Dominik Boras
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Dominik Boras has a total of 14 co-authors. Here are the top co-authors by number of shared publications:
Danny Petschke
Department of Chemistry LCTM, University Würzburg, Würzburg, Germany
2 shared publicationsAlexander Buckel
Altris AB, Uppsala, Sweden
1 shared publicationD. Petschke
University Würzburg, Department of Chemistry, LCTM, Röntgenring 11, Würzburg D-97070, Germany
1 shared publication- Danny Petschke
Department of Chemistry, LCTM, University Würzburg, Röntgenring 11, Würzburg D-97070, Germany
1 shared publication - Ida Nielsen
Department of Chemistry – Ångström Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala, Sweden
1 shared publication Lennart Häggström
Department of Chemistry - Ångström Laboratory, Uppsala University, Uppsala, Sweden
1 shared publication
Latest Publications
- Open Access
- 1 November 2025
- Published by IOP Publishing in Journal of Physics: Conference Series
- Vol. 3149 (1)
A machine learning approach using XGBoost for classification and filtering of 1275/511 pile-up events
Using 180° detector setups with plastic scintillators in positron annihilation lifetime spectroscopy (PALS), 1275/511 pile-up events evidently lead to significant spectrum distortions. Here, we present a machine learning approach, based on seven pulse-shape features, using XGBoost to identify and filter such superimposed events. The model was trained on simulated and experimental data and achieved prediction accuracies of 90.6% and 86.8%, respectively. Applied to real PALS measurements on high-purity copper, 17.67% of the total coincidence events are classified as 1275/511 pile-up-affected events. The resulting lifetime spectrum closely matches a reference measurement from a 90° configuration in terms of the extracted characteristic lifetimes and corresponding contributions. This demonstrates the method’s effectiveness for non-invasive 1275/511 pile-up suppression.
- 1 November 2025
- Published by IOP Publishing in Journal of Physics: Conference Series
- Vol. 3149 (1)
Open AccessA machine learning approach using XGBoost for classification and filtering of 1275/511 pile-up events
Using 180° detector setups with plastic scintillators in positron annihilation lifetime spectroscopy (PALS), 1275/511 pile-up events evidently lead to significant spectrum distortions. Here, we present a machine learning approach, based on seven pulse-shape features, using XGBoost to identify and filter such superimposed events. The model was trained on simulated and experimental data and achieved prediction accuracies of 90.6% and 86.8%, respectively. Applied to real PALS measurements on high-purity copper, 17.67% of the total coincidence events are classified as 1275/511 pile-up-affected events. The resulting lifetime spectrum closely matches a reference measurement from a 90° configuration in terms of the extracted characteristic lifetimes and corresponding contributions. This demonstrates the method’s effectiveness for non-invasive 1275/511 pile-up suppression.
- 1 October 2025
- Published by IOP Publishing in Journal of Instrumentation
- Vol. 20 (10) , T10006
Improving positron lifetime spectra quality by suppressing corrupted coincidences via pulse-height spectrum window adjustments
Positron Annihilation Lifetime Spectroscopy (PALS) is a powerful technique for detecting microstructural defects in various material classes. In a commonly used 180^∘ detector configuration equipped with plastic scintillators, measurement accuracy is mainly affected by simultaneous detection of 1275 keV and 511 keV gamma quanta in the same detector. This study introduces an optimization approach that significantly improves spectra quality without requiring hardware modifications. By systematically adjusting the upper threshold of the start window in the Pulse Height Spectrum (PHS), this method effectively reduces unwanted 1275/511 piled-up events. Experimental validation with high purity aluminium samples demonstrates that lowering this threshold effectively suppresses corrupted coincidences, yielding extracted characteristic lifetimes closer to those from a 90° configuration. While a reduced upper threshold slightly broadens the instrument response function (IRF) due to an effectively reduced number of scintillation photons, the overall impact on timing resolution remains negligible. This approach enhances the reliability of PALS measurements while still preserving the benefits of a 180° configuration, i.e. high solid-angle efficiency.
- 1 October 2025
- Published by IOP Publishing in Journal of Instrumentation
- Vol. 20 (10) , T10006
Improving positron lifetime spectra quality by suppressing corrupted coincidences via pulse-height spectrum window adjustments
Positron Annihilation Lifetime Spectroscopy (PALS) is a powerful technique for detecting microstructural defects in various material classes. In a commonly used 180^∘ detector configuration equipped with plastic scintillators, measurement accuracy is mainly affected by simultaneous detection of 1275 keV and 511 keV gamma quanta in the same detector. This study introduces an optimization approach that significantly improves spectra quality without requiring hardware modifications. By systematically adjusting the upper threshold of the start window in the Pulse Height Spectrum (PHS), this method effectively reduces unwanted 1275/511 piled-up events. Experimental validation with high purity aluminium samples demonstrates that lowering this threshold effectively suppresses corrupted coincidences, yielding extracted characteristic lifetimes closer to those from a 90° configuration. While a reduced upper threshold slightly broadens the instrument response function (IRF) due to an effectively reduced number of scintillation photons, the overall impact on timing resolution remains negligible. This approach enhances the reliability of PALS measurements while still preserving the benefits of a 180° configuration, i.e. high solid-angle efficiency.
- Open Access
Improving Positron Lifetime Spectra Quality by Suppressing Corrupted Coincidences via Pulse-Height Spectrum Window Adjustments
Positron Annihilation Lifetime Spectroscopy (PALS) is a powerful technique for detecting microstructural defects in various material classes. In a commonly used 180° detector configuration equipped with plastic scintillators, measurement accuracy is mainly affected by simultaneous detection of 1275 keV and 511 keV gamma quanta in the same detector. This study introduces an optimization approach that significantly improves spectra quality without requiring hardware modifications. By systematically adjusting the upper threshold of the start window in the Pulse Height Spectrum (PHS), this method effectively reduces unwanted 1275/511 piled-up events. Experimental validation with high purity aluminium samples demonstrates that lowering this threshold effectively suppresses corrupted coincidences, yielding extracted characteristic lifetimes closer to those from a 90° configuration. While a reduced upper threshold slightly broadens the instrument response function (IRF) due to an effectively reduced number of scintillation photons, the overall impact on timing resolution remains negligible. This approach enhances the reliability of PALS measurements while still preserving the benefits of a 180° configuration, i.e. high solid-angle efficiency.
Open AccessImproving Positron Lifetime Spectra Quality by Suppressing Corrupted Coincidences via Pulse-Height Spectrum Window Adjustments
Positron Annihilation Lifetime Spectroscopy (PALS) is a powerful technique for detecting microstructural defects in various material classes. In a commonly used 180° detector configuration equipped with plastic scintillators, measurement accuracy is mainly affected by simultaneous detection of 1275 keV and 511 keV gamma quanta in the same detector. This study introduces an optimization approach that significantly improves spectra quality without requiring hardware modifications. By systematically adjusting the upper threshold of the start window in the Pulse Height Spectrum (PHS), this method effectively reduces unwanted 1275/511 piled-up events. Experimental validation with high purity aluminium samples demonstrates that lowering this threshold effectively suppresses corrupted coincidences, yielding extracted characteristic lifetimes closer to those from a 90° configuration. While a reduced upper threshold slightly broadens the instrument response function (IRF) due to an effectively reduced number of scintillation photons, the overall impact on timing resolution remains negligible. This approach enhances the reliability of PALS measurements while still preserving the benefits of a 180° configuration, i.e. high solid-angle efficiency.
- 1 January 2025
- Published by IOP Publishing in Journal of Instrumentation
- Vol. 20 (01) , T01009
Geant4-based technical simulation study of plastic scintillators for Positron Annihilation Lifetime Spectroscopy (PALS)
The influence of detector setup configuration and scintillator material choice on spectrum quality in Positron Annihilation Lifetime Spectroscopy (PALS) is fundamentally acknowledged primarily by empirical observation. However, this study quantifies the effects of ultra-fast plastic scintillators (BC422Q) within a conventional collinear (180-degree) detector setup used in the laboratory using the Geant4 simulation toolkit. We examine the impact of the scintillator's dimension and geometry (truncated cone vs. cylinder) on the detection efficiency for specific gamma-ray energies (1274 keV and 511 keV) and their proportion of corrupt events such as backscattering or multiple detections. Results indicate that the selection of scintillator dimension and shape significantly enhances detection efficiency albeit with an increase in corrupt events. Furthermore, we investigate the influence on the instrument response function (IRF) of the scintillators, showing how truncated cones offer superior precision and, thus, a narrower IRF compared to cylindrical shapes. Additionally, the effect of the sample material itself, in the case of a truncated cone as the scintillator shape, on the scintillator response was studied. It is observed that with an increasing atomic number of the sample the detection efficiency substantially decreases while the proportion of corrupt events also diminishes. Despite the sample material's influence on the energy of gamma-quanta interacting with the scintillator, no measurable impact on the IRF was detected for the chosen windows of the pulse height spectra. This investigation encourages a profound examination of the influences on spectrum quality in PALS measurements using Geant4 as a simulation tool highlighting the critical balance between detection efficiency and corrupt event frequencies.
- 1 January 2025
- Published by IOP Publishing in Journal of Instrumentation
- Vol. 20 (01) , T01009
Geant4-based technical simulation study of plastic scintillators for Positron Annihilation Lifetime Spectroscopy (PALS)
The influence of detector setup configuration and scintillator material choice on spectrum quality in Positron Annihilation Lifetime Spectroscopy (PALS) is fundamentally acknowledged primarily by empirical observation. However, this study quantifies the effects of ultra-fast plastic scintillators (BC422Q) within a conventional collinear (180-degree) detector setup used in the laboratory using the Geant4 simulation toolkit. We examine the impact of the scintillator's dimension and geometry (truncated cone vs. cylinder) on the detection efficiency for specific gamma-ray energies (1274 keV and 511 keV) and their proportion of corrupt events such as backscattering or multiple detections. Results indicate that the selection of scintillator dimension and shape significantly enhances detection efficiency albeit with an increase in corrupt events. Furthermore, we investigate the influence on the instrument response function (IRF) of the scintillators, showing how truncated cones offer superior precision and, thus, a narrower IRF compared to cylindrical shapes. Additionally, the effect of the sample material itself, in the case of a truncated cone as the scintillator shape, on the scintillator response was studied. It is observed that with an increasing atomic number of the sample the detection efficiency substantially decreases while the proportion of corrupt events also diminishes. Despite the sample material's influence on the energy of gamma-quanta interacting with the scintillator, no measurable impact on the IRF was detected for the chosen windows of the pulse height spectra. This investigation encourages a profound examination of the influences on spectrum quality in PALS measurements using Geant4 as a simulation tool highlighting the critical balance between detection efficiency and corrupt event frequencies.
- Open Access
Geant4-based technical simulation study of plastic scintillators for Positron Annihilation Lifetime Spectroscopy (PALS)
The influence of detector setup configuration and scintillator material choice on spectrum quality in Positron Annihilation Lifetime Spectroscopy (PALS) is fundamentally acknowledged primarily by empirical observation. However, this study quantifies the effects of ultra-fast plastic scintillators (BC422Q) within a conventional collinear (180-degree) detector setup used in the laboratory using the Geant4 simulation toolkit. We examine the impact of the scintillator's dimension and geometry (truncated cone vs. cylinder) on the detection efficiency for specific gamma-ray energies (1274 keV and 511 keV) and their proportion of corrupt events such as backscattering or multiple detections. Results indicate that the selection of scintillator dimension and shape significantly enhances detection efficiency albeit with an increase in corrupt events. Furthermore, we investigate the influence on the instrument response function (IRF) of the scintillators, showing how truncated cones offer superior precision and, thus, a narrower IRF compared to cylindrical shapes.
Open AccessGeant4-based technical simulation study of plastic scintillators for Positron Annihilation Lifetime Spectroscopy (PALS)
The influence of detector setup configuration and scintillator material choice on spectrum quality in Positron Annihilation Lifetime Spectroscopy (PALS) is fundamentally acknowledged primarily by empirical observation. However, this study quantifies the effects of ultra-fast plastic scintillators (BC422Q) within a conventional collinear (180-degree) detector setup used in the laboratory using the Geant4 simulation toolkit. We examine the impact of the scintillator's dimension and geometry (truncated cone vs. cylinder) on the detection efficiency for specific gamma-ray energies (1274 keV and 511 keV) and their proportion of corrupt events such as backscattering or multiple detections. Results indicate that the selection of scintillator dimension and shape significantly enhances detection efficiency albeit with an increase in corrupt events. Furthermore, we investigate the influence on the instrument response function (IRF) of the scintillators, showing how truncated cones offer superior precision and, thus, a narrower IRF compared to cylindrical shapes.
- Open Access
- 2 November 2023
- Published by Springer Nature in Journal of Materials Science
- Vol. 58 (42) , 16344-16356
Determining internal porosity in Prussian blue analogue cathode materials using positron annihilation lifetime spectroscopy
Prussian blue analogues (PBAs), $${{A}_x{M}[{M'}({\text {CN}})_{6}]_{1-{{y}}}\cdot {z} {\text {H}}_{2}{\text {O}}}$$ , are a highly functional class of materials with use in a broad range of applications, such as energy storage, due to their porous structure and tunable composition. The porosity is particularly important for the properties and is deeply coupled to the cation, water, and $${[{M'}({\text {CN}})_{6}]^{{{n}}-}}$$ vacancy content. Determining internal porosity is especially challenging because the three compositional parameters are dependent on each other. In this work, we apply a new method, positron annihilation lifetime spectroscopy (PALS), which can be employed for the characterization of defects and structural changes in crystalline materials. Four samples were prepared to evaluate the method’s ability to detect changes in internal porosity as a function of the cation, water, and $${[{M'}({\text {CN}})_{6}]^{{{n}}-}}$$ vacancy content. Three of the samples have identical $${[{M'}({\text {CN}})_{6}]^{{{n}}-}}$$ vacancy content and gradually decreasing sodium and water content, while one sample has no sodium and 25% $${[{M'}({\text {CN}})_{6}]^{{n}-}}$$ vacancies. The samples were thoroughly characterized using inductively coupled plasma-optical emission spectroscopy (ICP-OES), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Mössbauer spectroscopy as well as applying the PALS method. Mössbauer spectroscopy, XRD, and TGA analysis revealed the sample compositions $${{\text {Na}}_{1.8(2)}{\text {Fe}}^{2+}_{0.64(6)}{\text {Fe}}^{2.6+}_{0.36(10)} [{\text {Fe}}^{2+}({\text {CN}})_{6}]}\cdot 2.09(2){{\text {H}}_{2}{\text {O}}},$$ $${{\text {Na}}_{1.1(2)}{\text {Fe}}^{2+}_{0.24(6)}{\text {Fe}}^{2.8+}_{0.76(6)} [{\text {Fe}}^{2.3+}({\text {CN}})_{6}]}\cdot 1.57(1){{\text {H}}_{2}{\text {O}}}$$ , $${{\text {Fe}}[{\text {Fe}}({\text {CN}})_{6}]}\cdot$$ 0.807(9) $${\text {H}}_{2}{\text {O}}$$ , and $${{\text {Fe}}[{\text {Fe}}({\text {CN}})_{6}]_{0.75}}\cdot$$ 1.5 $${{\text {H}}_{2}{\text {O}}}$$ , confirming the absence of vacancies in the three main samples. It was shown that the final composition of PBAs could only be unambiguously confirmed through the combination of ICP, XRD, TGA, and Mössbauer spectroscopy. Two positron lifetimes of 205 and 405 ps were observed with the 205 ps lifetime being independent of the sodium, water, and/or $${[{\text {Fe}}({\text {CN}})_{6}]^{{{n}}-}}$$ vacancy content, while the lifetime around 405 ps changes with varying sodium and water content. However, the origin and nature of the 405 ps lifetime yet remains unclear. The method shows promise for characterizing changes in the internal porosity in PBAs as a function of the composition and further development work needs to be carried out to ensure the applicability to PBAs generally. Graphical- 2 November 2023
- Published by Springer Nature in Journal of Materials Science
- Vol. 58 (42) , 16344-16356
Open AccessDetermining internal porosity in Prussian blue analogue cathode materials using positron annihilation lifetime spectroscopy
Prussian blue analogues (PBAs), $${{A}_x{M}[{M'}({\text {CN}})_{6}]_{1-{{y}}}\cdot {z} {\text {H}}_{2}{\text {O}}}$$ , are a highly functional class of materials with use in a broad range of applications, such as energy storage, due to their porous structure and tunable composition. The porosity is particularly important for the properties and is deeply coupled to the cation, water, and $${[{M'}({\text {CN}})_{6}]^{{{n}}-}}$$ vacancy content. Determining internal porosity is especially challenging because the three compositional parameters are dependent on each other. In this work, we apply a new method, positron annihilation lifetime spectroscopy (PALS), which can be employed for the characterization of defects and structural changes in crystalline materials. Four samples were prepared to evaluate the method’s ability to detect changes in internal porosity as a function of the cation, water, and $${[{M'}({\text {CN}})_{6}]^{{{n}}-}}$$ vacancy content. Three of the samples have identical $${[{M'}({\text {CN}})_{6}]^{{{n}}-}}$$ vacancy content and gradually decreasing sodium and water content, while one sample has no sodium and 25% $${[{M'}({\text {CN}})_{6}]^{{n}-}}$$ vacancies. The samples were thoroughly characterized using inductively coupled plasma-optical emission spectroscopy (ICP-OES), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Mössbauer spectroscopy as well as applying the PALS method. Mössbauer spectroscopy, XRD, and TGA analysis revealed the sample compositions $${{\text {Na}}_{1.8(2)}{\text {Fe}}^{2+}_{0.64(6)}{\text {Fe}}^{2.6+}_{0.36(10)} [{\text {Fe}}^{2+}({\text {CN}})_{6}]}\cdot 2.09(2){{\text {H}}_{2}{\text {O}}},$$ $${{\text {Na}}_{1.1(2)}{\text {Fe}}^{2+}_{0.24(6)}{\text {Fe}}^{2.8+}_{0.76(6)} [{\text {Fe}}^{2.3+}({\text {CN}})_{6}]}\cdot 1.57(1){{\text {H}}_{2}{\text {O}}}$$ , $${{\text {Fe}}[{\text {Fe}}({\text {CN}})_{6}]}\cdot$$ 0.807(9) $${\text {H}}_{2}{\text {O}}$$ , and $${{\text {Fe}}[{\text {Fe}}({\text {CN}})_{6}]_{0.75}}\cdot$$ 1.5 $${{\text {H}}_{2}{\text {O}}}$$ , confirming the absence of vacancies in the three main samples. It was shown that the final composition of PBAs could only be unambiguously confirmed through the combination of ICP, XRD, TGA, and Mössbauer spectroscopy. Two positron lifetimes of 205 and 405 ps were observed with the 205 ps lifetime being independent of the sodium, water, and/or $${[{\text {Fe}}({\text {CN}})_{6}]^{{{n}}-}}$$ vacancy content, while the lifetime around 405 ps changes with varying sodium and water content. However, the origin and nature of the 405 ps lifetime yet remains unclear. The method shows promise for characterizing changes in the internal porosity in PBAs as a function of the composition and further development work needs to be carried out to ensure the applicability to PBAs generally. Graphical