Study of 12C(α,γ)16O reaction via the transfer reaction 12C(7Li,t)16O

International audienceThe 12C(a,g )16O reaction plays an important role in helium burning in massive stars and their evolution. However, despite many experimental studies, the low-energy cross section of 12C(a,g )16O remains highly uncertain. The extrapolation of the measured cross sections to stellar energies (E=300 keV) is made difficult by the presence of the two sub-threshold states at 6.92 (2+) and 7.12 (1−) MeV of 16O. In order to further investigate the contribution of these twosubthreshold resonances to the 12C(a,g )16O cross section, we performed a new determination of the a-reduced widths of the 6.92 and 7.12 MeV of 16O via a measurement of the transfer reaction 12C(7Li,t)16O at two incident energies, 34 and 28 MeV. The measured and calculated differential cross sections are presented as well as the obtained spectroscopic factors and the a-reduced widths for the 2+ and 1− sub-threshold states and their effect on the R-matrix calculations of 12C(a,g )16O

Organic Compounds Evaluation from Fumes Generated in Laboratory by Bio-recycled Asphalt Mixtures

Using bio-binder and bio-additives as recycling agents for asphalt mixtures with high-content of reclaimed asphalt (RA) is proving to be feasible. It is still not clear whether this combination might provide new known hazardous emissions from airborne binder fumes. The health hazard related to airborne bitumen fume generation is primarily relevant for paving crews, whereas there is little opportunity for exposure for asphalt plant workers. In this study, measurements of gaseous organic compounds from airborne binder fumes of selected bio-asphalt mixtures have been measured during the laboratory mixing process by using a thermo-mixer equipped with a chimney at University Gustave Eiffel. Parameters studied are the binder nature, mix formula, and mixing temperatures. Results showthat generally combining bio-based materials and RA is as safe as using conventional bitumen and RA; however, thanks to this approach, it was possible to identify a strong link between bituminous materials’ composition and their emission potential.This article is published as V. Gaudefroy, D. L. Presti, L. Porot, S. Pouget, J.-P. Planche, C. Williams, and E. Chailleux, “Organic Compounds Evaluation from Fumes Generated in Laboratory by Bio-recycled Asphalt Mixtures,” Journal of Testing and Evaluation 50, no. 2 (March/April 2022): 920–927. https://doi.org/10.1520/JTE20210201. Copyright © 2021 by ASTM International. Posted with permission

Prolate-Spherical Shape Coexistence at N=28 in 44^{44}S

The structure of $^{44}$S has been studied using delayed $\gamma$ and electron spectroscopy at \textsc{ganil}. The decay rates of the 0$^+_2$ isomeric state to the 2$^+_1$ and 0$^+_1$ states have been measured for the first time, leading to a reduced transition probability B(E2~:~2$^{+}_1$$\rightarrow$0$^{+}_2)$= 8.4(26)~e$^2$fm$^4$ and a monopole strength $\rho^2$(E0~:~0$^{+}_2$$\rightarrow$0$^{+}_1)$ =~8.7(7)$\times$10$^{-3}$. Comparisons to shell model calculations point towards prolate-spherical shape coexistence and a phenomenological two level mixing model is used to extract a weak mixing between the two configurations.Comment: 5 pages, 3 figures, accepted for publication in Physical Review Letter

Spectroscopy of 28^{28}Na: shell evolution toward the drip line

Excited states in $^{28}$Na have been studied using the $\beta$-decay of implanted $^{28}$Ne ions at GANIL/LISE as well as the in-beam $\gamma$-ray spectroscopy at the NSCL/S800 facility. New states of positive (J$^{\pi}$=3,4$^+$) and negative (J$^{\pi}$=1-5$^-$) parity are proposed. The former arise from the coupling between 0d$\_{5/2}$ protons and a 0d$\_{3/2}$ neutron, while the latter are due to couplings with 1p$\_{3/2}$ or 0f$\_{7/2}$ neutrons. While the relative energies between the J$^{\pi}$=1-4$^+$ states are well reproduced with the USDA interaction in the N=17 isotones, a progressive shift in the ground state binding energy (by about 500 keV) is observed between $^{26}$F and $^{30}$Al. This points to a possible change in the proton-neutron 0d$\_{5/2}$-0d$\_{3/2}$ effective interaction when moving from stability to the drip line. The presence of J$^{\pi}$=1-4$^-$ negative parity states around 1.5 MeV as well as of a candidate for a J$^{\pi}$=5$^-$ state around 2.5 MeV give further support to the collapse of the N=20 gap and to the inversion between the 0f$\_{7/2}$ and 1p$\_{3/2}$ levels below Z=12. These features are discussed in the framework of Shell Model and EDF calculations, leading to predicted negative parity states in the low energy spectra of the $^{26}$F and $^{25}$O nuclei.Comment: Exp\'erience GANIL/LISE et NSCL/S80

BioRePavation - Innovation In Bio-Recycling

The main scientific and technical objectives of the BioRePavation project have been to prove that alternative binders can be used to recycle asphaltic pavement with the same level of performance as conventional solutions with petroleum bitumen. To do so, the consortium proposed to build a demonstration where three innovative pavement solutions using bio-materials were tested using an accelerated pavement testing facility (IFSTTAR fatigue carousel): - A bio-based additive from pine chemistry designed to Increase RA content to 70%, even 100% in theory - A Bio-based additive designed to increase compatibility between fresh bitumen and RA: Epoxidized Methyl Soyate - A Biobitumen designed for full replacement of fresh bitumen The survey of performance was performed by both measuring the traffic level needed for the pavement solution to reach a distress mechanism and investigating the binder physicochemical evolution using an innovative non-destructive method. BioRePavation also assessed the environmental impacts of the combined use of bio-binders and high-content of RA in asphalt mixes. Special attention was given to airborne emissions that were directly measured in the laboratory. Obtained data were used to perform a risk assessment, as well as a Life Cycle Assessment (LCA) for the aforementioned BioRePavation technologies. Finally, the proof of concept was demonstrated: the innovative pavement mixes assessed in the BioRePavation international project behave better than a conventional reference mix. They now provide durable solutions, assessed by a full scale accelerated test and an environmental analysis, to build roads using high rate recycling and involving biomaterials as additive or alternative to bitumen.This proceeding is published as Pouget, S.; Chailleux, E.; Porot, L.; Williams, R.C.; Planche, J.P.; Lo Presti, D.; Blanc, J.; Hornych, P.; Del Barco Carrion, A.J.; and Gaudefroy, V. “BioRePavation - Innovation In Bio-Recycling”, 7th Eurasphalt & Eurobitume Congress- Asphalt 4.0 for future mobility, Madrid, Spain (Virtual), June 2021. Copyright 2021, European Asphalt Pavement Association and the European Bitumen Association. Posted with permission

Structure of the N=27 isotones derived from the 44^{44}Ar(d,p)45^{45}Ar

Expérience GANIL/SPIRAL, détecteur CATS, détecteur MUST, 7 figures,International audienceThe $^{44}$Ar(d,p)$^{45}$Ar neutron transfer reaction was performed at 10~A.MeV. Measured excitation energies, deduced angular momenta and spectroscopic factors of the states populated in $^{45}$Ar are reported. A satisfactory description of these properties is achieved in the shell model framework using a new $sdpf$ interaction. The model analysis is extended to more exotic even-Z nuclei down to $^{41}_{14}$Si$_{27}$ to study how collectivity impacts the low lying structure of N~=~27 neutron-rich nuclei

Structure around the island of inversion with single-neutron knockout reactions at GANIL

CERN-Proceedings-2010-001 available at http://www.fluka.org/Varenna2009/procmat.htmInternational audienceThe nuclear structure of the 31Mg nucleus has been studied with the singleneutron knockout reaction. We report on the preliminary results of an experiment performed with the EXOGAM array coupled, for the first time, to the SPEG spectrometer at GANIL.We present a provisional result for the inclusive single-neutron knockout cross section of σinc= 90(5) mb. Preliminary exclusive cross sections for the measured bound states, including the ground state, are also presented. Finally, preliminary longitudinal momentum distributions for the ground state and first excited state are also shown. These results are compared to Monte Carlo Shell-Model calculations in the sd-pf region

Structure around the island of inversion with single-neutron knockout reactions at GANIL

The nuclear structure of the 31Mg nucleus has been studied with the singleneutron knockout reaction. We report on the preliminary results of an experiment performed with the EXOGAM array coupled, for the first time, to the SPEG spectrometer at GANIL.We present a provisional result for the inclusive single-neutron knockout cross section of σinc= 90(5) mb. Preliminary exclusive cross sections for the measured bound states, including the ground state, are also presented. Finally, preliminary longitudinal momentum distributions for the ground state and first excited state are also shown. These results are compared to Monte Carlo Shell-Model calculations in the sd-pf region

In-beam spectroscopic studies of 44^{44}S nucleus

The structure of the $^{44}$S nucleus has been studied at GANIL through the one proton knock-out reaction from a $^{45}$Cl secondary beam at 42 A$\cdot$MeV. The $\gamma$ rays following the de-excitation of $^{44}$S were detected in flight using the 70 BaF${_2}$ detectors of the Ch\^{a}teau de Cristal array. An exhaustive $\gamma\gamma$-coincidence analysis allowed an unambiguous construction of the level scheme up to an excitation energy of 3301 keV. The existence of the spherical 2$^+_2$ state is confirmed and three new $\gamma$-ray transitions connecting the prolate deformed 2$^+_1$ level were observed. Comparison of the experimental results to shell model calculations further supports a prolate and spherical shape coexistence with a large mixing of states built on the ground state band in $^{44}$S.Comment: 6 pages, 5 figures, accepted for publication in Physical Review