Michal Mateusz Rawlik

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Rawlik

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Michal Mateusz

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0000-0002-1232-4497

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Publications1 - 10 of 26

Quantifying grating defects in X-ray Talbot-Lau interferometry through a comparative study of two fabrication techniques
Pereira, Alexandre; Spindler, Simon; Shi, Zhitian; et al. (2025)
Scientific Reports
The performance of an X-ray grating interferometry system depends on the geometry and quality of the gratings. Fabrication of micrometer-pitch high-aspect-ratio gold gratings, which are essential for measuring small refraction angles at higher energies, is challenging. The two widely used technologies for manufacturing gratings are based on gold electroplating in polymeric or silicon templates. Here, gratings manufactured by both approaches were inspected using conventional microscopy, X-ray synchrotron radiography, and computed laminography to extract characteristic features of the gratings profile to be modeled accurately. These models were used in a wave-propagation simulation to predict the effects of the gratings’ geometry and defects on the quality of a Talbot-Lau interferometer in terms of visibility and absorption capabilities. The simulated outcomes of grating features produced with both techniques could eventually be observed and evaluated in a table-top Talbot-Lau-Interferometer.
Search for axionlike dark matter through nuclear spin precession in electric and magnetic fields
Abel, Christopher; Ayres, Nicholas John; Ban, Giles; et al. (2017)
Physical Review X
We report on a search for ultralow-mass axionlike dark matter by analyzing the ratio of the spin-precession frequencies of stored ultracold neutrons and 199Hg atoms for an axion-induced oscillating electric dipole moment of the neutron and an axion-wind spin-precession effect. No signal consistent with dark matter is observed for the axion mass range 10−24≤ma≤10−17 eV. Our null result sets the first laboratory constraints on the coupling of axion dark matter to gluons, which improve on astrophysical limits by up to 3 orders of magnitude, and also improves on previous laboratory constraints on the axion coupling to nucleons by up to a factor of 40.
Bottom-up Gold Filling of Trenches in Curved Wafers
Josell, Daniel; Raciti, David; Gnaupel-Herold, Thomas; et al. (2024)
Journal of the Electrochemical Society
A Bi³⁺-stimulated Au electrodeposition process in slightly alkaline Na₃Au(SO₃)₂ + Na₂SO₃ electrolytes has been previously demonstrated for void-free extreme bottom-up filling of high aspect ratio trenches in gratings that are key to advanced X-ray imaging technologies. Effective use of the full area of the gratings with conventional X-ray sources requires they have a finite radius of curvature to align the high aspect ratio Au-filled trenches with divergent X-rays. With that in mind, this work demonstrates bottom-up Au filling in gratings that are attached to curved holders. Contactless mapping of the Au-filled gratings captures residual curvature that is retained after their release from the curved holders (i.e., intrinsic curvature). X-ray diffraction captures the elastic strains in the Si underlying the Au-filled trenches of the grating. Complementary measurements on the surfaces of unpatterned Si wafers mounted on curved holders capture the actual curvatures and strains imposed in the mounted gratings. The gratings, either intrinsically curved or re-bent, provide high visibility across the entire field of view of an X-ray phase contrast imaging system with elastic strains substantially below those in planar gratings bent to the same radius.
Measurement of the Permanent Electric Dipole Moment of the Neutron
Abel, Christopher; Afach, Samer; Ayres, Nicholas John; et al. (2020)
Physical Review Letters
We present the result of an experiment to measure the electric dipole moment (EDM) of the neutron at the Paul Scherrer Institute using Ramsey’s method of separated oscillating magnetic fields with ultracold neutrons. Our measurement stands in the long history of EDM experiments probing physics violating time-reversal invariance. The salient features of this experiment were the use of a 199Hg comagnetometer and an array of optically pumped cesium vapor magnetometers to cancel and correct for magnetic-field changes. The statistical analysis was performed on blinded datasets by two separate groups, while the estimation of systematic effects profited from an unprecedented knowledge of the magnetic field. The measured value of the neutron EDM is dn=(0.0±1.1stat±0.2sys)×10−26 e.cm.
Towards virtual histology with X-ray grating interferometry
Polikarpov, Maxim; Vila-Comamala, Joan; Wang, Zhentian; et al. (2023)
Scientific Reports
Breast cancer is the most common type of cancer worldwide. Diagnosing breast cancer relies on clinical examination, imaging and biopsy. A core-needle biopsy enables a morphological and biochemical characterization of the cancer and is considered the gold standard for breast cancer diagnosis. A histopathological examination uses high-resolution microscopes with outstanding contrast in the 2D plane, but the spatial resolution in the third, Z-direction, is reduced. In the present paper, we propose two high-resolution table-top systems for phase-contrast X-ray tomography of soft-tissue samples. The first system implements a classical Talbot–Lau interferometer and allows to perform ex-vivo imaging of human breast samples with a voxel size of 5.57 μm. The second system with a comparable voxel size relies on a Sigray MAAST X-ray source with structured anode. For the first time, we demonstrate the applicability of the latter to perform X-ray imaging of human breast specimens with ductal carcinoma in-situ. We assessed image quality of both setups and compared it to histology. We showed that both setups made it possible to target internal features of breast specimens with better resolution and contrast than previously achieved, demonstrating that grating-based phase-contrast X-ray CT could be a complementary tool for clinical histopathology.
Synchrotron radiation based analyzer-free dual-phase dark-field lung imaging approach for radiography and CT
Spindler, Simon; Pereira, Alexandre; Organista, Caori; et al. (2025)
Scientific Reports
Lung diseases such as chronic obstructive pulmonary disease are a major health burden to society for which early detection plays a crucial role for treatment success. For detection, as well as diagnosis and serial evaluation, imaging plays a major role, but lung diseases are often still diagnosed in progressed states for which effective causal therapies do not presently exist. Recently, dark-field lung imaging has been introduced as a promising technique for early stage detection of alterations in lung micro-structures. This work presents an analyzer-free, full-scale lung imaging system based on a dual-phase interferometer, which allows tuning and direct resolution of grating induced intensity fringes. It provides the classical absorption chest image with additional dark-field information without significant attenuation of the patient-exposed photon-flux or the cost of large area absorption gratings. The detailed system achieves a dark-field sensitivity adequate for lung imaging, governed by system autocorrelation lengths of up to 0.6. The computed tomography (CT) reconstructions show further evidence of the emergence of the dark-field in the parenchyma.
Mapping of the magnetic field to correct systematic effects in a neutron electric dipole moment experiment
Abel, Christopher; Ayres, Nicholas John; Ban, Gilles; et al. (2022)
Physical Review A
Experiments dedicated to the measurement of the electric dipole moment of the neutron require outstanding control of the magnetic-field uniformity. The neutron electric dipole moment (nEDM) experiment at the Paul Scherrer Institute uses a Hg199 co-magnetometer to precisely monitor temporal magnetic-field variations. This co-magnetometer, in the presence of field nonuniformity, is, however, responsible for the largest systematic effect of this measurement. To evaluate and correct that effect, offline measurements of the field nonuniformity were performed during mapping campaigns in 2013, 2014, and 2017. We present the results of these campaigns, and the improvement the correction of this effect brings to the neutron electric dipole moment measurement.
The n2EDM experiment at the Paul Scherrer Institute
Abel, Christopher; Ayres, Nicholas John; Ban, Gilles; et al. (2019)
EPJ Web of Conferences
We present the new spectrometer for the neutron electric dipole moment (nEDM) search at the Paul Scherrer Institute (PSI), called n2EDM. The setup is at room temperature in vacuum using ultracold neutrons. n2EDM features a large UCN double storage chamber design with neutron transport adapted to the PSI UCN source. The design builds on experience gained from the previous apparatus operated at PSI until 2017. An order of magnitude increase in sensitivity is calculated for the new baseline setup based on scalable results from the previous apparatus, and the UCN source performance achieved in 2016.
Intensity-based iterative reconstruction for helical grating interferometry breast CT with static grating configuration
Xu, Jinqiu; Wang, Zhentian; van Gogh, Stefano; et al. (2022)
Optics Express
Grating interferometry breast computed tomography (GI-BCT) has the potential to provide enhanced soft tissue contrast and to improve visualization of cancerous lesions for breast imaging. However, with a conventional scanning protocol, a GI-BCT scan requires longer scanning time and higher operation complexity compared to conventional attenuation-based CT. This is mainly due to multiple grating movements at every projection angle, so-called phase stepping, which is used to retrieve attenuation, phase, and scattering (dark-field) signals. To reduce the measurement time and complexity and extend the field of view, we have adopted a helical GI-CT setup and present here the corresponding tomographic reconstruction algorithm. This method allows simultaneous reconstruction of attenuation, phase contrast, and scattering images while avoiding grating movements. Experiments on simulated phantom and real initial intensity, visibility and phase maps are provided to validate our method.
Generating a highly uniform magnetic field inside the magnetically shielded room of the n2EDM experiment
Abel, Christopher; Ayres, Nicholas John; Ban, Gilles; et al. (2025)
The European Physical Journal C
We present a coil system designed to generate a highly uniform magnetic field for the n2EDM experiment at the Paul Scherrer Institute. It consists of a main B$_0$ coil and a set of auxiliary coils mounted on a cubic structure with a side length of 273 cm, inside a large magnetically shielded room (MSR). We have assembled this system and characterized its performances with a mapping robot. The apparatus is able to generate a 1 µT vertical field with a relative root mean square deviation σ(B$_z$)/B$_z$ = 3 x 10$^{-5}$ over the volume of interest, a cylinder of radius 40 cm and height 30 cm. This level of uniformity overcomes the n2EDM requirements, allowing a measurement of the neutron Electric Dipole Moment with a sensitivity better than 1 x 10$^{-27}$e cm.

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Michal Mateusz Rawlik

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