNR. The OTPC at ACCULINNA
by Dr. GRZEGORZ KAMINSKI (Joint Institut for Nuclear Research, DUBNA)
at Universe ( 1001-Primera-1-1-1 - Paterna. Seminario )
During the last two decades, the ACCULINNA separator at FLNR, JINR was successfully providing radioactive ion beams (RIBs) to study nuclear reactions and properties of light unstable nuclei . Despite of simple construction and a modest size, the facility gains on the high-intensity primary beams of the U-400M cyclotron. RIBs energies of 20–40 AMeV are well situated for direct reaction studies, as well as the low energy reaction experiments and ‘stopped beam experiments’. Recent results at ACCULINNA will be reported.
To extent possibilities for studies with RIBs, a project of new in-flight facility for low energy 35-60 AMeV primary beams with 3 ≤ Z ≤ 36 has been started in 2011. In the status of the project is presented. Unique instrumentation as a cryogenic tritium target system and a variety of detector setups, which are actively being developed at FLNR with ACCULINNNA collaborators opens a new possibilities for low-energy nuclear-reaction studies.
An important instrumentation at ACCULINNA facility is the Optical Time Projection Chamber (OTPC), developed at the University of Warsaw [2,3]. The OTPC represents a modern type of ionization chamber with amplification stage formed by a stack of GEM foils and optical readout consisting of a CCD camera and a photomultiplier tube (PMT). The images recorded by the CCD camera together with the time distribution of light collected in the PMT allows to reconstruct the trajectory of the decay products [2,3]. Such an approach is ideally suited to study the decay by (multi-) particle emission of very exotic isotopes the angular correlations between emitted particles . The OTPC technique opens the possibility to investigate a broad range of rare decay modes with very high sensitivity. The detection of one decay event is sufficient to unambiguously identify the decay mode and whereas a few events is enough to establish its branching ratio.
In the last few years ‘the OTPC detection technique’ has been successfully applied measure β-delayed proton emission [3-7]. The results of the last experiment at ACCULINNA - β-delayed particle emission from 27S are presented .
The possibilities for the OTPC setup at the ACCULINNA separator and at the new ACCULINNA-2 in-flight facility will be discussed.