Papers by Michał Silarski
Springer Proceedings in Physics, 2020
We briefly report the recent results obtained by the AMADEUS collaboration on experimental studie... more We briefly report the recent results obtained by the AMADEUS collaboration on experimental studies of the K- low-energy interactions with light nuclei and outline the future perspectives
Few-Body Systems, 2021
The aim of the AMADEUS collaboration is to provide experimental information on the low-energy str... more The aim of the AMADEUS collaboration is to provide experimental information on the low-energy strong interaction of antikaons with nucleons, exploiting the absorptions of low momentum K − mesons (p K ∼ 127 MeV/c) produced at the DA NE collider, in the materials composing the KLOE detector setup, used as an active target. The K − single and multi-nucleon absorptions in light nuclei (4 He and 12 C) are investigated by reconstructing hyperon-pion, hyperon-nucleon/nucleus pairs, emitted in the final state of the reactions. In this paper the results obtained from the study of π − , p and t correlated production are presented.
Measurement Science and Technology, 2021
A large area silicon drift detectors (SDDs) system and its readout electronics have been develope... more A large area silicon drift detectors (SDDs) system and its readout electronics have been developed by the SIDDHARTA-2 Collaboration, aiming to perform high-precision light kaonic atoms x-ray spectroscopy for the investigation of the KˉN strong interaction in the low-energy QCD regime. To perform these measurements, a linear energy response and a good energy resolution are mandatory requirements for the system, to be preserved along the whole DAQ (analog and digital) chain; such task is made even harder in the experimental environment of particles colliders, where the high background due to ionizing particles and radiation is present. The energy response of the SDDs system has been characterized with the beam-originating background generated during the commissioning phase of the DAΦNE electron–positron collider (INFN-LNF) in early 2020. The data analysis has been optimized to describe the system’s response and the background. The calibration procedure demonstrates that, despite the high and variable background of the collider, the energy response of the system is linear at the level of few eV ( (ΔE/E)<10−3 ), with an energy resolution of 157.8±0.3−0.2+0.2 eV for the Fe K α line.
IEEE Transactions on Instrumentation and Measurement, 2021
Research conducted in the framework of the J-PET project aims to develop a cost-effective total-b... more Research conducted in the framework of the J-PET project aims to develop a cost-effective total-body positron emission tomography scanner. As a first step on the way to construct a full-scale J-PET tomograph from long strips of plastic scintillators, a 24-strip prototype was built and tested. The prototype consists of detection modules arranged axially forming a cylindrical diagnostic chamber with the inner diameter of 360 mm and the axial field-of-view of 300 mm. Promising perspectives for a low-cost construction of a total-body PET scanner are opened due to an axial arrangement of strips of plastic scintillators, wchich have a small light attenuation, superior timing properties, and the possibility of cost-effective increase of the axial field-of-view. The presented prototype comprises dedicated solely digital front-end electronic circuits and a triggerless data acquisition system which required development of new calibration methods including time, thresholds and gain synchronization. The system and elaborated calibration methods including first results of the 24-module J-PET prototype are presented and discussed. The achieved coincidence resolving time equals to CRT = 490 ± 9 ps. This value can be translated to the position reconstruction accuracy σ (∆l) = 18 mm which is fairly position-independent.
Science Advances, 2021
Positronium created in a human body during PET scans hallmarks neoplastic tissues.
Nature Communications, 2021
Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (C... more Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remains scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron–positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by knowledge of the latter. Here, we demonstrate tomographic reconstruction techniques applied to three-photon annihilations of ortho-positronium atoms to estimate their spin polarisation without magnetic field or polarised positronium source. We use a plastic-scintillator-based positron-emission-tomography scanner to record ortho-positronium (o-Ps) annihilations with single-event estimation of o-Ps spin and determine the complete spectrum of an angular correlation ope...
Proceedings of 54th International Winter Meeting on Nuclear Physics — PoS(BORMIO2016), 2016
EPJ Web of Conferences, 2018
A positronium - a bound state of electron and positron - is an eigenstate of parity and charge co... more A positronium - a bound state of electron and positron - is an eigenstate of parity and charge conjugation operators which decays into photons. It is a unique laboratory to study discrete symmetries whose precision is limited, in principle, by the effects due to the weak interactions expected at the level of 10−14 and photon-photon interactions expected at the level of 10−9. The Jagiellonian Positron Emission Tomograph (J-PET) is a detector for medical imaging as well as for physics studies involving detection of electronpositron annihilation into photons. The physics case covers the areas of discrete symmetries studies and genuine multipartite entanglement. The J-PET detector has high angular and time resolution and allows for determination of spin of the positronium and the momenta and polarization vectors of annihilation quanta. In this article, we present the potential of the J-PET system for studies of discrete symmetries in decays of positronium atoms.
Acta Physica Polonica A, 2017
The positron annihilation lifetime spectroscopy was applied to the samples of the human uterine l... more The positron annihilation lifetime spectroscopy was applied to the samples of the human uterine leiomyomas and the normal myometrium tissues taken from the selected place of the uterus during a surgery. The method indicated differences in values of the measured positron annihilation lifetime spectroscopy parameters (lifetimes and intensities) between healthy and diseased tissue samples. The additional measurements were performed either in darkness or in presence of visible light which influenced the free radicals present in both kind of tissues and, as a result, made changes in free annihilation and o-Ps decay lifetime and intensity values.
EPJ Web of Conferences, 2019
The AMADEUS experiment at the DAΦNE collider of LNF-INFN deals with the investigation of the at-r... more The AMADEUS experiment at the DAΦNE collider of LNF-INFN deals with the investigation of the at-rest, or low-momentum, K− interactions in light nuclear targets, with the aim to constrain the low energy QCD models in the strangeness sector. The 0 step of the experiment consisted in the reanalysis of the 2004/2005 KLOE data, exploiting K− absorptions in H, 4He, 9Be and 12C, leading to the first invariant mass spectroscopic study with very low momentum (about 100 MeV) in-flight K− captures. With AMADEUS step 1 a dedicated pure Carbon target was implemented in the central region of the KLOE detector, providing a high statistic sample of pure at-rest K− nuclear interaction. The first measurement of the non-resonant transition amplitude $\left| {{A_{{K^ - }n \to \Lambda {\pi ^ - }}}} \right|$ at $\sqrt s = 33\,MeV$ below the K̄N threshold is presented, in relation with the Λ(1405) properties studies. The analysis procedure adopted in the serarch for K− multi-nucleon absorption cross secti...
Acta Physica Polonica A, 2017
The J-PET detector, based on long plastic scintillator strips, was recently constructed at the Ja... more The J-PET detector, based on long plastic scintillator strips, was recently constructed at the Jagiellonian University. It consists of 192 modules axially arranged into three layers, read out from both sides by digital constant-threshold front-end electronics. This work presents preliminary results of measurements of the spatial resolution of the J-PET tomograph performed with 22 Na source placed at selected position inside the detector chamber.
Physics Letters B, 2016
A measurement of the vector to pseudoscalar conversion decay φ → π 0 e + e − with the KLOE experi... more A measurement of the vector to pseudoscalar conversion decay φ → π 0 e + e − with the KLOE experiment is presented. A sample of ∼ 9500 signal events was selected from a data set of 1.7 fb −1 of e + e − collisions at √ s ∼ m φ collected at the DAΦNE e + e − collider. These events were used to perform the first measurement of the transition form factor |F φπ 0 (q 2)| and a new measurement of the branching ratio of the decay: BR (φ → π 0 e + e −) = (1.35 ± 0.05 +0.05 −0.10) × 10 −5. The result improves significantly on previous measurements and is in agreement with theoretical predictions.
EPJ Web of Conferences, 2017
Physica Medica, 2016
Positron Annihilation Lifetime Spectroscopy (PALS) allows examining structure of materials at nan... more Positron Annihilation Lifetime Spectroscopy (PALS) allows examining structure of materials at nano and sub-nanometer level. This technique is based on the lifetime and production intensity of ortho-positronium atoms in free volumes of given structures. It is mostly used for studies of organic materials. However there exist also few results, e.g. by groups of Y. C. Jean and R. Pietrzak, showing that morphology of cells is correlated with the PALS parameters. Jagiellonian Positron Emission Tomograph (J-PET) is a multi-purpose detector which will be used for investigations with positronium atoms in life-sciences as well as for medical diagnostics. Such prototype based on plastic scintillators and fully compatible with MRI is currently being developed at the Jagiellonian University in Krakow, Poland. In this talk results of the first experiments conducted by the J-PET collaboration will be presented. We performed PALS studies of well known structures such as silica and of some model micro-organisms, e.g. Saccharomyces cerevisiae both with dry and aqueous samples allowing to determine the correlation between hygroscopicity of the cell and PALS parameters. As a result, we proved that PALS can be successfully used for studies of living organisms their dynamics and its relation to the cells morphology. This result opens perspective for simultaneous determination of early and advanced stages of carcinogenesis by observing changes in biomechanical parameters between normal and tumour cells and standard PET examination. J-PET detection system combined with PALS technique will be more accurate and affordable for cancer diagnostics. Disclosure Authors disclose any relationship that may bias the presentation.
AIP Conference Proceedings, 2007
Measurements of the pp → ppK + K − reaction, performed with the experiment COSY-11 at the Cooler ... more Measurements of the pp → ppK + K − reaction, performed with the experiment COSY-11 at the Cooler Synchrotron COSY, reveal a significant discrepancy between obtained excitation function and theoretical expectations neglecting interactions of kaons. Thus, the observed enhancement of the data above the predictions may be plausibly assigned to the influence of K + K − or K p interaction. This may manifest itself even stronger in the distributions of the differential cross-sections. Therefore, in order to deepen our knowledge about the low energy dynamics of the ppKK system we investigate population of events for the pp → ppK + K − reaction as a function of the invariant masses of two particle subsystems. In particular generalizations of the Dalitz plot for the four particles proposed by Chodrow and Goldhaber will be presented.
Radiotherapy and Oncology, 2016
S47 numerically modeled as a combination of multiple Bragg peak signals and linear decomposition ... more S47 numerically modeled as a combination of multiple Bragg peak signals and linear decomposition can disentangle different WET contributions, thus building up WET histogram at each raster point. The Gaussian model of the lateral pencil beam profile is calculated for each raster point as convolution between beam spot and MCS models, thus defining a neighborhood on the radiography space. The MCS model is based on WET with maximum probability, typically considered in integrationmode. The integral of the WET histogram is normalized to unity, thus expressing WET probability. The WET probability, originally assigned to the raster point, is spatially distributed based on corresponding WET probabilities of adjacent raster points, weighted according to the Gaussian model of beam intensity. Quantification is performed in comparison with list-mode in radiography space, prior to image reconstruction. Analytical and Monte Carlo simulations of proton radiographies for phantom and Computed Tomography (CT) patient data are considered. Results: The enhancement of spatial resolution from IE-mode with respect to list-mode is observable in Fig.1. The method does not modify the typical integration-mode radiography based on WET with maximum probability for each raster point, unless at the edges where the neighborhood is not centered at the raster point position (Fig.1). On analytical simulations, WET root mean square difference of IE-mode with respect to list-mode is 9.39±0.83 mm. On Monte Carlo simulations of patient data this difference is reduced down to 3 mm because of absence of sharp anatomical details in CT data. Conclusions: The redundancy of information collected by integration-mode detector offers possibilities to enhance spatial resolution. Similar to list-mode radiographies, the spatial resolution will be optimized by tomographic image reconstruction algorithms embedding this spatial information. Quantification will be performed in both radiography end tomography spaces, with respect to MCSfree gold standard.
Physics in medicine and biology, Jan 19, 2016
Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) c... more Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomu...
Nukleonika, 2015
The polystyrene doped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenyl)benzoxazo... more The polystyrene doped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenyl)benzoxazole as a wavelength shifter prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260, 283, and 370 K were found in the material. In the
Nukleonika, 2015
The Jagiellonian Positron Emission Tomograph (J-PET) collaboration is developing a prototype time... more The Jagiellonian Positron Emission Tomograph (J-PET) collaboration is developing a prototype time of flight (TOF)-positron emission tomograph (PET) detector based on long polymer scintillators. This novel approach exploits the excellent time properties of the plastic scintillators, which permit very precise time measurements. The very fast field programmable gate array (FPGA)-based front-end electronics and the data acquisition system, as well as low- and high-level reconstruction algorithms were specially developed to be used with the J-PET scanner. The TOF-PET data processing and reconstruction are time and resource demanding operations, especially in the case of a large acceptance detector that works in triggerless data acquisition mode. In this article, we discuss the parallel computing methods applied to optimize the data processing for the J-PET detector. We begin with general concepts of parallel computing and then we discuss several applications of those techniques in the J-...
Bio-Algorithms and Med-Systems, 2014
This paper describes three methods regarding the production of plastic scintillators. One method ... more This paper describes three methods regarding the production of plastic scintillators. One method appears to be suitable for the manufacturing of plastic scintillators, revealing properties which fulfill the requirements of novel positron emission tomography scanners based on plastic scintillators. The key parameters of the manufacturing process are determined and discussed.
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Papers by Michał Silarski