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Characterization of the HIBEAM time projection chamber prototype

Hehl, Verena LU (2025) FYSK04 20251
Department of Physics
Particle and nuclear physics
Abstract
The HIBEAM/NNBAR collaboration at the European Spallation Source (ESS) aims to discover processes of baryon number violation, such as neutron-antineutron oscillations, and it furthermore includes searches for sterile neutrons, ultralight axion dark matter particles, and nonzero neutron electric charge. The following investigation presents the characterization of the HIBEAM time projection chamber (TPC) prototype. Using cosmic muon measurements, the detector's response was evaluated under varying operational parameters, such as changes in the gas electron multiplier (GEM) foil voltage, shaping time (influencing the pulse width), applied drift field, or different scintillator configurations. The data analysis is based on clustering... (More)
The HIBEAM/NNBAR collaboration at the European Spallation Source (ESS) aims to discover processes of baryon number violation, such as neutron-antineutron oscillations, and it furthermore includes searches for sterile neutrons, ultralight axion dark matter particles, and nonzero neutron electric charge. The following investigation presents the characterization of the HIBEAM time projection chamber (TPC) prototype. Using cosmic muon measurements, the detector's response was evaluated under varying operational parameters, such as changes in the gas electron multiplier (GEM) foil voltage, shaping time (influencing the pulse width), applied drift field, or different scintillator configurations. The data analysis is based on clustering algorithms and centroid-based track reconstruction. By determining the dE/dx and residual distributions, where the residuals are defined as the right-angle distances of the centroids to the fitted track, it becomes possible to test the performance of the TPC, but also the robustness of the data analysis algorithm. The following document provides a full characterization of the prototype. According to the results, a GEM voltage of 350V (at a drift field of 500V/cm and shaping time of 120ns) is optimal. Having a shaping time of 60ns, which is closest to the settings at the future HIBEAM TPC, provided satisfactory $dE/dx$ and residual distributions. Furthermore, a charge pulse shape analysis of inclined tracks was performed, where the spread in arrival time along the track of the amplified electron cloud allowed resolution of the evolution of the charge amplitude over time. This was done at a shaping time of 60ns and different drift fields, where a drift field of 243V/cm led to the most detailed pulse shapes. By splitting the readout padrows into finer rows using timing information, it was possible to further increase the position resolution. Further studies in this direction could provide improvements to the tracking algorithm. (Less)
Popular Abstract
Since the Big Bang, the universe has been in an imbalance: we observe significantly more matter than antimatter. A possible explanation is that matter particles can change into their own antimatter particle, and vice versa. As this has not yet been observed, the HIBEAM/NNBAR collaboration at the European Spallation Source (ESS) is aiming to discover this process. For this, neutrons provided by ESS are used and hopefully, an instance can be observed of a neutron changing into an antineutron, where the antineutron would interact with the detector material in a process called annihilation, creating other particles in the process.

Part of this work is designing a detector capable of measuring the created particles and thus, detector... (More)
Since the Big Bang, the universe has been in an imbalance: we observe significantly more matter than antimatter. A possible explanation is that matter particles can change into their own antimatter particle, and vice versa. As this has not yet been observed, the HIBEAM/NNBAR collaboration at the European Spallation Source (ESS) is aiming to discover this process. For this, neutrons provided by ESS are used and hopefully, an instance can be observed of a neutron changing into an antineutron, where the antineutron would interact with the detector material in a process called annihilation, creating other particles in the process.

Part of this work is designing a detector capable of measuring the created particles and thus, detector prototypes need to be built and tested. The HIBEAM/NNBAR collaboration is using a time projection chamber (TPC) prototype. The TPC is a cylindrical chamber filled with gas. If now certain types of cosmic particles, called muons, fly through the TPC chamber, they will leave a trace in the gas, due to the muons knocking out the gas atoms' electrons. As electrons are charged particles, they can be moved by applying an electric field. This will guide them to one side of the detector, where they can be read out.The goal is to measure those electrons as precisely as possible, so we can extract information about the position of the path the muon took through the chamber and also the energy it lost along the track.

To achieve this, the TPC prototype needs to be tested under different conditions, for example, by varying the strength of the applied electric field. This thesis aimed to characterize the detector by determining how varying those different parameters affects the measurements. Preferred settings for the setup were determined. Furthermore, the changes in pulse shapes of the charge distributions with time were studied for inclined tracks with respect to the readout plane. Using timing information of the pulses could provide the detector with an improved tracking algorithm in the future. (Less)
Please use this url to cite or link to this publication:
author
Hehl, Verena LU
supervisor
organization
course
FYSK04 20251
year
type
M2 - Bachelor Degree
subject
language
English
id
9203174
date added to LUP
2025-06-24 14:46:40
date last changed
2025-06-24 14:46:40
@misc{9203174,
  abstract     = {{The HIBEAM/NNBAR collaboration at the European Spallation Source (ESS) aims to discover processes of baryon number violation, such as neutron-antineutron oscillations, and it furthermore includes searches for sterile neutrons, ultralight axion dark matter particles, and nonzero neutron electric charge. The following investigation presents the characterization of the HIBEAM time projection chamber (TPC) prototype. Using cosmic muon measurements, the detector's response was evaluated under varying operational parameters, such as changes in the gas electron multiplier (GEM) foil voltage, shaping time (influencing the pulse width), applied drift field, or different scintillator configurations. The data analysis is based on clustering algorithms and centroid-based track reconstruction. By determining the dE/dx and residual distributions, where the residuals are defined as the right-angle distances of the centroids to the fitted track, it becomes possible to test the performance of the TPC, but also the robustness of the data analysis algorithm. The following document provides a full characterization of the prototype. According to the results, a GEM voltage of 350V (at a drift field of 500V/cm and shaping time of 120ns) is optimal. Having a shaping time of 60ns, which is closest to the settings at the future HIBEAM TPC, provided satisfactory $dE/dx$ and residual distributions. Furthermore, a charge pulse shape analysis of inclined tracks was performed, where the spread in arrival time along the track of the amplified electron cloud allowed resolution of the evolution of the charge amplitude over time. This was done at a shaping time of 60ns and different drift fields, where a drift field of 243V/cm led to the most detailed pulse shapes. By splitting the readout padrows into finer rows using timing information, it was possible to further increase the position resolution. Further studies in this direction could provide improvements to the tracking algorithm.}},
  author       = {{Hehl, Verena}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Characterization of the HIBEAM time projection chamber prototype}},
  year         = {{2025}},
}