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Magdalena Skurzok

Publications and source records attributed to Magdalena Skurzok.

At least 37 records · Page 2Linked to original sources
arXiv2023

Comparative studies of the sensitivities of sparse and full geometries of Total-Body PET scanners built from crystals and plastic scintillators

Background: Total-Body imaging offers high sensitivity, single-bed position, and low dose, but high construction costs limit worldwide utilization. This study compares existing and developing tomographs using plastic scintillators via simulations to propose a cost-efficient Total-Body PET scanner. Methods: Simulations of eight uEXPLORER tomographs with different scintillator materials, axial field-of-view, and detector configuration, and eight J-PET scanners with various field-of-view, plastic scintillator cross-sections, and layers were performed. Biograph Vision was also simulated. Two types of simulations were conducted with a central source and a water-filled phantom. Results: BGO crystal-based scanners showed the best sensitivity (350 cps/kBq at the center). Sparse geometry or LYSO crystals reduced sensitivity. J-PET design showed similar sensitivity to sparse LYSO detectors, with full body coverage and additional gain for brain imaging. Conclusion: The J-PET tomography system using plastic scintillators could be a cost-efficient alternative for Total-Body PET scanners, overcoming high construction costs while maintaining sensitivity

physics.med-ph↗
arXiv2023

Feasibility of the J-PET to monitor range of therapeutic proton beams

Objective: The aim of this work is to investigate the feasibility of the Jagiellonian Positron Emission Tomography (J-PET) scanner for intra-treatment proton beam range monitoring. Approach: The Monte Carlo simulation studies with GATE and PET image reconstruction with CASToR were performed in order to compare six J-PET scanner geometries (three dual-heads and three cylindrical). We simulated proton irradiation of a PMMA phantom with a Single Pencil Beam (SPB) and Spread-Out Bragg Peak (SOBP) of various ranges. The sensitivity and precision of each scanner were calculated, and considering the setup's cost-effectiveness, we indicated potentially optimal geometries for the J-PET scanner prototype dedicated to the proton beam range assessment. Main results: The investigations indicate that the double-layer cylindrical and triple-layer double-head configurations are the most promising for clinical application. We found that the scanner sensitivity is of the order of 10$^{-5}$ coincidences per primary proton, while the precision of the range assessment for both SPB and SOBP irradiation plans was found below 1 mm. Among the scanners with the same number of detector modules, the best results are found for the triple-layer dual-head geometry. Significance: We performed simulation studies demonstrating that the feasibility of the J-PET detector for PET-based proton beam therapy range monitoring is possible with reasonable sensitivity and precision enabling its pre-clinical tests in the clinical proton therapy environment. Considering the sensitivity, precision and cost-effectiveness, the double-layer cylindrical and triple-layer dual-head J-PET geometry configurations seem promising for the future clinical application. Experimental tests are needed to confirm these findings.

physics.med-ph↗
arXiv2022

First Simultaneous K$^-$p $\rightarrow (Σ^0/Λ) \, π^0$ Cross Sections Measurements at 98 MeV/c

We report the first simultaneous and independent measurements of the K$^{-}$p $\rightarrow Σ^0 \, π^{0}$ and K$^{-}$p $\rightarrow Λ\, π^{0}$ cross sections around 100 MeV/c kaon momentum. The kaon beam delivered by the DA$Φ$NE collider was exploited to detect K$^-$ absorptions on Hydrogen atoms, populating the gas mixture of the KLOE drift chamber. The precision of the measurements ($σ_{K^- p \rightarrow Σ^0 π^0} = 42.8 \pm 1.5 (stat.) ^{+2.4}_{-2.0}(syst.) \ \mathrm{mb}$ and $σ_{K^- p \rightarrow Λπ^0} = 31.0 \pm 0.5 (stat.) ^{+1.2}_{-1.2}(syst.) \ \mathrm{mb}\,$) is the highest yet obtained in the low kaon momentum regime.

nucl-ex↗
arXiv2021

Positronium imaging with the novel multiphoton PET scanner

In vivo assessment of cancer and precise location of altered tissues at initial stages of molecular disorders are important diagnostic challenges. Positronium is copiously formed in the free molecular spaces in the patient's body during positron emission tomography (PET). The positronium properties vary according to the size of inter- and intramolecular voids and the concentration of molecules in them such as, e.g., molecular oxygen, O2; therefore, positronium imaging may provide information about disease progression during the initial stages of molecular alterations. Current PET systems do not allow acquisition of positronium images. This study presents a new method that enables positronium imaging by simultaneous registration of annihilation photons and deexcitation photons from pharmaceuticals labeled with radionuclides. The first positronium imaging of a phantom built from cardiac myxoma and adipose tissue is demonstrated. It is anticipated that positronium imaging will substantially enhance the specificity of PET diagnostics.

physics.med-ph↗
arXiv2021

Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

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 operator sensitive to CPT-violating effects. We find no violation at the precision level of 10^{-4}, with an over threefold improvement on the previous measurement.

nucl-ex↗
arXiv2021

Silicon Drift Detectors spectroscopic response during the SIDDHARTA-2 Kaonic Helium run at the DAΦNE collider

A large-area Silicon Drift Detectors (SDDs) system has been developed by the SIDDHARTA2 collaboration for high precision light kaonic atoms X-ray spectroscopy at the DAΦNE collider of Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Frascati. The SDDs geometry and electric field configuration, combined with their read-out electronics, make these devices suitable to perform high precision light kaonic atoms spectroscopy measurements in the high background of the DAΦNE collider. This work presents the spectroscopic response of the SDDs system during the kaonic helium first exotic atoms run of SIDDHARTA-2, preliminary to the kaonic deuterium data taking campaign

physics.ins-det↗
arXiv2018

Updating spin-dependent Regge intercepts

We use new high statistics data from CLAS and COMPASS on the nucleon's spin structure function at low Bjorken x and low virtuality, Q^2 < 0.5 GeV^2, together with earlier measurements from the SLAC E-143, HERMES and GDH experiments to estimate the effective intercept(s) for spin dependent Regge theory. We find alpha_{a_1} = 0.31 \pm 0.04 for the intercept describing the high-energy behaviour of spin dependent photoabsorption together with a new estimate for the high-energy part of the Gerasimov-Drell-Hearn sum-rule, -15 \pm 2 mu b from photon-proton centre-of-mass energy greater than 2.5 GeV. Our value of alpha_[a_1} suggests QCD physics beyond a simple straight-line a_1 trajectory.

hep-ph↗
arXiv2018

Estimating the NEMA characteristics of the J-PET tomograph using the GATE package

The novel whole-body PET system based on plastic scintillators is developed by the {J-PET} Collaboration. It consists of plastic scintillator strips arranged axially in the form of a cylinder, allowing the cost-effective construction of the total-body PET. In order to determine properties of the scanner prototype and optimize its geometry, advanced computer simulations using the GATE software were performed. The spatial resolution, the sensitivity, the scatter fraction and the noise equivalent count rate were estimated according to the NEMA norm as a function of the length of the tomograph, number of the detection layers, diameter of the tomographic chamber and for various types of the applied readout. For the single-layer geometry with the diameter of 85 cm, strip length of 100 cm, cross-section of 4 mm x 20 mm and silicon photomultipliers with the additional layer of wavelength shifter as the readout, the spatial resolution (FWHM) in the centre of the scanner is equal to 3 mm (radial, tangential) and 6 mm (axial). For the analogous double-layer geometry with the same readout, diameter and scintillator length, with the strip cross-section of 7 mm x 20 mm, the NECR peak of 300 kcps was reached at 40 kBq/cc activity concentration, the scatter fraction is estimated to about 35% and the sensitivity at the centre amounts to 14.9 cps/kBq. Sensitivity profiles were also determined.

physics.ins-det↗
arXiv2016

Search for $η$-mesic helium via $dd\to {}^3{\rm He}\,nπ^0$ reaction by means of the WASA-at-COSY facility

In November 2010, we performed a search for a $^{4}\mbox{He}$-$η$ bound state by measuring the excitation function for the $dd\rightarrow$ $^{3}\mbox{He} n π^{0}$ and $dd\rightarrow$ $^{3}\mbox{He} p π^{-}$ reactions in the vicinity of the $η$ production threshold with the WASA detector.~The experiment was carried out using a deuteron COSY beam and deuteron pellet target. The beam momentum varied continuously in each of acceleration cycle from 2.127 GeV/c to 2.422 GeV/c, which corresponds to a range of excess energy $Q$ $\in$(-70,30)MeV. This dissertation is about the search for $^{4}\mbox{He}$-$η$ bound state in $dd\rightarrow$ $^{3}\mbox{He} n π^{0}$ reaction. The excitation function for the process was determined after identification of all outgoing particles and the application of the selection conditions based on Monte Carlo simulations of $η$-mesic helium production and its decay via excitation of the $N^{*}$ resonance. No narrow structure of the $η$-mesic helium was observed in the excitation function. The upper limit of the total cross section for the bound state formation and its decay in $dd\rightarrow({}^{4}\mbox{He}$-$η)_{bound} \rightarrow$ $^{3}\mbox{He} n π^{0}$ process was determined on the 90% confidence level. It varies from 21 to 36 nb for the bound state width ranging from 5 MeV to 50 MeV, respectively. However, an indication for a broad state was observed. The kinematic region, where we expect the evidence of the signal from the bound state, cannot be fully described only by the combination of the considered background processes. In contrast, the experimental excitation function is very well fitted by the background contributions for the region where the signal is not expected.

nucl-ex↗
arXiv2016

Production and interaction of the eta meson with nucleons and nuclei

We report on the status of the search for eta-mesic nuclei and the studies of the interaction of the eta meson with nucleons. Recently we have completed the analysis of the new WASA-at-COSY data on the production of the eta meson with polarized proton beam. New results on the analyzing power for the pp->ppeta reaction with more than an order of magnitude improved precision shed a new light on the production mechanism of the eta meson in nucleon-nucleon collisions. Also, the latest results of the search for eta-mesic nuclei are discussed.

nucl-ex↗
arXiv2016

Determination of the $\boldsymbol{η^3{\rm He}}$ threshold structure from the low energy $\boldsymbol{pd \to η^3{\rm He}}$ reaction

We analyze the data on cross sections and asymmetries for the $pd (dp) \to η^3{\rm He}$ reaction close to threshold and look for bound states of the $η^3 {\rm He}$ system. Rather than parameterizing the scattering matrix, as is usually done, we develop a framework in which the $η^3 {\rm He}$ optical potential is the key ingredient, and its strength, together with some production parameters, are fitted to the available experimental data. The relationship of the scattering matrix to the optical potential is established using the Bethe-Salpeter equation and the $η^3 {\rm He}$ loop function incorporates the range of the interaction given by the empirical $^3 {\rm He}$ density. We find a local Breit Wigner form of the $η^3$He amplitude $T$ below threshold with a clear peak in $|T|^2$, which corresponds to an $η^3 {\rm He}$ binding of about 0.3 MeV and a width of about 3 MeV. By fitting the potential we can also evaluate the $η^3 {\rm He}$ scattering length, including its sign, thus resolving the ambiguity in the former analyses.

nucl-th↗
arXiv2016

Status and Perspectives of the Search for Eta-Mesic Nuclei

In this report the search for eta-mesic nuclei is reviewed. The brief description of the experimental studies is presented with a focus on the possible production of the eta-nucleus bound states for light nuclei like 4He and 3He.

nucl-ex↗
arXiv2015

Search for eta-mesic nuclei with WASA-at-COSY

We search for an evidence of eta-mesic He with the WASA detector. Two dedicated experiments were performed at the Cooler Synchrotron COSY-Juelich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: dd->3Heppi- and dd->3Henpi0, where the outgoing N-pi pairs originate from the conversion of the eta meson on a nucleon inside the He nucleus.In this contribution, the experimental method is shortly described and the current status of the analysis is presented.

nucl-ex↗
arXiv2014

Search for the manifestation of the mesic-nuclei on the dd-->3HeNpi excitation function measured with WASA-at-COSY

We search for an evidence of eta-mesic 4He with the WASA-at-COSY detector. Two dedicated experiments were performed at the Cooler Synchrotron COSY-Juelich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: dd-->3Heppi- and dd-->3Henpi0, where the outgoing N-pi pairs originate from the conversion of the eta meson on a nucleon inside the He nucleus. In this contribution, the experimental method is shortly described and preliminary excitation functions from the 2010 data are presented.

nucl-ex↗
arXiv2013

Search for eta-mesic helium via deuteron-deuteron reactions with the WASA-at-COSY facility

The eta-mesic nuclei in which the eta meson is bound with nucleus via strong interaction was postulated already in 1986, however till now no experiment confirmed empirically its existence. The discovery of this new kind of an exotic nuclear matter would be very important for better understanding of the eta meson structure and its interaction with nucleons. The search for eta-mesic helium is carried out with high statistic and high acceptance with the WASA-at-COSY detection setup in the Forschungszentrum Julich. The search is conducted via the measurement of the excitation function for the chosen decay channels of the 4He-eta system. Untill now two reactions dd->(4He-eta)bs->3He p pi- and dd->(4He-eta)bs->3He n pi0 have been measured with the beam momentum ramped around the eta production threshold. This report includes the description of experimental method and status of the analysis.

nucl-ex↗
arXiv2012

Search for eta-mesic Helium with the WASA-at-COSY detector

A search for the 4He-eta bound state via exclusive measurement of the excitation function for the dd->3Heppi- reaction, was performed at the Cooler Synchrotron COSY-Juelich with the WASA-at-COSY detection system. The data were taken during a slow acceleration of the beam from 2.185 GeV/c to 2.400 GeV/c crossing the kinematic threshold for the eta production in the dd -> 4He-eta reaction at 2.336 GeV/c. The corresponding excess energy in the 4He-eta system varied from -51.4 MeV to 22 MeV. The shape of the excitation function for the dd -> 3Heppi- was examined. No signal of the 4He-eta bound state was observed in the excitation function.

nucl-ex↗