arXiv subjects

Thomas Rudzki

Publications and source records attributed to Thomas Rudzki.

5 recordsLinked to original sources

arXiv2026

High-Resolution Timing for Vertex-Reconstructed Muon-Spin Spectroscopy Using Plastic Scintillators and MuTRiG

Vertex-reconstructed muon-spin spectroscopy (vx-{\mu}SR) based on silicon pixel detectors has recently demonstrated unprecedented lateral resolution and operation at muon stop rates exceeding 400 kHz. However, the intrinsic timing resolution of current silicon pixel detector technology limits the accessible frequency range and restricts {\mu}SR measurements with fast relaxation rates. In this work, we report on the integration of plastic scintillator detectors (PSD) read out with the MuTRiG ASIC into the MuSiP vx-{\mu}SR spectrometer. This complements the spatial resolution achieved by using silicon pixel detectors with high-precision timing information for incoming muons and decay positrons. We demonstrate stable operation of MuTRiG in vacuum and achieve sub-300 ps time resolution after time-walk correction. Standard transverse-field {\mu}SR measurements on a SiO$_2$ sample confirm that the combined MuTRiG-PSD system resolves precession frequencies beyond 50 MHz, far exceeding the capabilities of silicon pixel detectors alone. These results establish a viable and scalable path towards high-rate, high-resolution {\mu}SR with both excellent spatial and temporal performance.

physics.ins-det↗

arXiv2025

Letter Of Intent for a future $\mu^+ \to \mathrm{e}^+ \gamma$ experiment at the High Intensity Muon Beam facility at PSI

Searches for charged lepton flavor violation in the muon sector stand out among the most sensitive and clean probes for physics beyond the Standard Model. Currently, $\mu^+ \to \mathrm{e}^+ \gamma$ experiments provide the best constraints in this field for a wide range of models while, in the coming years, new experiments investigating the processes of $\mu^+ \to \mathrm{e}^+ \mathrm{e}^+ \mathrm{e}^-$ and $\mu \to \mathrm{e}$ conversion in the nuclear field are anticipated to reach comparable or higher sensitivities. The High-Intensity Muon Beam (HIMB) facility at PSI, which is expected to deliver muon beam intensities up to two orders of magnitude higher than the existing beam lines, offers a unique opportunity to significantly enhance the sensitivity of $\mu^+ \to \mathrm{e}^+ \gamma$ searches. The discovery potential could be substantially boosted and a sensitivity comparable to that of all the other projects could be reestablished, which is essential for discriminating among competing new-physics scenarios should an observation occur in any of the channels. In this document, we express our interest in developing a $\mu^+ \to \mathrm{e}^+ \gamma$ experimental program at HIMB, with the goal of improving, within the next decade, the sensitivity of the $\mu^+ \to \mathrm{e}^+ \gamma$ search by more than one order of magnitude relative to the expected final result of the current leading experiment, MEG II. This effort would ensure that PSI retains its leadership in this field.

hep-ex↗

arXiv2025

New Frontiers in Muon-Spin Spectroscopy Using Si-Pixel Detectors

The study of novel quantum materials relies on muon-spin rotation, relaxation, or resonance (\mSR) measurements. Yet, a fundamental limitation persists: many of these materials can only be synthesized in extremely small quantities, often at sub-millimeter scales. While \mSR ~offers unique insights into electronic and magnetic properties, existing spectrometers lack a sub-millimeter spatial resolution and the possibility of triggerless pump-probe data acquisition, which would enable more advanced measurements. The General Purpose Surface-muon instrument (GPS) at the Paul Scherrer Institute (PSI) is currently limited to a muon stopping rate of \SI{40}{\kilo\hertz} to \SI{120}{\kilo\hertz}, a constraint that will become more pressing with the upcoming High-Intensity Muon Beam (HIMB) project. To overcome these challenges, we demonstrate the feasibility of employing ultra-thin monolithic Si-pixel detectors to reconstruct the stopping position of muons within the sample, thereby significantly enhancing the capability of measuring at higher muon rate. Additionally, we explore the first steps toward a triggerless pump-probe \mSR ~measurement scheme. Unlike conventional pump-probe techniques that require external triggers, a triggerless readout system can continuously integrate stimuli pulses into the data stream, allowing real-time tracking of ultra-fast dynamics in quantum materials. This approach will enable the study of transient states, spin dynamics, and quantum coherence under external stimuli.

physics.ins-det↗

arXiv2025

Advanced muon-spin spectroscopy with high lateral resolution using Si-pixel detectors

Muon-spin spectroscopy at continuous sources has stagnated at a stopped muons rate of ~40 kHz for the last few decades. The major limiting factor is the requirement of a single muon in the sample during the typical 10 {\mu}s data gate window. To overcome this limit and to be able to perform muon-spin relaxation ({\mu}SR) measurements on millimeter-sized samples, one can use vertex reconstruction methods to construct {\mu}SR spectra. This is now possible thanks to the availability of very thin monolithic Si-pixel chips, which offer minimal particle scattering and high count rate. Here we present results from a Si-pixel based spectrometer that utilizes vertex reconstruction schemes for the incoming muons and emitted positrons. With this spectrometer we were able to obtain a first vertex reconstructed {\mu}SR (VR-{\mu}SR) spectrum. The unique capabilities and benefits of such a spectrometer are discussed.

physics.ins-det↗

arXiv2021

The Mu3e experiment: Toward the construction of an HV-MAPS vertex detector

The Mu3e experiment searches for the lepton flavor violating decay $μ^+~\rightarrow~e^+~e^+~e^-$ with an ultimate aimed sensitivity of 1 event in $10^{16}$ decays. This goal can only be achieved by reducing the material budget per tracking layer to $X/X_0 \approx 0.1 \%$. High-Voltage Monolithic Active Pixel Sensors (HV-MAPS) which are thinned to $50\ μm$ serve as sensors. Gaseous helium is chosen as coolant. Results of recent studies related to the sensor prototypes, the helium cooling, and module prototyping are presented. The recent chip submission MuPix10 has proven its functionality regarding efficiency and time resolution. The helium cooling system for the inner tracker could be verified using a full-scale prototype. A complete prototype equipped with MuPix10 chips will be tested inside the Mu3e magnet in summer 2021.

physics.ins-det↗