arXiv subjects

MinJung Kweon

Publications and source records attributed to MinJung Kweon.

5 recordsLinked to original sources

arXiv2026

Development and demonstration of the Korea ALICE Telescope using electron beams at KEK PF-AR

The development of ultra-low-mass, high-precision vertex detectors is a key requirement for future collider experiments and motivates extensive research and development of novel silicon tracking technologies. In this work, we present the development and beam-test demonstration of the Korea ALICE Telescope (KATS), a silicon-tracking telescope designed to support R&D on next-generation cylindrical vertex detectors, such as the proposed ALICE ITS3 upgrade. The telescope consists of six ALPIDE Monolithic Active Pixel Sensors (MAPS) used as reference tracking planes, a bent ALPIDE sensor serving as the device under test, and a scintillating-fiber-based trigger system, all housed in a light-tight modular enclosure. This setup enables precise track reconstruction and detailed performance studies of both planar and curved silicon sensors. Beam tests were carried out using high-energy electron beams at the KEK Photon Factory Advanced Ring (PF-AR). The telescope system operated stably under realistic beam conditions, and its tracking performance was successfully validated. The bent ALPIDE sensor was operated at a bending radius of approximately 18 mm, consistent with ITS3's design goals, without any observable degradation in detection performance. The measured results confirm that the KATS provides a versatile and reliable platform for studies of curved MAPS technologies, alignment precision, and tracking performance. These results provide important experimental validation of key technologies for future low-mass cylindrical silicon vertex detectors and establish KATS as a valuable facility for ongoing and future detector R&D.

physics.ins-det↗

arXiv2026

Comparison of Image Processing Models in Quark Gluon Jet Classification

We present a comprehensive comparison of convolutional and transformer-based models for distinguishing quark and gluon jets using simulated jet images from Pythia 8. By encoding jet substructure into a three-channel representation of particle kinematics, we evaluate the performance of convolutional neural networks (CNNs), Vision Transformers (ViTs), and Swin Transformers (Swin-Tiny) under both supervised and self-supervised learning setups. Our results show that fine-tuning only the final two transformer blocks of the Swin-Tiny model achieves the best trade-off between efficiency and accuracy, reaching 81.4% accuracy and an AUC (area under the ROC curve) of 88.9%. Self-supervised pretraining with Momentum Contrast (MoCo) further enhances feature robustness and reduces the number of trainable parameters. These findings highlight the potential of hierarchical attention-based models for jet substructure studies and for domain transfer to real collision data.

physics.data-an↗

arXiv2024

Investigation of suppression of $Υ(nS)$ in relativistic heavy-ion collisions at RHIC and LHC energies

The primary purpose of studying quarkonium production in relativistic heavy-ion collisions is to understand the properties of the quark-gluon plasma. At various collision systems, measurements of quarkonium states of different binding energies, such as $Υ(nS)$, can provide comprehensive information. A model study has been performed to investigate the modification of $Υ(nS)$ production in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV and Au-Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 200 GeV. The Monte-Carlo simulation study is performed with a publicly available hydrodynamic simulation package for the quark-gluon plasma medium and a theoretical calculation of temperature-dependent thermal width of $Υ(nS)$ considering the gluo-dissociation and inelastic parton scattering for dissociation inside the medium. In addition, we perform a systematic study with different descriptions of initial collision geometry and formation time of $Υ(nS)$ to investigate their impacts on yield modification. The model calculation with a varied parameter set can describe the experimental data of $Υ(nS)$ in Pb-Pb collisions at 5.02 TeV and $Υ(2S)$ in Au-Au collisions at 200 GeV but underestimates the modification of $Υ(1S)$ at the lower collision energy. The nuclear absorption mechanism is explored to understand the discrepancy between the data and simulation.

nucl-th↗

arXiv2022

Model study on $Υ(nS)$ modification in small collision systems

Quarkonium production has been studied extensively in relativistic heavy-ion collision experiments to understand the properties of the quark gluon plasma. The experimental results on the yield modification in heavy-ion collisions relative to that in $p$+$p$ collisions can be described by several models considering dissociation and regeneration effects. A yield modification beyond initial-state effects has also been observed in small collision systems such as $p$+Au and $p$+Pb collisions, but it is still premature to claim any hot medium effect. A model study in various small collision systems such as $p$+$p$, $p$+Pb, $p$+O, and O+O collisions will help quantitatively understanding nuclear effects on the $Υ(nS)$ production. A theoretical calculation considering the gluo-dissociation and inelastic parton scattering and their inverse reaction reasonably describes the suppression of $Υ(1S)$ in Pb+Pb collisions. Based on this calculation, a Monte-Carlo simulation is developed to more realistically incorporate the medium produced in heavy-ion collisions with event-by-event initial collision geometry and hydrodynamic evolution. We extend this framework to small systems to study the medium effects. In this work, we quantify the nuclear modification factor of $Υ(nS)$ as a function of charged particle multiplicity ($dN_{ch}/dη$) and transverse momentum. We also calculate the elliptic flow of $Υ(nS)$ in small collision systems.

nucl-th↗

arXiv2012

Measurement of electrons from heavy-flavour decays in pp and Pb-Pb collisions with ALICE at the LHC

The ALICE experiment has measured at mid-rapidity electrons from heavy-flavour decays in pp collisions at $\sqrt{s}$ = 2.76 and 7 TeV, and in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV. In pp collisions, electrons from charm-hadron and from beauty-hadron decays are identified by applying cuts on displaced vertices. The relative yield of electrons from beauty-hadron decays to those from heavy-flavour decays is extracted using electron-hadron correlations. Results are compared to pQCD-based calculations. In Pb-Pb collisions, the $p_{\rm T}$ dependence of the nuclear modification factor of electrons from heavy-flavour decays is presented in two centrality classes. The status on the analysis of electrons from beauty-hadron decays is reported in Pb-Pb collisions, in view of the measurement of the corresponding nuclear modification factor.

nucl-ex↗