Annual Swedish Nuclear Physics and SFAIR meeting 2025

28 Oct 2025, 12:00 → 30 Oct 2025, 14:00 Europe/Stockholm

Vasa A (Vasa Hus 2-3 entréhall)

Joanna Sobczyk (Chalmers University of Technology)

Kärnfysiksektionen inom Svenska Fysikersamfundet (SFS-KF), tillsammans med det svenska FAIR-konsortiet, organiserar svenskt kärnfysikermöte vid Chalmers tekniska högskola den 28–30 oktober 2025 (tisdag–torsdag).

Mötet inleds med registrering kl. 13:00 tisdagen den 28 oktober, följt av det första vetenskapliga föredraget kl. 13:30. Programmet kommer att innehålla en blandning av inbjudna och bidragna föredrag:

• Inbjudna föredrag: 55 minuter (45 min presentation + 10 min diskussion)

• Bidragna föredrag: cirka 25 minuter (20 min presentation + 5 min diskussion)
  
  

Programmet kommer att innehålla presentationer av aktuell kärnfysikforskning som grupper vid svenska lärosäten är engagerade i. Presentationerna ges i form av översiktsföredrag av inbjudna talare (se nedan) samt bidragna föredrag. Vi inbjuder kärnfysikgrupperna i Sverige att föreslå korta presentationer till mötet (abstrakt skickas in via indico). Föredrag av doktorander och unga forskare kommer att prioriteras.

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The Nuclear Physics Section of the Swedish Physical Society (SFS-KF), together with the Swedish FAIR Consortium, organizes the Swedish Nuclear Physics Meeting, hosted at Chalmers University of Technology, 28–30 October 2025 (Tuesday–Thursday).

The meeting will open with registration at 13:00 on Tuesday, 28 October, followed by the first scientific talk at 13:30. The programme will include a mix of invited and contributed talks:

• Invited talks: 55 minutes (45’ presentation + 10’ discussion)

• Contributed talks: approx. 25 minutes (20’ presentation + 5’ discussion)
  
  

This year’s meeting will highlight recent advances and exciting developments in nuclear physics, featuring several distinguished invited speakers from international institutions:

• Prof. Thomas Nilsson, GSI/FAIR

• Dr. Umberto Tamponi, INFN Sezione di Torino

• Dr. Francesca Bonaiti, Oak Ridge National Laboratory

• Prof. Oscar Cabellos, Universidad Politécnica de Madrid

We warmly welcome contributions from Swedish research groups in nuclear physics (abstract submission via indico), with priority given to Ph.D. students and early-career researchers.

Tuesday 28 October

13:00 → 13:20 Registration

13:20 → 13:30 Welcome

13:30 → 14:50 Session

Convener: Prof. Andreas Ekström

13:30 Nuclear dynamics from an ab initio time-dependent approach

Speaker: Dr Francesca Bonaiti

14:25 Capturing Many-Body Correlations within the Nuclear Ab initio Framework

Ab initio nuclear many-body methods have become powerful tools for describing nuclei across the nuclear chart, providing predictive insights into nuclear structure and dynamics from realistic QCD-based interactions. This talk reviews the basic principles of these approaches, highlights recent advances in their extension to deformed nuclei, including the newly developed deformed self-consistent Green’s function method, and discusses strategies to mitigate their demanding computational cost, with a particular emphasis on emulators.

Speaker: Alberto Scalesi (Chalmers University of Technology)

14:50 → 15:20 Coffee break

15:20 → 17:05 Session

Convener: Prof. Andreas Ekström

15:20 Response function reconstruction via Chebyshev expansions

We propose an optimized histogram binning strategy to reconstruct nuclear response functions via the Chebyshev expansion bound-state method. Our approach employs a stochastic regularization of the density of states to define adaptive, equal-area bins. Using the deuteron solved in a harmonic-oscillator basis with a chiral interaction, we benchmark on dipole and longitudinal responses, obtaining excellent agreement with exact theory and experiment. This general framework readily extends to other many-body systems and opens the door to new ab initio calculations of lepton-nucleus cross sections in medium-mass nuclei.

Speaker: Immo Reis

15:45 Experiments on light-ion production in neutron-induced reactions

A deeper understanding of nucleon-induced reactions remains essential for nuclear theory as for applications in nuclear data. Several approaches have been developed in the last decades to correctly describe cross-sections for light particle emission, but it is still not possible to predict them for any nucleus in an arbitrary energy range with reasonable accuracy for practical applications. On the other hand, the nuclear data cycle strongly relies on experimental measurements, more abundant for energies up to 14 MeV due to historical limitations. Therefore, providing new data for higher energies remains as a goal of great interest.
Particles emitted from nucleon induced reactions with energies above 14 MeV can be described by the pre-equilibrium process, which considers multiple nucleon-nucleon interactions within the nucleus, leading to particle emission prior to statistical equilibrium. Structure effects are gradually “washed out” for higher energies. Such models are implemented in codes for calculating double differential cross-sections for different nuclei, such as TALYS [1], and uses experimental data as an input for correctly choosing its free parameters.

In this contribution, we report on the status of a series of experiments dedicated to measure the production cross-sections for the emission of light-ions in neutron-induced reactions. Those experiments have been carried out in the white neutron beam of the Neutrons for Science (NFS) facility, at GANIL (France), and within the framework of a collaboration between Uppsala University, GANIL, and the UK Atomic Energy Agency.

Speaker: Mr Lucas De Arruda (Uppsala University)

16:10 Beta-delayed two-proton spectroscopy at FRIB

13 beta-delayed two-proton (β2p) emitters are known today: $^{22}$Al, $^{22,23}$Si, $^{26}$P, $^{27}$S, $^{31}$Ar, $^{35}$Ca, $^{39}$Ti, $^{43}$Cr, $^{45,46}$Fe, $^{50,51}$Ni. The Q-value (the energy released in the decay) is a major determining factor for what type of beta-delayed decays occur, and therefore two-proton emitters are found at or close to the dripline. Nuclear structure also plays a role as clustering in light nuclei evolves into competition between single particle and collective (rotational and vibrational) degrees of freedom. The cross-over happens in this interesting region of the chart of nuclei where the known β2p emitters are found. The relation between two-proton emission and many-body nuclear structure is still poorly understood.

Of the 13 known cases, only $^{31}$Ar has been studied with sufficient statistics and beam quality to provide a deep study of the mechanism of the two-proton emission, this being the only case possible to produce at an ISOL facility (ISOLDE-CERN). Short-lived isotopes of the elements between Mg and Cl are difficult, or impossible, to produce at ISOL facilities due to the chemical properties of those elements.

With FRIB coming on-line and the Gas Stopping Area working excellently it is now possible to make low energy beams of most of these isotopes with unprecedented yields. With FRIB Experiment 21010 on the decays of $^{22}$Al and $^{26}$P we have initiated the exploration of this fertile region of nuclear structure and decay phenomena. The experiment is the first successful FRIB Experiment conducted in the Stopped Beam Area with yields of the two species of respectively 10 and 60 particles per second. The experiment provided much improved data not only for $^{22}$Al and $^{26}$P, but also for $^{21}$Mg and $^{25}$Si (beta-delayed one-proton emitters), which were present as contaminants and/or were used for calibration purposes.

In this contribution I will present results from FRIB Experiment 21010 including a clarification of the mechanism of two-proton emission in the decays of $^{22}$Al and $^{26}$P. Plans for future studies at FRIB will also be presented.

Speaker: Erik Jensen (Chalmers)

16:35 Deuteron Evaporation from N=Z Compound Nuclei

Deuteron evaporation was observed from the $N=Z$ compound nuclei $^{52}$Fe$^\star$, $^{56}$Ni$^\star$, and $^{64}$Ge$^\star$ in an experiment conducted at Argonne National Laboratory, USA. The experiment included a novel combination of two highly pixelated double-sided Si-strip detectors inside the Microball charged-particle detection array, allowing for unequivocal discrimination of evaporated deuterons from protons and $\alpha$ particles. In conjunction with the Gammasphere array, Neutron Shell, and additional ancillary detectors, decay paths into various residual nuclei were investigated. The study provides insights into the competition of deuteron vs.~proton-neutron evaporation as a function of available excitation energy and populated angular momentum. Results are interpreted using a statistical evaporation formalism for multiple subsequent particle emissions. Findings from the comparison of single-nucleon and deuteron evaporation will be presented in the talk.

Speaker: Yuliia Hrabar (lu.se)

Wednesday 29 October

09:00 → 10:20 Session

Convener: Prof. Karin Schönning

09:00 What about Nuclear Data (ND) in a Nuclear Physics Meeting? The Nuclear Data Life Cycle

Speaker: Prof. Oscar Cabellos

09:55 Commissioning tests of the Advanced Radwaste Characterisation (ARC) scanner system at KTH

Ensuring a safe long-term disposal of radioactive waste is essential for several reasons – environment and public safety, meeting requirements related to nuclear safeguards and non-proliferation, but also to support the continued development of nuclear applications in research, medicine and industry. In Sweden, a large inventory of radioactive waste, so called legacy waste, was produced during early years of nuclear research, including defense-related research and long-lived radionuclides from the industry and healthcare sectors. Before such waste is separated into the relevant categories, it has to be characterised with respect to current waste acceptance criteria. There are special challenges associated with the Swedish legacy waste that require careful non-destructive assay (NDA) of waste drums before they are opened for waste processing. For example, the legacy waste often contains mixed or heterogeneous materials including liquids with significant radiochemical hazards. To address these issues, a novel multi-modality tomographic scanning system has been developed for NDA of legacy waste drums in collaboration with the company charged with managing such waste in Sweden, AB Svafo. This Advanced Radwaste Characterisation (ARC) system integrates three different imaging techniques within a unified scanning platform, featuring a neutron-gamma emission tomography (NGET) detection system coupled with 3D gamma-ray densitometry (CT) and a spectrometric gamma-ray emission tomography (SPECT) system.

The NGET technique was invented at KTH and uses fast organic scintillator detectors to measure correlated fast neutrons and gamma rays emitted in the spontaneous or induced fission of actinide materials. By analyzing these time and energy correlations, the system enables three-dimensional localization of neutron-emitting sources [1-4]. The gamma-ray transmission CT system provides structural and attenuation information, which can be used for attenuation correction and material differentiation. The SPECT subsystem, based on a collimated high-purity germanium (HPGe) detector, maps gamma-emitting radionuclides within the drum and supports isotope identification.

Monte Carlo simulations and experimental measurements have been carried out as part of the ARC system’s testing and commissioning phase to evaluate and optimize its performance. The results from simulated and measured datasets show that the system can accurately localize neutron- and gamma-emitting sources in typical shielded waste matrix geometries. The integrated design enables multi-modal localization of both radioactive and non-radioactive components, providing a comprehensive three-dimensional characterization capability.

This work represents a significant step toward automated NDA of legacy waste drums and demonstrates the potential of combining these techiniques for enhanced localization, identification, and quantification of actinides and other radionuclides. We present the initial measurements and images obtained using the different systems, which are compared with Geant4 simulations of the complete setup.

[1] Jana Petrović, Alf Göök, and Bo Cederwall, Rapid imaging of special nuclear materials for nuclear nonproliferation and terrorism prevention, Sci. Adv. 7, 1 (2021). https://doi.org/10.1126/sciadv.abg3032

[2] B. Cederwall, A novel 3D-imaging and characterisation technique for special nuclear materials in radioactive waste,
EPJ Nuclear Sci. Technol., 9, 8 (2023) https://doi.org/10.1051/epjn/2022037

[3] Jana Vasiljević, Vivian Peters, Anders Puranen & Bo Cederwall,
Sensitive imaging of actinide materials in shielded radioactive waste,
Nature Scientific Reports, 14, 26798 (2024) https://doi.org/10.1038/s41598-024-78027-9

[4] Rafael Escudeiro, Ihor Tavrovskyi, Vivian Peters, Jana Vasiljević, Anders Puranen and Bo Cederwall, Spatial resolution of an organic scintillator-based Neutron-Gamma Emission Tomography system with different detector cell sizes, Nucl. Instrum.Methods Phys.Res. A, 1080, 170788 (2025) https://doi.org/10.1016/j.nima.2025.170788

Speaker: Rafael Escudeiro (kth.se)

10:20 → 10:50 Coffee break

10:50 → 12:10 Session

Convener: Prof. Karin Schönning

10:50 A simulation approach to evaluating the minimum detectable activity of coincidence gamma-ray spectrometers

Atmospheric radionuclide monitoring with high-purity germanium (HPGe) detectors is a crucial component of verifying compliance with treaties that prohibit the use of nuclear weapons, such as the Comprehensive Nuclear-Test-Ban Treaty (CTBT). To improve detection sensitivity, coincidence gamma-ray spectrometers, which measure gamma rays emitted in a cascade, are being developed. The CoSpeR collaboration between Uppsala University and the Swedish Defence Research Agency (FOI) aims to optimize the minimum detectable activity of key radionuclides for coincidence gamma-ray spectrometers using simulations in Geant4. This talk will discuss the theory behind the detection technique, present progress in simulating detector performance, and outline the future course toward optimized detector designs.

Speaker: Elias Arnqvist (Uppsala University)

11:15 Entanglement and accidental symmetries in the nucleon-nucleon system

We study the connection between accidental symmetries in the nuclear interaction and spin entanglement in two-nucleon scattering. Specifically, we incorporate different levels of Wigner $SU(4)$ and Serber symmetries into leading-order potentials derived from chiral effective field theory. We conduct a quantitative analysis by computing the full $S$ matrix, demonstrating that the neutron-proton spin entanglement can be related to the symmetry properties of the interaction and the presence of certain operators and partial waves. Furthermore, we study the order-by-order evolution of the spin entanglement, up to next-to-next-to-leading order in Weinberg power counting, for both neutron-proton and neutron-neutron scattering. Entanglement suppression is not observed in neutron-neutron scattering, which can be attributed to the Pauli principle and the absence of accidental symmetries in this system. We conclude that entanglement is a useful guide for studying the power counting and symmetries in nuclear interactions derived from effective field theories.

Speaker: Alma Cavallin (chalmers.se)

11:40 Correlated effective field theory truncation errors: from neutron-proton scattering amplitudes to observables

The strong force governing Nucleon-Nucleon (NN) scattering can be modelled using chiral effective field theory -- a systematic low-energy expansion that preserves the symmetries of quantum chromodynamics. In this framework, NN scattering observables are predicted order-by-order. The series is truncated to facilitate computations, and the omission of higher-order terms leads to a theoretical truncation error.

This work investigates how these truncation errors are correlated across scattering energies and angles, but also across different observable types by utilising the fact that all neutron-proton (np) scattering observables depend on only five complex amplitudes.

A Gaussian process-based Bayesian uncertainty quantification model was used to predict truncation errors of the scattering amplitudes, effectively incorporating all symmetries of the scattering event, except the unitarity of the scattering operator. The resulting uncertainties were then propagated to various observables, revealing strong correlations. We showed that these correlations reduced the number of independent np scattering data points.

The error model could enhance the physical robustness of effective field theory parameter inference and the reliability of theoretical predictions for nuclear observables.

Speaker: Lucas Abrahamsson (Chalmers)

12:10 → 13:30 Lunch break

13:30 → 14:50 Session

Convener: Prof. Dirk Rudolph

13:30 QCD studies with the Belle II experiment

Speaker: Dr Umberto Tamponi

14:25 Charm Physics at Belle II: Opportunities and Recent Result

The Belle II experiment at the SuperKEKB collider in Japan is a high-luminosity B-factory designed to study B mesons in detail. However, due to the large number of charm quarks produced in electron-positron collisions, Belle II also functions effectively as a charm-factory. Its excellent vertexing, tracking, and particle identification allow precise studies of charm meson decays, including phenomena such as mixing and CP violation. This talk will give an overview of the current and future charm physics program at Belle II, highlighting its potential to improve our understanding of fundamental particle interactions.

Speaker: Martina Laurenza (Uppsala University)

14:50 → 15:15 Coffee break

15:15 → 16:10 Session

Convener: Prof. Dirk Rudolph

15:15 IInvestigating double-hyperon systems using HADES and CBM: Insights into Λ-Λ interactions and neutron star cores

On behalf of the HADES and CBM collaborations.

Hyperons, baryons containing at least one strange quark, are pivotal to advancing our understanding of matter under extreme conditions. They are hypothesized to play a crucial role in the dense cores of neutron stars, where their emergence is expected at densities exceeding nuclear saturation. Among hyperons, Λ hyperons are of particular interest as they have been shown to significantly soften the equation of state (EoS) under the absence of strong repulsive two or three-body forces. This softening leads to pronounced effects on the maximum mass and radius of neutron stars, introducing discrepancies between observational data and theoretical predictions [1]. The so-called ”hyperon puzzle” is therefore a key topic in nuclear astrophysics. A deeper comprehension of QCD driven hyperon-hyperon interactions in extreme astrophysical environments is essential to address these challenges.
The study presented in this talk focuses on the production and interaction of Λ-Λ pairs, in the reaction channel pp → ΛΛK+K+, a doubly strange baryonic system, in proton-proton collisions at √s = 3.46 GeV at the High Acceptance Di-Electron Spectrometer (HADES) at GSI. As a foundational step, the near-threshold (at 0.24 GeV above the threshold in the CoM) production cross-section is determined. In this talk, I will detail the experimental methods, analysis procedure and preliminary results on the production cross-section.
Additionally, I will present recent studies on ΛΛ interaction signatures such as cusp formation based on simulation data from the Compressed Baryonic Matter (CBM) experiment at FAIR [2]. These complementary results offer valuable comparative insights into multi-strange baryon dynamics across different experimental platforms.

References
[1] D. Logoteta, I. Vidana, and I. Bombaci, “Impact of chiral hyperonic three-body forces on neutron stars,” The European Physical Journal A, vol. 55, no. 11, p. 207, 2019.
[2] X.-K. Dong, F.-K. Guo, B.-S. Zou, “Explaining the many threshold structures in the heavy-quark hadron spectrum”, Phys. Rev. Lett. 126 (15) (2021) 152001

Speaker: Gandharva Appagere (su.se)

15:40 From Protons to Photons: Strangeness Production with ALICE at the LHC

The ALICE group at Lund studies collisions of protons and heavy ions at the Large Hadron Collider to explore the behavior of nuclear matter under extreme conditions. These studies aim to understand how quarks and gluons interact and form the particles we observe.

Measurements of strange hadrons in small collision systems have revealed unexpected features, such as enhanced strangeness production and collective-like behavior at high multiplicity. These observations challenge the traditional view that thermal equilibration and quark–gluon plasma formation occur only in large systems. Current QCD-inspired models reproduce the general trends but struggle to describe the observed yields and spectra quantitatively, indicating that the microscopic mechanisms of strangeness production and hadronisation are not yet fully understood.

I will present ongoing analyses of strange hadron production (K, Λ, Ξ) in proton–proton and ultra-peripheral Pb–Pb collisions. The results probe the system-size dependence of strangeness production and provide constraints on modern hadronisation models.

References

1. ALICE Collaboration, S. Acharya et al., Phys. Rev. C 99(2), 024906 (2019).
2. ALICE Collaboration, S. Acharya et al., Eur. Phys. J. C 80, 1–26 (2020).
3. ALICE Collaboration, J. Adam et al., Nat. Phys. 13, 535–539 (2017).
4. K. Werner, Phys. Rev. C 109(1), 014910 (2024).

Speaker: Roman Nepeivoda (Lund University (SE))

16:10 → 17:10 SFS-KF Annual Meeting

18:00 → 22:00 Dinner

Thursday 30 October

09:00 → 10:20 Session

Convener: Prof. Per-Erik Tegner

09:00 Current status and future prospects of FAIR

Speaker: Prof. Thomas Nilsson

09:55 Isomeric yield ratio measurements for fission dynamics

The fission process forms highly excited fragments carrying significant amounts of angular momentum. This formation is generally described via a shape evolution on the potential energy landscape of the fissioning system. Among the aspects that are still hard to describe in this process is the generation of the fragment angular momenta, highlighted by the work of Wilhelmy et al. in the early 1970s. Isomeric yield ratios (IYR) offer the possibility to address this question.

Traditionally, gamma-spectrometry has been used to measure IYR but risk suffering from incomplete information on the nuclear level scheme and decay branching ratios. To avoid this problem, we employ direct ion counting using mass measurement techniques and unambiguously determine IYR from fission. With recent advances such as the Phase-Imaging Ion-Cyclotron-Resonance (PI-ICR) technique, isomers with mass differences as low as a few tens of keV can be resolved. Over the past years, IYR for many different isomeric pairs resulting from 232Th(p,f), 232Th(a,f), and 238U(p,f) could be obtained at IGISOL of the University of Jyväskylä [1-5].

We present the employed experimental technique, recent experimental results, interpretation of the experimental data in terms of fragment angular momenta and our planned activities.

[1] V. Rakopoulos, et al., Phys. Rev. C 98, 024612 (2018).
[1] V. Rakopoulos, et al., Phys. Rev. C 99, 014617 (2019).
[2] Z. Gao, et al., Phys. Rev. C 108, 054613 (2023).
[3] S. Cannarozzo, et al., Phys. Rev. C 111, L031601 (2025).
[4] S. Cannarozzo, et al., [https://arxiv.org/abs/2504.11274v3][1] (2025).

Speaker: Stephan Pomp (Uppsala University)

10:20 → 10:50 Coffee break

10:50 → 12:50 Session

Convener: Prof. Per-Erik Tegner

10:50 Transfer-induced fission at the ISOLDE Solenoidal Spectrometer

The study of nuclear fission remains a critical area of research, not only for understanding fundamental nuclear properties but also for its implications in the production of heavy elements in astrophysical environments. In r-process nucleosynthesis, fission plays a crucial role as it ultimately limits the mass of nuclei that can be produced. Currently, very limited data on fission barriers of neutron-rich nuclei are available. Moreover, studying fission barriers is essential for investigating the influence of nuclear structure on fission dynamics.

The ISOLDE Solenoidal Spectrometer (ISS) offers a new approach to investigate fission probabilities of neutron-rich actinides via (d,pF) reactions using Radioactive Ion Beams. This approach utilises a novel setup designed to enhance the detection efficiency for fission fragments in coincidence with transfer-like protons in a solenoidal field. This optimised method provides access to the fission probability as a function of the excitation energy. Additionally, complementary $\gamma$-ray measurements offer insight into the total energy and multiplicity of $\gamma$-rays emitted during the fission process.

In this context, the measurement of the fission barrier of $^{233}$U has been performed, as a first step to establish this new approach. This data might also be relevant for the thorium fuel cycle.

In this contribution, the experimental setup will be presented, and preliminary results of the experiment will be discussed, highlighting its potential for advancing our understanding of nuclear fission.

Beyond this study, this method has the potential to be extended to investigate even more exotic nuclei farther from the valley of stability, opening new opportunities to explore fission in regions of the nuclear chart that have so far remained experimentally inaccessible.

Speaker: Maria Vittoria Managlia (Chalmers University of Technology)

11:15 Free-running MDPP-32 integration at ISS

The experiment IS739 studied fission reactions of radioactive beams in inverse kinematics at the ISOLDE Solenoidal Spectrometer (ISS). It required about 150 new channels of silicon detector readout. Placed after the REX/HIE-ISOLDE post-accelerator, ISS uses a free-running data acquisition system to cope with the low but intense duty cycle of the accelerator.

Readout of the new fission fragment Si CD and next-generation luminosity monitor detectors was realised through integration of a new free-running readout mode of Mesytec MDPP-32 modules with the existing system. Data-taking for the experiment took place this summer. The entire analysis chain was tested beforehand through simulations, generating data acquisition (DAQ) look-alike raw data files.

The layout and performance of the DAQ system and the simulation tools will be presented and discussed.

Speaker: Håkan T Johansson (chalmers.se)

11:40 Dalitz Plot Analysis of charmless $B$ Meson Decays at Belle II

The $\mbox{Belle}~\mbox{II}$ experiment began collecting data in 2019 and has since accumulated approximately 500 million $B\bar{B}$ meson pair events produced in $e^+e^-$ collisions. The decays of these $B$ mesons into charmless final states, i.e. those containing no charm quarks, are dominated by loop transitions. Potential new physics particles may be able to enter these loops, making such decays sensitive to new physics beyond the Standard Model.

An analysis of $B$ meson decays into charmless three-body final states will be presented. These multibody decays exhibit a rich intermediate resonance structure that can be resolved performing an amplitude (Dalitz plot) analysis.

Internal symmetries, such as isospin, can then be exploited to combine multiple decay modes into so-called sum rules, which provide a precise null test of the Standard Model. Any experimental violation would suggest the presence of new physics in these decays.

Speaker: Markus Reif (Uppsala University)

12:05 Belle II Tracking, and Optimisation

Reliable track reconstruction is vital for Belle II, especially as detector conditions evolve. The full tracking chain in the Belle II Analysis Software Framework (basf2) combines CDC-seeded and SVD-seeded tracking stages, which are merged and cleaned to produce final tracks. We focus on optimising the SVD-seeded CKF extension into the CDC, where SVD-only tracks are extrapolated to attach CDC hits. This step is sensitive to CDC inefficiencies caused by ageing electronics and inactive wires. A grid search is used to tune key CKF hyperparameters—such as allowed layer skips—using an F1 score built from hit efficiency and hit purity as the optimisation objective. The resulting parameter set, which yields the highest F1 score, is integrated into the full tracking chain, thereby improving tracking robustness and performance under degraded detector conditions.

Speaker: Adeel Akram (Uppsala University)