arXiv subjects

H. Desilets

Publications and source records attributed to H. Desilets.

7 recordsLinked to original sources

arXiv2026

Comparing the fusion of $^{19}$O and $^{20}$O ions with protons at near barrier energies

Proton capture on $^{19,20}$O nuclei was measured in inverse kinematics with the active-target detector MuSIC@Indiana using CH$_4$ as the target gas. Direct measurement of the (p,n) cross section was enabled by the intrinsically high efficiency and self-normalizing nature of the measurement. The excitation function of both (p,n) reactions exhibits an oscillatory behavior. For the neutron-rich nuclei studied, determining the (p,n) cross section provides access to the proton fusion cross section because the proton's de Broglie wavelength is much larger than that of the heavy ion. A significant suppression of the cross section in $^{19}$O compared to $^{20}$O is observed, suggesting level-density differences. While the coupled channel calculations reproduce the oscillatory behavior observed in the case of $^{20}$O, they fail to predict the oscillatory behavior observed in $^{19}$O or the overall suppression of the fusion cross section.

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arXiv2026

Neutron dynamics in the fusion of neutron-rich O ions with $^{12}$C

The fusion excitation function for $^{21}$O + $^{12}$C was measured for the first time and compared to the fusion of less neutron-rich isotopes. The impact of valence neutrons in the d$_{5/2}$ shell on the fusion excitation function is examined. The experimental data manifest a clear dependence of the extracted barrier height, V$_B$, and barrier position, R$_B$ on neutron excess. To assess the role of dynamics the experimental data are compared with both density constrained frozen Hartree Fock (DCFHF) and density constrained time-dependent Hartree Fock (DCTDHF) theories.

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arXiv2026

Measuring $^{19,20}$O(p,n)$^{19,20}$F reactions using an active target detector

Proton capture on $^{19,20}$O nuclei is measured in inverse kinematics with the active target detector MuSIC@Indiana using CH$_4$ as the target gas. Rejection of unreacted and inelastically scattered beam, along with transfer and fusion on the $^{12}$C allows extraction of the (p,n) cross section. As the cross-section for direct (p,n) processes at these energies is small, the measurement provides access to the proton fusion cross-section. An analysis approach that allows extraction of the proton fusion cross-section is detailed.

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arXiv2025

Observation of oscillations and near-barrier suppression in the fusion of $^{20}$O + p

Using an active target detector, the fusion excitation function for $^{20}$O + $^1$H was measured for the first time. Near the barrier, the fusion cross section manifests an oscillatory behavior with broad peaks $\sim$50-100 keV wide. The presence of these peaks likely reflects the low density of low-angular-momentum states in the quasibound regime. R-matrix coupled channel (CC) calculations that include the first excited 2$^+$ state in $^{20}$O are able to reproduce the observed oscillations. However, one channel CC calculations fail to reproduce the decrease in the sub-barrier cross section experimentally observed.

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arXiv2025

Resonant suppression of the above-barrier fusion cross-section in $^{19}$O + $^{12}$C

Fusion excitation functions for $^{19}$O and $^{19}$F + $^{12}$C were simultaneously measured along with $^{20}$O + $^{12}$C using the active-target detector MuSIC@Indiana. Examination of the cross-section just above the barrier reveals a significant suppression of fusion for the $^{19}$O + $^{12}$C system at E$_{c.m.}$~12 MeV. This suppression may be due to the formation of a transient $^{18}$O-n-$^{12}$C molecule-like complex favored at a particular angular momentum. Mean-field level models are used as a reference to understand the measured fusion excitation functions.

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arXiv2025

Deconstructing the emission order of protons, neutrons and $α$-particles following fusion in $^{28,30,32}$Si + $^{28}$Si

A high-quality measurement of proton and $α$-particle emission associated with fusion of $^{28,30,32}$Si with a $^{28}$Si target is described. Evaporation residues produced by de-excitation of the compound nucleus were identified by an energy time-of-flight (ETOF) measurement while emitted light-charged particles were identified using the $Δ$E-E technique. Comparison of the experimentally measured charged particle multiplicities and energy spectra with the predictions of the statistical decay model code, GEMINI++, allows one to deduce interesting details of the de-excitation cascade and its dependence on neutron-excess. The impact of modifying the sequence of particle emissions on the average energy and multiplicity is examined.

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arXiv2023

Influence of additional neutrons on the fusion cross-section beyond the N=8 shell

Fusion enhancement for neutron-rich isotopes of oxygen on carbon nuclei was probed. To measure the fusion cross-section a $^{20}$O beam accelerated to E$_{lab}$/A=2.7 MeV bombarded the active-target detector MuSIC@Indiana with a fill gas of CH$_4$. Examination of the average fusion cross-section over the interval 12 MeV $\leq$E$_{c.m.}$$\leq$ 17 MeV for $^{16-20}$O + $^{12}$C reveals that while even isotopes of oxygen exhibit essentially the same cross-section, the cross-section for odd isotopes can be either enhanced or suppressed relative to the even A members of the isotopic chain. Theoretical models fail to explain the observed experimental results.

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