Seminarium Fizyki Jądra Atomowego

During the last two decades, the ACCULINNA separator at FLNR, JINR [1] was successfully providing radioactive ion beams (RIBs) to study nuclear reactions and properties of light unstable nuclei [2]. Initially, ACCULINNA was aimed to study of light neutron-rich 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 A MeV are well situated for direct reaction studies, as well as the low energy reaction experiments and ‘stopped beam experiments’ [4]. 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 A MeV primary beams with 3 ≤ Z ≤ 36 has been started in 2011. In this report description of the evolution of the project, from functional needs to final working solutions and status of ACCULINNA-2 commissioning is given. The next steps are installation of a zero-angle spectrometer (2017 year) and RF-kicker (2018-2019 years). Moreover, 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 new possibilities for low-energy nuclear-reaction studies. The first experiments (the end of 2017 year) and the RIBs program at new facility will be discussed.
In 2017 the first set of radioactive ion beams (RIBs) was obtained from the new in-flight fragment separator ACCULINNA-2 [1] operating at the primary beam line of the U-400M cyclotron [2]. Observed RIB characteristics (intensity, purity, beam spots in all focal planes) were in agreement with estimations. The new separator provides high quality secondary beams and it opens new opportunities for experiments with RIBs in the intermediate energy range 10÷50 AMeV [3].
The 6He + d experiment, aimed at the study of elastic and inelastic scattering in a wide angular range, was chosen for the first run. The data obtained on the 6He + d scattering, and in the subsequent measurements of the 8He + d scattering, are necessary to complete MC simulation of the flagship experiment: search of the enigmatic nucleus 7H in the reactions d(8He,3He)7H and p(8He,pp)7H.
Opportunities of day-two experiments with RIBs using additional heavy equipment (radio frequency filter, zero angle spectrometer, cryogenic tritium target) will be also reported. In particular, the study of several exotic nuclei 16Be, 24O, 17Ne, 26S and its decay schemes are foreseen.

1. http://aculina.jinr.ru/acc-2.php
2. http://flerovlab.jinr.ru/flnr/u400m.html
3. A.S. Fomichev et al., Eur. Phys. J. A (2018) 54: 97.
4. L.V.Grigorenko et al. // Physics – Uspekhi 2016. V.59. P.321.