Dr. rer. nat. Johannes Müllers
Personalized Digital Health and Telemedicine
Affiliation:
Department for Epileptology
University Hospital Bonn
Location:
Venusberg-Campus 1
Building 74, Room 2G-015
53127 Bonn, Germany
Telephone: +49-228/287-51699
Email: johannes.muellers@ukbonn.de
Short CV: Johannes has earned his bachelor’s (2011) and master’s (2013) degree in experimental physics in the group of Prof. Dr. Reinhard Beck, specializing in electronics and firmware development for sensor readout. In his dissertation (2019) in the group of Prof. Dr. Ulrike Thoma he built an FPGA-based ADC-readout system for the Crystal Barrel experiment, which he continued to develop during a three year postdoc phase. Together with Prof. Dr. Björn Krüger he developed a posture-tracking wearable for a California-based health institute. In 2023 Johannes joined Björn’s group as a postdoctoral researcher.
Johannes is an avid member of the famous Bonn Physikshow.
Publications
2026
Steininger, Melissa; Jansen, Anna; Müllers, Johannes; von Wrede, Randi; Krüger, Björn
Toward Interpretable Cognitive Screening in Epilepsy: Eye Tracking in a VR Trail Making Test Proceedings Article
In: IEEE VR 2026 Workshop: GEMINI, 2026.
@inproceedings{steininger2026b,
title = {Toward Interpretable Cognitive Screening in Epilepsy: Eye Tracking in a VR Trail Making Test},
author = {Melissa Steininger and Anna Jansen and Johannes Müllers and Randi von Wrede and Björn Krüger},
url = {https://www.computer.org/csdl/proceedings-article/vrw/2026/052900a106/2gdqrMPo2s0},
year = {2026},
date = {2026-03-31},
urldate = {2026-03-31},
booktitle = {IEEE VR 2026 Workshop: GEMINI},
abstract = {Cognitive screening is a routine component of epilepsy care. Established pen-and-paper instruments such as the Trail Making Test (TMT) primarily yield summary outcomes (e.g., completion time) that provide limited insight into visual search and executive-control processes affected by epilepsy-related brain network dysfunction. We present an eye-tracked Virtual Reality TMT (VR-TMT) as a controlled research instrument that enables process-level interpretable measurements. The system synchronizes continuous eye-movement streams with timestamped task events (task start/stop and node selections) and logs gaze-to-Area-of-Interest (AOI) intersections. To reduce VR-specific confounds that can compromise cognitive interpretation, we specify concrete design guidelines for 3D stimulus geometry and the VR+eye-tracking setup (e.g., viewing distance, field-of-view placement, target size).
In a feasibility pilot (n=8) usability ratings were favorable and cybersickness was low. Building on this foundation, we outline an analysis framework that derives contextualized gaze features and evaluates their added value in explaining established cognitive screening outcomes in epilepsy cohorts.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Cognitive screening is a routine component of epilepsy care. Established pen-and-paper instruments such as the Trail Making Test (TMT) primarily yield summary outcomes (e.g., completion time) that provide limited insight into visual search and executive-control processes affected by epilepsy-related brain network dysfunction. We present an eye-tracked Virtual Reality TMT (VR-TMT) as a controlled research instrument that enables process-level interpretable measurements. The system synchronizes continuous eye-movement streams with timestamped task events (task start/stop and node selections) and logs gaze-to-Area-of-Interest (AOI) intersections. To reduce VR-specific confounds that can compromise cognitive interpretation, we specify concrete design guidelines for 3D stimulus geometry and the VR+eye-tracking setup (e.g., viewing distance, field-of-view placement, target size).
In a feasibility pilot (n=8) usability ratings were favorable and cybersickness was low. Building on this foundation, we outline an analysis framework that derives contextualized gaze features and evaluates their added value in explaining established cognitive screening outcomes in epilepsy cohorts.
In a feasibility pilot (n=8) usability ratings were favorable and cybersickness was low. Building on this foundation, we outline an analysis framework that derives contextualized gaze features and evaluates their added value in explaining established cognitive screening outcomes in epilepsy cohorts.
2025
Jansen, Anna; Morev, Nikita; Steininger, Melissa; Müllers, Johannes; Krüger, Björn
Synthetic Hand Dataset Generation: Multi-View Rendering and Annotation with Blender Proceedings Article
In: 2025 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct), pp. 809-810, IEEE Computer Society, 2025.
@inproceedings{jansen2025c,
title = {Synthetic Hand Dataset Generation: Multi-View Rendering and Annotation with Blender},
author = {Anna Jansen and Nikita Morev and Melissa Steininger and Johannes Müllers and Björn Krüger},
url = {https://www.computer.org/csdl/proceedings-article/ismar-adjunct/2025/934700a809/2bKcNnpvzTG},
doi = {10.1109/ISMAR-Adjunct68609.2025.00201},
year = {2025},
date = {2025-10-06},
urldate = {2025-10-06},
booktitle = {2025 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct)},
pages = {809-810},
publisher = {IEEE Computer Society},
abstract = {Pose estimation is a common method for precise handtracking, which is important for natural interaction in virtual reality (VR). However, training those models requires large-scale datasets with accurate 3D annotations. Those are difficult to obtain due to the time-consuming data collection and the limited variety in captured scenarios. We present a work-in-progress Blender-based pipeline for generating synthetic multi-view hand datasets. Our system simulates Ultraleap Stereo IR 170-style images and extracts joint positions directly from a rigged hand model, eliminating the need for manual labeling or external tracking processes. The current pipeline version supports randomized static poses with per-frame annotations of joint positions, camera parameters, and rendered images. While extended hand variation, animation features, and different sensor-type simulations are still in progress, our pipeline already provides a flexible foundation for customizable dataset generation and reproducible hand-tracking model training.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Pose estimation is a common method for precise handtracking, which is important for natural interaction in virtual reality (VR). However, training those models requires large-scale datasets with accurate 3D annotations. Those are difficult to obtain due to the time-consuming data collection and the limited variety in captured scenarios. We present a work-in-progress Blender-based pipeline for generating synthetic multi-view hand datasets. Our system simulates Ultraleap Stereo IR 170-style images and extracts joint positions directly from a rigged hand model, eliminating the need for manual labeling or external tracking processes. The current pipeline version supports randomized static poses with per-frame annotations of joint positions, camera parameters, and rendered images. While extended hand variation, animation features, and different sensor-type simulations are still in progress, our pipeline already provides a flexible foundation for customizable dataset generation and reproducible hand-tracking model training.
Mustafa, Sarah Al-Haj; Jansen, Anna; Steininger, Melissa; Müllers, Johannes; Surges, Rainer; von Wrede, Randi; Krüger, Björn; Helmstaedter, Christoph
Eyes on Cognition: Exploring Oculomotor Correlates of Cognitive Function in Patients with Epilepsy Journal Article
In: Epilepsy & Behavior, vol. 173, iss. December 2025, no. 110562, 2025.
@article{alhaj2025,
title = {Eyes on Cognition: Exploring Oculomotor Correlates of Cognitive Function in Patients with Epilepsy},
author = {Sarah Al-Haj Mustafa and Anna Jansen and Melissa Steininger and Johannes Müllers and Rainer Surges and Randi von Wrede and Björn Krüger and Christoph Helmstaedter},
doi = {10.1016/j.yebeh.2025.110562},
year = {2025},
date = {2025-06-30},
urldate = {2025-06-30},
journal = {Epilepsy & Behavior},
volume = {173},
number = {110562},
issue = {December 2025},
abstract = {Objective
This study investigates the relationship between eye tracking parameters and cognitive performance during the Trail Making Test (TMT) in individuals with epilepsy and healthy controls. By analyzing ocular behaviors such as saccade velocity, fixation duration, and pupil diameter, we aim to determine how these metrics reflect executive functioning and attentional control.
Methods
A sample of 95 participants with epilepsy and 34 healthy controls completed the TMT while their eye movements were recorded. Partial correlations, controlling for age, sex, education, medication count, seizure status and epilepsy duration, examined associations between eye tracking measures and cognitive performance derived from EpiTrack and TMT performance.
Results
In the patient group, faster TMT-A performance was associated with shorter fix- ation durations (r = 0.31, p = 0.006). Lower minimum saccade velocity correlated with slower performance on both TMT-A (r = −0.35, p = 0.002) and TMT-B (r = −0.40, p<0.001), whereas higher peak saccade velocities were linked to worse performance (TMT-A: r = 0.45, p<0.001; TMT-B: r = 0.41, p<0.001). Pupil diameter findings indicated that slower TMT performance was associated with smaller minimum pupil sizes (r = −0.23 to r = −0.36), wich may indicate increased cognitive effort and attentional load. Higher EpiTrack scores also correlated with a smaller minimum pupil diameter − but only during the more demanding TMT-B − and with a more restricted saccade velocity range, reflecting greater motor control and attentional stability. No significant correlations emerged within the control group.
Conclusion
These findings highlight the potential of eye tracking as a non-invasive tool for assessing cognitive function in epilepsy. Efficient cognitive performance was characterized by stable and controlled eye movements, whereas impaired performance involved erratic saccade dynamics and prolonged fixations. Importantly, eye tracking parameters provide additional information beyond simple speed measurements, potentially enhancing the differential diagnostic capabilities of the TMT in epilepsy. The observed associations between oculomotor parameters and cognitive performance were not present in the control group, suggesting that these relationships may be specific to epilepsy. Future research should investigate whether both basic and advanced metrics of search strategies are sensitive to disease dynamics and treatment effects in epilepsy.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Objective
This study investigates the relationship between eye tracking parameters and cognitive performance during the Trail Making Test (TMT) in individuals with epilepsy and healthy controls. By analyzing ocular behaviors such as saccade velocity, fixation duration, and pupil diameter, we aim to determine how these metrics reflect executive functioning and attentional control.
Methods
A sample of 95 participants with epilepsy and 34 healthy controls completed the TMT while their eye movements were recorded. Partial correlations, controlling for age, sex, education, medication count, seizure status and epilepsy duration, examined associations between eye tracking measures and cognitive performance derived from EpiTrack and TMT performance.
Results
In the patient group, faster TMT-A performance was associated with shorter fix- ation durations (r = 0.31, p = 0.006). Lower minimum saccade velocity correlated with slower performance on both TMT-A (r = −0.35, p = 0.002) and TMT-B (r = −0.40, p<0.001), whereas higher peak saccade velocities were linked to worse performance (TMT-A: r = 0.45, p<0.001; TMT-B: r = 0.41, p<0.001). Pupil diameter findings indicated that slower TMT performance was associated with smaller minimum pupil sizes (r = −0.23 to r = −0.36), wich may indicate increased cognitive effort and attentional load. Higher EpiTrack scores also correlated with a smaller minimum pupil diameter − but only during the more demanding TMT-B − and with a more restricted saccade velocity range, reflecting greater motor control and attentional stability. No significant correlations emerged within the control group.
Conclusion
These findings highlight the potential of eye tracking as a non-invasive tool for assessing cognitive function in epilepsy. Efficient cognitive performance was characterized by stable and controlled eye movements, whereas impaired performance involved erratic saccade dynamics and prolonged fixations. Importantly, eye tracking parameters provide additional information beyond simple speed measurements, potentially enhancing the differential diagnostic capabilities of the TMT in epilepsy. The observed associations between oculomotor parameters and cognitive performance were not present in the control group, suggesting that these relationships may be specific to epilepsy. Future research should investigate whether both basic and advanced metrics of search strategies are sensitive to disease dynamics and treatment effects in epilepsy.
This study investigates the relationship between eye tracking parameters and cognitive performance during the Trail Making Test (TMT) in individuals with epilepsy and healthy controls. By analyzing ocular behaviors such as saccade velocity, fixation duration, and pupil diameter, we aim to determine how these metrics reflect executive functioning and attentional control.
Methods
A sample of 95 participants with epilepsy and 34 healthy controls completed the TMT while their eye movements were recorded. Partial correlations, controlling for age, sex, education, medication count, seizure status and epilepsy duration, examined associations between eye tracking measures and cognitive performance derived from EpiTrack and TMT performance.
Results
In the patient group, faster TMT-A performance was associated with shorter fix- ation durations (r = 0.31, p = 0.006). Lower minimum saccade velocity correlated with slower performance on both TMT-A (r = −0.35, p = 0.002) and TMT-B (r = −0.40, p<0.001), whereas higher peak saccade velocities were linked to worse performance (TMT-A: r = 0.45, p<0.001; TMT-B: r = 0.41, p<0.001). Pupil diameter findings indicated that slower TMT performance was associated with smaller minimum pupil sizes (r = −0.23 to r = −0.36), wich may indicate increased cognitive effort and attentional load. Higher EpiTrack scores also correlated with a smaller minimum pupil diameter − but only during the more demanding TMT-B − and with a more restricted saccade velocity range, reflecting greater motor control and attentional stability. No significant correlations emerged within the control group.
Conclusion
These findings highlight the potential of eye tracking as a non-invasive tool for assessing cognitive function in epilepsy. Efficient cognitive performance was characterized by stable and controlled eye movements, whereas impaired performance involved erratic saccade dynamics and prolonged fixations. Importantly, eye tracking parameters provide additional information beyond simple speed measurements, potentially enhancing the differential diagnostic capabilities of the TMT in epilepsy. The observed associations between oculomotor parameters and cognitive performance were not present in the control group, suggesting that these relationships may be specific to epilepsy. Future research should investigate whether both basic and advanced metrics of search strategies are sensitive to disease dynamics and treatment effects in epilepsy.
2024
Krüger, Björn; Weber, Christian; Müllers, Johannes; Greß, Hannah; Beyer, Franziska; Knaub, Jessica; Pukropski, Jan; Hütwohl, Daniela; Hahn, Kai; Grond, Martin; Jonas, Stephan; Surges, Rainer
Teleconsultation to Improve Epilepsy Diagnosis and Therapy Book Chapter
In: Herrmann, Wolfram J.; Leser, Ulf; Möller, Sebastian; Voigt-Antons, Jan-Niklas; Gellert, Paul (Ed.): pp. 18-23, Future-Proofing Healthcare for Older Adults Through Digitalization, 2024.
@inbook{krueger2024a,
title = {Teleconsultation to Improve Epilepsy Diagnosis and Therapy},
author = {Björn Krüger and Christian Weber and Johannes Müllers and Hannah Greß and Franziska Beyer and Jessica Knaub and Jan Pukropski and Daniela Hütwohl and Kai Hahn and Martin Grond and Stephan Jonas and Rainer Surges},
editor = {Wolfram J. Herrmann and Ulf Leser and Sebastian Möller and Jan-Niklas Voigt-Antons and Paul Gellert},
doi = {10.14279/depositonce-20417},
year = {2024},
date = {2024-08-01},
urldate = {2024-08-01},
pages = {18-23},
edition = {Future-Proofing Healthcare for Older Adults Through Digitalization},
abstract = {Teleconsultation in epileptology significantly enhances patient diagnosis and treatment, often eliminating the necessity for physical referral to a specialized clinic. In this paper, we detail the typical teleconsultation process, exploring its technical requirements and legal boundaries. Notably, we focus on the groundwork for establishing a teleconsultation specifically between the University Hospital Bonn and the Klinikum Siegen. Additionally, we provide an overview of currently implemented teleconsultations in epileptology in Germany, concluding with research questions stemming from these advancements. },
keywords = {},
pubstate = {published},
tppubtype = {inbook}
}
Teleconsultation in epileptology significantly enhances patient diagnosis and treatment, often eliminating the necessity for physical referral to a specialized clinic. In this paper, we detail the typical teleconsultation process, exploring its technical requirements and legal boundaries. Notably, we focus on the groundwork for establishing a teleconsultation specifically between the University Hospital Bonn and the Klinikum Siegen. Additionally, we provide an overview of currently implemented teleconsultations in epileptology in Germany, concluding with research questions stemming from these advancements.
2023
Jermann, N.; Krusche, B.; Metag, V.; Afzal, F.; Badea, M.; Beck, R.; Bielefeldt, P.; Bieling, J.; Biroth, M.; Blanke, E.; Borisov, N.; Bornstein, M.; Brinkmann, K. -T.; Ciupka, S.; Crede, V.; Dolzhikov, A.; Drexler, P.; Dutz, H.; Elsner, D.; Fedorov, A.; Frommberger, F.; Gardner, S.; Ghosal, D.; Goertz, S.; Gorodnov, I.; Grüner, M.; Hammann, C.; Hartmann, J.; Hillert, W.; Hoffmeister, P.; Honisch, C.; Jude, T. C.; Kalischewski, F.; Ketzer, B.; Klassen, P.; Klein, F.; Klempt, E.; Knaust, J.; Kolanus, N.; Kreit, J.; Krönert, P.; Lang, M.; Lazarev, A. B.; Livingston, K.; Lutterer, S.; Mahlberg, P.; Meier, C.; Meyer, W.; Mitlasoczki, B.; Müllers, Johannes; Nanova, M.; Neganov, A.; Nikonov, K.; Noël, J. F.; Ostrick, M.; Ottnad, J.; Otto, B.; Penman, G.; Poller, T.; Proft, D.; Reicherz, G.; Reinartz, N.; Richter, L.; Runkel, S.; Salisbury, B.; Sarantsev, A. V.; Schaab, D.; Schmidt, C.; Schmieden, H.; Schultes, J.; Seifen, T.; Spieker, K.; Stausberg, N.; Steinacher, M.; Taubert, F.; Thiel, A.; Thoma, U.; Thomas, A.; Urban, M.; Urff, G.; Usov, Y.; van Pee, H.; Wang, Y. C.; Wendel, C.; Wiedner, U.; Wunderlich, Y.
Measurement of polarization observables T, P, and H in 𝛑⁰ and 𝛈 photoproduction off quasi-free nucleons Journal Article
In: The European Physical Journal A, vol. 59, 2023.
@article{articleb,
title = {Measurement of polarization observables T, P, and H in 𝛑⁰ and 𝛈 photoproduction off quasi-free nucleons},
author = {N. Jermann and B. Krusche and V. Metag and F. Afzal and M. Badea and R. Beck and P. Bielefeldt and J. Bieling and M. Biroth and E. Blanke and N. Borisov and M. Bornstein and K.-T. Brinkmann and S. Ciupka and V. Crede and A. Dolzhikov and P. Drexler and H. Dutz and D. Elsner and A. Fedorov and F. Frommberger and S. Gardner and D. Ghosal and S. Goertz and I. Gorodnov and M. Grüner and C. Hammann and J. Hartmann and W. Hillert and P. Hoffmeister and C. Honisch and T. C. Jude and F. Kalischewski and B. Ketzer and P. Klassen and F. Klein and E. Klempt and J. Knaust and N. Kolanus and J. Kreit and P. Krönert and M. Lang and A. B. Lazarev and K. Livingston and S. Lutterer and P. Mahlberg and C. Meier and W. Meyer and B. Mitlasoczki and Johannes Müllers and M. Nanova and A. Neganov and K. Nikonov and J. F. Noël and M. Ostrick and J. Ottnad and B. Otto and G. Penman and T. Poller and D. Proft and G. Reicherz and N. Reinartz and L. Richter and S. Runkel and B. Salisbury and A. V. Sarantsev and D. Schaab and C. Schmidt and H. Schmieden and J. Schultes and T. Seifen and K. Spieker and N. Stausberg and M. Steinacher and F. Taubert and A. Thiel and U. Thoma and A. Thomas and M. Urban and G. Urff and Y. Usov and H. van Pee and Y. C. Wang and C. Wendel and U. Wiedner and Y. Wunderlich},
doi = {10.1140/epja/s10050-023-01134-0},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {The European Physical Journal A},
volume = {59},
abstract = {The target asymmetry T , recoil asymmetry P, and beam-target double polarization observable H were determined in exclusive π0 and η photoproduction off quasi-
free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the γ p → π0 p and γ p → ηp reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the ηn system at W = 1.68 GeV. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the S11(1535) and S11(1650) resonances within the S11 -partial wave.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The target asymmetry T , recoil asymmetry P, and beam-target double polarization observable H were determined in exclusive π0 and η photoproduction off quasi-
free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the γ p → π0 p and γ p → ηp reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the ηn system at W = 1.68 GeV. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the S11(1535) and S11(1650) resonances within the S11 -partial wave.
free protons and, for the first time, off quasi-free neutrons. The experiment was performed at the electron stretcher accelerator ELSA in Bonn, Germany, with the Crystal Barrel/TAPS detector setup, using a linearly polarized photon beam and a transversely polarized deuterated butanol target. Effects from the Fermi motion of the nucleons within deuterium were removed by a full kinematic reconstruction of the final state invariant mass. A comparison of the data obtained on the proton and on the neutron provides new insight into the isospin structure of the electromagnetic excitation of the nucleon. Earlier measurements of polarization observables in the γ p → π0 p and γ p → ηp reactions are confirmed. The data obtained on the neutron are of particular relevance for clarifying the origin of the narrow structure in the ηn system at W = 1.68 GeV. A comparison with recent partial wave analyses favors the interpretation of this structure as arising from interference of the S11(1535) and S11(1650) resonances within the S11 -partial wave.
2022
Honisch, C.; Klassen, P.; Müllers, Johannes; Urban, M.; Afzal, F.; Bieling, J.; Ciupka, S.; Hartmann, J.; Hoffmeister, P.; Lang, M.; Schaab, D.; Schmidt, C.; Steinacher, M.; Walther, D.; Beck, R.; Brinkmann, K. -T.; Crede, V.; Dutz, H.; Elsner, D.; Erni, W.; Fix, E.; Frommberger, F.; Grüner, M.; Jude, T.; Kalischewski, F.; Keshelashvili, I.; Krönert, P.; Krusche, B.; Mahlberg, P.; Metag, V.; Meyer, W.; Müller, F.; Nanova, M.; Otto, B.; Richter, L.; Runkel, S.; Salisbury, B.; Schmieden, H.; Schultes, J.; Seifen, T.; Stausberg, N.; Taubert, F.; Thiel, A.; Thoma, U.; Urff, G.; Wendel, C.; Wiedner, U.; Wunderlich, Y.; Zaunick, H. -G.
The new APD-Based Readout of the Crystal Barrel Calorimeter – An Overview Working paper
2022, (Momentan im Review).
@workingpaper{newapdreadout,
title = {The new APD-Based Readout of the Crystal Barrel Calorimeter – An Overview},
author = {C. Honisch and P. Klassen and Johannes Müllers and M. Urban and F. Afzal and J. Bieling and S. Ciupka and J. Hartmann and P. Hoffmeister and M. Lang and D. Schaab and C. Schmidt and M. Steinacher and D. Walther and R. Beck and K. -T. Brinkmann and V. Crede and H. Dutz and D. Elsner and W. Erni and E. Fix and F. Frommberger and M. Grüner and T. Jude and F. Kalischewski and I. Keshelashvili and P. Krönert and B. Krusche and P. Mahlberg and V. Metag and W. Meyer and F. Müller and M. Nanova and B. Otto and L. Richter and S. Runkel and B. Salisbury and H. Schmieden and J. Schultes and T. Seifen and N. Stausberg and F. Taubert and A. Thiel and U. Thoma and G. Urff and C. Wendel and U. Wiedner and Y. Wunderlich and H. -G. Zaunick},
doi = {10.48550/arXiv.2212.12364},
year = {2022},
date = {2022-12-23},
urldate = {2022-12-23},
abstract = {The Crystal Barrel is an electromagnetic calorimeter consisting of 1380 CsI(Tl) scintillators, and is currently installed at the CBELSA/TAPS experiment where it is used to detect decay products from photoproduction of mesons. The readout of the Crystal Barrel has been upgraded in order to integrate the detector into the first level of the trigger and to increase its sensitivity for neutral final states. The new readout uses avalanche photodiodes in the front-end and a dual back-end with branches optimized for energy and time measurement, respectively. An FPGA-based cluster finder processes the whole hit pattern within less than 100 ns. The important downside of APDs -- the temperature dependence of their gain -- is handled with a temperature stabilization and a compensating bias voltage supply. Additionally, a light pulser system allows the APDs' gains to be measured during beamtimes. },
note = {Momentan im Review},
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}
The Crystal Barrel is an electromagnetic calorimeter consisting of 1380 CsI(Tl) scintillators, and is currently installed at the CBELSA/TAPS experiment where it is used to detect decay products from photoproduction of mesons. The readout of the Crystal Barrel has been upgraded in order to integrate the detector into the first level of the trigger and to increase its sensitivity for neutral final states. The new readout uses avalanche photodiodes in the front-end and a dual back-end with branches optimized for energy and time measurement, respectively. An FPGA-based cluster finder processes the whole hit pattern within less than 100 ns. The important downside of APDs -- the temperature dependence of their gain -- is handled with a temperature stabilization and a compensating bias voltage supply. Additionally, a light pulser system allows the APDs' gains to be measured during beamtimes.
2021
Gottschall, M.; Afzal, F.; Anisovich, A. V.; Bayadilov, D.; Beck, R.; Bichow, M.; Brinkmann, K. Th.; Crede, V.; Dieterle, M.; Dietz, F.; Dutz, H.; Eberhardt, H.; Elsner, D.; Ewald, R.; Fornet-Ponse, K.; Friedrich, St.; Frommberger, F.; Gridnev, A.; Grüner, M.; Gutz, E.; Hammann, Ch.; Hannappel, J.; Hartmann, J.; Hillert, W.; Hoffmeister, Ph.; Honisch, Ch.; Jude, T.; Kammer, S.; Kalinowsky, H.; Keshelashvili, I.; Klassen, P.; Klein, F.; Klempt, E.; Koop, K.; Krusche, B.; Kube, M.; Lang, M.; Lopatin, I.; Mahlberg, P.; Makonyi, K.; Metag, V.; Meyer, W.; Müller, J.; Müllers, Johannes; Nanova, M.; Nikonov, V.; Novotny, R.; Piontek, D.; Reicherz, G.; Rostomyan, T.; Sarantsev, A.; Schmidt, Ch.; Schmieden, H.; Seifen, T.; Sokhoyan, V.; Spieker, K.; Thiel, A.; Thoma, U.; Urban, M.; Pee, H.; Walther, D.; Wendel, Ch.; Werthmüller, D.; Wiedner, U.; Wilson, A.; Winnebeck, A.; Witthauer, L.; Wunderlich, Y.
Measurement of the helicity asymmetry E for the reaction γp→π0p Journal Article
In: The European Physical Journal A, vol. 57, pp. 40, 2021.
@article{articlec,
title = {Measurement of the helicity asymmetry E for the reaction γp→π0p},
author = {M. Gottschall and F. Afzal and A. V. Anisovich and D. Bayadilov and R. Beck and M. Bichow and K. Th. Brinkmann and V. Crede and M. Dieterle and F. Dietz and H. Dutz and H. Eberhardt and D. Elsner and R. Ewald and K. Fornet-Ponse and St. Friedrich and F. Frommberger and A. Gridnev and M. Grüner and E. Gutz and Ch. Hammann and J. Hannappel and J. Hartmann and W. Hillert and Ph. Hoffmeister and Ch. Honisch and T. Jude and S. Kammer and H. Kalinowsky and I. Keshelashvili and P. Klassen and F. Klein and E. Klempt and K. Koop and B. Krusche and M. Kube and M. Lang and I. Lopatin and P. Mahlberg and K. Makonyi and V. Metag and W. Meyer and J. Müller and Johannes Müllers and M. Nanova and V. Nikonov and R. Novotny and D. Piontek and G. Reicherz and T. Rostomyan and A. Sarantsev and Ch. Schmidt and H. Schmieden and T. Seifen and V. Sokhoyan and K. Spieker and A. Thiel and U. Thoma and M. Urban and H. Pee and D. Walther and Ch. Wendel and D. Werthmüller and U. Wiedner and A. Wilson and A. Winnebeck and L. Witthauer and Y. Wunderlich},
doi = {10.1140/epja/s10050-020-00334-2},
year = {2021},
date = {2021-01-28},
urldate = {2021-01-28},
journal = {The European Physical Journal A},
volume = {57},
pages = {40},
abstract = {A measurement of the double-polarization observable E for the reaction γp→π0p is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C 4 H 9 OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from Eγ=600 to 2310 MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A measurement of the double-polarization observable E for the reaction γp→π0p is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C 4 H 9 OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from Eγ=600 to 2310 MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.
2020
Afzal, F.; Wunderlich, Y.; Anisovich, A. V.; Bayadilov, D.; Beck, R.; Becker, M.; Blanke, E.; Brinkmann, K. -Th.; Ciupka, S.; Crede, V.; Dieterle, M.; Dutz, H.; Elsner, D.; Friedrich, S.; Frommberger, F.; Gridnev, A.; Gottschall, M.; Grüner, M.; Gutz, E.; Hammann, C.; Hannappel, J.; Hartmann, J.; Hillert, W.; Hoff, J.; Hoffmeister, P.; Honisch, C.; Jude, T.; Kalinowsky, H.; Kalischewski, F.; Keshelashvili, I.; Klassen, P.; Klein, F.; Klempt, E.; Koop, K.; Kroenert, P.; Krusche, B.; Lang, M.; Lopatin, I.; Mahlberg, P.; Meißner, U. -G.; Messi, F.; Metag, V.; Meyer, W.; Mitlasóczki, B.; Müller, J.; Müllers, Johannes; Nanova, M.; Nikonov, K.; Nikonov, V.; Novinskiy, V.; Novotny, R.; Piontek, D.; Reicherz, G.; Richter, L.; Rönchen, D.; Rostomyan, T.; Salisbury, B.; Sarantsev, A.; Schaab, D.; Schmidt, C.; Schmieden, H.; Schultes, J.; Seifen, T.; Sokhoyan, V.; Sowa, C.; Spieker, K.; Stausberg, N.; Thiel, A.; Thoma, U.; Triffterer, T.; Urban, M.; Urff, G.; Pee, H.; Walther, D.; Wendel, Ch.; Wiedner, U.; Wilson, A.; Winnebeck, A.; Witthauer, L.
Observation of the p𝛈' Cusp in the New Precise Beam Asymmetry 𝛴 Data for 𝛾 p → p 𝜂 Journal Article
In: Phys. Rev. Lett., vol. 125, iss. 15, pp. 152002, 2020.
@article{PhysRevLett.125.152002,
title = {Observation of the p𝛈' Cusp in the New Precise Beam Asymmetry 𝛴 Data for 𝛾 p → p 𝜂},
author = {F. Afzal and Y. Wunderlich and A. V. Anisovich and D. Bayadilov and R. Beck and M. Becker and E. Blanke and K. -Th. Brinkmann and S. Ciupka and V. Crede and M. Dieterle and H. Dutz and D. Elsner and S. Friedrich and F. Frommberger and A. Gridnev and M. Gottschall and M. Grüner and E. Gutz and C. Hammann and J. Hannappel and J. Hartmann and W. Hillert and J. Hoff and P. Hoffmeister and C. Honisch and T. Jude and H. Kalinowsky and F. Kalischewski and I. Keshelashvili and P. Klassen and F. Klein and E. Klempt and K. Koop and P. Kroenert and B. Krusche and M. Lang and I. Lopatin and P. Mahlberg and U. -G. Meißner and F. Messi and V. Metag and W. Meyer and B. Mitlasóczki and J. Müller and Johannes Müllers and M. Nanova and K. Nikonov and V. Nikonov and V. Novinskiy and R. Novotny and D. Piontek and G. Reicherz and L. Richter and D. Rönchen and T. Rostomyan and B. Salisbury and A. Sarantsev and D. Schaab and C. Schmidt and H. Schmieden and J. Schultes and T. Seifen and V. Sokhoyan and C. Sowa and K. Spieker and N. Stausberg and A. Thiel and U. Thoma and T. Triffterer and M. Urban and G. Urff and H. Pee and D. Walther and Ch. Wendel and U. Wiedner and A. Wilson and A. Winnebeck and L. Witthauer},
url = {https://link.aps.org/doi/10.1103/PhysRevLett.125.152002},
doi = {10.1103/PhysRevLett.125.152002},
year = {2020},
date = {2020-10-09},
urldate = {2020-10-09},
journal = {Phys. Rev. Lett.},
volume = {125},
issue = {15},
pages = {152002},
publisher = {American Physical Society},
abstract = {Data on the beam asymmetry Σ in the photoproduction of η mesons off protons are reported for tagged photon energies from 1130 to 1790 MeV (mass range from W=1748 MeV to W=2045 MeV). The data cover the full solid angle that allows for a precise moment analysis. For the first time, a strong cusp effect in a polarization observable has been observed that is an effect of a branch-point singularity at the pη′ threshold [Eγ=1447 MeV (W=1896 MeV)]. The latest BnGa partial wave analysis includes the new beam asymmetry data and yields a strong indication for the N(1895)12− nucleon resonance, demonstrating the importance of including all singularities for a correct determination of partial waves and resonance parameters.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Data on the beam asymmetry Σ in the photoproduction of η mesons off protons are reported for tagged photon energies from 1130 to 1790 MeV (mass range from W=1748 MeV to W=2045 MeV). The data cover the full solid angle that allows for a precise moment analysis. For the first time, a strong cusp effect in a polarization observable has been observed that is an effect of a branch-point singularity at the pη′ threshold [Eγ=1447 MeV (W=1896 MeV)]. The latest BnGa partial wave analysis includes the new beam asymmetry data and yields a strong indication for the N(1895)12− nucleon resonance, demonstrating the importance of including all singularities for a correct determination of partial waves and resonance parameters.
Müller, J.; Hartmann, J.; Grüner, M.; Afzal, F.; Anisovich, A. V.; Bantes, B.; Bayadilov, D.; Beck, R.; Becker, M.; Beloglazov, Y.; Berlin, A.; Bichow, M.; Böse, S.; Brinkmann, K. -T.; Challand, T.; Crede, V.; Dietz, F.; Dieterle, M.; Drexler, P.; Dutz, H.; Eberhardt, H.; Elsner, D.; Ewald, R.; Fornet-Ponse, K.; Friedrich, S.; Frommberger, F.; Funke, C.; Gottschall, M.; Gridnev, A.; Goertz, S.; Gutz, E.; Hammann, C.; Hannen, V.; Hannappel, J.; Herick, J.; Hillert, W.; Hoffmeister, P.; Honisch, C.; Jahn, O.; Jude, T.; Jaegle, I.; Käser, A.; Kaiser, D.; Kalinowsky, H.; Kalischewski, F.; Kammer, S.; Keshelashvili, I.; Klassen, P.; Kleber, V.; Klein, F.; Klempt, E.; Koop, K.; Krusche, B.; Kube, M.; Lang, M.; Lopatin, I.; Maghrbi, Y.; Mahlberg, P.; Makonyi, K.; Messi, F.; Metag, V.; Meyer, W.; Müllers, Johannes; Nanova, M.; Nikonov, V.; Novinski, D.; Novotny, R.; Piontek, D.; Reicherz, G.; Rosenbaum, C.; Rostomyan, T.; Roth, B.; Sarantsev, A.; Schmidt, C.; Schmieden, H.; Schmitz, R.; Seifen, T.; Sokhoyan, V.; Thiel, A.; Thoma, U.; Urban, M.; Pee, H.; Walther, D.; Wendel, C.; Wiedner, U.; Wilson, A.; Winnebeck, A.; Witthauer, L.
New data on γp→ηp with polarized photons and protons and their implications for N⁎ → Nη decays Journal Article
In: Physics Letters B, vol. 803, pp. 135323, 2020, ISSN: 0370-2693.
@article{2020135323,
title = {New data on γp→ηp with polarized photons and protons and their implications for N⁎ → Nη decays},
author = {J. Müller and J. Hartmann and M. Grüner and F. Afzal and A. V. Anisovich and B. Bantes and D. Bayadilov and R. Beck and M. Becker and Y. Beloglazov and A. Berlin and M. Bichow and S. Böse and K. -T. Brinkmann and T. Challand and V. Crede and F. Dietz and M. Dieterle and P. Drexler and H. Dutz and H. Eberhardt and D. Elsner and R. Ewald and K. Fornet-Ponse and S. Friedrich and F. Frommberger and C. Funke and M. Gottschall and A. Gridnev and S. Goertz and E. Gutz and C. Hammann and V. Hannen and J. Hannappel and J. Herick and W. Hillert and P. Hoffmeister and C. Honisch and O. Jahn and T. Jude and I. Jaegle and A. Käser and D. Kaiser and H. Kalinowsky and F. Kalischewski and S. Kammer and I. Keshelashvili and P. Klassen and V. Kleber and F. Klein and E. Klempt and K. Koop and B. Krusche and M. Kube and M. Lang and I. Lopatin and Y. Maghrbi and P. Mahlberg and K. Makonyi and F. Messi and V. Metag and W. Meyer and Johannes Müllers and M. Nanova and V. Nikonov and D. Novinski and R. Novotny and D. Piontek and G. Reicherz and C. Rosenbaum and T. Rostomyan and B. Roth and A. Sarantsev and C. Schmidt and H. Schmieden and R. Schmitz and T. Seifen and V. Sokhoyan and A. Thiel and U. Thoma and M. Urban and H. Pee and D. Walther and C. Wendel and U. Wiedner and A. Wilson and A. Winnebeck and L. Witthauer},
url = {https://www.sciencedirect.com/science/article/pii/S0370269320301271},
doi = {https://doi.org/10.1016/j.physletb.2020.135323},
issn = {0370-2693},
year = {2020},
date = {2020-04-10},
urldate = {2020-04-10},
journal = {Physics Letters B},
volume = {803},
pages = {135323},
abstract = {The polarization observables T,E,P,H, and G in photoproduction of η mesons off protons are measured for photon energies from threshold to W=2400 MeV (T), 2280 MeV (E), 1620 MeV (P,H), or 1820 MeV (G), covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, JüBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the Nη decay of nucleon resonances. A Nη-branching ratio of 0.33±0.04 for N(1650)1/2− is found, which reduces the large and controversially discussed Nη-branching ratio difference of the two lowest mass JP=1/2−-resonances significantly.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The polarization observables T,E,P,H, and G in photoproduction of η mesons off protons are measured for photon energies from threshold to W=2400 MeV (T), 2280 MeV (E), 1620 MeV (P,H), or 1820 MeV (G), covering nearly the full solid angle. The data are compared to predictions from the SAID, MAID, JüBo, and BnGa partial-wave analyses. A refit within the BnGa approach including further data yields precise branching ratios for the Nη decay of nucleon resonances. A Nη-branching ratio of 0.33±0.04 for N(1650)1/2− is found, which reduces the large and controversially discussed Nη-branching ratio difference of the two lowest mass JP=1/2−-resonances significantly.
2019
Müllers, Johannes
An FPGA-based Sampling ADC for the Crystal Barrel Calorimeter PhD Thesis
Rheinische Friedrich-Wilhelms-Universität Bonn, 2019.
@phdthesis{handle:20.500.11811/8118,
title = {An FPGA-based Sampling ADC for the Crystal Barrel Calorimeter},
author = {Johannes Müllers},
url = {https://hdl.handle.net/20.500.11811/8118},
year = {2019},
date = {2019-12-01},
urldate = {2019-12-01},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
abstract = {The CBELSA/TAPS experiment in Bonn investigates the excitation spectra of protons and neutrons through meson-photoproduction. With its ability to polarize the target nucleons and the incident photon beam, the experiment has contributed significantly to a better understanding of the baryon excitation spectrum, and with that also to the understanding of the strong interaction in the non-perturbative regime. Since a recent upgrade, the experiment's main electromagnetic calorimeter, the Crystal Barrel, is read out by avalanche photo-diodes. Their signal is digitized by integrating Fastbus ADCs, providing a value proportional to the energy deposited in the calorimeter crystals. As a result of long conversion and transfer times, those ADCs have become the limiting factor in the data acquisition, with possible readout rates of less than 2 kHz. Moreover, the possibility to identify pile-up, i.e. quickly-succeeding energy deposits that overlap in the integration window, is presently missing.
Already years ago, it has been investigated whether this readout system could be replaced by faster and more modern sampling ADCs, which offer access to the waveform representation for a more sophisticated analysis, but the investigations were limited to commercially available digitizers with high cost and low channel densities. In addition, the firmware (operating system) of such digitizers is usually closed-source, which does not allow for the implementation of experiment-specific algorithms. Due to the above reasons, the investigations had not led to a satisfactory solution, and the Fastbus ADCs are still in operation today.
In this thesis, the development and test of a custom (non-commercial) FPGA-based sampling ADC, which will replace the Fastbus ADC, has been driven forward. This so-called CB-SADC (Crystal Barrel Sampling Analog-to-Digital Converter) has been adapted from a prototype of the PANDA experiment in such a way that it is suited to operate within the specific conditions of the CBELSA/TAPS experiment.
Apart from the hardware development, the firmware for the FPGA, which processes the digitized data, was designed and tested extensively. Specific algorithms allow not only the determination of the deposited energy and the timestamps of each event, but also an event-wise baseline determination and the detection of pile-up events. An online correction of pileup events, which occur with significant frequency in the forward region of the calorimeter, leads to a higher data quality and improved efficiency and statistics.
Apart from the hardware development, the firmware for the FPGA, which processes the digitized data, was designed and tested extensively. Specific algorithms allow not only the determination of the deposited energy and the timestamps of each event, but also an event-wise baseline determination and the detection of pile-up events. An online correction of pileup events, which occur with significant frequency in the forward region of the calorimeter, leads to a higher data quality and improved efficiency and statistics.
Two prototype iterations of the CB-SADC have been produced and were tested thoroughly in the laboratory and in connection with the CBELSA/TAPS experiment. The results of those tests, and preliminary analyses of production beam times with 50% of the calorimeter's forward half being read out by the CB-SADCs, showed an improvement of the data quality. The timestamp determination of the CB-SADCs in the energy regime below 10MeV has provided data where the experiment's TDC (Time-to-Digital Converter) either has worse resolution or cannot provide timestamps at all. In addition, standalone tests in the laboratory and tests with the data acquisition system have confirmed a much higher readout speed compared to the integrating Fastbus ADCs. Based on the achieved results, it was finally decided to equip the whole calorimeter with the new CB-SADC readout.
At the time of finalizing this thesis, all CB-SADCs have been produced and are prepared for installation in the experimental hall. They will be running in parallel with the integrating Fastbus ADCs during the next production beam times, offering an opportunity to test the CB-SADC readout system as a whole. As soon as it is proven that the new readout works reliably, the limiting integrating Fastbus ADCs will be decommissioned and the CBELSA/TAPS experiment can start taking data with an increased readout rate.},
keywords = {},
pubstate = {published},
tppubtype = {phdthesis}
}
The CBELSA/TAPS experiment in Bonn investigates the excitation spectra of protons and neutrons through meson-photoproduction. With its ability to polarize the target nucleons and the incident photon beam, the experiment has contributed significantly to a better understanding of the baryon excitation spectrum, and with that also to the understanding of the strong interaction in the non-perturbative regime. Since a recent upgrade, the experiment's main electromagnetic calorimeter, the Crystal Barrel, is read out by avalanche photo-diodes. Their signal is digitized by integrating Fastbus ADCs, providing a value proportional to the energy deposited in the calorimeter crystals. As a result of long conversion and transfer times, those ADCs have become the limiting factor in the data acquisition, with possible readout rates of less than 2 kHz. Moreover, the possibility to identify pile-up, i.e. quickly-succeeding energy deposits that overlap in the integration window, is presently missing.
Already years ago, it has been investigated whether this readout system could be replaced by faster and more modern sampling ADCs, which offer access to the waveform representation for a more sophisticated analysis, but the investigations were limited to commercially available digitizers with high cost and low channel densities. In addition, the firmware (operating system) of such digitizers is usually closed-source, which does not allow for the implementation of experiment-specific algorithms. Due to the above reasons, the investigations had not led to a satisfactory solution, and the Fastbus ADCs are still in operation today.
In this thesis, the development and test of a custom (non-commercial) FPGA-based sampling ADC, which will replace the Fastbus ADC, has been driven forward. This so-called CB-SADC (Crystal Barrel Sampling Analog-to-Digital Converter) has been adapted from a prototype of the PANDA experiment in such a way that it is suited to operate within the specific conditions of the CBELSA/TAPS experiment.
Apart from the hardware development, the firmware for the FPGA, which processes the digitized data, was designed and tested extensively. Specific algorithms allow not only the determination of the deposited energy and the timestamps of each event, but also an event-wise baseline determination and the detection of pile-up events. An online correction of pileup events, which occur with significant frequency in the forward region of the calorimeter, leads to a higher data quality and improved efficiency and statistics.
Apart from the hardware development, the firmware for the FPGA, which processes the digitized data, was designed and tested extensively. Specific algorithms allow not only the determination of the deposited energy and the timestamps of each event, but also an event-wise baseline determination and the detection of pile-up events. An online correction of pileup events, which occur with significant frequency in the forward region of the calorimeter, leads to a higher data quality and improved efficiency and statistics.
Two prototype iterations of the CB-SADC have been produced and were tested thoroughly in the laboratory and in connection with the CBELSA/TAPS experiment. The results of those tests, and preliminary analyses of production beam times with 50% of the calorimeter's forward half being read out by the CB-SADCs, showed an improvement of the data quality. The timestamp determination of the CB-SADCs in the energy regime below 10MeV has provided data where the experiment's TDC (Time-to-Digital Converter) either has worse resolution or cannot provide timestamps at all. In addition, standalone tests in the laboratory and tests with the data acquisition system have confirmed a much higher readout speed compared to the integrating Fastbus ADCs. Based on the achieved results, it was finally decided to equip the whole calorimeter with the new CB-SADC readout.
At the time of finalizing this thesis, all CB-SADCs have been produced and are prepared for installation in the experimental hall. They will be running in parallel with the integrating Fastbus ADCs during the next production beam times, offering an opportunity to test the CB-SADC readout system as a whole. As soon as it is proven that the new readout works reliably, the limiting integrating Fastbus ADCs will be decommissioned and the CBELSA/TAPS experiment can start taking data with an increased readout rate.
Already years ago, it has been investigated whether this readout system could be replaced by faster and more modern sampling ADCs, which offer access to the waveform representation for a more sophisticated analysis, but the investigations were limited to commercially available digitizers with high cost and low channel densities. In addition, the firmware (operating system) of such digitizers is usually closed-source, which does not allow for the implementation of experiment-specific algorithms. Due to the above reasons, the investigations had not led to a satisfactory solution, and the Fastbus ADCs are still in operation today.
In this thesis, the development and test of a custom (non-commercial) FPGA-based sampling ADC, which will replace the Fastbus ADC, has been driven forward. This so-called CB-SADC (Crystal Barrel Sampling Analog-to-Digital Converter) has been adapted from a prototype of the PANDA experiment in such a way that it is suited to operate within the specific conditions of the CBELSA/TAPS experiment.
Apart from the hardware development, the firmware for the FPGA, which processes the digitized data, was designed and tested extensively. Specific algorithms allow not only the determination of the deposited energy and the timestamps of each event, but also an event-wise baseline determination and the detection of pile-up events. An online correction of pileup events, which occur with significant frequency in the forward region of the calorimeter, leads to a higher data quality and improved efficiency and statistics.
Apart from the hardware development, the firmware for the FPGA, which processes the digitized data, was designed and tested extensively. Specific algorithms allow not only the determination of the deposited energy and the timestamps of each event, but also an event-wise baseline determination and the detection of pile-up events. An online correction of pileup events, which occur with significant frequency in the forward region of the calorimeter, leads to a higher data quality and improved efficiency and statistics.
Two prototype iterations of the CB-SADC have been produced and were tested thoroughly in the laboratory and in connection with the CBELSA/TAPS experiment. The results of those tests, and preliminary analyses of production beam times with 50% of the calorimeter's forward half being read out by the CB-SADCs, showed an improvement of the data quality. The timestamp determination of the CB-SADCs in the energy regime below 10MeV has provided data where the experiment's TDC (Time-to-Digital Converter) either has worse resolution or cannot provide timestamps at all. In addition, standalone tests in the laboratory and tests with the data acquisition system have confirmed a much higher readout speed compared to the integrating Fastbus ADCs. Based on the achieved results, it was finally decided to equip the whole calorimeter with the new CB-SADC readout.
At the time of finalizing this thesis, all CB-SADCs have been produced and are prepared for installation in the experimental hall. They will be running in parallel with the integrating Fastbus ADCs during the next production beam times, offering an opportunity to test the CB-SADC readout system as a whole. As soon as it is proven that the new readout works reliably, the limiting integrating Fastbus ADCs will be decommissioned and the CBELSA/TAPS experiment can start taking data with an increased readout rate.
2018
Müllers, Johannes; Marciniewski, Pawel; Poller, Timo; Schmidt, Christoph; Schultes, Jan; Thoma, Ulrike
Adaption of an FPGA-based Sampling-ADC for the Crystal Barrel Calorimeter Proceedings Article
In: Proceedings of Science, pp. 052, 2018.
@inproceedings{inproceedings,
title = {Adaption of an FPGA-based Sampling-ADC for the Crystal Barrel Calorimeter},
author = {Johannes Müllers and Pawel Marciniewski and Timo Poller and Christoph Schmidt and Jan Schultes and Ulrike Thoma},
doi = {10.22323/1.313.0052},
year = {2018},
date = {2018-01-01},
urldate = {2018-01-01},
booktitle = {Proceedings of Science},
volume = {313},
pages = {052},
series = {Topical Workshop on Electronics for Particle Physics (TWEPP-17)},
abstract = {The digitization stage of the main electromagnetic calorimeter of the CBELSA/TAPS experiment in Bonn (Germany) is being equipped with 80MS/s, 14 bit sampling-ADCs (SADCs), which were adapted from a prototype for the PANDA experiment. Onboard data processing with FPGAs allows determination of the signal characteristics, reducing the data volume substantially. The optional readout of the unprocessed sampled waveforms allows offline analysis and refinement of the FPGA algorithms.
A partial setup has shown promising results during a photoproduction-beamtime. It has been demonstrated that the readout-rate limitation of the current QDC readout can be overcome. The full setup is planned to be commissioned within the next year.
This paper will present an overview of the SADC project. After an introduction of the CBELSA/TAPS experiment, the new SADC readout will be motivated, followed by its technical specifications and the setup in the experiment. An outline of the firmware and findings from first tests conclude the paper.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
The digitization stage of the main electromagnetic calorimeter of the CBELSA/TAPS experiment in Bonn (Germany) is being equipped with 80MS/s, 14 bit sampling-ADCs (SADCs), which were adapted from a prototype for the PANDA experiment. Onboard data processing with FPGAs allows determination of the signal characteristics, reducing the data volume substantially. The optional readout of the unprocessed sampled waveforms allows offline analysis and refinement of the FPGA algorithms.
A partial setup has shown promising results during a photoproduction-beamtime. It has been demonstrated that the readout-rate limitation of the current QDC readout can be overcome. The full setup is planned to be commissioned within the next year.
This paper will present an overview of the SADC project. After an introduction of the CBELSA/TAPS experiment, the new SADC readout will be motivated, followed by its technical specifications and the setup in the experiment. An outline of the firmware and findings from first tests conclude the paper.
A partial setup has shown promising results during a photoproduction-beamtime. It has been demonstrated that the readout-rate limitation of the current QDC readout can be overcome. The full setup is planned to be commissioned within the next year.
This paper will present an overview of the SADC project. After an introduction of the CBELSA/TAPS experiment, the new SADC readout will be motivated, followed by its technical specifications and the setup in the experiment. An outline of the firmware and findings from first tests conclude the paper.
Stollenwerk, Katharina; Müllers, Johannes; Müller, Jonas; Hinkenjann, André; Krüger, Björn
Evaluating an Accelerometer-based System for Spine Shape Monitoring Proceedings Article
In: Computational Science and Its Applications – ICCSA 2018, 2018.
@inproceedings{stollenwerk-2018a,
title = {Evaluating an Accelerometer-based System for Spine Shape Monitoring},
author = {Katharina Stollenwerk and Johannes Müllers and Jonas Müller and André Hinkenjann and Björn Krüger},
url = {https://digital-health-bonn.de/wp-content/uploads/2024/03/2018_ICCSA_PostureSensei_Preprint.pdf, Paper},
doi = {10.1007/978-3-319-95171-3_58},
year = {2018},
date = {2018-01-01},
urldate = {2018-01-01},
booktitle = {Computational Science and Its Applications – ICCSA 2018},
abstract = {In western societies a huge percentage of the population suffers from some kind of back pain at least once in their life. There are several approaches addressing back pain by postural modifications. Postural training and activity can be tracked by various wearable devices most of which are based on accelerometers. We present research on the accuracy of accelerometer-based posture measurements. To this end, we took simultaneous recordings using an optical motion capture system and a system consisting of five accelerometers in three different settings: On a test robot, in a template, and on actual human backs. We compare the accelerometer-based spine curve reconstruction against the motion capture data. Results show that tilt values from the accelerometers are captured highly accurate, and the spine curve reconstruction works well.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
In western societies a huge percentage of the population suffers from some kind of back pain at least once in their life. There are several approaches addressing back pain by postural modifications. Postural training and activity can be tracked by various wearable devices most of which are based on accelerometers. We present research on the accuracy of accelerometer-based posture measurements. To this end, we took simultaneous recordings using an optical motion capture system and a system consisting of five accelerometers in three different settings: On a test robot, in a template, and on actual human backs. We compare the accelerometer-based spine curve reconstruction against the motion capture data. Results show that tilt values from the accelerometers are captured highly accurate, and the spine curve reconstruction works well.
2016
Dreiner, Herbi; Becker, Max; Borzyszkowski, Mikolaj; Braun, Maxim; Faßbender, Alexander; Hampel, Julia; Hansen, Maike; Hebecker, Dustin; Heepenstrick, Timo; Heinz, Sascha; Hortmanns, Katharina; Jost, Christian; Kortmann, Michael; Kruckow, Matthias; Leuteritz, Till; Lütz, Claudia; Mahlberg, Philip; Müllers, Johannes; Opferkuch, Toby; Wagner-Carena, Sebastian
"What's (the) Matter?", A Show on Elementary Particle Physics with 28 Demonstration Experiments Working paper
2016.
@workingpaper{article,
title = {"What's (the) Matter?", A Show on Elementary Particle Physics with 28 Demonstration Experiments},
author = {Herbi Dreiner and Max Becker and Mikolaj Borzyszkowski and Maxim Braun and Alexander Faßbender and Julia Hampel and Maike Hansen and Dustin Hebecker and Timo Heepenstrick and Sascha Heinz and Katharina Hortmanns and Christian Jost and Michael Kortmann and Matthias Kruckow and Till Leuteritz and Claudia Lütz and Philip Mahlberg and Johannes Müllers and Toby Opferkuch and Sebastian Wagner-Carena},
url = {https://arxiv.org/abs/1607.07478},
year = {2016},
date = {2016-07-25},
urldate = {2016-07-25},
abstract = {We present the screenplay of a physics show on particle physics, by the Physikshow of Bonn University. The show is addressed at non-physicists aged 14+ and communicates basic concepts of elementary particle physics including the discovery of the Higgs boson in an entertaining fashion. It is also demonstrates a successful outreach activity heavily relying on the university physics students. This paper is addressed at anybody interested in particle physics and/or show physics. This paper is also addressed at fellow physicists working in outreach, maybe the experiments and our choice of simple explanations will be helpful. Furthermore, we are very interested in related activities elsewhere, in particular also demonstration experiments relevant to particle physics, as often little of this work is published.
Our show involves 28 live demonstration experiments. These are presented in an extensive appendix, including photos and technical details. The show is set up as a quest, where 2 students from Bonn with the aid of a caretaker travel back in time to understand the fundamental nature of matter. They visit Rutherford and Geiger in Manchester around 1911, who recount their famous experiment on the nucleus and show how particle detectors work. They travel forward in time to meet Lawrence at Berkeley around 1950, teaching them about the how and why of accelerators. Next, they visit Wu at DESY, Hamburg, around 1980, who explains the strong force. They end up in the LHC tunnel at CERN, Geneva, Switzerland in 2012. Two experimentalists tell them about colliders and our heroes watch live as the Higgs boson is produced and decays. The show was presented in English at Oxford University and University College London, as well as Padua University and ICTP Trieste. It was 1st performed in German at the Deutsche Museum, Bonn (5/'14). The show has eleven speaking parts and involves in total 20 people. },
keywords = {},
pubstate = {published},
tppubtype = {workingpaper}
}
We present the screenplay of a physics show on particle physics, by the Physikshow of Bonn University. The show is addressed at non-physicists aged 14+ and communicates basic concepts of elementary particle physics including the discovery of the Higgs boson in an entertaining fashion. It is also demonstrates a successful outreach activity heavily relying on the university physics students. This paper is addressed at anybody interested in particle physics and/or show physics. This paper is also addressed at fellow physicists working in outreach, maybe the experiments and our choice of simple explanations will be helpful. Furthermore, we are very interested in related activities elsewhere, in particular also demonstration experiments relevant to particle physics, as often little of this work is published.
Our show involves 28 live demonstration experiments. These are presented in an extensive appendix, including photos and technical details. The show is set up as a quest, where 2 students from Bonn with the aid of a caretaker travel back in time to understand the fundamental nature of matter. They visit Rutherford and Geiger in Manchester around 1911, who recount their famous experiment on the nucleus and show how particle detectors work. They travel forward in time to meet Lawrence at Berkeley around 1950, teaching them about the how and why of accelerators. Next, they visit Wu at DESY, Hamburg, around 1980, who explains the strong force. They end up in the LHC tunnel at CERN, Geneva, Switzerland in 2012. Two experimentalists tell them about colliders and our heroes watch live as the Higgs boson is produced and decays. The show was presented in English at Oxford University and University College London, as well as Padua University and ICTP Trieste. It was 1st performed in German at the Deutsche Museum, Bonn (5/'14). The show has eleven speaking parts and involves in total 20 people.
Our show involves 28 live demonstration experiments. These are presented in an extensive appendix, including photos and technical details. The show is set up as a quest, where 2 students from Bonn with the aid of a caretaker travel back in time to understand the fundamental nature of matter. They visit Rutherford and Geiger in Manchester around 1911, who recount their famous experiment on the nucleus and show how particle detectors work. They travel forward in time to meet Lawrence at Berkeley around 1950, teaching them about the how and why of accelerators. Next, they visit Wu at DESY, Hamburg, around 1980, who explains the strong force. They end up in the LHC tunnel at CERN, Geneva, Switzerland in 2012. Two experimentalists tell them about colliders and our heroes watch live as the Higgs boson is produced and decays. The show was presented in English at Oxford University and University College London, as well as Padua University and ICTP Trieste. It was 1st performed in German at the Deutsche Museum, Bonn (5/'14). The show has eleven speaking parts and involves in total 20 people.