Showing 1–50 of 100 results for author: Schwarz, C

ePIC Early Science Report

Authors: D. Abbott, N. Abdelrahman, S. Abhijit, I. Abualrob, R. B. Achari, J. Adam, L. Adamczyk, K. Adkins, A. Affolder, K. Agarwal, J. Agarwala, N. Agrawal, C. A. Aidala, W. Akers, A. Al-bataineh, S. N. Alam, M. Alekseev, P. R. Altieri, J. -S. Alvarado Gallenao, S. B. L. Amar, R. Ammendola, I. Amos Cali, G. An, D. Anderson, E. Anderssen , et al. (774 additional authors not shown)

Abstract: This Early Science Report from the ePIC Collaboration outlines the compelling physics program achievable during the first years of operation of the Electron-Ion Collider (EIC), prior to the establishment of the full design luminosity and energy range. The analyses are based on realistic early-running beam configurations and detailed Geant4 ePIC detector simulations, hit digitization and data recon… ▽ More This Early Science Report from the ePIC Collaboration outlines the compelling physics program achievable during the first years of operation of the Electron-Ion Collider (EIC), prior to the establishment of the full design luminosity and energy range. The analyses are based on realistic early-running beam configurations and detailed Geant4 ePIC detector simulations, hit digitization and data reconstruction. The projected studies from the physics working groups of ePIC span inclusive, semi-inclusive, exclusive, diffractive and tagging, as well as jet and heavy flavor measurements in both electron-proton and electron-ion collisions. Even before the collider reaches its full design performance, these measurements will constrain parton distribution functions in nucleons and nuclei, access transverse-momentum-dependent and spin-dependent observables, probe gluon dynamics in nuclei, and initiate a program of imaging of quarks and gluons. Each measurement is directly connected to the core science pillars of the EIC, identified in the 2018 report by the National Academy of Sciences: understanding the origin of the nucleon mass, unraveling the spin structure of the nucleon, and exploring the emergent properties of dense gluonic matter. The results presented here provide examples that demonstrate that the early years of EIC running with ePIC will deliver novel world-leading insights into Quantum Chromodynamics. In addition, the early science program will establish measurement and analysis methodologies that will pave the way to the subsequent full EIC physics program. △ Less

Submitted 5 August, 2026; originally announced August 2026.

Report number: epic-AN-AC-2026-004

The PANDA Barrel DIRC: From design to assembly

Authors: G. Schepers, A. Belias, R. Dzhygadlo, A. Gerhardt, D. Lehmann, K. Peters, C. Schwarz, J. Schwiening, M. Traxler, Y. Wolf, L. Schmitt, M. Böhm, K. Gumbert, S. Krauss, A. Lehmann, D. Miehling, M. Schmidt, C. Sfienti, A. Ali

Abstract: The Barrel DIRC counter will serve as the primary particle identification detector in the PANDA experiment, enabling high-precision hadron physics studies through antiproton-proton annihilations across a momentum range of 1.5 GeV/c to 15 GeV/c. It is designed to distinguish charged pions from kaons with a separation of at least 3 standard deviations up to 3.5 GeV/c within polar angles of 22 degree… ▽ More The Barrel DIRC counter will serve as the primary particle identification detector in the PANDA experiment, enabling high-precision hadron physics studies through antiproton-proton annihilations across a momentum range of 1.5 GeV/c to 15 GeV/c. It is designed to distinguish charged pions from kaons with a separation of at least 3 standard deviations up to 3.5 GeV/c within polar angles of 22 degrees to 140 degrees. A lens focusing is used the first time in a DIRC detector. After a successful evaluation in particle beams, the key components, i.e. radiator bars and photon sensors, were purchased and tested. △ Less

Submitted 16 December, 2025; originally announced December 2025.

Comments: 12 pages, 13 figures

Journal ref: j.nima.2025.171028

The Content Moderator's Dilemma: Removal of Toxic Content and Distortions to Online Discourse

Authors: Mahyar Habibi, Dirk Hovy, Carlo Schwarz

Abstract: There is an ongoing debate about how to moderate toxic speech on social media and the impact of content moderation on online discourse. This paper proposes and validates a methodology for measuring the content-moderation-induced distortions in online discourse using text embeddings from computational linguistics. Applying the method to a representative sample of 5 million US political Tweets, we f… ▽ More There is an ongoing debate about how to moderate toxic speech on social media and the impact of content moderation on online discourse. This paper proposes and validates a methodology for measuring the content-moderation-induced distortions in online discourse using text embeddings from computational linguistics. Applying the method to a representative sample of 5 million US political Tweets, we find that removing toxic Tweets alters the semantic composition of content. This finding is consistent across different embedding models, toxicity metrics, and samples. Importantly, we demonstrate that these effects are not solely driven by toxic language but by the removal of topics often expressed in toxic form. We propose an alternative approach to content moderation that uses generative Large Language Models to rephrase toxic Tweets, preserving their salvageable content rather than removing them entirely. We show that this rephrasing strategy reduces toxicity while minimizing distortions in online content. △ Less

Submitted 2 March, 2026; v1 submitted 20 December, 2024; originally announced December 2024.

Isotopic Transparency in Central Xe+Sn Collisions at 100 MeV/nucleon

Authors: Arnaud Le Fèvre, Abdelouahad Chbihi, Quentin Fable, Tom Génard, Jerzy Łukasik, Wolfgang Trautmann, Ketel Turzó, Rémi Bougault, Sylvie Hudan, Olivier Lopez, Walter F. J. Müller, Carsten Schwarz, Concettina Sfienti, Giuseppe Verde, Mariano Vigilante, Bogdan Zwiegliński

Abstract: A new method, based on comparing isotopic yield ratios measured at forward and sideward polar angles and on cross-bombarding heavy nuclei with different neutron-to-proton ratios, is used to quantify the stopping power of nuclear matter in heavy-ion collisions. For central collisions of isotopically separated $^{124,129}$Xe+$^{112,124}$Sn at 100~MeV/nucleon bombarding energy, measured with the 4… ▽ More A new method, based on comparing isotopic yield ratios measured at forward and sideward polar angles and on cross-bombarding heavy nuclei with different neutron-to-proton ratios, is used to quantify the stopping power of nuclear matter in heavy-ion collisions. For central collisions of isotopically separated $^{124,129}$Xe+$^{112,124}$Sn at 100~MeV/nucleon bombarding energy, measured with the 4$π$ multidetector INDRA at GSI, a moderate transparency is deduced for hydrogen isotopes, whereas for heavier fragmentation products with atomic number $Z \ge 3$ a high transparency exceeding 50\% is observed. An anomalously large transparency is found for alpha particles, and possible explanations are presented. △ Less

Submitted 26 May, 2025; v1 submitted 16 December, 2024; originally announced December 2024.

Comments: 15 pages, 5 figures

Journal ref: Physics Letters B Volume 868, September 2025, 139749

Deep Multimodal Representation Learning for Stellar Spectra

Authors: Tobias Buck, Christian Schwarz

Abstract: Recently, contrastive learning (CL), a technique most prominently used in natural language and computer vision, has been used to train informative representation spaces for galaxy spectra and images in a self-supervised manner. Following this idea, we implement CL for stars in the Milky Way, for which recent astronomical surveys have produced a huge amount of heterogeneous data. Specifically, we i… ▽ More Recently, contrastive learning (CL), a technique most prominently used in natural language and computer vision, has been used to train informative representation spaces for galaxy spectra and images in a self-supervised manner. Following this idea, we implement CL for stars in the Milky Way, for which recent astronomical surveys have produced a huge amount of heterogeneous data. Specifically, we investigate Gaia XP coefficients and RVS spectra. Thus, the methods presented in this work lay the foundation for aggregating the knowledge implicitly contained in the multimodal data to enable downstream tasks like cross-modal generation or fused stellar parameter estimation. We find that CL results in a highly structured representation space that exhibits explicit physical meaning. Using this representation space to perform cross-modal generation and stellar label regression results in excellent performance with high-quality generated samples as well as accurate and precise label predictions. △ Less

Submitted 18 November, 2024; v1 submitted 21 October, 2024; originally announced October 2024.

Comments: accepted to the Machine Learning and the Physical Sciences Workshop, NeurIPS 2024

Boolean basis, formula size, and number of modal operators

Authors: Christoph Berkholz, Dietrich Kuske, Christian Schwarz

Abstract: Is it possible to write significantly smaller formulae when using Boolean operators other than those of the De Morgan basis (and, or, not, and the constants)? For propositional logic, a negative answer was given by Pratt: formulae over one set of operators can always be translated into an equivalent formula over any other complete set of operators with only polynomial increase in size. Surprisingl… ▽ More Is it possible to write significantly smaller formulae when using Boolean operators other than those of the De Morgan basis (and, or, not, and the constants)? For propositional logic, a negative answer was given by Pratt: formulae over one set of operators can always be translated into an equivalent formula over any other complete set of operators with only polynomial increase in size. Surprisingly, for modal logic the picture is different: we show that elimination of bi-implication is only possible at the cost of an exponential number of occurrences of the modal operator $\lozenge$ and therefore of an exponential increase in formula size, i.e., the De Morgan basis and its extension by bi-implication differ in succinctness. Moreover, we prove that any complete set of Boolean operators agrees in succinctness with the De Morgan basis or with its extension by bi-implication. More precisely, these results are shown for the modal logic $\mathrm{T}$ (and therefore for $\mathrm{K}$). We complement them showing that the modal logic $\mathrm{S5}$ behaves as propositional logic: the choice of Boolean operators has no significant impact on the size of formulae. △ Less

Submitted 25 July, 2025; v1 submitted 21 August, 2024; originally announced August 2024.

Journal ref: Logical Methods in Computer Science, Volume 21, Issue 3 (July 28, 2025) lmcs:14094

Analysis of the 2024 BraTS Meningioma Radiotherapy Planning Automated Segmentation Challenge

Authors: Dominic LaBella, Valeriia Abramova, Mehdi Astaraki, Andre Ferreira, Zhifan Jiang, Mason C. Cleveland, Ramandeep Kang, Uma M. Lal-Trehan Estrada, Cansu Yalcin, Rachika E. Hamadache, Clara Lisazo, Adrià Casamitjana, Joaquim Salvi, Arnau Oliver, Xavier Lladó, Iuliana Toma-Dasu, Tiago Jesus, Behrus Puladi, Jens Kleesiek, Victor Alves, Jan Egger, Daniel Capellán-Martín, Abhijeet Parida, Austin Tapp, Xinyang Liu , et al. (80 additional authors not shown)

Abstract: The 2024 Brain Tumor Segmentation Meningioma Radiotherapy (BraTS-MEN-RT) challenge aimed to advance automated segmentation algorithms using the largest known multi-institutional dataset of 750 radiotherapy planning brain MRIs with expert-annotated target labels for patients with intact or postoperative meningioma that underwent either conventional external beam radiotherapy or stereotactic radiosu… ▽ More The 2024 Brain Tumor Segmentation Meningioma Radiotherapy (BraTS-MEN-RT) challenge aimed to advance automated segmentation algorithms using the largest known multi-institutional dataset of 750 radiotherapy planning brain MRIs with expert-annotated target labels for patients with intact or postoperative meningioma that underwent either conventional external beam radiotherapy or stereotactic radiosurgery. Each case included a defaced 3D post-contrast T1-weighted radiotherapy planning MRI in its native acquisition space, accompanied by a single-label "target volume" representing the gross tumor volume (GTV) and any at-risk post-operative site. Target volume annotations adhered to established radiotherapy planning protocols, ensuring consistency across cases and institutions, and were approved by expert neuroradiologists and radiation oncologists. Six participating teams developed, containerized, and evaluated automated segmentation models using this comprehensive dataset. Team rankings were assessed using a modified lesion-wise Dice Similarity Coefficient (DSC) and 95% Hausdorff Distance (95HD). The best reported average lesion-wise DSC and 95HD was 0.815 and 26.92 mm, respectively. BraTS-MEN-RT is expected to significantly advance automated radiotherapy planning by enabling precise tumor segmentation and facilitating tailored treatment, ultimately improving patient outcomes. We describe the design and results from the BraTS-MEN-RT challenge. △ Less

Submitted 21 July, 2025; v1 submitted 28 May, 2024; originally announced May 2024.

Comments: 23 pages, 9 figures, 5 tables

DADIT: A Dataset for Demographic Classification of Italian Twitter Users and a Comparison of Prediction Methods

Authors: Lorenzo Lupo, Paul Bose, Mahyar Habibi, Dirk Hovy, Carlo Schwarz

Abstract: Social scientists increasingly use demographically stratified social media data to study the attitudes, beliefs, and behavior of the general public. To facilitate such analyses, we construct, validate, and release publicly the representative DADIT dataset of 30M tweets of 20k Italian Twitter users, along with their bios and profile pictures. We enrich the user data with high-quality labels for gen… ▽ More Social scientists increasingly use demographically stratified social media data to study the attitudes, beliefs, and behavior of the general public. To facilitate such analyses, we construct, validate, and release publicly the representative DADIT dataset of 30M tweets of 20k Italian Twitter users, along with their bios and profile pictures. We enrich the user data with high-quality labels for gender, age, and location. DADIT enables us to train and compare the performance of various state-of-the-art models for the prediction of the gender and age of social media users. In particular, we investigate if tweets contain valuable information for the task, since popular classifiers like M3 don't leverage them. Our best XLM-based classifier improves upon the commonly used competitor M3 by up to 53% F1. Especially for age prediction, classifiers profit from including tweets as features. We also confirm these findings on a German test set. △ Less

Submitted 8 March, 2024; originally announced March 2024.

Comments: Accepted to LREC-COLING 2024

The PANDA Barrel DIRC

Authors: R. Dzhygadlo, A. Belias, A. Gerhardt, D. Lehmann, K. Peters, G. Schepers, C. Schwarz, J. Schwiening, M. Traxler, Y. Wolf, L. Schmitt, M. Böhm, K. Gumbert, S. Krauss, A. Lehmann, D. Miehling, M. Düren, A. Hayrapetyan, I. Köseoglu, M. Schmidt, T. Wasem, C. Sfienti, A. Ali

Abstract: The PANDA experiment at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR), Darmstadt, Germany, will address fundamental questions of hadron physics using $\bar{p}p$ annihilations. Excellent Particle Identification (PID) over a large range of solid angles and particle momenta will be essential to meet the objectives of the rich physics program. Charged PID in t… ▽ More The PANDA experiment at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR), Darmstadt, Germany, will address fundamental questions of hadron physics using $\bar{p}p$ annihilations. Excellent Particle Identification (PID) over a large range of solid angles and particle momenta will be essential to meet the objectives of the rich physics program. Charged PID in the target region will be provided by a Barrel DIRC (Detection of Internally Reflected Cherenkov light) counter. The Barrel DIRC, covering the polar angle range of 22-140 degrees, will provide a $π/K$ separation power of at least 3 standard deviations for charged particle momenta up to 3.5 GeV/c. The design of the Barrel DIRC features narrow radiator bars made from synthetic fused silica, an innovative multi-layer spherical lens focusing system, a prism-shaped synthetic fused silica expansion volume, and an array of lifetime-enhanced Microchannel Plate PMTs (MCP-PMTs) to detect the hit location and arrival time of the Cherenkov photons. Detailed Monte-Carlo simulations were performed, and reconstruction methods were developed to study the performance of the system. All critical aspects of the design and the performance were validated with system prototypes in a mixed hadron beam at the CERN PS. In 2020 the PANDA Barrel DIRC project advanced from the design stage to component fabrication. The series production of the fused silica bars was successfully completed in 2021 and delivery of the MCP-PMTs started in May 2022. △ Less

Submitted 12 January, 2024; originally announced January 2024.

Comments: XI International Workshop on Ring Imaging Cherenkov Detectors

Journal ref: Nucl. Instr. and Meth. Res. Sect. A 1055 (2023) 168480

Performance of the most recent Microchannel-Plate PMTs for the PANDA DIRC detectors at FAIR

Authors: S. Krauss, M. Böhm, K. Gumbert, A. Lehmann, D. Miehling, A. Belias, R. Dzhygadlo, A. Gerhardt, D. Lehmann, K. Peters, G. Schepers, C. Schwarz, J. Schwiening, M. Traxler, Y. Wolf, L. Schmitt, M. Düren, A. Hayrapetyan, I. Köseoglu, M. Schmidt, T. Wasem, C. Sfienti, A. Ali

Abstract: In the PANDA experiment at the FAIR facility at GSI two DIRC (Detection of Internally Reflected Cherenkov light) detectors will be used for $π$/K separation up to 4 GeV/c. Due to their location in a high magnetic field and other stringent requirements like high detection efficiency, low dark count rate, radiation hardness, long lifetime and good timing, MCP-PMTs (microchannel-plate photomultiplier… ▽ More In the PANDA experiment at the FAIR facility at GSI two DIRC (Detection of Internally Reflected Cherenkov light) detectors will be used for $π$/K separation up to 4 GeV/c. Due to their location in a high magnetic field and other stringent requirements like high detection efficiency, low dark count rate, radiation hardness, long lifetime and good timing, MCP-PMTs (microchannel-plate photomultiplier) were the best choice of photon sensors for the DIRC detectors in the PANDA experiment. This paper will present the performance of some of the latest 2$\times$2 inch$^2$ MCP-PMTs from Photek and Photonis, including the first mass production tubes for the PANDA Barrel DIRC from Photonis. Performance parameters like the collection efficiency (CE), quantum efficiency (QE), and gain homogeneity were determined. The effect of magnetic fields on some properties like gain and charge cloud width was investigated as well. Apart from that the spatial distribution of many internal parameters like time resolution, dark count rate, afterpulse ratio, charge sharing crosstalk and recoil electrons were measured simultaneously with a multihit capable DAQ system. The latest generation of Photonis MCP-PMTs shows an unexpected "escalation" effect where the MCP-PMT itself produces photons. △ Less

Submitted 28 November, 2023; originally announced November 2023.

Comments: Proceedings contribution to RICH2022 (11th International Workshop on Ring Imaging Cherenkov Detectors)

Journal ref: Nuclear Inst. and Methods in Physics Research, A 1057 (2023) 168659

Lifetime and performance of the very latest microchannel-plate photomultipliers

Authors: D. Miehling, M. Böhm, K. Gumbert, S. Krauss, A. Lehmann, A. Belias, R. Dzhygadlo, A. Gerhardt, D. Lehmann, K. Peters, G. Schepers, C. Schwarz, J. Schwiening, M. Traxler, Y. Wolf, L. Schmitt, M. Düren, A. Hayrapetyan, I. Köseoglu, M. Schmidt, T. Wasem, C. Sfienti, A. Ali

Abstract: The PANDA experiment at the FAIR facility at GSI will study hadron physics using a high intensity antiproton beam of up to 15 GeV/c momentum to perform high precision spectroscopy. Two DIRC detectors with their image planes residing in an $\sim$1 T magnetic field will be used in the experiment. The only suitable photon detectors for both DIRCs were identified to be Microchannel-Plate Photomultipli… ▽ More The PANDA experiment at the FAIR facility at GSI will study hadron physics using a high intensity antiproton beam of up to 15 GeV/c momentum to perform high precision spectroscopy. Two DIRC detectors with their image planes residing in an $\sim$1 T magnetic field will be used in the experiment. The only suitable photon detectors for both DIRCs were identified to be Microchannel-Plate Photomultipliers (MCP-PMTs). Since the aging problems of MCP-PMTs were solved recently by coating the MCPs with the so-called ALD-technique (atomic layer deposition) we are investigating devices which are significantly improved with respect to other parameters, as, e.g., the collection efficiency (CE) and the quantum efficiency (QE). The latest generation of MCP-PMTs can reach a detective quantum efficiency DQE = QE - CE of 30%. This paper will present the performance of the most advanced 53 $\times$ 53 mm$^2$ ALD-coated MCP-PMTs from Photonis (8 $\times$ 8 and 3 $\times$ 100 anodes) and Photek (8 $\times$ 8 anodes), also inside the magnetic field. With a picosecond laser and a multi-hit capable DAQ system which allows read out up to 300 pixels simultaneously, parameters like darkcount rate, afterpulse probability and time resolution can be investigated as a function of incident photon position. △ Less

Submitted 28 November, 2023; originally announced November 2023.

Comments: Proceedings contribution to NDIP20 (9th Conference on New Developments in Photodetection)

Journal ref: Nuclear Inst. and Methods in Physics Research, A 1049 (2023) 168047

Neutrons from projectile fragmentation at 600 MeV/nucleon

Authors: P. Pawłowski, J. Brzychczyk, N. Buyukcizmeci, H. T. Johansson, W. Trautmann, A. Wieloch, P. Adrich, T. Aumann, T. Barczyk, S. Bianchin, K. Boretzky, A. S. Botvina, A. Chbihi, J. Cibor, B. Czech, H. Emling, J. D. Frankland, M. Heil, A. Le Fèvre, Y. Leifels, J. Lühning, J. Łukasik, U. Lynen, Z. Majka, I. N. Mishustin , et al. (11 additional authors not shown)

Abstract: The neutron emission in projectile fragmentation at relativistic energies was studied with the Large-Area-Neutron-Detector LAND coupled to the ALADIN forward spectrometer at the GSI Schwerionen-Synchrotron (SIS). Stable 124Sn and radioactive 107Sn and 124La beams with an incident energy of 600 MeV/nucleon were used to explore the N/Z dependence of the identified neutron source. A cluster-recogniti… ▽ More The neutron emission in projectile fragmentation at relativistic energies was studied with the Large-Area-Neutron-Detector LAND coupled to the ALADIN forward spectrometer at the GSI Schwerionen-Synchrotron (SIS). Stable 124Sn and radioactive 107Sn and 124La beams with an incident energy of 600 MeV/nucleon were used to explore the N/Z dependence of the identified neutron source. A cluster-recognition algorithm is applied for identifying individual particles within the hit distributions registered with LAND. The obtained momentum distributions are extrapolated over the full phase space occupied by the neutrons from the projectile-spectator source. The mean multiplicities of spectator neutrons reach values of up to about 11 and depend strongly on the isotopic composition of the projectile. An effective source temperature of T \approx 2-5 MeV, monotonically increasing with decreasing impact parameter, is deduced from the transverse momentum distributions. For the interpretation of the data, calculations with the statistical multifragmentation model were performed. The variety of excited projectile spectators assumed to decay statistically is represented by an ensemble of excited sources with parameters determined previously from the fragment production observed in the same experiments. The obtained agreement is very satisfactory for more peripheral collisions where, according to the model, neutrons are mainly emitted during the secondary decays of excited fragments. The neutron multiplicity in more central collisions is underestimated, indicating that other sources besides the modeled statistical breakup contribute to the observed neutron yield. The choice made for the symmetry-term coefficient of the liquid-drop description of produced fragments has a weak effect on the predicted neutron multiplicities. △ Less

Submitted 30 September, 2023; originally announced October 2023.

Comments: 22 pages, 24 figures, to appear in Physical Review C

Journal ref: Phys. Rev. C 108, 044610 (2023)

Integrated Model Predictive Control of High-Speed Railway Running Gears with Driven Independently Rotating Wheels

Authors: Jan-Hendrik Ewering, Christoph Schwarz, Simon F. G. Ehlers, Hans-Georg Jacob, Thomas Seel, Andreas Heckmann

Abstract: Railway running gears with independently rotating wheels (IRW) can significantly improve wear figures, comfort, and safety in railway transportation, but certain measures for wheelset stabilization are required. This is one reason why the application of traditional wheelsets is still common practice in industry. Apart from lateral guidance, the longitudinal control is of crucial importance for rai… ▽ More Railway running gears with independently rotating wheels (IRW) can significantly improve wear figures, comfort, and safety in railway transportation, but certain measures for wheelset stabilization are required. This is one reason why the application of traditional wheelsets is still common practice in industry. Apart from lateral guidance, the longitudinal control is of crucial importance for railway safety. In the current contribution, an integrated controller for joined lateral and longitudinal control of a high-speed railway running gear with driven IRW is designed. To this end, a novel adhesion-based traction control law is combined with linear time-variant and nonlinear model predictive control (MPC) schemes for lateral guidance. The MPC schemes are able to use tabulated track geometry data and preview information about set points to minimize the lateral displacement error. Co-simulation results with a detailed multi-body simulation show the effectiveness of the approach compared with state-of-the-art techniques in various scenarios, including curving, varying velocities up to 400 km/h and abruptly changing wheel-rail adhesion conditions. △ Less

Submitted 4 January, 2024; v1 submitted 18 September, 2023; originally announced September 2023.

Comments: 13 pages, 9 figures, accepted for publication in IEEE Transactions on Vehicular Technology

Journal ref: IEEE Transactions on Vehicular Technology (Volume: 73, Issue: 6, June 2024)

Parameterised Approximation of the Fixation Probability of the Dominant Mutation in the Multi-Type Moran Process

Authors: Leslie Ann Goldberg, Marc Roth, Tassilo Constantin Schwarz

Abstract: The multi-type Moran process is an evolutionary process on a connected graph $G$ in which each vertex has one of $k$ types and, in each step, a vertex $v$ is chosen to reproduce its type to one of its neighbours. The probability of a vertex $v$ being chosen for reproduction is proportional to the fitness of the type of $v$. So far, the literature was almost solely concerned with the $2$-type Moran… ▽ More The multi-type Moran process is an evolutionary process on a connected graph $G$ in which each vertex has one of $k$ types and, in each step, a vertex $v$ is chosen to reproduce its type to one of its neighbours. The probability of a vertex $v$ being chosen for reproduction is proportional to the fitness of the type of $v$. So far, the literature was almost solely concerned with the $2$-type Moran process in which each vertex is either healthy (type $0$) or a mutant (type $1$), and the main problem of interest has been the (approximate) computation of the so-called fixation probability, i.e., the probability that eventually all vertices are mutants. In this work we initiate the study of approximating fixation probabilities in the multi-type Moran process on general graphs. Our main result is an FPTRAS (fixed-parameter tractable randomised approximation scheme) for computing the fixation probability of the dominant mutation; the parameter is the number of types and their fitnesses. In the course of our studies we also provide novel upper bounds on the expected absorption time, i.e., the time that it takes the multi-type Moran process to reach a state in which each vertex has the same type. △ Less

Submitted 14 March, 2023; originally announced March 2023.

Comments: 14 pages

ATHENA Detector Proposal -- A Totally Hermetic Electron Nucleus Apparatus proposed for IP6 at the Electron-Ion Collider

Authors: ATHENA Collaboration, J. Adam, L. Adamczyk, N. Agrawal, C. Aidala, W. Akers, M. Alekseev, M. M. Allen, F. Ameli, A. Angerami, P. Antonioli, N. J. Apadula, A. Aprahamian, W. Armstrong, M. Arratia, J. R. Arrington, A. Asaturyan, E. C. Aschenauer, K. Augsten, S. Aune, K. Bailey, C. Baldanza, M. Bansal, F. Barbosa, L. Barion , et al. (415 additional authors not shown)

Abstract: ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its e… ▽ More ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges. △ Less

Submitted 13 October, 2022; originally announced October 2022.

Journal ref: JINST 17 (2022) 10, P10019

Design of the ECCE Detector for the Electron Ion Collider

Authors: J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari, A. Bylinkin, R. Capobianco , et al. (259 additional authors not shown)

Abstract: The EIC Comprehensive Chromodynamics Experiment (ECCE) detector has been designed to address the full scope of the proposed Electron Ion Collider (EIC) physics program as presented by the National Academy of Science and provide a deeper understanding of the quark-gluon structure of matter. To accomplish this, the ECCE detector offers nearly acceptance and energy coverage along with excellent track… ▽ More The EIC Comprehensive Chromodynamics Experiment (ECCE) detector has been designed to address the full scope of the proposed Electron Ion Collider (EIC) physics program as presented by the National Academy of Science and provide a deeper understanding of the quark-gluon structure of matter. To accomplish this, the ECCE detector offers nearly acceptance and energy coverage along with excellent tracking and particle identification. The ECCE detector was designed to be built within the budget envelope set out by the EIC project while simultaneously managing cost and schedule risks. This detector concept has been selected to be the basis for the EIC project detector. △ Less

Submitted 20 July, 2024; v1 submitted 6 September, 2022; originally announced September 2022.

Comments: 34 pages, 30 figures, 9 tables

Report number: JLAB-PHY-24-4124

CORE -- a COmpact detectoR for the EIC

Authors: CORE Collaboration, R. Alarcon, M. Baker, V. Baturin, P. Brindza, S. Bueltmann, M. Bukhari, R. Capobianco, E. Christy, S. Diehl, M. Dugger, R. Dupré, R. Dzhygadlo, K. Flood, K. Gnanvo, L. Guo, T. Hayward, M. Hattawy, M. Hoballah, M. Hohlmann, C. E. Hyde, Y. Ilieva, W. W. Jacobs, K. Joo, G. Kalicy , et al. (34 additional authors not shown)

Abstract: The COmpact detectoR for the Eic (CORE) Proposal was submitted to the EIC "Call for Collaboration Proposals for Detectors". CORE comprehensively covers the physics scope of the EIC Community White Paper and the National Academies of Science 2018 report. The design exploits advances in detector precision and granularity to minimize size. The central detector includes a 3Tesla, 2.5m solenoid. Tracki… ▽ More The COmpact detectoR for the Eic (CORE) Proposal was submitted to the EIC "Call for Collaboration Proposals for Detectors". CORE comprehensively covers the physics scope of the EIC Community White Paper and the National Academies of Science 2018 report. The design exploits advances in detector precision and granularity to minimize size. The central detector includes a 3Tesla, 2.5m solenoid. Tracking is primarily silicon. Electromagnetic calorimetry is based on the high performance crystals. Ring-imaging Cherenkov detectors provide hadronic particle identification. △ Less

Submitted 1 September, 2022; originally announced September 2022.

Comments: Contact authors: C.E. Hyde, chyde@odu.edu and P. Nadel-Turonski, turonski@jlab.org

Detector Requirements and Simulation Results for the EIC Exclusive, Diffractive and Tagging Physics Program using the ECCE Detector Concept

Authors: A. Bylinkin, C. T. Dean, S. Fegan, D. Gangadharan, K. Gates, S. J. D. Kay, I. Korover, W. B. Li, X. Li, R. Montgomery, D. Nguyen, G. Penman, J. R. Pybus, N. Santiesteban, R. Trotta, A. Usman, M. D. Baker, J. Frantz, D. I. Glazier, D. W. Higinbotham, T. Horn, J. Huang, G. Huber, R. Reed, J. Roche , et al. (258 additional authors not shown)

Abstract: This article presents a collection of simulation studies using the ECCE detector concept in the context of the EIC's exclusive, diffractive, and tagging physics program, which aims to further explore the rich quark-gluon structure of nucleons and nuclei. To successfully execute the program, ECCE proposed to utilize the detecter system close to the beamline to ensure exclusivity and tag ion beam/fr… ▽ More This article presents a collection of simulation studies using the ECCE detector concept in the context of the EIC's exclusive, diffractive, and tagging physics program, which aims to further explore the rich quark-gluon structure of nucleons and nuclei. To successfully execute the program, ECCE proposed to utilize the detecter system close to the beamline to ensure exclusivity and tag ion beam/fragments for a particular reaction of interest. Preliminary studies confirmed the proposed technology and design satisfy the requirements. The projected physics impact results are based on the projected detector performance from the simulation at 10 or 100 fb^-1 of integrated luminosity. Additionally, a few insights on the potential 2nd Interaction Region can (IR) were also documented which could serve as a guidepost for the future development of a second EIC detector. △ Less

Submitted 6 March, 2023; v1 submitted 30 August, 2022; originally announced August 2022.

ECCE unpolarized TMD measurements

Authors: R. Seidl, A. Vladimirov, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari , et al. (258 additional authors not shown)

Abstract: We performed feasibility studies for various measurements that are related to unpolarized TMD distribution and fragmentation functions. The processes studied include semi-inclusive Deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The single hadron cross sections and multiplicities were extracted as a function of the DIS… ▽ More We performed feasibility studies for various measurements that are related to unpolarized TMD distribution and fragmentation functions. The processes studied include semi-inclusive Deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The single hadron cross sections and multiplicities were extracted as a function of the DIS variables $x$ and $Q^2$, as well as the semi-inclusive variables $z$, which corresponds to the momentum fraction the detected hadron carries relative to the struck parton and $P_T$, which corresponds to the transverse momentum of the detected hadron relative to the virtual photon. The expected statistical precision of such measurements is extrapolated to accumulated luminosities of 10 fb$^{-1}$ and potential systematic uncertainties are approximated given the deviations between true and reconstructed yields. △ Less

Submitted 22 July, 2022; originally announced July 2022.

Comments: 12 pages, 9 figures, to be submitted in joint ECCE proposal NIM-A volume

Report number: ecce-paper-phys-2022-09

ECCE Sensitivity Studies for Single Hadron Transverse Single Spin Asymmetry Measurements

Authors: R. Seidl, A. Vladimirov, D. Pitonyak, A. Prokudin, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks , et al. (260 additional authors not shown)

Abstract: We performed feasibility studies for various single transverse spin measurements that are related to the Sivers effect, transversity and the tensor charge, and the Collins fragmentation function. The processes studied include semi-inclusive deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The data were obtained in {\sc… ▽ More We performed feasibility studies for various single transverse spin measurements that are related to the Sivers effect, transversity and the tensor charge, and the Collins fragmentation function. The processes studied include semi-inclusive deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The data were obtained in {\sc pythia}6 and {\sc geant}4 simulated e+p collisions at 18 GeV on 275 GeV, 18 on 100, 10 on 100, and 5 on 41 that use the ECCE detector configuration. Typical DIS kinematics were selected, most notably $Q^2 > 1 $ GeV$^2$, and cover the $x$ range from $10^{-4}$ to $1$. The single spin asymmetries were extracted as a function of $x$ and $Q^2$, as well as the semi-inclusive variables $z$, and $P_T$. They are obtained in azimuthal moments in combinations of the azimuthal angles of the hadron transverse momentum and transverse spin of the nucleon relative to the lepton scattering plane. The initially unpolarized MonteCarlo was re-weighted in the true kinematic variables, hadron types and parton flavors based on global fits of fixed target SIDIS experiments and $e^+e^-$ annihilation data. The expected statistical precision of such measurements is extrapolated to 10 fb$^{-1}$ and potential systematic uncertainties are approximated given the deviations between true and reconstructed yields. The impact on the knowledge of the Sivers functions, transversity and tensor charges, and the Collins function has then been evaluated in the same phenomenological extractions as in the Yellow Report. The impact is found to be comparable to that obtained with the parameterized Yellow Report detector and shows that the ECCE detector configuration can fulfill the physics goals on these quantities. △ Less

Submitted 22 July, 2022; originally announced July 2022.

Comments: 22 pages, 22 figures, to be submitted to joint ECCE proposal NIM-A volume

Report number: ecce-paper-phys-2022-08

Open Heavy Flavor Studies for the ECCE Detector at the Electron Ion Collider

Authors: X. Li, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari, A. Bylinkin , et al. (262 additional authors not shown)

Abstract: The ECCE detector has been recommended as the selected reference detector for the future Electron-Ion Collider (EIC). A series of simulation studies have been carried out to validate the physics feasibility of the ECCE detector. In this paper, detailed studies of heavy flavor hadron and jet reconstruction and physics projections with the ECCE detector performance and different magnet options will… ▽ More The ECCE detector has been recommended as the selected reference detector for the future Electron-Ion Collider (EIC). A series of simulation studies have been carried out to validate the physics feasibility of the ECCE detector. In this paper, detailed studies of heavy flavor hadron and jet reconstruction and physics projections with the ECCE detector performance and different magnet options will be presented. The ECCE detector has enabled precise EIC heavy flavor hadron and jet measurements with a broad kinematic coverage. These proposed heavy flavor measurements will help systematically study the hadronization process in vacuum and nuclear medium especially in the underexplored kinematic region. △ Less

Submitted 23 July, 2022; v1 submitted 21 July, 2022; originally announced July 2022.

Comments: Open heavy flavor studies with the EIC reference detector design by the ECCE consortium. 11 pages, 11 figures, to be submitted to the Nuclear Instruments and Methods A

Report number: LANL report number: LA-UR-22-27181

Exclusive J/$ψ$ Detection and Physics with ECCE

Authors: X. Li, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari, A. Bylinkin , et al. (262 additional authors not shown)

Abstract: Exclusive heavy quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. The momentum transfer dependence of this process is sensitive to the interaction sites, which provides a powerful tool to probe the… ▽ More Exclusive heavy quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. The momentum transfer dependence of this process is sensitive to the interaction sites, which provides a powerful tool to probe the spatial distribution of gluons in the nucleus. Recently the problem of the origin of hadron mass has received lots of attention in determining the anomaly contribution $M_{a}$. The trace anomaly is sensitive to the gluon condensate, and exclusive production of quarkonia such as J/$ψ$ and $Υ$ can serve as a sensitive probe to constrain it. In this paper, we present the performance of the ECCE detector for exclusive J/$ψ$ detection and the capability of this process to investigate the above physics opportunities with ECCE. △ Less

Submitted 21 July, 2022; originally announced July 2022.

Comments: 11 pages, 14 figures, 1 table

Search for $e\toτ$ Charged Lepton Flavor Violation at the EIC with the ECCE Detector

Authors: J. -L. Zhang, S. Mantry, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari , et al. (262 additional authors not shown)

Abstract: The recently approved Electron-Ion Collider (EIC) will provide a unique new opportunity for searches of charged lepton flavor violation (CLFV) and other new physics scenarios. In contrast to the $e \leftrightarrow μ$ CLFV transition for which very stringent limits exist, there is still a relatively large discovery space for the $e \to τ$ CLFV transition, potentially to be explored by the EIC. With… ▽ More The recently approved Electron-Ion Collider (EIC) will provide a unique new opportunity for searches of charged lepton flavor violation (CLFV) and other new physics scenarios. In contrast to the $e \leftrightarrow μ$ CLFV transition for which very stringent limits exist, there is still a relatively large discovery space for the $e \to τ$ CLFV transition, potentially to be explored by the EIC. With the latest detector design of ECCE (EIC Comprehensive Chromodynamics Experiment) and projected integral luminosity of the EIC, we find the $τ$-leptons created in the DIS process $ep\to τX$ are expected to be identified with high efficiency. A first ECCE simulation study, restricted to the 3-prong $τ$-decay mode and with limited statistics for the Standard Model backgrounds, estimates that the EIC will be able to improve the current exclusion limit on $e\to τ$ CLFV by an order of magnitude. △ Less

Submitted 20 July, 2022; originally announced July 2022.

Comments: 11 pages, 8 figures, to be submitted to NIM

Design and Simulated Performance of Calorimetry Systems for the ECCE Detector at the Electron Ion Collider

Authors: F. Bock, N. Schmidt, P. K. Wang, N. Santiesteban, T. Horn, J. Huang, J. Lajoie, C. Munoz Camacho, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, W. Boeglin, M. Borysova, E. Brash , et al. (263 additional authors not shown)

Abstract: We describe the design and performance the calorimeter systems used in the ECCE detector design to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapdity range from -3.7 to 3.8 and two hadronic calorimeters. Key… ▽ More We describe the design and performance the calorimeter systems used in the ECCE detector design to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapdity range from -3.7 to 3.8 and two hadronic calorimeters. Key calorimeter performances which include energy and position resolutions, reconstruction efficiency, and particle identification will be presented. △ Less

Submitted 19 July, 2022; originally announced July 2022.

Comments: 19 pages, 22 figures, 5 tables

AI-assisted Optimization of the ECCE Tracking System at the Electron Ion Collider

Authors: C. Fanelli, Z. Papandreou, K. Suresh, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann , et al. (258 additional authors not shown)

Abstract: The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably, EIC is one of the first large-scale facilities to… ▽ More The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably, EIC is one of the first large-scale facilities to leverage Artificial Intelligence (AI) already starting from the design and R&D phases. The EIC Comprehensive Chromodynamics Experiment (ECCE) is a consortium that proposed a detector design based on a 1.5T solenoid. The EIC detector proposal review concluded that the ECCE design will serve as the reference design for an EIC detector. Herein we describe a comprehensive optimization of the ECCE tracker using AI. The work required a complex parametrization of the simulated detector system. Our approach dealt with an optimization problem in a multidimensional design space driven by multiple objectives that encode the detector performance, while satisfying several mechanical constraints. We describe our strategy and show results obtained for the ECCE tracking system. The AI-assisted design is agnostic to the simulation framework and can be extended to other sub-detectors or to a system of sub-detectors to further optimize the performance of the EIC detector. △ Less

Submitted 19 May, 2022; v1 submitted 18 May, 2022; originally announced May 2022.

Comments: 16 pages, 18 figures, 2 appendices, 3 tables

Scientific Computing Plan for the ECCE Detector at the Electron Ion Collider

Authors: J. C. Bernauer, C. T. Dean, C. Fanelli, J. Huang, K. Kauder, D. Lawrence, J. D. Osborn, C. Paus, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, F. Bock, W. Boeglin, M. Borysova, E. Brash , et al. (256 additional authors not shown)

Abstract: The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECCE consortium began identifying and addressing thes… ▽ More The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECCE consortium began identifying and addressing these challenges in the process of producing a complete detector proposal based upon detailed detector and physics simulations. In this document, the software and computing efforts to produce this proposal are discussed; furthermore, the computing and software model and resources required for the future of ECCE are described. △ Less

Submitted 17 May, 2022; originally announced May 2022.

Journal ref: NIMA 1047, 167859 (2023)

PANDA Barrel DIRC: From Design to Component Production

Authors: G Schepers, A Belias, R Dzhygadlo, A Gerhardt, D Lehmann, K Peters, C Schwarz, J Schwiening, M Traxler, L Schmitt, M Böhm, S Krauss, A Lehmann, D Miehling, M Pfaffinger, M Düren, E Etzelmüller, K Föhl, A Hayrapetyan, I Köseoglu, M Schmidt, T Wasem, C Sfienti, A Ali, A Barnyakov , et al. (3 additional authors not shown)

Abstract: Excellent particle identification (PID) will be essential for the PANDA experiment at FAIR. The Barrel DIRC will separate kaons and pions with at least 3 s.d. for momenta up to 3.5 GeV/c and polar angles between 22 and 140 deg. After successful validation of the final design in the CERN PS/T9 beam line, the tendering process for the two most time- and cost-intensive items, radiator bars and MCP-PM… ▽ More Excellent particle identification (PID) will be essential for the PANDA experiment at FAIR. The Barrel DIRC will separate kaons and pions with at least 3 s.d. for momenta up to 3.5 GeV/c and polar angles between 22 and 140 deg. After successful validation of the final design in the CERN PS/T9 beam line, the tendering process for the two most time- and cost-intensive items, radiator bars and MCP-PMTs, started in 2018. In Sep. 2019 Nikon was selected to build the fused silica bars and successfully completed the series production of 112 bars in Feb. 2021. Measurements of the mechanical quality of the bars were performed by Nikon and the optical quality was evaluated at GSI. In Dec. 2020, the contract for the fabrication of the MCP-PMTs was awarded to PHOTONIS and the delivery of the first-of-series MCP-PMTs is expected in July 2021. We present the design of the PANDA Barrel DIRC as well as the status of the component series production and the result of the quality assurance measurements. △ Less

Submitted 26 January, 2022; originally announced January 2022.

Comments: 5 pages, 5 figures, TIPP2021 TRIUMF Vancouver, Canada

Intelligent Traffic Light via Policy-based Deep Reinforcement Learning

Authors: Yue Zhu, Mingyu Cai, Chris Schwarz, Junchao Li, Shaoping Xiao

Abstract: Intelligent traffic lights in smart cities can optimally reduce traffic congestion. In this study, we employ reinforcement learning to train the control agent of a traffic light on a simulator of urban mobility. As a difference from existing works, a policy-based deep reinforcement learning method, Proximal Policy Optimization (PPO), is utilized other than value-based methods such as Deep Q Networ… ▽ More Intelligent traffic lights in smart cities can optimally reduce traffic congestion. In this study, we employ reinforcement learning to train the control agent of a traffic light on a simulator of urban mobility. As a difference from existing works, a policy-based deep reinforcement learning method, Proximal Policy Optimization (PPO), is utilized other than value-based methods such as Deep Q Network (DQN) and Double DQN (DDQN). At first, the obtained optimal policy from PPO is compared to those from DQN and DDQN. It is found that the policy from PPO performs better than the others. Next, instead of the fixed-interval traffic light phases, we adopt the light phases with variable time intervals, which result in a better policy to pass the traffic flow. Then, the effects of environment and action disturbances are studied to demonstrate the learning-based controller is robust. At last, we consider unbalanced traffic flows and find that an intelligent traffic light can perform moderately well for the unbalanced traffic scenarios, although it learns the optimal policy from the balanced traffic scenarios only. △ Less

Submitted 27 December, 2021; originally announced December 2021.

Measuring the photoelectron emission delay in the molecular frame

Authors: Jonas Rist, Kim Klyssek, Nikolay M. Novikovskiy, Max Kircher, Isabel Vela-Pérez, Daniel Trabert, Sven Grundmann, Dimitrios Tsitsonis, Juliane Siebert, Angelina Geyer, Niklas Melzer, Christian Schwarz, Nils Anders, Leon Kaiser, Kilian Fehre, Alexander Hartung, Sebastian Eckart, Lothar Ph. H. Schmidt, Markus S. Schöffler, Vernon T. Davis, Joshua B. Williams, Florian Trinter, Reinhard Dörner, Philipp V. Demekhin, Till Jahnke

Abstract: If matter absorbs a photon of sufficient energy it emits an electron. The question of the duration of the emission process has intrigued scientists for decades. With the advent of attosecond metrology, experiments addressing such ultrashort intervals became possible. While these types of studies require attosecond experimental precision, we present here a novel measurement approach that avoids tho… ▽ More If matter absorbs a photon of sufficient energy it emits an electron. The question of the duration of the emission process has intrigued scientists for decades. With the advent of attosecond metrology, experiments addressing such ultrashort intervals became possible. While these types of studies require attosecond experimental precision, we present here a novel measurement approach that avoids those experimental difficulties. We instead extract the emission delay from the interference pattern generated as the emitted photoelectron is diffracted by the parent ion's potential. Targeting core electrons in CO, we measured a 2d map of photoelectron emission delays in the molecular frame over a wide range of electron energies. The measured emission times depend drastically on the emission direction and exhibit characteristic changes along the shape resonance of the molecule. Our approach can be routinely extended to other electron orbitals and more complex molecules. △ Less

Submitted 13 July, 2021; originally announced July 2021.

Journal ref: Nat Commun 12, 6657 (2021)

PANDA Phase One

Authors: G. Barucca, F. Davì, G. Lancioni, P. Mengucci, L. Montalto, P. P. Natali, N. Paone, D. Rinaldi, L. Scalise, B. Krusche, M. Steinacher, Z. Liu, C. Liu, B. Liu, X. Shen, S. Sun, G. Zhao, J. Zhao, M. Albrecht, W. Alkakhi, S. Bökelmann, S. Coen, F. Feldbauer, M. Fink, J. Frech , et al. (399 additional authors not shown)

Abstract: The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of hadron-, nuclear- and atomic physics experiments. The future antiProton ANnihilations at DArmstadt (PANDA or $\overline{\rm P}$ANDA) experiment at FAIR will offer a broad physics programme, covering different aspects of the strong interaction. Understanding the latter in… ▽ More The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of hadron-, nuclear- and atomic physics experiments. The future antiProton ANnihilations at DArmstadt (PANDA or $\overline{\rm P}$ANDA) experiment at FAIR will offer a broad physics programme, covering different aspects of the strong interaction. Understanding the latter in the non-perturbative regime remains one of the greatest challenges in contemporary physics. The antiproton-nucleon interaction studied with PANDA provides crucial tests in this area. Furthermore, the high-intensity, low-energy domain of PANDA allows for searches for physics beyond the Standard Model, e.g. through high precision symmetry tests. This paper takes into account a staged approach for the detector setup and for the delivered luminosity from the accelerator. The available detector setup at the time of the delivery of the first antiproton beams in the HESR storage ring is referred to as the \textit{Phase One} setup. The physics programme that is achievable during Phase One is outlined in this paper. △ Less

Submitted 9 June, 2021; v1 submitted 28 January, 2021; originally announced January 2021.

Comments: 35 pages, 15 figures

Journal ref: European Physics Journal A57, 44 (2021)

The PANDA DIRCs

Authors: C. Schwarz, A. Ali, A. Belias, R. Dzhygadlo, A. Gerhardt, M. Krebs, D. Lehmann, K. Peters, G. Schepers, J. Schwiening, M. Traxler, L. Schmitt, M. Böhm, A. Lehmann, M. Pfaffinger, S. Stelter, M. Düren, E. Etzelmüller, K. Föhl, A. Hayrapetyan, I. Köseoglu, K. Kreutzfeld, M. Schmidt, T. Wasem, C. Sfienti , et al. (6 additional authors not shown)

Abstract: The PANDA experiment at the FAIR facility adresses open questions in hadron physics with antiproton beams in the momentum range of 1.5-15 GeV/c. The antiprotons are stored and cooled in a High Energy Storage RING (HESR) with a momentum spread down to Dp/p = 4*10^-5. A high luminosity of up to 2*10^32 cm-2 s-1 can be achieved. An excellent hadronic particle identification (PID) will be provided by… ▽ More The PANDA experiment at the FAIR facility adresses open questions in hadron physics with antiproton beams in the momentum range of 1.5-15 GeV/c. The antiprotons are stored and cooled in a High Energy Storage RING (HESR) with a momentum spread down to Dp/p = 4*10^-5. A high luminosity of up to 2*10^32 cm-2 s-1 can be achieved. An excellent hadronic particle identification (PID) will be provided by two Cherenkov detectors using the priciple of Detection of Internally Reflected Cherenkov light (DIRC). In the forward direction from polar angles of 5 degree to 22 degree, the Endcap Disc DIRC (EDD) separates pions from kaons up to momenta of 4 GeV/c. Between 22 degree and 140 degree the Barrel DIRC cleanly separates pions from kaons for momenta up to 3.5 GeV/c. This article describes the design of the Barrel DIRC and of the Endcap Disc DIRC and the validation of their designs in particle beams at the CERN PS. △ Less

Submitted 26 January, 2021; originally announced January 2021.

Comments: 10 pages, 8 figures

Journal ref: 2020 JINST 15 C09059

Time imaging reconstruction for the PANDA Barrel DIRC

Authors: R. Dzhygadlo, A. Ali, A. Belias, A. Gerhardt, M. Krebs, D. Lehmann, K. Peters, G. Schepers, C. Schwarz, J. Schwiening, M. Traxler, L. Schmitt, M. Böhm, A. Lehmann, M. Pfaffinger, S. Stelter, F. Uhlig, M. Düren, E. Etzelmüller, K. Föhl, A. Hayrapetyan, I. Köseoglu, K. Kreutzfeld, J. Rieke, M. Schmidt , et al. (2 additional authors not shown)

Abstract: The innovative Barrel DIRC (Detection of Internally Reflected Cherenkov light) counter will provide hadronic particle identification (PID) in the central region of the PANDA experiment at the new Facility for Antiproton and Ion Research (FAIR), Darmstadt, Germany. This detector is designed to separate charged pions and kaons with at least 3 standard deviations for momenta up to 3.5 GeV/c, covering… ▽ More The innovative Barrel DIRC (Detection of Internally Reflected Cherenkov light) counter will provide hadronic particle identification (PID) in the central region of the PANDA experiment at the new Facility for Antiproton and Ion Research (FAIR), Darmstadt, Germany. This detector is designed to separate charged pions and kaons with at least 3 standard deviations for momenta up to 3.5 GeV/c, covering the polar angle range of 22$^{\circ}$-140$^{\circ}$. An array of microchannel plate photomultiplier tubes is used to detect the location and arrival time of the Cherenkov photons with a position resolution of 2 mm and time precision of about 100 ps. The time imaging reconstruction has been developed to make optimum use of the observables and to determine the performance of the detector. This reconstruction algorithm performs particle identification by directly calculating the maximum likelihoods using probability density functions based on detected photon propagation time in each pixel, determined directly from the data, or analytically, or from detailed simulations. △ Less

Submitted 21 September, 2020; originally announced September 2020.

Comments: International Workshop on Fast Cherenkov Detectors (DIRC2019)

Radner equilibrium and systems of quadratic BSDEs with discontinuous generators

Authors: Luis Escauriaza, Daniel C. Schwarz, Hao Xing

Abstract: Motivated by an equilibrium problem, we establish the existence of a solution for a family of Markovian backward stochastic differential equations with quadratic nonlinearity and discontinuity in $Z$. Using unique continuation and backward uniqueness, we show that the set of discontinuity has measure zero. In a continuous-time stochastic model of an endowment economy, we prove the existence of an… ▽ More Motivated by an equilibrium problem, we establish the existence of a solution for a family of Markovian backward stochastic differential equations with quadratic nonlinearity and discontinuity in $Z$. Using unique continuation and backward uniqueness, we show that the set of discontinuity has measure zero. In a continuous-time stochastic model of an endowment economy, we prove the existence of an incomplete Radner equilibrium with nondegenerate endogenous volatility. △ Less

Submitted 5 May, 2021; v1 submitted 8 August, 2020; originally announced August 2020.

Comments: 49 pages, 2 figures

The GlueX Beamline and Detector

Authors: S. Adhikari, C. S. Akondi, H. Al Ghoul, A. Ali, M. Amaryan, E. G. Anassontzis, A. Austregesilo, F. Barbosa, J. Barlow, A. Barnes, E. Barriga, R. Barsotti, T. D. Beattie, J. Benesch, V. V. Berdnikov, G. Biallas, T. Black, W. Boeglin, P. Brindza, W. J. Briscoe, T. Britton, J. Brock, W. K. Brooks, B. E. Cannon, C. Carlin , et al. (165 additional authors not shown)

Abstract: The GlueX experiment at Jefferson Lab has been designed to study photoproduction reactions with a 9-GeV linearly polarized photon beam. The energy and arrival time of beam photons are tagged using a scintillator hodoscope and a scintillating fiber array. The photon flux is determined using a pair spectrometer, while the linear polarization of the photon beam is determined using a polarimeter based… ▽ More The GlueX experiment at Jefferson Lab has been designed to study photoproduction reactions with a 9-GeV linearly polarized photon beam. The energy and arrival time of beam photons are tagged using a scintillator hodoscope and a scintillating fiber array. The photon flux is determined using a pair spectrometer, while the linear polarization of the photon beam is determined using a polarimeter based on triplet photoproduction. Charged-particle tracks from interactions in the central target are analyzed in a solenoidal field using a central straw-tube drift chamber and six packages of planar chambers with cathode strips and drift wires. Electromagnetic showers are reconstructed in a cylindrical scintillating fiber calorimeter inside the magnet and a lead-glass array downstream. Charged particle identification is achieved by measuring energy loss in the wire chambers and using the flight time of particles between the target and detectors outside the magnet. The signals from all detectors are recorded with flash ADCs and/or pipeline TDCs into memories allowing trigger decisions with a latency of 3.3 $μ$s. The detector operates routinely at trigger rates of 40 kHz and data rates of 600 megabytes per second. We describe the photon beam, the GlueX detector components, electronics, data-acquisition and monitoring systems, and the performance of the experiment during the first three years of operation. △ Less

Submitted 26 October, 2020; v1 submitted 28 May, 2020; originally announced May 2020.

Comments: Accepted by Nuclear Instruments and Methods A, 78 pages, 54 figures

Report number: JLAB-PHY-20-3195

Journal ref: Nucl. Instrum. & Meth. A987, 164807 (2021)

Status of the PANDA Barrel DIRC

Authors: C. Schwarz, A. Ali, A. Belias, R. Dzhygadlo, A. Gerhardt, M. Krebs, D. Lehmann, K. Peters, G. Schepers, J. Schwiening, M. Traxler, L. Schmitt, M. Böhm, A. Lehmann, M. Pfaffinger, S. Stelter, F. Uhlig, M. Düren, E. Etzelmüller, K. Föhl, A. Hayrapetyan, I. Köseoglu, K. Kreutzfeld, J. Rieke, M. Schmidt , et al. (2 additional authors not shown)

Abstract: The PANDA experiment will use cooled antiproton beams with high intensity stored1 in the High Energy Storage Ring at FAIR. Reactions on a fixed target producing charmed hadrons will shed light on the strong QCD. Three ring imaging Cherenkov counters are used for charged particle identification. The status of the Barrel DIRC (Detection of Internally Reflected Cherenkov light) is described. Its desi… ▽ More The PANDA experiment will use cooled antiproton beams with high intensity stored1 in the High Energy Storage Ring at FAIR. Reactions on a fixed target producing charmed hadrons will shed light on the strong QCD. Three ring imaging Cherenkov counters are used for charged particle identification. The status of the Barrel DIRC (Detection of Internally Reflected Cherenkov light) is described. Its design is robust and its performance validated in experiments with test beams. The PANDA Barrel DIRC has entered the construction phase and will be installed in 2023/2024. △ Less

Submitted 2 April, 2020; originally announced April 2020.

Comments: 7 pages, 5 figures

The GlueX DIRC Program

Authors: A. Ali, F. Barbosa, J. Bessuille, E. Chudakov, R. Dzhygadlo, C. Fanelli, J. Frye, J. Hardin, A. Hurley, G. Kalicy, J. Kelsey, W. Li, M. Patsyuk, C. Schwarz, J. Schwiening, M. Shepherd, J. R. Stevens, T. Whitlatch, M. Williams, Y. Yang

Abstract: The GlueX experiment is located in experimental Hall D at Jefferson Lab (JLab) and provides a unique capability to search for hybrid mesons in high-energy photoproduction, utilizing a ~9 GeV linearly polarized photon beam. The initial, low-intensity phase of GlueX was recently completed and a high-intensity phase has begun in 2020 which includes an upgraded kaon identification system, known as the… ▽ More The GlueX experiment is located in experimental Hall D at Jefferson Lab (JLab) and provides a unique capability to search for hybrid mesons in high-energy photoproduction, utilizing a ~9 GeV linearly polarized photon beam. The initial, low-intensity phase of GlueX was recently completed and a high-intensity phase has begun in 2020 which includes an upgraded kaon identification system, known as the DIRC (Detection of Internally Reflected Cherenkov light), utilizing components from the decommissioned BaBar DIRC. The identification of kaon final states will significantly enhance the GlueX physics program, to aid in inferring the quark flavor content of conventional (and potentially hybrid) mesons. In these proceedings we describe the installation of the GlueX DIRC and the analysis of initial commissioning data △ Less

Submitted 12 March, 2020; v1 submitted 18 February, 2020; originally announced February 2020.

Technical Design Report for the PANDA Endcap Disc DIRC

Authors: Panda Collaboration, F. Davi, W. Erni, B. Krusche, M. Steinacher, N. Walford, H. Liu, Z. Liu, B. Liu, X. Shen, C. Wang, J. Zhao, M. Albrecht, T. Erlen, F. Feldbauer, M. Fink, V. Freudenreich, M. Fritsch, F. H. Heinsius, T. Held, T. Holtmann, I. Keshk, H. Koch, B. Kopf, M. Kuhlmann , et al. (441 additional authors not shown)

Abstract: PANDA (anti-Proton ANnihiliation at DArmstadt) is planned to be one of the four main experiments at the future international accelerator complex FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. It is going to address fundamental questions of hadron physics and quantum chromodynamics using cooled antiproton beams with a high intensity and and momenta between 1.5 and 15 GeV/c.… ▽ More PANDA (anti-Proton ANnihiliation at DArmstadt) is planned to be one of the four main experiments at the future international accelerator complex FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. It is going to address fundamental questions of hadron physics and quantum chromodynamics using cooled antiproton beams with a high intensity and and momenta between 1.5 and 15 GeV/c. PANDA is designed to reach a maximum luminosity of 2x10^32 cm^2 s. Most of the physics programs require an excellent particle identification (PID). The PID of hadronic states at the forward endcap of the target spectrometer will be done by a fast and compact Cherenkov detector that uses the detection of internally reflected Cherenkov light (DIRC) principle. It is designed to cover the polar angle range from 5° to 22° and to provide a separation power for the separation of charged pions and kaons up to 3 standard deviations (s.d.) for particle momenta up to 4 GeV/c in order to cover the important particle phase space. This document describes the technical design and the expected performance of the novel PANDA Disc DIRC detector that has not been used in any other high energy physics experiment (HEP) before. The performance has been studied with Monte-Carlo simulations and various beam tests at DESY and CERN. The final design meets all PANDA requirements and guarantees suffcient safety margins. △ Less

Submitted 29 December, 2019; originally announced December 2019.

Comments: TDR for Panda/Fair to be published

Particle Identification with DIRCs at PANDA

Authors: M. Düren, A. Ali, A. Belias, R. Dzhygadlo, A. Gerhardt, M. Krebs, D. Lehmann, K. Peters, G. Schepers, C. Schwarz, J. Schwiening, M. Traxler, L. Schmitt, M. Boehm, A. Lehmann, M. Pfaffinger, S. Stelter, F. Uhlig, E. Etzelmueller, K. Foehl, A. Hayrapetyan, K. Kreutzfeld, J. Rieke, M. Schmidt, T. Wasem , et al. (1 additional authors not shown)

Abstract: The DIRC technology (Detection of Internally Reflected Cherenkov light) offers an excellent possibility to minimize the form factor of Cherenkov detectors in hermetic high energy detectors. The PANDA experiment at FAIR in Germany will combine a barrel-shaped DIRC with a disc-shaped DIRC to cover an angular range of 5 to 140 degrees. Particle identification for pions and kaons with a separation pow… ▽ More The DIRC technology (Detection of Internally Reflected Cherenkov light) offers an excellent possibility to minimize the form factor of Cherenkov detectors in hermetic high energy detectors. The PANDA experiment at FAIR in Germany will combine a barrel-shaped DIRC with a disc-shaped DIRC to cover an angular range of 5 to 140 degrees. Particle identification for pions and kaons with a separation power of 3 standard deviations or more will be provided for momenta between 0.5 GeV/c and 3.5 GeV/c in the barrel region and up to 4 GeV/c in the forward region. Even though the concept is simple, the design and construction of a DIRC is challenging. High precision optics and mechanics are required to maintain the angular information of the Cherenkov photons during multiple internal reflections and to focus the individual photons onto position sensitive photon detectors. These sensors must combine high efficiencies for single photons with low dark count rates and good timing resolution at high rates. The choice of radiation hard fused silica for the optical material and of MCP-PMT photon sensors is essential for DIRC detectors to survive in an environment of radiation and strong magnetic field. The two DIRC detectors differ in the focusing optics, in the treatment of chromatic dispersion and in the electronic readout systems. The technical design of the two DIRC detectors and their validation by testing prototypes in a mixed particle beam at CERN are presented. △ Less

Submitted 27 December, 2019; originally announced December 2019.

Comments: Proceedings of VCI 15th Vienna Conference on Instrumentation Feb. 18-22, 2019, Nuclear Inst. and Methods in Physics Research, A (2019)

NADS-Net: A Nimble Architecture for Driver and Seat Belt Detection via Convolutional Neural Networks

Authors: Sehyun Chun, Nima Hamidi Ghalehjegh, Joseph B. Choi, Chris W. Schwarz, John G. Gaspar, Daniel V. McGehee, Stephen S. Baek

Abstract: A new convolutional neural network (CNN) architecture for 2D driver/passenger pose estimation and seat belt detection is proposed in this paper. The new architecture is more nimble and thus more suitable for in-vehicle monitoring tasks compared to other generic pose estimation algorithms. The new architecture, named NADS-Net, utilizes the feature pyramid network (FPN) backbone with multiple detect… ▽ More A new convolutional neural network (CNN) architecture for 2D driver/passenger pose estimation and seat belt detection is proposed in this paper. The new architecture is more nimble and thus more suitable for in-vehicle monitoring tasks compared to other generic pose estimation algorithms. The new architecture, named NADS-Net, utilizes the feature pyramid network (FPN) backbone with multiple detection heads to achieve the optimal performance for driver/passenger state detection tasks. The new architecture is validated on a new data set containing video clips of 100 drivers in 50 driving sessions that are collected for this study. The detection performance is analyzed under different demographic, appearance, and illumination conditions. The results presented in this paper may provide meaningful insights for the autonomous driving research community and automotive industry for future algorithm development and data collection. △ Less

Submitted 8 October, 2019; originally announced October 2019.

ACM Class: I.4; I.2.1

The Innovative Design of the Endcap Disc DIRC Detector for PANDA at FAIR

Authors: M. Schmidt, M. Düren, E. Etzelmüller, K. Föhl, A. Hayrapetyan, I. Köseoglu, K. Kreutzfeld, J. Rieke, A. Ali, A. Belias, R. Dzhygadlo, A. Gerhardt, M. Krebs, D. Lehmann, K. Peters, G. Schepers, C. Schwarz, J. Schwiening, M. Traxler, L. Schmitt, M. Böhm, A. Lehmann, M. Pfaffinger, S. Stelter, F. Uhlig , et al. (1 additional authors not shown)

Abstract: The key component of the future PANDA experiment at FAIR is a fixed-target detector for collisions of antiprotons with a proton target up to a beam momentum of 15 GeV/c and is designed to address a large number of open questions in the hadron physics sector. In order to guarantee an excellent PID for charged hadrons in the polar angle range between $5^\circ$ and $22^\circ$, a new type of Cherenkov… ▽ More The key component of the future PANDA experiment at FAIR is a fixed-target detector for collisions of antiprotons with a proton target up to a beam momentum of 15 GeV/c and is designed to address a large number of open questions in the hadron physics sector. In order to guarantee an excellent PID for charged hadrons in the polar angle range between $5^\circ$ and $22^\circ$, a new type of Cherenkov detector called Endcap Disc DIRC (EDD) has been developed for the forward endcap of the PANDA target spectrometer. The desired separation power of at least 3 s.d. for the separation of $π^\pm$ and $K^\pm$ up to particle momenta of 4 GeV/c was determined with simulation studies and validated during various testbeam campaigns at CERN and DESY. △ Less

Submitted 21 September, 2019; originally announced September 2019.

Comments: Talk presented at the 2019 Meeting of the Division of Particles and Fields of the American Physical Society (DPF2019), July 29 - August 2, 2019, Northeastern University, Boston, C1907293

Investigation of neutron-induced reaction at the Goethe University Frankfurt

Authors: Rene Reifarth, Lukas Bott, Benjamin Brückner, Ozan Dogan, Markus Dworac, Anne Endres, Philipp Erbacher, Stefan Fiebiger, Roman Gernhäuser, Kathrin Göbel, Fabian Hebermehl, Tanja Heftrich, Christoph Langer, Tanja Kausch, Nadine Klapper, Kafa Khasawneh, Christoph Köppchen, Sabina Krasilovskaja, Deniz Kurtulgil, Markus Reich, Markus S. Schöffler, Lothar Ph. H. Schmidt, Christian Schwarz, Zuzana Slavkovská, Kurt E. Stiebing , et al. (5 additional authors not shown)

Abstract: We present first results and plans for future neutron activation measurements at the Goethe University Frankfurt. The measurements were performed at the Van-de-Graaff accelerator employing the 7Li(p,n) reaction. We present first results and plans for future neutron activation measurements at the Goethe University Frankfurt. The measurements were performed at the Van-de-Graaff accelerator employing the 7Li(p,n) reaction. △ Less

Submitted 11 May, 2019; originally announced May 2019.

Comments: 5 pages, 5 figures, accepted as proceeding of the Nuclei in the Cosmos XV conference 2018

Journal ref: Nuclei in the Cosmos XV. Springer Proceedings in Physics, vol 219. Springer, Cham (2019)

The Innovative Design of the PANDA Barrel DIRC

Authors: G. Schepers, A. Ali, A. Belias, R. Dzhygadlo, A. Gerhardt, M. Krebs, D. Lehmann, K. Peters, C. Schwarz, J. Schwiening, M. Traxler, L. Schmitt, M. Böhm, A. Lehmann, M. Pfaffinger, S. Stelter, F. Uhlig, M. Düren, E. Etzelmüller, K. Föhl, A. Hayrapetyan, K. Kreutzfeld, J. Rieke, M. Schmidt, T. Wasem , et al. (7 additional authors not shown)

Abstract: The Barrel DIRC of the PANDA experiment at FAIR will cleanly separate pions from kaons for the physics program of PANDA. Innovative solutions for key components of the detector sitting in the strong magnetic field of the compact PANDA target spectrometer as well as two reconstruction methods were developed in an extensive prototype program. The technical design and present results from the test be… ▽ More The Barrel DIRC of the PANDA experiment at FAIR will cleanly separate pions from kaons for the physics program of PANDA. Innovative solutions for key components of the detector sitting in the strong magnetic field of the compact PANDA target spectrometer as well as two reconstruction methods were developed in an extensive prototype program. The technical design and present results from the test beam campaigns at the CERN PS in 2017 and 2018 are discussed. △ Less

Submitted 5 April, 2019; originally announced April 2019.

Comments: 4 pages, 6 figures

The Barrel DIRC detector of PANDA

Authors: C. Schwarz, A. Ali, A. Belias, R. Dzhygadlo, A. Gerhardt, M. Krebs, D. Lehmann, K. Peters, G. Schepers, J. Schwiening, M. Traxler, L. Schmitt, M. Böhm, A. Lehmann, M. Pfaffinger, F. Uhlig, S. Stelter, M. Düren, E. Etzelmüller, K. Föhl, A. Hayrapetyan, K. Kreutzfeld, J. Rieke, M. Schmidt, T. Wasem , et al. (7 additional authors not shown)

Abstract: The PANDA experiment is one of the four large experiments being built at FAIR in Darmstadt. It will use a cooled antiproton beam on a fixed target within the momentum range of 1.5 to 15 GeV/c to address questions of strong QCD, where the coupling constant $α_s \gtrsim 0.3$. The luminosity of up to $2 \cdot 10^{32} cm^{-2}s^{-1}$ and the momentum resolution of the antiproton beam down to \mbox{$Δ$p… ▽ More The PANDA experiment is one of the four large experiments being built at FAIR in Darmstadt. It will use a cooled antiproton beam on a fixed target within the momentum range of 1.5 to 15 GeV/c to address questions of strong QCD, where the coupling constant $α_s \gtrsim 0.3$. The luminosity of up to $2 \cdot 10^{32} cm^{-2}s^{-1}$ and the momentum resolution of the antiproton beam down to \mbox{$Δ$p/p = 4$\cdot10^{-5}$} allows for high precision spectroscopy, especially for rare reaction processes. Above the production threshold for open charm mesons the production of kaons plays an important role for identifying the reaction. The DIRC principle allows for a compact particle identification for charged particles in a hermetic detector, limited in size by the electromagnetic lead tungstate calorimeter. The Barrel DIRC in the target spectrometer covers polar angles between $22^\circ$ and $140^\circ$ and will achieve a pion-kaon separation of 3 standard deviations up to 3.5 GeV/$c$. Here, results of a test beam are shown for a single radiator bar coupled to a prism with $33^\circ$ opening angle, both made from synthetic fused silica read out with a photon detector array with 768 pixels. △ Less

Submitted 24 January, 2019; originally announced January 2019.

Comments: PisaMeeting2018 - 14th Pisa Meeting on Advanced Detectors submitted to Nuclear Inst. and Methods in Physics Research, A

Medical Image Synthesis for Data Augmentation and Anonymization using Generative Adversarial Networks

Authors: Hoo-Chang Shin, Neil A Tenenholtz, Jameson K Rogers, Christopher G Schwarz, Matthew L Senjem, Jeffrey L Gunter, Katherine Andriole, Mark Michalski

Abstract: Data diversity is critical to success when training deep learning models. Medical imaging data sets are often imbalanced as pathologic findings are generally rare, which introduces significant challenges when training deep learning models. In this work, we propose a method to generate synthetic abnormal MRI images with brain tumors by training a generative adversarial network using two publicly av… ▽ More Data diversity is critical to success when training deep learning models. Medical imaging data sets are often imbalanced as pathologic findings are generally rare, which introduces significant challenges when training deep learning models. In this work, we propose a method to generate synthetic abnormal MRI images with brain tumors by training a generative adversarial network using two publicly available data sets of brain MRI. We demonstrate two unique benefits that the synthetic images provide. First, we illustrate improved performance on tumor segmentation by leveraging the synthetic images as a form of data augmentation. Second, we demonstrate the value of generative models as an anonymization tool, achieving comparable tumor segmentation results when trained on the synthetic data versus when trained on real subject data. Together, these results offer a potential solution to two of the largest challenges facing machine learning in medical imaging, namely the small incidence of pathological findings, and the restrictions around sharing of patient data. △ Less

Submitted 13 September, 2018; v1 submitted 26 July, 2018; originally announced July 2018.

Comments: Accepted for 2018 Workshop on Simulation and Synthesis in Medical Imaging - SASHIMI2018

The PANDA DIRC Detectors at FAIR

Authors: C. Schwarz, A. Ali, A. Belias, R. Dzhygadlo, A. Gerhardt, K. Goetzen, G. Kalicy, M. Krebs, D. Lehmann, F. Nerling, M. Patsyuk, K. Peters, G. Schepers, L. Schmitt, J. Schwiening, M. Traxler, M. Zuehlsdorf, M. Boehm, A. Britting, W. Eyrich, A. Lehmann, M. Pfaffinger, F. Uhlig, M. Dueren, E. Etzelmueller , et al. (17 additional authors not shown)

Abstract: The PANDA detector at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR) addresses fundamental questions of hadron physics. An excellent hadronic particle identification (PID) will be accomplished by two DIRC (Detection of Internally Reflected Cherenkov light) counters in the target spectrometer. The design for the barrel region covering polar angles between 22… ▽ More The PANDA detector at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR) addresses fundamental questions of hadron physics. An excellent hadronic particle identification (PID) will be accomplished by two DIRC (Detection of Internally Reflected Cherenkov light) counters in the target spectrometer. The design for the barrel region covering polar angles between 22 deg. to 140 deg. is based on the successful BABAR DIRC with several key improvements, such as fast photon timing and a compact imaging region. The novel Endcap Disc DIRC will cover the smaller forward angles between 5 deg. (10 deg.) to 22 deg. in the vertical (horizontal) direction. Both DIRC counters will use lifetime-enhanced microchannel plate PMTs for photon detection in combination with fast readout electronics. Geant4 simulations and tests with several prototypes at various beam facilities have been used to evaluate the designs and validate the expected PID performance of both PANDA DIRC counters. △ Less

Submitted 28 July, 2017; originally announced July 2017.

Comments: 7 pages, 5 figures, INSTR17 conference proceedings

Different Realizations of Cooper-Frye Sampling with Conservation Laws

Authors: C. Schwarz, D. Oliinychenko, L. -G. Pang, S. Ryu, H. Petersen

Abstract: Approaches based on viscous hydrodynamics for the hot and dense stage and hadronic transport for the final dilute rescattering stage are successfully applied to the dynamic description of heavy ion reactions at high beam energies. One crucial step in such hybrid approaches is the so called particlization, the transition between the hydrodynamic description to microscopic degrees of freedom. For th… ▽ More Approaches based on viscous hydrodynamics for the hot and dense stage and hadronic transport for the final dilute rescattering stage are successfully applied to the dynamic description of heavy ion reactions at high beam energies. One crucial step in such hybrid approaches is the so called particlization, the transition between the hydrodynamic description to microscopic degrees of freedom. For this purpose, individual particles are sampled on the Cooper-Frye hypersurface. In this work, 4 different realizations of sampling algorithms are compared, where three of them incorporate global conservation laws of quantum numbers in each event. The algorithms are compared within two types of scenarios: simple "box" hypersurface consisting of only one static cell and a typical particlization hypersurface for Au+Au collisions at $\sqrt{s_\mathrm{NN}} = 200$ GeV. For all algorithms the mean multiplicities (or particle spectra) remain unaffected by global conservation laws in the case of large volumes. In contrast, the fluctuations of the particle numbers are affected considerably. The fluctuations of the newly developed SPREW algorithm based on exponential weights and the recently suggested SER algorithm based on ensemble rejection are smaller than without conservation laws and agree with the expectation from the canonical ensemble. The previously applied mode sampling algorithm produces dramatically larger fluctuations, than it is expected in the corresponding microcanonical ensemble, and therefore should be avoided in fluctuation studies. This study might be of interest for investigations of particle fluctuations and correlations, e.g. the suggested signatures for a phase transition or a critical endpoint, in hybrid approaches that are affected by global conservation laws. △ Less

Submitted 12 October, 2017; v1 submitted 21 July, 2017; originally announced July 2017.

Comments: 11 pages, 8 figures, version accepted to publication in Journal of Physics G

Measurement of the beam asymmetry $Σ$ for $π^0$ and $η$ photoproduction on the proton at $E_γ= 9$ GeV

Authors: GlueX Collaboration, H. Al Ghoul, E. G. Anassontzis, A. Austregesilo, F. Barbosa, A. Barnes, T. D. Beattie, D. W. Bennett, V. V. Berdnikov, T. Black, W. Boeglin, W. J. Briscoe, W. K. Brooks, B. E. Cannon, O. Chernyshov, E. Chudakov, V. Crede, M. M. Dalton, A. Deur, S. Dobbs, A. Dolgolenko, M. Dugger, R. Dzhygadlo, H. Egiyan, P. Eugenio , et al. (101 additional authors not shown)

Abstract: We report measurements of the photon beam asymmetry $Σ$ for the reactions $\vecγp\to pπ^0$ and $\vecγp\to pη$ from the GlueX experiment using a 9 GeV linearly-polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous $π^0$ measurements and are the fir… ▽ More We report measurements of the photon beam asymmetry $Σ$ for the reactions $\vecγp\to pπ^0$ and $\vecγp\to pη$ from the GlueX experiment using a 9 GeV linearly-polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous $π^0$ measurements and are the first $η$ measurements in this energy regime. The results are compared with theoretical predictions based on $t$-channel, quasi-particle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models. △ Less

Submitted 15 May, 2017; v1 submitted 27 January, 2017; originally announced January 2017.

Comments: 6 pages, 6 figures, Published in Physical Review C: Rapid Communication

Report number: JLAB-PHY-17-2403

Journal ref: Phys. Rev. C 95, 042201 (2017)

Feasibility study for the measurement of $πN$ TDAs at PANDA in $\bar{p}p\to J/ψπ^0$

Authors: PANDA Collaboration, B. Singh, W. Erni, B. Krusche, M. Steinacher, N. Walford, H. Liu, Z. Liu, B. Liu, X. Shen, C. Wang, J. Zhao, M. Albrecht, T. Erlen, M. Fink, F. H. Heinsius, T. Held, T. Holtmann, S. Jasper, I. Keshk, H. Koch, B. Kopf, M. Kuhlmann, M. Kümmel, S. Leiber , et al. (488 additional authors not shown)

Abstract: The exclusive charmonium production process in $\bar{p}p$ annihilation with an associated $π^0$ meson $\bar{p}p\to J/ψπ^0$ is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the $J/ψ\to e^+e^-$ decay channel with the PANDA (AntiProton ANnihilation at DArmstadt) experiment is investigated. Simulations on signal reconstruction efficiency as… ▽ More The exclusive charmonium production process in $\bar{p}p$ annihilation with an associated $π^0$ meson $\bar{p}p\to J/ψπ^0$ is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the $J/ψ\to e^+e^-$ decay channel with the PANDA (AntiProton ANnihilation at DArmstadt) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the $\bar{p}p\toπ^+π^-π^0$ and $\bar{p}p\to J/ψπ^0π^0$ reactions are performed with PandaRoot, the simulation and analysis software framework of the PANDA experiment. It is shown that the measurement can be done at PANDA with significant constraining power under the assumption of an integrated luminosity attainable in four to five months of data taking at the maximum design luminosity. △ Less

Submitted 7 October, 2016; originally announced October 2016.

Comments: 25 pages, 22 figures

Journal ref: Phys. Rev. D 95, 032003 (2017)

Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR

Authors: PANDA Collaboration, B. Singh, W. Erni, B. Krusche, M. Steinacher, N. Walford, B. Liu, H. Liu, Z. Liu, X. Shen, C. Wang, J. Zhao, M. Albrecht, T. Erlen, M. Fink, F. Heinsius, T. Held, T. Holtmann, S. Jasper, I. Keshk, H. Koch, B. Kopf, M. Kuhlmann, M. Kümmel, S. Leiber , et al. (482 additional authors not shown)

Abstract: Simulation results for future measurements of electromagnetic proton form factors at \PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel $\bar p p \to e^+ e^-$ is studied on the basis of two different but consistent procedures. The suppression of the main background chann… ▽ More Simulation results for future measurements of electromagnetic proton form factors at \PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel $\bar p p \to e^+ e^-$ is studied on the basis of two different but consistent procedures. The suppression of the main background channel, $\textit{i.e.}$ $\bar p p \to π^+ π^-$, is studied. Furthermore, the background versus signal efficiency, statistical and systematical uncertainties on the extracted proton form factors are evaluated using two different procedures. The results are consistent with those of a previous simulation study using an older, simplified framework. However, a slightly better precision is achieved in the PandaRoot study in a large range of momentum transfer, assuming the nominal beam conditions and detector performance. △ Less

Submitted 29 September, 2016; v1 submitted 3 June, 2016; originally announced June 2016.

Deviation from the normal mode expansion in a coupled graphene-nanomechanical system

Authors: Cornelia Schwarz, Benjamin Pigeau, Laure Mercier de Lépinay, Aurélien Kuhn, Dipankar Kalita, Nedjma Bendiab, Laëtitia Marty, Vincent Bouchiat, Olivier Arcizet

Abstract: We optomechanically measure the vibrations of a nanomechanical system made of a graphene membrane suspended on a silicon nitride nanoresonator. When probing the thermal noise of the coupled nanomechanical device, we observe a significant deviation from the normal mode expansion. It originates from the heterogeneous character of mechanical dissipation over the spatial extension of coupled eigenmode… ▽ More We optomechanically measure the vibrations of a nanomechanical system made of a graphene membrane suspended on a silicon nitride nanoresonator. When probing the thermal noise of the coupled nanomechanical device, we observe a significant deviation from the normal mode expansion. It originates from the heterogeneous character of mechanical dissipation over the spatial extension of coupled eigenmodes, which violates one of the fundamental prerequisite for employing this commonly used description of the nanoresonators' thermal noise. We subsequently measure the local mechanical susceptibility and demonstrate that the fluctuation-dissipation theorem still holds and permits a proper evaluation of the thermal noise of the nanomechanical system. Since it naturally becomes delicate to ensure a good spatial homogeneity at the nanoscale, this approach is fundamental to correctly describe the thermal noise of nanomechanical systems which ultimately impact their sensing capacity. △ Less

Submitted 2 January, 2016; originally announced January 2016.

Journal ref: Phys. Rev. Applied 6, 064021 (2016)