Some Evidence of the Cluster Struture Inside of9Be

2017

High accuracy [sup 18]O(p,α)[sup 15]N reaction rate in the 8⋅10[sup 6]–5⋅10[sup 9] K temperature range

2011

The 18O(p,α)15N reaction is of great importance in several astrophysical scenarios, as it influences the production of key isotopes such as 19F, 18O and 15N. In this work, a high accuracy 18O(p,α)15N reaction rate is proposed, based on the simultaneous fit of direct measurements and of the results of a new Trojan Horse experiment. In particular, we have focused on the study of the broad 660 keV 1/2+ resonance. Since Γ∼100–300 keV, it strongly influences the nearly‐zero‐energy region of the cross section by means of the low‐energy tail of the resonant contribution and dominates the cross section at higher energies. Here we provide a factor of 2 larger reaction rate above T∼0.5 109 K based ov…

Cluster Structure of9Be from3He+9Be Reaction

2016

The study of inelastic scattering and multi-nucleon transfer reactions was performed by bombarding a 9Be target with a 3He beam at an incident energy of 30 MeV. Angular distributions for 9Be(3He,3He)9Be, 9Be(3He,4He)8Be, 9Be(3He,7Be)5He, 9Be(3He,6Li)6Li and 9Be(3He,7Li)5Li reaction channels were measured. Cross sections for channels leading to unbound 5He g.s ., 5Li g.s . and 8Be systems were obtained from singles measurements where the relationship between the energy and the scattering angle of the observed stable ejectile is constrained by two-body kinematics. Information on the cluster structure of 9Be was obtained from the transfer channels. It was concluded that cluster transfer is an …

New Insight into the Cluster Structure of $^9$Be by Reactions with Deuteron Beam

2018

International audience; Angular distributions of protons, deuterons, tritons, and alpha particles emitted in the reaction 2H+9Be at Elab=19.5, 25, and 35 MeV were measured to study the structure of 9Be, especially to shed light on the internal clusters and possible cluster transfer of 5He. The experiments were performed at sufficiently high energies to ensure suppression of compound nucleus contribution. Thus, the direct reaction mechanism should be mainly responsible for the measured five-nucleon transfer cross section. The analysis suggests a significant contribution of simultaneous five-nucleon transfer in the reaction channel 9Be (d,4He) 7Li.

Clusterization and strong coupled-channels effects in deuteron interaction with $^9$Be nuclei

2019

Angular distributions of protons, deuterons, tritons and alpha particles emitted in the d + alt;supagt;9alt;/supagt;Be reaction at Ealt;subagt;labalt;/subagt;=19.5 and 35.0 MeV have been measured.a#13; The elastic scattering channel is analysed in the framework of both the Optical Model and the Coupled-Channel approach. a#13; The interaction potential of the alt;iagt;dalt;/iagt; + alt;supagt;9alt;/supagt;Be system is calculated in the framework of the Double-Folding model using the α+α+alt;iagt;nalt;/iagt; three-body wave function of the alt;supagt;9alt;/supagt;Be nucleus.a#13; The (alt;iagt;dalt;/iagt;,alt;iagt;palt;/iagt;) and (alt;iagt;dalt;/iagt;,alt;iagt;talt;/iagt;) one-nucleon-transf…

Beta-decay half-lives at the N = 28 shell closure

2004

Abstract Measurements of the beta-decay half-lives of neutron-rich nuclei (MgAr) in the vicinity of the N =28 shell closure are reported. Some 22 half-lives have been determined, 12 of which for the first time. Particular emphasis is placed on the results for the Si isotopes, the half-lives of which have been extended from N =25 to 28. Comparison with QRPA calculations suggests that 42 Si is strongly deformed. This is discussed in the light of a possible weakening of the spin–orbit potential.

First measurement of the 18O(p,α)15N cross section at astrophysical energies

2009

International audience; The 18O(p,α)15N reaction rate has been deduced by means of the Trojan horse method. For the first time the contribution of the 20 keV resonance has been directly evaluated, giving a value about 35% larger than the one in the literature. Moreover, the present approach has allowed to improve the accuracy by a factor 8.5, as it is based on the measured strength instead of spectroscopic measurements. The contribution of the 90 keV resonance has been also determined, which turned out to be of negligible importance to astrophysics.

Cluster Structure of $^9$Be by Scattering of Deuterons

2017

International audience; Angular distributions of protons, deuterons, tritons and alpha particles emitted in the reaction 2H+9Be at Elab=19.5 MeV were measured with an aim to shed light on the internal cluster structure of 9Be and to study possible cluster transfer of 5He. The analyses suggest a significant contribution of five-nucleon transfer in the reaction channel 9Be(d,4He)7Li.

A novel approach to measure the cross section of the 18O(p, α)15N resonant reaction in the 0-200 keV energy range

2009

The 18O(p, ?)15N reaction is of primary importance to pin down the uncertainties, due to nuclear physics input, affecting present-day models of asymptotic giant branch stars. Its reaction rate can modify both fluorine nucleosynthesis inside such stars and oxygen and nitrogen isotopic ratios, which allow one to constrain the proposed astrophysical scenarios. Thus, an indirect measurement of the low-energy region of the 18O(p, ?)15N reaction has been performed to access, for the first time, the range of relevance for astrophysical application. In particular, a full, high-accuracy spectroscopic study of the 20 and 90 keV resonances has been performed and the strengths deduced to evaluate the r…

New High-Precision Measurement of the Reaction Rate of the 18O(p, α)15N Reaction via THM

2008

The 18O(p,alpha)15N reaction rate has been extracted by means of the Trojan-Horse method. For the first time the contribution of the 20-keV peak has been directly evaluated, giving a value about 35% larger than previously estimated. The present approach has allowed to improve the accuracy of a factor 8.5, as it is based on the measured strength instead of educated guesses or spectroscopic measurements. The contribution of the 90-keV resonance has been determined as well, which turned out to be of negligible importance to astrophysics.

Investigation of the elastic and inelastic scattering of He-3 from Be-9 in the energy range 30-60 MeV

2018

We have measured the differential cross-sections for the elastic as well as inelastic scattering populating the 2.43[Formula: see text]MeV [Formula: see text] excited state in [Formula: see text] using [Formula: see text] beams at energies of 30, 40 and 47[Formula: see text]MeV on a [Formula: see text] target. The experimental results for the elastic scattering were analyzed within the framework of the optical model using the Woods–Saxon and double-folding potentials. The theoretical calculations for the concerned excited states were performed using the coupled-channel method. The optimal deformation parameters for the excited states of [Formula: see text] nucleus were extracted.

Clusterization and Strong Coulpled-Channels Effects in Deuteron Interaction with 9Be Nuclei

2019

Angular distributions of protons, deuterons, tritons and alphaparticles emitted in the d + 9Be reaction at Elab=19.5 and 35.0 MeV have been measured. The elastic scattering channel is analysed in the framework of both the Optical Model and the Coupled-Channel approach. The interaction potential of the d + 9Be system is calculated in the framework of the Double-Folding model using the α + α + n three-body wave function of the 9Be nucleus. The (d, p) and (d, t) one-nucleon-transfer reactions are analysed within the coupledreaction-channel approach. The spectroscopic amplitudes for the different nuclear cluster configurations are calculated. Differential cross sections for the reaction channel…

Evidence of Cluster Structure of $^9$Be from $^3$He+$^9$Be Reaction

2015

The study of inelastic scattering and multi-nucleon transfer reactions was performed by bombarding a $^{9}$Be target with a $^3$He beam at an incident energy of 30 MeV. Angular distributions for $^9$Be($^3$He,$^3$He)$^{9}$Be, $^9$Be($^3$He,$^4$He)$^{8}$Be, $^9$Be($^3$He,$^5$He)$^{7}$Be, $^9$Be($^3$He,$^6$Li)$^6$Li and $^9$Be($^3$He,$^5$Li)$^7$Li reaction channels were measured. Experimental angular distributions for the corresponding ground states (g.s.) were analysed within the framework of the optical model, the coupled-channel approach and the distorted-wave Born approximation. Cross sections for channels leading to unbound $^5$He$_{g.s.}$, $^5$Li$_{g.s.}$ and $^8$Be systems were obtaine…

High-sensitivity study of levels in 30Al following β decay of 30Mg

2016

γ -ray and fast-timing spectroscopy were used to study levels in 30Al populated following the β− decay of 30Mg. Five new transitions and three new levels were located in 30Al. A search was made to identify the third 1+ state expected at an excitation energy of ∼2.5 MeV. Two new levels were found, at 3163.9 and 3362.5 keV, that are firm candidates for this state. Using the advanced time-delayed (ATD) βγγ (t) method we have measured the lifetime of the 243.8-keV state to be T1/2 = 15(4) ps, which implies that the 243.8-keV transition is mainly of M1 character. Its fast B(M1; 2+ → 3+) value of 0.10(3) W.u. is in very good agreement with the USD shell-model prediction of 0.090 W.u. The 1801.5-k…

Normal and intruder configurations in $^{34}$Si populated in the $\beta^-$ decay of $^{34}$Mg and $^{34}$Al

2019

The structure of Si34 was studied through γ spectroscopy separately in the β− decays of Mg34 and Al34 at the ISOLDE facility of CERN. Different configurations in Si34 were populated independently from the two recently identified β-decaying states in Al34 having spin-parity assignments Jπ=4− dominated by the normal configuration π(d5/2)−1⊗ν(f7/2) and Jπ=1+ by the intruder configuration π(d5/2)−1⊗ν(d3/2)−1(f7/2)2. The paper reports on spectroscopic properties of Si34 such as an extended level scheme, spin and parity assignments based on log(ft) values and γ-ray branching ratios, absolute β feeding intensities, and neutron emission probabilities. A total of 11 newly identified levels and 26 tr…

Some Evidence of the Cluster Struture Inside of 9Be

2017

Angular distributions of protons, deuterons, tritons and alpha-particles emitted from the reactions in the 2H+9Be-system at Elab=19.5 MeV were measured with an aim to shed light on the internal cluster structure of 9Be and the study of possible cluster transfer of 5He. The analyses suggest a significant contribution of five-nucleon transfer in the reaction channel 9Be(d,4He)7Li. peerReviewed