Characterization of the excited states of C-11, C-12, C-13 isotopes was performed using experimental data collected at the INFN-LNL in Italy. The study employed a 95 MeV N-14 beam on B-10 targets to probe clustering phenomena in carbon isotopes. The experimental setup included a detector system covering polar angles from 15 degrees to 72 degrees, enabling the study of reactions with two and three products in the exit channel. Analysis of the three-product exit channels is presented to provide insight into the process of analyzing such reactions. Presented results for the Be-7+He-4, Be-8+He-4, and Be-9 + He-4 decays of C-11, C-12, C-13, respectively, unveil states at 7.6, 9.7, and 14.1 MeV in C-12, 8.1 and 8.4 MeV in C-11, as well as a broad peak centered at 13.6 MeV with a possible contribution of states from 13.4 to 14.1 MeV in C-13. The detection of these states serves as a crucial validation of the analysis and data selection procedures, representing an initial step before exploring other exit channels.

D. Jelavić Malenica,1,* M. Milin,2,† S. Blagus,1 A. Di Pietro,3 P. Figuera,3 M. Lattuada,3 Đ. Miljanić,1 A. Musumarra,3 M. G. Pellegriti,3 L. Prepolec,1 V. Scuderi,3 N. Skukan,1 N. Soić,1 S. Szilner,1 D. Torresi,3 and M. Uroić1 1Division of Experimental Physics, Ruđer Bošković Institute, HR-10000 Zagreb, Croatia 2Physics Department, Faculty of Science, University of Zagreb, HR-10000 Zagreb, Croatia 3INFN Laboratori Nazionali del Sud and Sezione di Catania, I-95123 Catania, Italy

B-10 + B-10 reactions are measured with 50 and 72 MeV beams. The large spin of both beam and target nuclei (J(pi) = 3(+)) is particularly suitable for the population of high spin states in the exit channels. Population and decay of different states in C-12 are studied through sequential decay reactions. The C-12 excitation energy spectrum obtained from the B-10(B-10, Be-8) reaction shows a number of both known and new states. In particular, a new state at E-x = 24.4 MeV is observed to be strongly populated in the triple alpha-particle coincidences. The rarely seen state at E-x = 30.3 MeV is found to be strong in the d + B-10 decay channel, reinforcing the previous suggestions that it has the exotic 2 alpha + 2d molecular structure.

In this contribution, a brief analysis of an experiment performed at LNS-INFN with the 30 and 52 MeV ^7 Li beam and the ^7 LiF and ^6 LiF targets is given. The ^7 Li+ ^6,7 Li reactions are measured to get information on different types of structures of several light nuclei. Special attention is paid to a search for molecular states in ^10 B and ^10 Be. Another goal is to find information for states with different cluster configurations in ^7 He, ^9 Be and ^10-12 B. The experimental setup consists of four telescopes covering polar angles in range from 20 ^∘ to 90 ^∘ and providing particle identification using traditional E-E techniques. The contribution includes previously published Uroić et al. (Eur Phys J A, 51, 93, 2015, [1]) procedures as well as the remaining plans for analysis.

The main source of F-19 in the universe has not yet been clearly identified and this issue represents one of the unanswered questions of stellar modeling. This lack of knowledge can be due to the F-19(alpha, p)Ne-22 reaction cross-section that has proven to be difficult at low energies: direct measurements stop only at about similar to 660 keV, leaving roughly half of the astrophysical relevant energy region (from 200 keV to 1.1 MeV) explored only by R-matrix calculations. In this work, we applied the Trojan Horse Method to the quasi-free three-body Li-6(F-19, p(22)Ne)d reaction performed at E-beam = 6 MeV in order to indirectly study the F-19(alpha, p)Ne-22 reaction in the sub-Coulomb energy region. In this way, we obtained the cross-section and the reaction rate in the temperature region of interest for astrophysics and free from electron screening effects. A brief analysis of the impact of the new measured reaction rate in AGB star nucleosynthesis is also presented.

V. Tokića, N. Soića, S. Blagusa, S. Fazinića D. Jelavić-Malenicaa, T. Mijatovića, Ð. Miljanića L. Prepoleca, N. Skukana, S. Szilnera, M. Uroića M. Milinb A. Di Pietroc, P. Figuerac, J.P. Fernández-Garcíac M. Fisichellac, M. Lattuadac, V. Scuderic, E. Stranoc D. Torresic, S. Baileyd, N. Curtisd, M. Freerd, R. Smithd J. Walshed, V. Zimand, L. Acostae, I. Martele G. Marquinez-Duráne, A.M. Sánchez-Beníteze, E. Fiorettof

The abundance of 19F in the universe is strictly related to standard and extramixing processes taking place inside AGB-stars, that are considered to be the most important sites for its production. Nevertheless the way in which it is destroyed is far from being well understood. For this reason we studied the 19F(α,p)22Ne reaction, that is supposed to be the main destruction channel in the Helium-rich part of the star. In this experiment, the reaction has been studied in the energy range of relevance for astrophysics (0÷1 MeV) via the Trojan Horse Method (THM), using the three-body reaction 6Li(19F,p22Ne)d.

The observational F-19 abundance in stellar environments systematically exceeds the predicted one, thus representing one of the unsolved challenges for stellar modeling. It is therefore clear that further investigation is needed in this field. In this work, we focus our attention on the measurement of the F-19(alpha, p)Ne-22 reaction in the astrophysical energy range, between 0.2 and 0.8. MeV (far below the Coulomb barrier, 3.8MeV), as it represents the main destruction channel in He-rich environments. The lowest energy at which this reaction has been studied with direct measurements is similar to 0.66. MeV, covering only the upper tail of the Gamow window, causing the reactionrate evaluation to be based on extrapolation. To investigate lower energies, the F-19(alpha, p) Ne-22 reaction has been studied by means of the Trojan horse method, applied to the quasi-free Li-6(F-19, p(22)Ne) H-2 reaction at E-beam = 6 MeV. The indirect cross section of the F-19(alpha, p)Ne-22 reaction at energies. less than or similar to 1 MeV was extracted, fully covering the astrophysical region of interest and overlapping. existing direct data for normalization. Several resonances have been detected for the first time inside the Gamow window. The reaction rate has been calculated, showing an increase up to a factor of 4 with respect to the literature at astrophysical temperatures. This might lead to potential major astrophysical implications.

The main idea of the two presented experiments is to study the decay of resonances in 24Mg at excitation energies above the 12C+12C decay threshold, in the astrophysical energy region of interest. The measurement of the 12C(16O, gamma)24Mg* reaction was performed at INFN-LNS in Catania. Only the alpha+20Ne decay channel of 24Mg is presented here, because it was a motivation for conducting a new experiment, a study of the4He(20Ne, 4He)20Ne reaction, performed at INFN-LNL in Legnaro. Some preliminary results of this measurement are also presented.

Learning how F-19 is produced and destructed in AGB-stars is crucial. Fluorine abundance is in fact important, given that it is strongly tied to standard and extra-mixing processes taking place in AGB-stars. This kind of objects are considered to be the main sources of fluorine in galactic environment, in which experimental abundances are far overestimated. For this reason the reaction F-19(alpha,p)Ne-22, that represents the main destruction channel in He-rich environment, was studied at energies corresponding to T similar to 2.10(8) K. Such reaction has been studied with direct method at E-beam = 1100 keV for alpha particles impinging on a fluorine target, corresponding to E-C.M. similar to 900 keV, still far from the Gamow window, placed at 390 divided by 800 keV, below the Coulomb barrier (3.81 MeV). An experiment was performed at Rujer Boskovic Institut (Zagreb), applying the Trojan Horse Method. With this experimental procedure we were able to select the quasi-free contribution coming from 6Li(F-19,p Ne-22)H-2 at E-beam = 6 MeV at kinematically useful angles. We measured the F-19(alpha,p)Ne-22 at 0 MeV <= E-C.M <= 0.9 MeV, extracting the two body cross-section in absolute units at energies of astrophysical interest.

Learning how 19F is produced and destructed in AGB-stars is crucial. Fluorine abundance is in fact important, given that it is strongly tied to standard and extra-mixing processes taking place in AGB-stars. This kind of objects are considered to be the main sources of fluorine in galactic environment, in which experimental abundances are far overestimated. For this reason the reaction 19F(α, p)22Ne, that represents the main destruction channel in He-rich environment, was studied at energies corresponding to T∼2·108 K. Such reaction has been studied with direct method at Ebeam = 1100 keV for alpha particles impinging on a fluorine target, corresponding to EC.M. ∼ 900 keV, still far from the Gamow window, placed at 390÷800 keV, below the Coulomb barrier (3.81 MeV). An experiment was performed at Rujer Boskovic Institut (Zagreb), applying the Trojan Horse Method. With this experimental procedure we were able to select the quasi-free contribution coming from 6Li(19F,p 22Ne)2H at Ebeam = 6 MeV at kinematically useful angles. We measured the 19F(α, p)22Ne at 0 MeV ≤ EC.M ≤ 0.9 MeV, extracting the two body cross-section in absolute units at energies of astrophysical interest.

19F experimental abundances is overestimated in respect to the theoretical one: it is therefore clear that further investigations are needed. We focused on the 19F(α, p)22 Ne reaction, representing the main destruction channel in He-rich environments. The lowest energy at which this reaction has been studied with direct methods is EC.M. ≈ 0.91 MeV, while the Gamow region is between 0.39 ÷ 0.8 MeV, far below the Coulomb barrier (3.8 MeV). For this reason, an experiment at Rudjer Boskovic Institute (Zagreb) was performed, applying the Trojan Horse Method. Following this method we selected the quasi-free contribution coming from 6Li(19F,p22 Ne)2 H at Ebeam=6 MeV at kinematically favourable angles, and the cross section at energies 0 < EC.M. < 1.4 MeV was extracted in arbitrary units, covering the astrophysical region of interest.

F-19 experimental abundances is overestimated in respect to the theoretical one: it is therefore clear that further investigations are needed. We focused on the F-19(alpha, p)Ne-22 reaction, representing the main destruction channel in He-rich environments. The lowest energy at which this reaction has been studied with direct methods is E-C.M. approximate to 0.91 MeV, while the Gamow region is between 0.39 divided by 0.8 MeV, far below the Coulomb barrier (3.8 MeV). For this reason, an experiment at Rudjer Boskovic Institut (Zagreb) was performed, applying the Trojan Horse Method. Following this method we selected the quasi-free contribution coming from Li-6(F-19,p(22)Ne)H-2 at E-beam=6 MeV at kinematically favourable angles, and the cross section at energies 0 < E-C.M. < 1.4 MeV was extracted in arbitrary units, covering the astrophysical region of interest.

Due to their high selectivity, transfer and sequential decay reactions are powerful tools for studies of both single particle (nucleon) and cluster states in light nuclei. Their use is particularly simple for investigations of α-particle clustering (because α-particle has Jπ=0+, which simplifies spin and parity assignments to observed cluster states), but they are also easily applicable to other types of clustering. Recent results on clustering in neutron-rich isotopes of beryllium, boron and carbon obtained measuring the 10B+10B reactions (at 50 and 72 MeV) are presented. The highly efficient and segmented detector systems used, built from 4 Double Sided Silicon Strip Detectors (DSSSD) allowed detection of double and multiple coincidences and, in that way, studies of states populated in transfer reactions, as well as their sequential decay.

Measurements were made of the 4He(40,44,48Ca,α) resonant scattering reactions at 180◦ and up to Ec.m. ∼11.5 MeV, using the Thick Target Inverse Kinematics technique. These measurements are discussed, with a focus on assessing their usefulness for investigating α-clustering in medium mass 44,48,52Ti nuclei.

The excitation function of Mg-28 above the alpha-decay threshold has been measured for the first time using the resonant scattering of alpha particles with the technique of a thick target in inverse kinematics. Thirteen new states are reported between E-x = 15.5 and E-x = 20.5 MeV, and suggestions for spin-parity assignments are given for two of these. Calculations of the branching ratio to a decay for these states as well as comparison of the measured cross sections to calculations suggest that alpha + Ne-24(g.s). clustering is not dominant in this energy regime.