J. E. Ramirez Vargas
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View article: Learning to Upscale 3D Segmentations in Neuroimaging
Learning to Upscale 3D Segmentations in Neuroimaging Open
Obtaining high-resolution (HR) segmentations from coarse annotations is a pervasive challenge in computer vision. Applications include inferring pixel-level segmentations from token-level labels in vision transformers, upsampling coarse ma…
View article: Reference-Free 3D Reconstruction of Brain Dissection Slabs via Learned Atlas Coordinates
Reference-Free 3D Reconstruction of Brain Dissection Slabs via Learned Atlas Coordinates Open
Correlation of neuropathology with MRI has the potential to transfer microscopic signatures of pathology to in vivo scans. There is increasing interest in building these correlations from 3D reconstructed stacks of slab photographs, which …
View article: Data-Efficient Kernel Methods for Learning Differential Equations and Their Solution Operators: Algorithms and Error Analysis
Data-Efficient Kernel Methods for Learning Differential Equations and Their Solution Operators: Algorithms and Error Analysis Open
We introduce a novel kernel-based framework for learning differential equations and their solution maps that is efficient in data requirements, in terms of solution examples and amount of measurements from each example, and computational c…
View article: Fission-fragment yields measured in Coulomb-induced fission of <sup>234,235,236,238</sup>U and <sup>237,238</sup>Np with the R<sup>3</sup>B/SOFIA setup
Fission-fragment yields measured in Coulomb-induced fission of <sup>234,235,236,238</sup>U and <sup>237,238</sup>Np with the R<sup>3</sup>B/SOFIA setup Open
Low energy fission of 234,235,236,238 U and 237,238 Np radioactive beams, provided by the GSI/FRS facility, has been studied using the R 3 B/SOFIA setup. The latter allows, on an event-by-event basis, to simultaneously identify, in terms o…
View article: Measurements of Xi(c)+ branching ratios
Measurements of Xi(c)+ branching ratios Open
Using data collected by the fixed target Fermilab experiment FOCUS, we measure the branching ratios of the Cabibbo favored decays $\\Xi_c^+ \\to \\Sigma^+K^-\\pi^+$, $\\Xi_c^+ \\to \\Sigma^+ \\bar{K}^{*}(892)^0$, and $\\Xi_c^+ \\to \\Lambd…
View article: Systematic study of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="normal">Δ</mml:mi></mml:math>(1232) resonance excitations using single isobaric charge-exchange reactions induced by medium-mass projectiles of Sn
Systematic study of (1232) resonance excitations using single isobaric charge-exchange reactions induced by medium-mass projectiles of Sn Open
The fragment separator FRS has been used for the first time to measure the (n,p)- and (p,n)-type isobaric charge-exchange cross sections of stable Sn112,124 isotopes accelerated at 1A GeV with an uncertainty of 3% and to separate quasielas…
View article: Systematic study of Δ(1232) resonance excitations using single isobaric charge-exchange reactions induced by medium-mass projectiles of Sn
Systematic study of Δ(1232) resonance excitations using single isobaric charge-exchange reactions induced by medium-mass projectiles of Sn Open
The fragment separator FRS has been for the first time used to measure the (n,p) and (p,n)-type isobaric charge-exchange cross sections of stable 112,124Sn isotopes accelerated at 1A GeV with an uncertainty of 3% and to separate quasi-elas…
View article: Isobaric charge-exchange reactions: a tool to study the excitation of baryonic resonances in exotic nuclear matter
Isobaric charge-exchange reactions: a tool to study the excitation of baryonic resonances in exotic nuclear matter Open
Isobaric charge-exchange reactions induced by beams of 112 Sn have been investigated at the GSI facility using the fragment separator FRS. The high-resolving power of this spectrometer makes it possible to obtain the isobaric charge-exchan…
View article: Excitation of baryonic resonances in stable medium-mass nuclei of Sn
Excitation of baryonic resonances in stable medium-mass nuclei of Sn Open
Isobaric charge-exchange reactions induced by beams of 112 Sn have been investigated at the GSI facilities using the fragment separator FRS. The high-resolving power of this spectrometer makes it possible to obtain the isobaric charge-exch…
View article: Excitation of baryonic resonances in stable medium-mass nuclei of Sn
Excitation of baryonic resonances in stable medium-mass nuclei of Sn Open
Isobaric charge-exchange reactions induced by beams of 112Sn have been investigated at the GSI facilities using the fragment separator FRS. The high-resolving power of this spectrometer makes it possible to obtain the isobaric charge-excha…
View article: Knockout and fragmentation reactions using a broad range of tin isotopes
Knockout and fragmentation reactions using a broad range of tin isotopes Open
Production cross sections of residual nuclei obtained by knockout and fragmentation reactions of different tin isotopes accelerated at 1A GeV have been measured with the fragment separator (FRS) at GSI, Darmstadt. The new measurements are …
View article: Fission dynamics at high excitation energies investigated in complete kinematics measurements
Fission dynamics at high excitation energies investigated in complete kinematics measurements Open
Light-charged particles emitted in proton-induced fission reactions on 208 Pb have been measured at different kinetic energies: 370A, 500A, and 650A MeV. The experiment was performed by the SOFIA collaboration at the GSI facilities in Darm…
View article: Dissipative effects in fission investigated in complete kinematics measurements
Dissipative effects in fission investigated in complete kinematics measurements Open
The study of dissipative effects in fission has been carried out with fusion-fission reactions by using a limited number of observables, such as the fission probabilities, the mass distribution of the fission fragments, or the neutron mult…
View article: Presaddle and postsaddle dissipative effects in fission using complete kinematics measurements
Presaddle and postsaddle dissipative effects in fission using complete kinematics measurements Open
A complete kinematics measurement of the two fission fragments was used for the first time to investigate fission dynamics at small and large deformations. Fissioning systems with high excitation energies, compact shapes, and low angular m…
View article: Exploiting multicore compute resources in the CMS experiment
Exploiting multicore compute resources in the CMS experiment Open
CMS has developed a strategy to efficiently exploit the multicore architecture of the compute resources accessible to the experiment. A coherent use of the multiple cores available in a compute node yields substantial gains in terms of res…
View article: Parameter-free calculation of charge-changing cross sections at high energy
Parameter-free calculation of charge-changing cross sections at high energy Open
Charge-changing cross sections at high energies are expected to provide useful information on nuclear charge radii. No reliable theory to calculate the cross section has yet been available. We develop a formula using Glauber and eikonal ap…
View article: Observation of large enhancements of charge exchange cross sections with neutron-rich carbon isotopes
Observation of large enhancements of charge exchange cross sections with neutron-rich carbon isotopes Open
Production cross sections of nitrogen isotopes from high-energy (∼950 MeV per nucleon) carbon isotopes on hydrogen and carbon targets have been measured for the first time for a wide range of isotopes (A=12 to 19). The fragment separator…
View article: Excitation of Δ and<i>N</i><sup>*</sup>resonances in isobaric charge-exchange reactions of heavy nuclei
Excitation of Δ and<i>N</i><sup>*</sup>resonances in isobaric charge-exchange reactions of heavy nuclei Open
We present a model for the study of the excitation of Δ(1232) and N*(1440) resonances in isobaric charge-exchange (AZ, A(Z ± 1)) reactions of heavy nuclei. Quasi-elastic and inelastic elementary processes contributing to the double differe…
View article: Dissipative effects in fission investigated with proton-on-lead reactions
Dissipative effects in fission investigated with proton-on-lead reactions Open
\nThe complete kinematic measurement of the two fission fragments permitted us to investigate dissipative effects at large deformations, between the saddle-point and the corresponding scission configurations. Up to now, this kind of study …
View article: The SOFIA experiment: Measurement of<sup>236</sup>U fission fragment yields in inverse kinematics
The SOFIA experiment: Measurement of<sup>236</sup>U fission fragment yields in inverse kinematics Open
The SOFIA (Studies On FIssion with Aladin) experiment aims at measuringfission-fragments isotopic yields with high accuracy using inverse kinematics at relativisticenergies. This experimental technique allows to fully identify the fission …
View article: New experimental approaches to investigate the fission dynamics
New experimental approaches to investigate the fission dynamics Open
The first ever achieved full identification of both fission fragments, in atomic and mass number, made it possible to define new observables sensitive to the fission dynamics along the fission path up to the scission point. Moreover, proto…
View article: Observation of Large Enhancement of Charge Exchange Cross Sections with Neutron-Rich Carbon Isotopes
Observation of Large Enhancement of Charge Exchange Cross Sections with Neutron-Rich Carbon Isotopes Open
Production cross sections of nitrogen isotopes from high-energy carbon isotopes on hydrogen and carbon targets have been measured for the first time for a wide range of isotopes. The fragment separator FRS at GSI was used to deliver C isot…
View article: Constraining the level density using fission of lead projectiles
Constraining the level density using fission of lead projectiles Open
The nuclear level density is one of the main ingredients for the statistical description of the fission process. In this work, we propose to constrain the description of this parameter by using fission reactions induced by protons and ligh…
View article: A Sample of the Results of the First SOFIA Experiment
A Sample of the Results of the First SOFIA Experiment Open
The first SOFIA experiment (Studies On FIssion with Aladin) was performed in August 2012 at GSI. The fission of several neutron-deficient actinides and pre-actinides was induced in flight at 700 A MeV by electromagnetic excitation. The use…
View article: Transient Effects in Fission Investigated with Proton-on-lead Reactions in Complete Kinematic Measurements
Transient Effects in Fission Investigated with Proton-on-lead Reactions in Complete Kinematic Measurements Open
Proton-induced fission of Pb-208 has been investigated at 370, 500 and 650 A MeV in complete kinematic measurements. The experiment was performed at GSI Darmstadt where the combined use of the inverse kinematics technique with an efficient…