arXiv subjects

Sebouh J. Paul

Publications and source records attributed to Sebouh J. Paul.

16 recordsLinked to original sources

arXiv2025

The CONDOR Observatory: A Gamma-Ray Observatory with a 100 GeV Threshold at 5300 Meters Above Sea Level

We present the design of the Compact Network of Detectors with Orbital Range (CONDOR), a proposed high-altitude gamma-ray and cosmic-ray (CR) observatory set to become the highest of its kind. Planned for installation at Cerro Toco in the Atacama Desert, Chile, at 5300 meters above sea level (m.a.s.l.), CONDOR is optimized to operate in the 100 GeV to 1 TeV range using the extensive air-shower technique. The design prioritizes simplicity, modularity, and robustness to ensure reliable performance in a harsh environment. The CONDOR array has a full coverage factor of 90 and consists of 6000 plastic scintillator panels, each approximately 1 m^2, read by wavelength-shifting fibers and SiPMs. The readout electronics are based on fast ADCs, with White Rabbit technology ensuring time synchronization. We present an analysis of angular resolution and effective area by variation of the CORSIKA design to meet the developing GeV threshold, complementing other ground-based observatories in gamma-ray and proton CR measurements. CONDOR has the potential to support an extensive research program in astroparticle physics and multimessenger astronomy from the Southern Hemisphere, operating in all-sky mode 24 hours per day, year-round, with satellite data ranges.

astro-ph.IM↗

arXiv2025

Design of a SiPM-on-Tile ZDC for the future EIC and its Performance with Graph Neural Networks

We present a design for a high-granularity zero-degree calorimeter (ZDC) for the upcoming Electron-Ion Collider (EIC). The design uses SiPM-on-tile technology and features a novel staggered-layer arrangement that improves spatial resolution. To fully leverage the design's high granularity and non-trivial geometry, we employ graph neural networks (GNNs) for energy and angle regression as well as signal classification. The GNN-boosted performance metrics meet, and in some cases, significantly surpass the requirements set in the EIC Yellow Report, laying the groundwork for enhanced measurements that will facilitate a wide physics program. Our studies show that GNNs can significantly enhance the performance of high-granularity CALICE-style calorimeters by automating and optimizing the software compensation algorithms required for these systems. This improvement holds true even in the case of complicated geometries that pose challenges for image-based AI/ML methods.

physics.ins-det↗

arXiv2025

Measurement of the helicity-dependent response in quasi-elastic proton knockout from $^{40}{\rm Ca}$

The role of the electron-helicity-dependent cross-section term and the structure function $f^{\prime}_{01}$ in the quasi-elastic $A(\vec{e}, e^{\prime}p)$ process was studied. The $f^{\prime}_{01}$ was measured for proton knockout from the $1\mathrm{d}_{3/2}$ shell in $^{40}\mathrm{Ca}$ via the $^{40}{\rm Ca}(\vec{e},e' p)^{39}{\rm K}_{\rm g.s.}$ reaction, leaving the residual nucleus in a well-defined state. It requires a longitudinally polarized electron beam and out-of-plane proton detection. This structure function vanishes in the absence of final-state interactions (FSI) involving the ejected proton. Presented are the dependencies of $f^{\prime}_{01}$ on the missing momentum (closely related to the initial proton's Fermi momentum) and the angle between the knocked-out proton and the virtual photon momenta. The role of the spin-orbit interaction in FSI through the $\vec{L}\cdot \vec{S}$ term in a nuclear optical potential is discussed.

nucl-ex↗

arXiv2025

Feasibility Study of Measuring $Λ^0\to nπ^{0}$ Using a High-Granularity Zero-Degree Calorimeter at the Future Electron-Ion Collider

Key measurements at the future Electron-Ion Collider (EIC), including first-of-their-kind studies of kaon structure, require the detection of $Λ^0$ at forward angles. We present a feasibility study of $Λ^0 \to nπ^0$ measurements using a high-granularity Zero Degree Calorimeter to be located about 35 m from the interaction point. We introduce a method to address the unprecedented challenge of identifying $Λ^0$s with energy $O(100)$ GeV that produce displaced vertices of $O(10)$ m. In addition, we present a reconstruction approach using graph neural networks. We find that the energy and angle resolution for $Λ^0$ is similar to that for neutrons, both of which meet the requirements outlined in the EIC Yellow Report.Furthermore, we estimate performance for measuring the neutron's direction in the $Λ^0$ rest frame, which reflects the $Λ^0$ spin polarization. We estimate that the neutral-decay channel $Λ^0 \to nπ^0$ will greatly extend the measurable energy range for the charged-decay channel $Λ^0 \to pπ^-$, which is limited by the location of small-angle trackers and the accelerator magnets. This work paves the way for EIC studies of kaon structure and spin phenomena.

nucl-ex↗

arXiv2025

First-Ever Deployment of a SiPM-on-Tile Calorimeter in a Collider: A Parasitic Test with 200 GeV $pp$ Collisions at RHIC

We describe the testing of a prototype SiPM-on-tile iron-scintillator calorimeter at the Relativistic Heavy Ion Collider (RHIC) during its 200 GeV $pp$ run in 2024. The prototype, measuring $20 \times 20 \, \text{cm}^{2}$ and 24 radiation lengths in depth, was positioned in the STAR experimental hall, approximately 8 m from the interaction point and 65 cm from the beam line, covering a pseudorapidity range of about $3.1<η<3.4$. By using the dark current of a reference SiPM as a radiation monitor, we estimate that the prototype was exposed to a fluence of about $10^{10}$ 1-MeV $n_{\mathrm{eq}}$/cm$^2$. Channel-by-channel calibration was performed in a data-driven way with the signature from minimum-ionizing particles during beam-on conditions. A Geant4 detector simulation, with inputs from the Pythia8 event generator, describes measurements of energy spectra and hit multiplicities reasonably well. These results mark the first deployment, commissioning, calibration, and long-term operation of a SiPM-on-tile calorimeter in a collider environment. This experimental campaign will guide detector designs and operational strategies for the ePIC detector at the future EIC, as well as other applications.

physics.ins-det↗

arXiv2024

Letter of Intent: Open Charm at JLab with the sPHENIX MAPS tracker

We propose a physics program at JLab with CLAS12 focusing on open-charm measurements, aiming to complement and expand current studies of $J/ψ$ at (sub) threshold. This program will aid us in elucidating the $J/ψ$ production mechanisms, which is crucial for interpreting data in terms of gluon form factors and offer potential insights into the intrinsic charm hypothesis and cold-nuclear matter effects. We discuss the technical feasibility of integrating the sPHENIX monolithic-active-pixel sensor (MAPS) tracker, known as MVTX, with the CLAS12 detector. The sPHENIX MTVX would support an open-charm program by providing excellent secondary-vertex performance for tagging $D$ mesons. We study the kinematics of $γp \to \bar{D}^{0}Λ_{c}$ through phase-space simulations and estimate rates for the tagged quasi-photoproduction regime available with the CLAS12 forward tagger. While open-charm cross-sections at threshold remain uncertain, various predictions suggest that these measurements could be feasible when combined with conservative estimates of detector acceptance and luminosity. These preliminary estimates motivate detailed Geant detector simulations of signals and backgrounds, along with thorough technical assessments of operating conditions, to further explore the feasibility of these measurements in future dedicated CLAS12 experiments at JLab.

nucl-ex↗

arXiv2023

Beam Test of the First Prototype of SiPM-on-Tile Calorimeter Insert for the Electron-Ion Collider Using 4 GeV Positrons at Jefferson Laboratory

We recently proposed a high-granularity calorimeter insert for the Electron-Ion Collider (EIC) that uses plastic scintillator tiles read out by SiPMs. Among its innovative features are an ASIC-away-of-SiPM strategy for reducing cooling requirements and minimizing space use, along with employing 3D-printed frames to reduce optical crosstalk and dead areas. To evaluate these features, we built a 40-channel prototype and tested it using a 4 GeV positron beam at Jefferson Laboratory. The measured energy spectra and 3D shower shapes are well described by simulations, confirming the effectiveness of the design, construction techniques, and calibration strategy. This constitutes the first use of SiPM-on-tile technology in EIC detector designs.

physics.ins-det↗

arXiv2023

Leveraging Staggered Tessellation for Enhanced Spatial Resolution in High-Granularity Calorimeters

We advance the concept of high-granularity calorimeters with staggered tessellations, underscoring the effectiveness of a design incorporating multifold staggering cycles based on hexagonal cells to enhance position resolution. Moreover, we introduce HEXPLIT, a sub-cell re-weighting algorithm tailored to harness staggered designs, resulting in additional performance improvements. By combining our proposed staggered design with HEXPLIT, we achieve an approximately twofold enhancement in position resolution for neutrons across a wide energy range, as compared to unstaggered designs. These findings hold the potential to elevate particle-flow performance across various forthcoming facilities.

physics.ins-det↗

arXiv2023

A Few-Degree Calorimeter for the future Electron-Ion Collider

Measuring the region $0.1 < Q^{2} < 1.0$ GeV$^{2}$ is essential to support searches for gluon saturation at the future Electron-Ion Collider. Recent studies have revealed that covering this region at the highest beam energies is not feasible with current detector designs, resulting in the so-called $Q^{2}$ gap. In this work, we present a design for the Few-Degree Calorimeter (FDC), which addresses this issue. The FDC uses SiPM-on-tile technology with tungsten absorber and covers the range of $-4.6 < η< -3.6$. It offers fine transverse and longitudinal granularity, along with excellent time resolution, enabling standalone electron tagging. Our design represents the first concrete solution to bridge the $Q^{2}$ gap at the EIC.

physics.ins-det↗

arXiv2023

Studies of time resolution, light yield, and crosstalk using SiPM-on-tile calorimetry for the future Electron-Ion Collider

We recently proposed a high-granularity calorimeter insert for the Electron-Ion Collider (EIC) that is based on plastic scintillator tiles readout with silicon photomultipliers. In this work, we concretize its design by characterizing its building blocks with measurements of light yield, optical crosstalk, and timing resolutions using cosmic-rays, an LED, and a beta source. We also compared two approaches for the optical isolation of cells: ``megatiles'' with grooved boundaries between cells, and a 3D-printed plastic frame hosting individual cells. We found that the latter suppresses optical crosstalk to negligible levels while providing an easier assembly method. Overall, these performance studies can help inform calorimeter design and realistic simulations of 5D showers (time, energy, position) for the EIC and other experiments.

physics.ins-det↗

arXiv2022

A high-granularity calorimeter insert based on SiPM-on-tile technology at the future Electron-Ion Collider

We present a design for a high-granularity calorimeter insert for future experiments at the Electron-Ion Collider (EIC). The sampling-calorimeter design uses scintillator tiles read out with silicon photomultipliers. It maximizes coverage close to the beampipe, while solving challenges arising from the beam-crossing angle and mechanical integration. It yields a compensated response that is linear over the energy range of interest for the EIC. Its energy resolution meets the requirements set in the EIC Yellow Report even with a basic reconstruction algorithm. Moreover, this detector will provide 5D shower data (position, energy, and time), which can be exploited with machine-learning techniques. This detector concept has the potential to unleash the power of imaging calorimetry at the EIC to enable measurements at extreme kinematics in electron-proton and electron-nucleus collisions.

physics.ins-det↗

arXiv2022

Neutrino-tagged jets at the Electron-Ion Collider

We explore the potential of jet observables in charged-current deep-inelastic scattering (CC DIS) events at the future Electron-Ion Collider (EIC). Tagging jets with a recoiling neutrino, which can be identified by the event's missing transverse momentum, will allow for flavor-sensitive measurements of Transverse Momentum Dependent parton distribution functions (TMDs). We present the first predictions for transverse-spin asymmetries in azimuthal neutrino-jet correlations and hadron-in-jet measurements. We study the kinematic reach and the precision of these measurements and explore their feasibility using parameterized detector simulations. We conclude that jet production in CC DIS, while challenging in terms of luminosity requirements, will complement the EIC experimental program to study the three-dimensional structure of the nucleon encoded in TMDs.

hep-ph↗

arXiv2021

Measurements of the electron-helicity asymmetry in the quasi-elastic ${\rm A}(\vec{e},e' p)$ process

We present measurements of the electron helicity asymmetry in quasi-elastic proton knockout from $^{2}$H and $^{12}$C nuclei by polarized electrons. This asymmetry depends on the fifth structure function, is antisymmetric with respect to the scattering plane, and vanishes in the absence of final-state interactions, and thus it provides a sensitive tool for their study. Our kinematics cover the full range in off-coplanarity angle $ϕ_{pq}$, with a polar angle $θ_{pq}$ coverage up to about 8 degrees. The missing energy resolution enabled us to determine the asymmetries for knock-out resulting in different states of the residual $^{11}$B system. We find that the helicity asymmetry for $p$-shell knockout from $^{12}$C depends on the final state of the residual system and is relatively large (up to $\approx 0.16$), especially at low missing momentum. It is considerably smaller (up to $\approx 0.01$) for $s$-shell knockout from both $^{12}$C and $^2$H. The data for $^2$H are in very good agreement with theoretical calculations, while the predictions for $^{12}$C exhibit differences with respect to the data.

nucl-ex↗

arXiv2020

Measurements of the induced polarization in the quasi-elastic $A(e,e'\vec p\,)$ process in non-coplanar kinematics

We report measurements of the induced polarization $\vec P$ of protons knocked out from $^2$H and $^{12}$C via the $A(e,e'\vec p\,)$ reaction. We have studied the dependence of $\vec P$ on two kinematic variables: the missing momentum $p_{\rm miss}$ and the "off-coplanarity" angle $ϕ_{pq}$ between the scattering and reaction planes. For the full 360$\degree$ range in $ϕ_{pq}$, both the normal ($P_y$) and, for the first time, the transverse ($P_x$) components of the induced polarization were measured with respect to the coordinate system associated with the scattering plane. $P_x$ vanishes in coplanar kinematics, however in non-coplanar kinematics, it is on the same scale as $P_y$. We find that the dependence on $ϕ_{pq}$ is sine-like for $P_x$ and cosine-like for $P_y$. For carbon, the magnitude of the induced polarization is especially large when protons are knocked out from the $p_{3/2}$ shell at very small $p_{\rm miss}$. For the deuteron, the induced polarization is near zero at small $|p_{\rm miss}|$, and its magnitude increases with $|p_{\rm miss}|$. For both nuclei such behavior is reproduced qualitatively by theoretical results, driven largely by the spin-orbit part of the final-state interactions. However, for both nuclei, sizeable discrepancies exist between experiment and theory.

nucl-ex↗

arXiv2020

Polarization transfer to bound protons measured by quasi-elastic electron scattering on $^{12}$C

We report the measurements of the transverse ($P'x$) and longitudinal ($P'z$) components of the polarization transfer to a bound proton in carbon via the quasi-free $^{12}{\rm C}(\vec e,e'\vec p)$ reaction, over a wide range of missing momenta. We determine these polarization-transfers separately for protons knocked out from the $s$- and $p$-shells. The electron-beam polarization was measured to determine the individual components with systematic uncertainties which allow a detailed comparison with theoretical calculations.

nucl-ex↗

arXiv2019

Quasi-elastic polarization-transfer measurements on the deuteron in anti-parallel kinematics

We present measurements of the polarization-transfer components in the $^2$H$(\vec e,e'\vec p)$ reaction, covering a previously unexplored kinematic region with large positive (anti-parallel) missing momentum, $p_{\rm miss}$, up to 220 MeV$/c$, and $Q^2=0.65$ $({\rm GeV}/c)^2$. These measurements, performed at the Mainz Microtron (MAMI), were motivated by theoretical calculations which predict small final-state interaction (FSI) effects in these kinematics, making them favorable for searching for medium modifications of bound nucleons in nuclei. We find in this kinematic region that the measured polarization-transfer components $P_x$ and $P_z$ and their ratio agree with the theoretical calculations, which use free-proton form factors. Using this, we establish upper limits on possible medium effects that modify the bound proton's form factor ratio $G_E/G_M$ at the level of a few percent. We also compare the measured polarization-transfer components and their ratio for $^2$H to those of a free (moving) proton. We find that the universal behavior of $^2$H, $^4$He and $^{12}$C in the double ratio $\frac{(P_x/P_z)^A}{(P_x/P_z)^{^1\rm H}}$ is maintained in the positive missing-momentum region.

nucl-ex↗