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BOREXINO has set new standards in the field of ultra-low background experiments. Such a success was only possible by a strict quality control program during the construction phase of the experiment. In this paper, we describe how construction materials and auxiliary systems of the BOREXINO detector were screened for their residual radioactivity with unprecedented high sensitivity. The highly sensitive assay techniques developed for this purpose were also used to validate the purity of water and nitrogen used in the experiment. Moreover, we report on the production of ²²²Rn-free nitrogen and synthetic air with very low ²²²Rn concentration as well as on the successful search for commercial nitrogen with a particularly low concentration of argon and krypton.

Level schemes of even–even neutron-rich ^88-92Kr and ⁸⁶Se have been investigated by measuring triple-γ coincidence data from the spontaneous fission of ²⁵²Cf with the Gammasphere detector array. The level scheme of ⁸⁸Kr has been extended up to 7169 keV state. Several new excited states with new transitions have been identified in ^90,92Kr and ⁸⁶Se. Spins and parities have been assigned to levels in these nuclei by following regional systematics and angular correlation measurements. The level structures of the N = 52, 54, Se, Kr, and Sr isotones are discussed.

The CNO cycle is not the main responsible for the production of energy in the Sun, but it is much more relevant for the production of the Solar neutrinos. Among the all different cycles of the CNO there are several reactions that have an important role and have to be studied deeply, especially the reactions that works as bridge between different cycles (for example ¹⁵N(p,γ)¹⁶O, ¹⁷O(p,γ)¹⁸F, and ¹⁷O(p,α)¹⁴N) and of course the bottleneck of the CN cycle: the ¹⁴N(p,γ)¹⁵O reaction. This is one of the main nuclear ingredients to calculate the neutrinos production from the Sun. It has been studied by many direct experiments during years, but still, to solve the so called solar composition problem, new data are requested. In particular, the uncertainties on its S-factor have to be lowered from the 8%, quoted by the recent database (Adelberger et al. 2011) to what requested by Solar models (5%). The previous experiments performed on this reaction together with measurements planned in the future will be presented in this contribution. For the reactions involved in the other CNO-cycles the studies performed at LUNA will be presented with comparison with other facilities.

The spectrometer for the measurement of the total reaction cross section “MULTI” is continuously upgraded to achieve better performance in the experimental measurements with radioactive beams. Characteristics of the gamma spectrometer with the new types of high precision detectors in various geometrical setups are investigated by Monte Carlo simulations in Geant4. Results of the simulations are discussed from the point of the registration efficiency, spectrometer resolution and geometrical conditions. Optimal geometry is suggested.

The study of nuclear structure far from stability, which mainly rely on the availability of radioactive nuclear beams, can complementary be addressed by means of high intensity beams of stable ions. Deep-inelastic and multi-nucleon transfer reactions are a powerful tool to populate yrast and non yrast states in neutron-rich nuclei. Particularly successful is here the combination of large acceptance spectrometers with highly segmented γ-detector arrays. Such devices, eventually complemented by large coverage particle detectors, can provide the necessary channel selectivity to identify very rare signals. An example is the CLARA γ-ray detector array coupled with the PRISMA spectrometer at the Legnaro National Laboratories (LNL). Large data sets have been recently collected for nuclei close to the N = 28, 40 and 50 shell closures. The obtained results complement studies performed with current radioactive beam (RIB) facilities. The data clearly show the evolution of the effective single particle energies in very good agreement with the predictions of the mean field model with tensor interaction. New experimental information has been obtained on a wide range of nuclei close to the N = 28, 40 and 50 shell closures allowing the population of medium and high-spin yrast states. The excited states of the N = 50 isotones, extended down to Z = 31, and of N = 51 isotones, extended down to Z = 34, have been used to test the predictions of the shell evolution based on the effects of the tensor interaction as well as of the different effective interactions. As future perspective the development of a γ-ray detection system capable of tracking the location of the energy deposited at every γ-ray interaction point will also provide an unparallel level of detection sensitivity, and will open new revenues for nuclear structure studies.

The comparison of analogue E1 transitions of mirror nuclei offers a valuable tool in the investigation of isospin symmetry breaking. Differences in the measured B(E1) reduced strengths in fact can be interpreted as the signature of isospin mixing. In this work, the isospin T_z = 1/2 nuclei ⁶⁷As and ⁶⁷Se were investigated. The nuclei were produced via the fusion evaporation reaction of ³²S on ⁴⁰Ca, at the ATLAS accelerator at Argonne National Laboratory. Gammasphere, Microball and the neutron wall arrays were employed for output channel selection.

The lifetime of the mirror 9/2⁺ states has been measured using the centroid shift method. A confirmation of the validity of this technique is given by the excellent reproduction of the known lifetime of the 9/2⁺ state in ⁶⁹As, previously determined via a recoil distance experiment. From a preliminary comparison of the extracted B(E1), our results indicate that isospin symmetry in these nuclei is not significantly broken. Further comparison with large scale shell model calculations is however still required.

In-flight gamma spectroscopy of rare isotopes at relativistic energies, from fifty to several hundreds of MeV/nucleon, is one of the most efficient tools to investigate shell effects in exotic nuclei.We propose a new method to increase the sensitivity of prompt-gamma spectroscopy by more than one order of magnitude compared to existing setups, leading to a significant step forward. The intended program is based on proton-induced knockout reactions such as (p, 2p). Experiments should take advantage of the most exotic neutron-rich beams produced at the RIBF¹ in RIKEN and the upcoming european FAIR facility. MINOS has been funded by the European Research Council for the 2010-2015 period.

The reaction ³⁴S + ¹⁸⁶W at E_lab = 160 MeV was investigated with the aim of diving into the features of the fusion-fission process. Gamma rays coincident with binary reaction fragments were measured using the high efficiency gamma-ray spectrometer ORGAM at the TANDEM Accelerator facility of I.P.N., Orsay, and the time-of-flight spectrometer for fission fragments registration CORSET of the Flerov Laboratory of Nuclear Reactions (FLNR), Dubna. Evidence of symmetric and asymmetric fission modes were observed in the mass and TKE distributions, occurring due to shell effects in the fragments. The coupling of the ORGAM and CORSET setups enables the FF-γ coincident measurement which offers the opportunity to extract the isotopic distribution of the fragments of different masses formed in the aforementioned reaction and to find the exact neutron multiplicity, the average spin and average angular momenta. Details regarding the experimental setup, methods of processing the acquisitioned data and preliminary results are presented.