arXiv subjects

S. Murillo Morales

Publications and source records attributed to S. Murillo Morales.

3 recordsLinked to original sources

arXiv2026

Direct measurement of Enhanced octupole collectivity in 148Dy

Excited states in $^{148}_{~66}$Dy were populated via $β^+/EC$ decay of $^{148m}$Ho using the GRIFFIN spectrometer at the TRIUMF ISAC-I facility. A combined measurement of the mean lifetime of the $3_1^-$ level using the Generalized Centroid Difference (GCD) method and branching fraction of the $3_1^-\rightarrow0_1^+$ $γ$-ray decay has been performed. From these results, an enhanced electric octupole $B(E3;3_1^-\rightarrow0_1^+)$ transition strength of 46(3)~W.u. has been determined in $^{148}_{~66}$Dy. This is the largest measured value across the closed neutron shell at $N=82$ and provides direct evidence of enhanced octupole collectivity beyond $Z=64$. The evolution of the $B(E3; 3^-_1 \rightarrow 0^+_1)$ strength along the $N=82$ isotonic chain is compared with quasiparticle random-phase approximation (QRPA) calculations using the SkI3 and SkM$^*$ Skyrme energy-density functionals, as well as with large-scale shell-model (SM) calculations. This result extends the boundaries of enhanced octupole collectivity far from the so-called `octupole magic numbers' $Z=56$ and $N=88$.

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arXiv2026

Independent Validation of Octupole Collectivity in radium-224 through lifetime measurements of low-lying negative-parity states

The nucleus $^{224}$Ra is a key benchmark for octupole deformation and for theoretical descriptions of enhanced Schiff moments in reflection-asymmetric nuclei. While Coulomb-excitation measurements have established strong octupole collectivity in $^{224}$Ra, theoretical models predict that its intrinsic electric-dipole moment should be strongly quenched by a cancellation between macroscopic and microscopic contributions. Direct fast-timing measurements of the low-lying $J^π= 1^-_1$ and $3^-_1$ states populated following the $β$-decay of $^{224}$Fr at TRIUMF-ISAC were performed. Using the LaBr$_3$(Ce) detectors of the GRIFFIN array, mean lifetimes of $τ(1^-_1) = 444(6)$~ps and $τ(3^-_1) = 460(18)$~ps were obtained. The corresponding reduced transition probabilities agree with values inferred from Coulomb excitation, but are determined with substantially improved precision. These results provide an independent validation of the electromagnetic matrix elements associated with octupole collectivity in $^{224}$Ra and confirm a strongly-quenched intrinsic dipole moment of $D_0 \simeq 0.032~e\mathrm{fm}$. The present measurements therefore provide a stringent experimental benchmark for nuclear-structure models used in the interpretation of Schiff moments and future searches for non-zero electric dipole moments.

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arXiv2022

Comprehensive investigation of fission yields by using spallation- and (p,2p)-induced fission reactions in inverse kinematics

In the last decades, measurements of spallation, fragmentation and Coulex induced fission reactions in inverse kinematics have provided valuable data to accurately investigate the fission dynamics and nuclear structure at large deformations of a large variety of stable and non-stable heavy nuclei. To go a step further, we propose now to induce fission by the use of quasi-free (p,2p) scattering reactions in inverse kinematics, which allows us to reconstruct the excitation energy of the compound fissioning system by using the four-momenta of the two outgoing protons. Therefore, this new approach might permit to correlate the excitation energy with the charge and mass distributions of the fission fragments and with the fission probabilities, given for the first time direct access to the simultaneous measurement of the fission yield dependence on temperature and fission barrier heights of exotic heavy nuclei, respectively. The first experiment based on this methodology was realized recently at the GSI/FAIR facility and a detailed description of the experimental setup is given here.

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