arXiv subjects

O. Shelbaya

Publications and source records attributed to O. Shelbaya.

4 recordsLinked to original sources

arXiv2026

Operational Accelerator Tuning via Model-Coupled Optics and Bayesian Steering

We present an on-line tuning strategy for the ISAC post-accelerator that pre-sets machine optics with a digital twin and then performs Bayesian optimization for steering under online operation with beam. The model computes end-to-end tunes in seconds and interfaces with the control system under device bounds, slew-rate limits, and loss interlocks. We report three experimental case studies demonstrating that decoupling optics from steering yields faster and more reliable convergence than a fully Bayesian optics-plus-steering baseline under identical conditions. Across these cases, iterations to high transmission tunes are reduced by a factor of 4-6, with final average transmissions in the mid- to high-90% range. By factorizing optics from steering, the dimensionality of the parameter space is reduced, convergence becomes more predictable, and operational safeguards are easier to enforce.

physics.acc-ph↗

arXiv2025

Matching Optimization for TRIUMF's Rare Isotope Linac

Fringe field effects are computed from simulated and measured quadrupole magnetic field gradients, enabling a more realistic modelling of the medium energy section optics in TRIUMF's RIB postaccelerator. Quantifying the fringe field optics using the method developed by Matsuda and Wollnik allows for the use of parallel modelling tune optimizations for machine operation, providing operators with an efficient means to re-tune the variable energy drift tube linac for RIB delivery.

physics.acc-ph↗

arXiv2025

Strategy for Bayesian Optimized Beam Steering at TRIUMF-ISAC's MEBT and HEBT Beamlines

In preparation for operation of multiple Rare Isotope Beams (RIBs) when the Advanced Rare Isotope Laboratory (ARIEL) becomes operational, TRIUMF embarked on a program of advanced beam tuning applications and machine learning tools. The strategy for operationalizing Bayesian Optimization for beam steering purposes is being developed. A previously reported centroid correction algorithm is used to tune accelerated charged particle beams at TRIUMF's ISAC postaccelerator facility. We present findings and results from multiple machine development experiments conducted between October and November 2024, as part of a pivot toward semi-automated machine tuning methods. These findings were instrumental in shaping the tuning strategy for the medium and high energy beam transport (MEBT, HEBT) lines at ISAC, by sequentially optimizing sub-sections of the beamlines.

physics.acc-ph↗

arXiv2011

First experimental determination of the charge radius of $^{74}$Rb and its application in tests of the unitarity of the CKM matrix

Collinear-laser spectroscopy with bunched-beams technique was used for the study of neutron deficient Rb isotopes, out to $^{74}$Rb ($N=Z=37$) at TRIUMF. The measured hyperfine coupling constants of $^{76,78m}$Rb were in agreement with literature values. The nuclear spin of $^{75}$Rb was confirmed to be $I=3/2$, and its hyperfine coupling constants were measured for the first time. The mean-square charge radius of $^{74}$Rb was determined for the first time. This result has improved the isospin symmetry breaking correction term used to calculate the $\mathcal{F}t$ value, with implications for tests of the unitarity of the Cabibbo-Kobayashi-Maskawa matrix.

nucl-ex↗