Regular Series

Vol. 51 (2020), No. 1, pp. 1 - 426

\(3^{\mathrm {rd}}\) Jagiellonian Symposium on Fundamental and Applied Subatomic Physics

full authors' list

A. Rucinski, J. Baran, G. Battistoni, A. Chrostowska, M. Durante, J. Gajewski, M. Garbacz, K. Kisielewicz, N. Krah, V. Patera, M. Pawlik-Niedźwiecka, I. Rinaldi, B. Rozwadowska-Bogusz, E. Scifoni, A. Skrzypek, F. Tommasino, A. Schiavi, P. Moskal

Investigations on Physical and Biological Range Uncertainties in Kraków Proton Beam Therapy Centre

Acta Phys. Pol. B 51, 9 (2020)

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Physical and biological range uncertainties limit the clinical potential of Proton Beam Therapy (PBT). In these proceedings, we report on two research projects, which we are conducting in parallel and which both tackle the problem of range uncertainties. One aims at developing software tools and the other at developing detector instrumentation. Regarding the first, we report on our development and pre-clinical application of a GPU-accelerated Monte Carlo (MC) simulation toolkit Fred. Concerning the letter, we report on our investigations of plastic-scintillator-based PET detectors for particle therapy delivery monitoring. We study the feasibility of Jagiellonian-PET detector technology for proton beam therapy range monitoring by means of MC simulations of the \(\beta ^+\) activity induced in a phantom-by-proton beams and present preliminary results of PET image reconstruction. Using a GPU-accelerated Monte Carlo simulation toolkit Fred and plastic-scintillator-based PET detectors, we aim at improving the patient treatment quality with protons.

full authors' list

A. Wrońska, R. Hetzel, J. Kasper, R. Lalik, A. Magiera, K. Rusiecka, A. Stahl

Characterisation of Components of a Scintillation-fiber-based Compton Camera

Acta Phys. Pol. B 51, 17 (2020)

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The next awaited breakthrough in proton therapy is the inclusion of the tools for online monitoring of beam range into clinical practice. Full, three-dimensional information on the deposited dose distribution can be obtained by means of prompt gamma imaging using Compton cameras. Large gamma detection efficiency and high-rate capacity can be achieved using detectors of high granularity made of a heavy scintillator. One of the possible design options is a stack of scintillating fibers. As the overall performance of such a camera depends on the position, time and energy resolution of the fibers, we investigate those properties both experimentally in measurements with a test bench as well as via Monte Carlo simulations. The obtained results point at LYSO:Ce as the best candidate for a sensitive material of a Compton camera of the discussed type.

full authors' list

T. Ishikawa, K. Aoki, H. Fujimura, H. Fukasawa, H. Fujioka, R. Hashimoto, Q. He, Y. Honda, T. Hotta, Y. Inoue, K. Itahashi, T. Iwata, S. Kaida, H. Kanda, J. Kasagi, A. Kawano, S. Kusawaki, H. Kawai, K. Maeda, S. Masumoto, Y. Matsumura, M. Miyabe, F. Miyahara, K. Mochizuki, S. Miyata, N. Muramatsu, A. Nakamura, K. Nawa, T. Nishi, S. Ohgushi, Y. Okada, H. Ohnishi, Y. Onodera, K. Ozawa, Y. Sakamoto, M. Sato, H. Shimizu, H. Sugai, K. Suzuki, R. Shirai, M. Tabata, Y. Tajima, S. Takahashi, Y. Taniguchi, A.O. Tokiyasu, Y. Tsuchikawa, H. Yamazaki, R. Yamazaki, C. Yoshida, H.Y. Yoshida

\(\eta N\) Scattering Parameters and Possible \(\eta 'd\) Bound State from \(\eta \) Photoproduction on the Deuteron

Acta Phys. Pol. B 51, 27 (2020)

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Two physics programs, determination of low-energy scattering parameters between the eta meson (\(\eta \)) and nucleon (\(N\)), and search for a possible bound state between the eta prime meson (\(\eta '\)) and deuteron, using \(\eta \) photoproduction from the deuteron target are conducted at the Research Center for Electron Photon Science (ELPH), Tohoku University. Among the two-body dynamics of the meson–nucleon systems, the \(\eta N\) interaction is not well-known although it has been found attractive. An experiment is carried out to determine the low-energy \(\eta N\) scattering parameters using a special kinematics. The energy and momentum of the emitted proton (\(p\)) are measured at 0 degrees for \(\eta \) photoproduction on the deuteron (\(d\)) at incident energies around 0.94 GeV, which gives the low relative momentum between \(\eta \) and neutron (\(n\)) in the final state. Low-energy \(\eta n\) scattering is likely to take place in this condition, and the scattering parameters can be determined from the differential cross section as a function of the \(\eta n\) invariant mass. The measurement is currently in progress to determine the real part of the \(\eta n\) scattering length. A possible \(\eta 'd\) bound state is theoretically predicted, and a structure corresponding to the state can be observed via the \(\gamma d\to \eta d\) reaction at incident energies around 1.2 GeV. In the case of backward \(\eta \) emission, the structure becomes prominent because a background contribution coming from quasi-free single-step \(\eta \) emission is highly suppressed. The \(\gamma d\to \eta d\) reaction has been also studied at ELPH below the incident energy of 1.15 GeV. The angular differential cross sections are determined at backward \(\eta \) emission angles. The tail of the corresponding peak is not observed, and the background level is much higher than predicted.

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

Acta Phys. Pol. B 51, 33 (2020)

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We report on the search for \(^{4}\hspace {-0.03cm}\)He–\(\eta \) and \(^{3}\hspace {-0.03cm}\)He–\(\eta \) mesic nuclei with WASA-at-COSY detection system. The description of the experimental method as well as recent status of the data analysis are presented.

full authors' list

Y.K. Tanaka, S. Bagchi, J. Benlliure, T. Dickel, V. Drozd, H. Ekawa, H. Fujioka, H. Geissel, F. Goldenbaum, C. Guo, E. Haettner, M.N. Harakeh, R.S. Hayano, S. Hirenzaki, C. Hornung, Y. Igarashi, N. Ikeno, K. Itahashi, M. Iwasaki, D. Jido, N. Kalantar-Nayestanaki, R. Kanungo, B. Kindler, R. Knöbel, D. Kostyleva, N. Kurz, N. Kuzminchuk, B. Lommel, Y. Ma, S.Y. Matsumoto, V. Metag, S. Minami, P. Moskal, I. Mukha, T. Nagae, H. Nagahiro, M. Nakagawa, H.J. Ong, H. Outa, S. Pietri, W.R. Plass, A. Prochazka, S. Purushothaman, C. Rappold, J. Ritman, J.L. Rodríguez-Sánchez, R. Ruber, O. Rundel, T.R. Saito, C. Scheidenberger, R. Sekiya, V. Serdyuk, H. Simon, B. Sitar, M. Skurzok, P. Strmen, B. Sun, I. Szarka, M. Takechi, I. Tanihata, S. Terashima, H. Weick, A. Yamamoto, J. Zhao

Spectroscopy of \(\eta ^{\prime }\)-mesic Nuclei with WASA at GSI/FAIR

Acta Phys. Pol. B 51, 39 (2020)

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We plan to conduct an experimental search for \(\eta ^\prime \)-mesic nuclei in order to investigate in-medium properties of the \(\eta ^\prime \) meson. A 2.5 GeV proton beam is employed to produce \(\eta ^\prime \)-mesic \(^{11}\)C nuclei with the \(^{12}\)C(\(p\),\(d\))\(\eta ^\prime \otimes ^{11}\)C reaction. Simultaneous measurements of the forward ejected deuterons and decay protons from \(\eta ^\prime \)-mesic nuclei will allow us to achieve high experimental sensitivity. The experiment will be performed at GSI by making full use of the fragment separator FRS and the WASA detector system. The plan of this proposed experiment is described.

Extracting \(\sigma _{\pi N}\) from Pionic Atoms

Acta Phys. Pol. B 51, 45 (2020)

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We discuss a recent extraction of the \(\pi N\) \(\sigma \) term \(\sigma _{\pi N}\) from a large-scale fit of pionic-atom strong-interaction data across the periodic table. The value thus derived, \(\sigma _{\pi N}^{\rm FG}=57\pm 7\) MeV, is directly connected via the Gell-Mann–Oakes–Renner expression to the medium-renormalized \(\pi N\) isovector scattering amplitude near threshold. It compares well with the value derived recently by the Bern–Bonn–Jülich group, \(\sigma _{\pi N}^{\rm RS}=58\pm 5\) MeV, using the Roy–Steiner equations to control the extrapolation of the vanishingly small near-threshold \(\pi N\) isoscalar scattering amplitude to zero pion mass.

The KLOE-2 Experiment at DA\(\Phi \)NE

Acta Phys. Pol. B 51, 55 (2020)

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The KLOE-2 experiment has finished its data-taking campaign at the DA\(\Phi \)NE collider, recording about \(5.5~\mathrm {fb^{-1}}\) of data. Together with the already collected events from the KLOE campaigns, the registered data represents the largest sample of \(\phi \)-mesons acquired in a \(\phi \)-factory. The article will cover the present status and plans of the experiment as well as the latest physics achievements of the collaboration.

Photoproduction of Mesons from Quasifree Nucleons

Acta Phys. Pol. B 51, 61 (2020)

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Recent results for photoproduction reactions of quasi-free nucleons are discussed mainly in view of the electromagnetic excitations of the neutron which cannot be studied in other ways. Such experiments are necessary in order to study the isospin degree of freedom in electromagnetic nucleon resonance excitations. In particular, experiments with the Crystal Ball/TAPS setup at the Mainz MAMI accelerator and the Crystal Barrel/TAPS setup at the Bonn ELSA accelerator are discussed. Both experiments use electromagnetic calorimeters which cover almost the full solid angle and can detect and identify photons from the decay of neutral mesons, recoil protons and neutrons and partly also charged pions. The complications from the Fermi motion of the bound nucleons and final-state interactions of the final-state particles will be discussed. Examples for the impact of the new data comprising absolute cross sections and polarization observables for single- and multiple-meson production reactions are given.

Critical Look at the Time–Energy Uncertainty Relations

Acta Phys. Pol. B 51, 71 (2020)

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We analyze the time–energy uncertainty relation postulated by Heisenberg and the derivation of the Mandelstam–Tamm time–energy uncertainty relation. The conclusion is that these relations cannot be considered as universally valid.

Modelling the Inverse Zeno Effect for the Neutron Decay

Acta Phys. Pol. B 51, 77 (2020)

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Beam- and trap-based methods find incompatible results for the lifetime of the neutron: the former delivers a value which is about \(8.7\pm 2.1\) s longer than the latter. Very recently (arXiv:1906.10024 [hep-ph]), it has been proposed that the inverse Zeno effect (IZE) could be responsible for the shorter lifetime in trap experiments. Here, we compare two different models of measurement, one obtained by ideal measurements at equal time intervals (sometimes called ‘bang–bang’) and by a continuous measurement: the IZE turns out to be in both cases very similar, showing that the results do not depend on the details of the measurement process.

Possible LENR Observation Due to Dineutron Formation as a Product of the \(^{159}\)Tb\((n,2n)^{158}\)Tb Nuclear Reaction

Acta Phys. Pol. B 51, 83 (2020)

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Possibility of low-energy nuclear reactions (LENR) occurrence is considered due to dineutron formation in the outgoing channel of a neutron-induced nuclear reaction on \(^{159}\)Tb. In the instrumental gamma-ray spectra of Tb sample irradiated with 6.85 MeV neutrons, we observed the surplus-induced activity of \(^{160}\)Tb/\(^{160}\)Dy in addition to \(^{160}\)Tb activity, originated from the \(^{159}\)Tb\((n,\gamma )^{160}\)Tb nuclear reaction. We assumed that accumulation of \(^{160}\)Tb/\(^{160}\)Dy activity results from strong processes via nuclear reactions at room temperature. The cross section for \(^{158}\)Tb\((d,\gamma ) ^{160}\)Dy is estimated as 44.5 b.

full authors' list

E. Milotti, K. Piscicchia, A. Amirkhani, S. Bartalucci, S. Bertolucci, M. Bazzi, M. Bragadireanu, M. Cargnelli, A. Clozza, R. Del Grande, L. De Paolis, J.-P. Egger, C. Fiorini, C. Guaraldo, M. Iliescu, M. Laubenstein, J. Marton, M. Miliucci, A. Pichler, D. Pietreanu, A. Scordo, H. Shi, D.L. Sirghi, F. Sirghi, L. Sperandio, O. Vazquez Doce, J. Zmeskal, C. Curceanu

New Concepts in Tests of the Pauli Exclusion Principle in Bulk Matter

Acta Phys. Pol. B 51, 91 (2020)

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The standard scheme of several tests of the Pauli Exclusion Principle in bulk matter — both in the experiment and in the subsequent data analysis — has long been based on the seminal paper by E. Ramberg, G.A. Snow [Phys. Lett. B 238, 438 (1990)]. The ideas exposed in that paper are so simple and immediate that they have long gone unchallenged. However, while some of the underlying approximations are still valid, other parts of the article must be reconsidered. Here, we discuss some new concepts that are related to the motion of the electrons in the test metal (the “target” of the experiment) and which have been recently studied in the framework of the VIP-2 Collaboration.

full authors' list

K. Piscicchia, A. Pichler, A. Amirkhani, S. Bartalucci, S. Bertolucci, M. Bazzi, M. Bragadireanu, M. Cargnelli, A. Clozza, R. Del Grande, L. De Paolis, J. Egger, C. Fiorini, C. Guaraldo, M. Iliescu, M. Laubenstein, J. Marton, M. Miliucci, E. Milotti, D. Pietreanu, A. Scordo, H. Shi, D.L. Sirghi, F. Sirghi, L. Sperandio, O. Vazquez Doce, J. Zmeskal, C. Curceanu

Testing the Pauli Exclusion Principle in the Cosmic Silence

Acta Phys. Pol. B 51, 97 (2020)

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The VIP Collaboration is performing high precision tests of the Pauli Exclusion Principle for electrons in the extremely low cosmic background environment of the Underground Gran Sasso Laboratories of INFN (Italy). The experimental technique consists in introducing a DC current in a copper conductor, searching for \(K_{\alpha }\) PEP-forbidden atomic transitions when the \(K\) shell is already occupied by two electrons. VIP set an upper limit on the PEP-violation probability \(\frac 12\beta ^2\lt \)4.7\(~\times ~10^{-29}\). The aim of the upgraded VIP-2 experiment is to improve this result at least by two orders of magnitude. The improved experimental setup and the results of a preliminary data analysis, corresponding to the the first run of the VIP-2 data taking (2016–2017), will be presented.

Nuclear Shapes and Symmetries Seen Through Measurement of Short Lifetimes

Acta Phys. Pol. B 51, 103 (2020)

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We have studied the signature and chiral symmetries in odd–odd nuclei \(^{126}\)I and \(^{130}\)La. In our earlier measurement, we observed signature splitting as well as inversion in \(^{126}\)I. The reduced transition probabilities \(B\)(M1) and \(B\)(E2) are the critical observables for various nuclear phenomena. To extract these observables, we have measured the nuclear lifetimes in picoseconds using the Doppler shift attenuation method (DSAM). From our results, we were able to find the nuclear shapes explaining both signature splitting and inversion in a definitive way. While the axial deformation remained the same (\(\beta \sim 0.13\)) below and above the inversion, the triaxiality (\(\gamma \)) changed from \(-10^\circ \) to \(+23^\circ \). We proposed a set of two bands — with similar energy levels and the same range of lifetimes values — to possess chiral symmetry, for which there is no clear evidence. Another nucleus of our interest, \(^{130}\)La, was found to possess weak chiral symmetry in literature. Our recent finding on lifetimes not only confirmed the earlier results, but also added some new data points near the bandhead.

An Advantage of “Upper Levels”

Acta Phys. Pol. B 51, 109 (2020)

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Hadronic atoms allow, in principle, to understand hadron–nucleon interactions just below thresholds. So far, the X-ray atomic transitions have offered atomic level shifts in the “lowest” of accessible atomic states. Level broadenings have been measured directly in these states and indirectly also in higher “upper” levels. Recent experimental progress allows to find level shifts also in some upper states. Such measurements are much easier to analyse as the levels are determined essentially by a single hadron–nucleon collision at a fairly well-determined subthreshold energy. Light anti-protonic and \(K\)-mesic atoms are discussed.

full authors' list

D. Bosnar, M. Bazzi, M. Cargnelli, A. Clozza, C. Curceanu, R. Del Grande, C. Guaraldo, M. Iliescu, M. Makek, J. Marton, M. Miliucci, L. De Paolis, K. Piscicchia, A. Scordo, D.L. Sirghi, F. Sirghi, M. Skurzok, M. Tüchler, J. Zmeskal, P. Žugec

Revisiting the Charged Kaon Mass

Acta Phys. Pol. B 51, 115 (2020)

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The precision of the charged kaon mass is an order of magnitude worse than the precision of the charged pion mass mainly due to two inconsistent measurements. We plan to improve this precision by determining the charged kaon mass with the requested accuracy in the measurements of X-ray transitions in kaonic atoms of selected solid targets with the HPGe detector at DA\(\Phi \)NE in Laboratori Nazionali di Frascati, Italy. The measurements will be performed in parallel with SIDDHARTA-2 measurements of X-ray transitions in gaseous targets. The status of the preparation of the measurements will be presented.

full authors' list

R. Del Grande, M. Bazzi, A.M. Bragadireanu, D. Bosnar, M. Cargnelli, C. Curceanu, L. De Paolis, L. Fabbietti, C. Fiorini, F. Ghio, C. Guaraldo, R.S. Hayano, M. Iliescu, M. Iwasaki, P. Levi Sandri, J. Marton, M. Miliucci, P. Moskal, S. Okada, K. Piscicchia, A. Ramos, A. Scordo, M. Silarski, D.L. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, O. Vazquez Doce, E. Widmann, S. Wycech, J. Zmeskal

Recent Experimental Results on the Low-energy \(K^-\) Interaction with Nucleons by AMADEUS

Acta Phys. Pol. B 51, 121 (2020)

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Recent results obtained by the AMADEUS Collaboration on the experimental investigation of the \(K^-\) low-energy interaction with light nuclei are summarised. The step 0 of AMADEUS consists in the analysis of the data collected at the DA\(\Phi \)NE collider with the KLOE detector during the 2004/2005 data taking campaign. The low momentum \(K^-\) particles (\(p_K \sim 127\) MeV/\(c\)) are absorbed in the light nuclei contained in the detector setup (H, \(^4\)He, \(^9\)Be and \(^{12}\)C) and hyperon–pion/hyperon–nucleons, emitted in the final state, are reconstructed. From the study of \({\mit \Lambda }\pi ^-\) and \({\mit \Lambda }p\) correlated production, important information on the \({\bar {K}}N\) strong interaction in the non-perturbative QCD regime are extracted.

full authors' list

J. Mareš, A. Cieplý, J. Hrtánková, M. Schäfer, B. Bazak, N. Barnea, E. Friedman, A. Gal

Calculations of \(\eta \) Nuclei, \(K^-\) Atoms and \(K^-\) Nuclei

Acta Phys. Pol. B 51, 129 (2020)

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We report on recent progress in theoretical studies of mesic atoms and nuclei performed by the Jerusalem–Prague Collaboration. We present calculations of \(\eta \) few-nucleon systems within the stochastic variational method. Further, we discuss \(K^-\) multinucleon interactions in the nuclear medium and demonstrate their role in kaonic atoms and nuclei. Finally, we introduce a microscopic model for \(K^- NN\) absorption in nuclear matter, developed very recently by J. Hrtánková and À. Ramos.

Bounds on Planck-scale Deformations of CPT from Lifetimes and Interference

Acta Phys. Pol. B 51, 135 (2020)

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Deformed relativistic kinematics, expected to emerge in a flat-spacetime limit of quantum gravity, predicts the Planck-scale violation of discrete symmeries. Momentum-dependent deformations of CPT are derived from the \(\kappa \)-deformed Poincaré algebra. Deformation of CPT symmetry leads to a subtle violation of Lorentz symmetry. This entails small but measurable phenomenological consequences as corrections to characteristics of time evolution: particle lifetimes or oscillations in two-particle states at high energy. We argue that using current experimental precisions on the muon lifetime, one can bound \(\kappa \gt 10^{14}\) GeV at the LHC energy and move this limit to \(10^{16}\) GeV at the Future Circular Collider. Weaker limits on deformation can be also obtained from interference of neutral mesons. In the case of \({B^0}\)s from \({\mit \Upsilon }\) decay, it amounts to \(\kappa \gt 10^8\) GeV at confidence level 99%.

Design of Novel Compact Detector Based on the Bismuth Germanate Scintillator and Silicon Photomultiplier for Ortho-positronium Physics

Acta Phys. Pol. B 51, 143 (2020)

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Positronium decay research is one of the sensitive probes to discover new physical phenomena. Because of the pairing system of electron (particle) and positron (antiparticle), we can study reactions which are forbidden by the Standard Model. In this study, we designed a novel compact detector for precise measurement of ortho-positronium (o-Ps) decay. Due to their compact size, silicon photomultipliers (SiPMs) are used for the photo-detection in the detector. The SiPM is well-known as a photodetector that can replace photomultiplier tube (PMT). In general, the size of the PMT is relatively large, so an SiPM was used to make compact trigger part for direct collection of scintillation light. In this research, the trigger part consists of plastic scintillator coupled directly to a single-channel SiPM to obtain the positron signal from the center of the detector. The trigger part is surrounded by the gamma-detection part to detect decay gammas in all directions. For dual readout, both sides of the Bismuth Germanate (BGO) scintillators are coupled with SiPMs. The designed frame and grid are used to support BGO scintillators and SiPMs. We obtained pretest data of a positron trigger signal and gamma-energy spectrum of \(^{22}\)Na and \(^{137}\)Cs radioactive sources for the novel compact detector. The detector will be used to study the C-parity violation, invisible, and rare decay search.

Towards Time Reversal Symmetry Test with o-Ps Decays Using the J-PET Detector

Acta Phys. Pol. B 51, 149 (2020)

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One of the features of the triplet state of positronium (ortho-positronium) atoms is its relatively longer lifetime when compared to the singlet states of positronium (para-positronium) atoms. The most probable decay of ortho-positronium is into three annihilation photons. In order to test the discrete symmetry using the time-reversal symmetry odd-operator, it is important to identify ortho-positronium decay. Identification of the decay of ortho-positronium atoms by measuring the positronium annihilation lifetime with the Jagiellonian-Positron Emission Tomograph (J-PET) is presented in this article.

Measurement of the CKM Angle \(\phi _3\) at Belle II

Acta Phys. Pol. B 51, 153 (2020)

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The precise measurement of the CKM angle \(\phi _3\) is important to further test the Standard Model description of CP violation. The small values of the branching fractions of the decays involved in the measurement limit the precision, hence a larger dataset has to be accumulated to improve the precision. The Belle II experiment at the SuperKEKB asymmetric-energy \(e^+e^-\) collider aims to collect 50 ab\(^{-1}\) of data, a factor of 50 more than that of its predecessor Belle. The accelerator has been successfully commissioned in 2016 and the first physics collisions were recorded in April 2018. The best sensitivity to \(\phi _3\) can be achieved by harnessing all possible final states of \(B \to D^{(*)}K^{(*)}\) decays. With the full dataset, Belle II is expected to achieve a precision of 1\(^{\circ }\) for the angle \(\phi _3\). The expected sensitivities and rediscoveries from 2018 data are presented here.

Melanoma Spheroids as a Model for Cancer Imaging Study

Acta Phys. Pol. B 51, 159 (2020)

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In contrast to standard 2D cell cultures, spheroids are three-dimensional (3D) models which can mimic natural conditions of cancer growth and metabolism. Their complex structure can be investigated and analyzed using fluorescence microscopy and micro-tomographic imaging (micro-CT) as a new technique. In this study, we show application of two different melanoma cell lines (WM115 and WM266) with different biological characteristics to form spheroids by a hanging drop method.

Feasibility of Ortho-positronium Lifetime Studies with the J-PET Detector in Context of Mirror Matter Models

Acta Phys. Pol. B 51, 165 (2020)

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We discuss the possibility to perform the experimental searches for invisible decays in the ortho-positronium system with the J-PET detector.

3D Reconstruction of Point-like Sources in a J-PET Scanner Using Total Variation Regularization

Acta Phys. Pol. B 51, 175 (2020)

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In this paper, we provide a comparative study of two image reconstruction algorithms for positron emission tomography (PET): a novel reconstruction method based on the concept of total variation (TV) regularization and a reference Time-Of-Flight filtered back-projection (TOF-FBP) technique. The methods are validated using experimental data of the Jagiellonian-PET (J-PET) scanner from measurement of six point-like sources. The spatial resolution of the J-PET scanner was determined by estimation of the full width half maximum in transverse and longitudinal directions of the point spread function at six positions inside the scanner volume. The comparison results show a superior spatial resolution of reconstructed images from the proposed TV-based method with respect to the TOF-FBP algorithm. Simultaneously, reconstruction time of the proposed technique was approximately 2.2 times shorter than required by the TOF-FBP method.

Estimation of Spatial Resolution for 3-layer J-PET Scanner Using TOF FBP Based on Event-by-Event Approach

Acta Phys. Pol. B 51, 181 (2020)

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We define a modified time-of-flight (TOF) filtered back projection (FBP) image reconstruction method, proposed for the Jagiellonian PET (J-PET) scanners of high temporal resolution. It is shown that TOF FBP could be represented as a sum of single-event reconstructions, each performed within a small volume in image space around the most likely position (MLP) of positronium annihilation, using TOF and filtering kernels. Such an approach, which resembles spherically-symmetric kernel density estimation (KDE), is highly scalable with the perspective of being employed for real time imaging. Using GATE (Geant4 Application for Tomographic Emission), we simulated the experiment conducted earlier for 1-mm spherical source put inside 3-layer 50-cm long J-PET prototype, eventually comparing the results. Estimated transverse spatial resolution of about 5–8 mm was achieved using TOF FBP for both simulations and real data, which is similar or better than obtained by KDE and non-TOF FBP from STIR software package. Axial resolution of \(\sim 20\) mm was estimated for the simulations using all reconstruction methods, which is consistent with temporal properties of tube photomultipliers utilised for the readout. Substantially worse result (\(\sim 35\) mm in axial direction for TOF FBP), obtained for the experiment, could be explained by unoptimised setup, data pre-selection and/or calibration issues.

Simulating the J-PET Detector on NVidia Ray Tracing Hardware

Acta Phys. Pol. B 51, 191 (2020)

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In this contribution, we present preliminary results of using graphic card with hardware support for ray tracing for physics simulation of a positron emission tomography (PET) scanner. On our simplistic setup, we notice an impressive (about 350 times) speedup compared to Geant4 code running on modern multicore CPU. We expect this speedup to come down but remain substantial also for other more complicated scenarios.

A Method for Time Calibration of PET Systems Using Fixed \(\beta ^+\) Radioactive Source

Acta Phys. Pol. B 51, 195 (2020)

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A method for the time calibration of the Time-of-Flight Positron Emmission Tomograph (TOF-PET) systems using fixed sources is described. Compared to the commercially used calibration methods, the new method gives a chance to run the calibration during the medical scan. Reduction of the time needed for calibration can increase the number of patients examined by PET. The process of calibration of the Jagiellonian Positron Emission Tomograph (J-PET) detector is shown as an example.

Shapes of the Free Volume Holes in Amorphous Polymers as Estimated by Positron Annihilation Lifetime Spectroscopy

Acta Phys. Pol. B 51, 201 (2020)

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Intermolecular spaces in polymer chains form the free volume, a useful concept to understand mechanical and transport properties of polymers. Quantification of the free volume can be obtained theoretically, using appropriate lattice models, as well as experimentally, through suitable probes. Among these, positronium (Ps) has become widespread due to the non-destructive character of the technique and the correlation between the Ps lifetime and the size of the holes. In most of the investigations, the cavity is approximated to a sphere. However, this may bias the evaluation of the free volume fraction. We show that by coupling results from Ps lifetime and specific volume measurement for amorphous polymers at equilibrium and the predictions of the Simha–Somcynsky equation of state, it is possible to shed light on dimensions of the holes as well as on their morphology.

Positron Scattering and Annihilation in Organic Molecules

Acta Phys. Pol. B 51, 207 (2020)

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In this paper, we address the problem of connecting positron lifetimes in liquids with collision cross sections in gases. We present the analyses of annihilation lifetime spectra of positrons in the liquid benzene, c-hexane, n-hexane, methanol and ethanol and calculations of scattering cross sections of positrons with benzene and c-hexane in the gas phase.

full authors' list

N. Zurlo, C. Amsler, M. Antonello, A. Belov, G. Bonomi, R.S. Brusa, M. Caccia, A. Camper, R. Caravita, F. Castelli, G. Cerchiari, D. Comparat, G. Consolati, A. Demetrio, L. Di Noto, M. Doser, M. Fanì, R. Ferragut, S. Gerber, M. Giammarchi, A. Gligorova, L. Gloggler, F. Guatieri, S. Haider, A. Hinterberger, A. Kellerbauer, O. Khalidova, D. Krasnický, V. Lagomarsino, C. Malbrunot, S. Mariazzi, V. Matveev, S.R. Müller, G. Nebbia, P. Nedelec, M. Oberthaler, E. Oswald, D. Pagano, L. Penasa, V. Petracek, F. Prelz, M. Prevedelli, B. Rienaecker, O.M. Røhne, A. Rotondi, H. Sandaker, R. Santoro, G. Testera, I.C. Tietje, V. Toso, T. Wolz, P. Yzombard, C. Zimmer

Calibration and Equalisation of Plastic Scintillator Detectors for Antiproton Annihilation Identification Over Positron/Positronium Background

Acta Phys. Pol. B 51, 213 (2020)

page 213 •


In this contribution, the system of the external plastic scintillator slabs of the AEgIS experiment is presented. These slabs, surrounding the superconducting magnet and operating at room temperature, are read out by photomultiplier tubes (PMTs) that are calibrated and equalised to be exploited as a whole detector with useful segmentation and redundancy to effectively detect single antiparticle annihilations. In particular, thanks to periodically recurring calibrations with cosmic rays and to a detailed study of the system in different operational conditions, including extensive Monte Carlo (MC) simulations, these scintillators can be used to identify antiproton annihilations over the constant background represented by cosmic rays and over the strongly time-dependent background due to positrons/positronium annihilations. By means of the sampling and digitization of the analog signal produced by each phototube and the consequent analysis of the amplitude of the recorded events, the energy released by the particle in the scintillator slab can be estimated consistently and with good accuracy. As a consequence, we are able to identify an amplitude range where positrons/positronium annihilations can be univocally excluded. This prerequisite allows us to exploit the array of external plastic scintillators for antihydrogen annihilations tagging.

Synthesis and Characterization of Plastic Scintillators for the Total-body J-PET Scanner

Acta Phys. Pol. B 51, 225 (2020)

page 225 •


The aim of the research was to develop a polystyrene scintillator for use in the novel time-of-flight Jagiellonian Positron Emission Tomography (J-PET) scanner being elaborated for the whole-body imaging. To achieve this goal, polystyrene-based plastic scintillators with the different chemical compositions were produced and characterized. Light output, decay time and emission spectra were measured to develop the best composition of the polystyrene scintillator.

Recent Progress and Prospects of the LEPS2/BGOegg Experiment at SPring-8

Acta Phys. Pol. B 51, 231 (2020)

page 231 •


The BGOegg experiment has extensively studied baryon resonances via single meson photoproduction off the proton. In parallel, \(\eta ^\prime \) mass inside the carbon nucleus has been intensively investigated in two complementary analyses. Recent results are described with the near future plans.

Hyperon Studies and Development of Forward Tracker for HADES Detector

Acta Phys. Pol. B 51, 239 (2020)

page 239 •


The HADES detector is a versatile detector specialized in dilepton and strangeness measurements at GSI/FAIR. It has been recently upgraded with an Electromagnetic Calorimeter (ECAL) and a new RICH photon detector. In the year 2020, an additional Forward Tracker (FT) will be installed. It will extend the acceptance of HADES at forward angles (\(0.5^\circ \) to \(7^\circ \)) essential for many reaction channels. The Straw Trackers are currently assembled by the Kraków and FZ Juelich teams, based on developments for the PANDA Forward Tracker. The increase of acceptance will play a significant role in studies of \(N(\pi )+N\) and \(p + A\) reactions, where this detector is essential for exclusive channels and PWA analysis of hyperon production and decays such as, for example, \({\mit \Lambda } \rightarrow p \pi ^-\), \({\mit \Lambda } ({\mit \Sigma }) \rightarrow {\mit \Lambda } e^+ e^-\) and \({\mit \Xi }^- \rightarrow {\mit \Lambda }\pi ^-\) (hyperon transition form factors). The feasibility studies of hyperon reconstruction together with performance of the tracking detectors in HADES framework are shown in this contribution.

Measurement of \(\pi ^0 \pi ^{+/-}\) Photoproduction off the Deuteron and Deuterated-butanol Targets

Acta Phys. Pol. B 51, 245 (2020)

page 245 •


Recent experiments using the Crystal Ball/TAPS setup at the MAMI accelerator in Mainz, Germany continue to study the properties and the excitation spectrum of the nucleon with meson photoproduction. Electromagnetic excitations of the proton and neutron are essential for understanding their isospin decomposition. The electromagnetic coupling of photons to protons is different than that of neutrons in certain states. Cross-section data alone is not sufficient for separating resonances, whereas polarization observables play a crucial role being essential in disentangling the contributing resonant and non-resonant amplitudes. Preliminary results of the polarization observable \(E\) of double \(\pi \) production measured with a polarized solid deuterated-butanol target are shown with comparison to predictions of recent analyses.

full authors' list

C. Curceanu, A. Amirkhani, A. Baniahmad, M. Bazzi, D. Bosnar, M. Bragadireanu, M. Carminati, M. Cargnelli, A. Clozza, L. De Paolis, R. Del Grande, L. Fabbietti, C. Fiorini, F. Ghio, C. Guaraldo, M. Iliescu, M. Iwasaki, P. Levi Sandri, J. Marton, M. Miliucci, P. Moskal, S. Niedźwiecki, S. Okada, D. Pietreanu, K. Piscicchia, A. Scordo, H. Shi, M. Silarski, D.L. Sirghi, F. Sirghi, M. Skurzok, A. Spallone, H. Tatsuno, M. Tüchler, O. Vazquez Doce, E. Widmann, J. Zmeskal

Kaonic Deuterium Measurement with SIDDHARTA-2 on DA\(\Phi \)NE

Acta Phys. Pol. B 51, 251 (2020)

page 251 •


The interaction of antikaons with nucleons and nuclei in the low-energy regime represents an active research field in hadron physics with still many important open questions. The investigation of light kaonic atoms is, in this context, a unique tool to obtain precise information on this interaction. The most precise kaonic hydrogen measurement to date, together with an exploratory measurement of kaonic deuterium, were carried out by the SIDDHARTA Collaboration at the DA\(\Phi \)NE electron–positron collider of LNF-INFN, by combining the excellent quality kaon beam delivered by the collider with new experimental techniques, as fast and precise Silicon-Drift X-ray detectors. The measurement of kaonic deuterium will be realized in the near future by SIDDHARTA-2, a major upgrade of SIDDHARTA.

Application of Multivariate Analysis in Search of the \(K_{\mathrm {S}} \rightarrow 3\pi ^0\) Decay in the KLOE Experiment

Acta Phys. Pol. B 51, 259 (2020)

page 259 •


According to the Standard Model, one of the purely CP-violating process is the never observed \(K_{\mathrm {S}} \rightarrow 3\pi ^0\) decay. The best upper limit on the branching ratio of this process BR(\(K_{\mathrm {S}} \rightarrow 3\pi ^0) \lt 2.6 \times 10^{-8}\) was obtained in the KLOE experiment using cut-based analysis. In this paper, we show preliminary results of an alternative approach to those studies using multivariate analysis methods.

Challenges in Radiotherapy Planning: Dose Verification in the Vicinity of the Border of Tissue-prosthesis Medium

Acta Phys. Pol. B 51, 263 (2020)

page 263 •


The success or failure of radiotherapy largely depends on the accuracy with which the dose will be delivered to a specific volume in the patient’s body. One of the problems associated with radiotherapy planning for patients with endoprostheses is the inaccuracy of the algorithm calculating the dose distribution in the treatment planning system for the area in the vicinity of the border of tissue–prosthesis medium. The aim of this study is verification of a planned dose on the border of hip prosthesis–acetabulum surface. At the examined energy — 6 MV — a dose results in decrease at the border of the medium, to achieve up to 10%. To verify this hypothesis, a water-filled phantom (soft tissue equivalent) was used with bone fragments (imitating hip joint) and metallic elements (hip joint endoprostheses) placed in a working stand. On acetabulum surface, thermoluminescent microdosimeters (TLD) based on lithium fluoride (LiF) was placed. The irradiation by medical linear accelerator was performed. The planned dose is higher compared with measured dose by approx. 9.8% (1.112 vs. 1.003 Gy for 2 Gy of fraction dose). It was confirmed that the treatment planning system overestimates the dose on the surface of acetabulum.

full authors' list

V. Soloviov, J. Golak, R. Skibiński, K. Topolnicki, Y. Volkotrub, H. Witała

Comparison of the JISP16 and the AV18 Forces-based Predictions for the Differential Cross Section and the Nucleon Analysing Power in \(d(n,nn)p\) Reaction

Acta Phys. Pol. B 51, 269 (2020)

page 269 •


The JISP16 nucleon–nucleon potential has been applied to explore the nucleon-induced deuteron breakup process at the incoming nucleon laboratory energy \(E=65\) MeV. We have found that the JISP16 model generally gives predictions for the differential cross section and the nucleon analysing power, which are similar to the ones obtained with the standard realistic nucleon–nucleon AV18 potential. However, there are some regions of the phase space, for which the cross section and the analysing power differ by approximately 50\(\%\). These kinematical configurations could be used to refit the JISP16 potential parameters.

Correlations Among Observables in Two- and Three-nucleon Systems

Acta Phys. Pol. B 51, 273 (2020)

page 273 •


We study the elastic nucleon–deuteron scattering process at incoming-nucleon laboratory energies up to \(E =200\) MeV working within the formalism of Faddeev equations. We focused here on the computation and systematic analysis of the correlation coefficients among various observables in nucleon-nucleon and nucleon–deuteron elastic scattering. As a result, we obtained pairs of correlated/uncorrelated observables or sets of very weakly correlated observables. The knowledge, if some observables are or are not correlated, would impact future methods of fixing free parameters of the two- and many-body potentials, and could possibly help determine observables which should be measured to increase the precision of potential parameters’ determination.

Design and Testing of a New Scintillation Probe for the PAL Spectrometry — Part I

Acta Phys. Pol. B 51, 277 (2020)

page 277 •


A new version of measuring probe for PAL spectrometry was designed and tested. Unlike commercial scintillation heads, silicon photomultipliers (SiPMs) were used as scintillation light detectors. The tests were carried out with two types of SiPMs (KETEK and ONSemi) and various scintillation materials, such as LYSO, BaF\(_2\) and BC412.

Development of J-PEM for Breast Cancer Detection and Diagnosis Using Positronium Imaging

Acta Phys. Pol. B 51, 281 (2020)

page 281 •


The purpose of the presented investigations is to design, construct and establish the characteristic performance of the Jagiellonian Positron Emission Mammography (J-PEM), being designed for the detection and diagnosis of breast cancer. Its construction is based on a novel idea of PET tomography based on plastic scintillators and wavelength shifter (WLS), and a new concept of positronium imaging. We have prepared a simulation program based on Monte Carlo methods for optimizing the geometry and material of the J-PEM prototype. Here, we present the first results from the simulations and a brief review of the state of art of breast imaging modalities and their characteristics motivating our investigation.

Construction of the Vacuum Chambers for J-PET Experiments with Positron Annihilation

Acta Phys. Pol. B 51, 293 (2020)

page 293 •


Vacuum chambers are necessary for the physics experiments planned to be carried out with the use of the J-PET detector. Two chambers manufactured and used for particular runs of experiments had generally cylindrical shapes, while the radioactive source was placed in the center of each chamber. The highly porous material, used as a target in which positrons/positronium atoms annihilate, was placed in the immediate vicinity of the source. Such orientation ensures the axially symmetrical response of J‑PET scintillators and allows to carry out correct calibration. The variation of material used for manufacturing of the chambers (aluminum/plastic), allows to observe the detector response with various rates of absorption and scattering of annihilation quanta. Such determination is necessary for proper analysis of multi-quanta annihilation, which will be needed for planned experiments.

Discovery of CP Violation in Charm Decays at the LHCb Experiment and Prospects for Run 3 and Run 4

Acta Phys. Pol. B 51, 301 (2020)

page 301 •


CP violation in decays of charm hadrons has been recently observed for the first time. The measured value of asymmetry differed from zero by more than five standard deviations. For further research of the CP asymmetry using the charm baryon decay modes, especially \({\mit \Xi }_{c}\), a new approach using the Kernel Density Estimation may prove useful. Its sensitivity has been tested on Monte Carlo samples with and without CP asymmetries. Further studies will be held to enhance its performance.

GATE Simulation Study of the 24-module J-PET Scanner: Data Analysis and Image Reconstruction

Acta Phys. Pol. B 51, 309 (2020)

page 309 •


The Jagiellonian Positron Emission Tomograph (J-PET) is a novel PET device that, in contrast to commercial PET scanners, is based on plastic scintillator strips. Modular J-PET is the latest prototype that consists of 24 modules arranged in a cylinder. In this study, 6 point-like sources defined in the NEMA spatial resolution standard were simulated twice with total activities of 60 kBq and 60 MBq, respectively. Results of simulations were processed with the GOJA software and reconstructed with the QETIR package.

Laser Peened Austenitic Stainless Steel Studied by Positron Annihilation Spectroscopy

Acta Phys. Pol. B 51, 317 (2020)

page 317 •


The paper presents preliminary results of positron annihilation spectroscopy studies of the subsurface zone created by Laser Shock Peening (LSP) in medical grade AISI 316L stainless steel. The positron lifetime measurements and variable energy positron beam were used to analyse LSP samples.

Measurement of the Charge Asymmetry for the \(K_{\mathrm {S}} \rightarrow \pi e \nu \) Decay and Test of CPT Symmetry with the KLOE Detector

Acta Phys. Pol. B 51, 323 (2020)

page 323 •


Studies presented in this paper were conducted using 1.63 fb\(^{-1}\) of integrated luminosity collected by the KLOE experiment. The excellent time resolution of the electromagnetic calorimeter and the very good accuracy on both momentum and vertex reconstruction of the tracking system allow to reconstruct about \(7\times 10^4\) \(K_{\mathrm {S}}\rightarrow \pi ^{\pm }e^{\mp }\nu \) decays. The measured value of the charge asymmetry for this decay is \(A_{\mathrm {S}} = (-4.9 \pm 5.7_{\mathrm {stat}} \pm 2.6_{\mathrm {syst}}) \times 10^{-3}\), which is almost twice more precise than the previous KLOE result. The combination of these two measurements gives \(A_{\mathrm {S}} = (-3.8 \pm 5.0_{\mathrm {stat}} \pm 2.6_{\mathrm {syst}}) \times 10^{-3}\) and, together with the asymmetry of the \(K_{\mathrm {L}}\) semileptonic decay, provides significant tests of the CPT symmetry. The obtained results are in agreement with CPT invariance.

full authors' list

T. Ishikawa, H. Fujimura, H. Fukasawa, R. Hashimoto, Q. He, Y. Honda, T. Iwata, S. Kaida, H. Kanda, J. Kasagi, A. Kawano, S. Kuwasaki, K. Maeda, S. Masumoto, M. Miyabe, F. Miyahara, K. Mochizuki, N. Muramatsu, A. Nakamura, K. Nawa, S. Ogushi, Y. Okada, Y. Onodera, K. Ozawa, Y. Sakamoto, M. Sato, H. Shimizu, H. Sugai, K. Suzuki, Y. Tajima, S. Takahashi, Y. Taniguchi, Y. Tsuchikawa, H. Yamazaki, R. Yamazaki, H.Y. Yoshida

Non-strange Dibaryons Studied in Coherent Double Neutral-meson Photoproduction on the Deuteron

Acta Phys. Pol. B 51, 329 (2020)

page 329 •


We have investigated the \(\gamma d\to \pi ^0\pi ^0d\) reaction to study dibaryon resonances. The total cross section as a function of the \(\gamma d\) center-of-mass energy shows resonance-like behavior peaked at around 2.47 and 2.63 GeV. The measured angular distribution of deuteron emission is rather flat, which cannot be reproduced by kinematics for quasi-free \(\pi ^0\pi ^0\) production with deuteron coalescence. A clear peak is observed at 2.14 GeV in the \(\pi ^0d\) invariant-mass distributions. The present work shows a sequential process \(\gamma d\to R_{\rm IS} \to \pi ^0 R_{\rm IV} \to \pi ^0\pi ^0d\) is dominant with two 2.47- and 2.63-GeV isoscalar dibaryons (\(R_{\rm IS}\)) and a 2.14-GeV isovector dibaryon (\(R_{\rm IV}\)).

Nuclear Deformation Effects to the Formation Cross Section of \(\eta '\)-mesic Nucleus

Acta Phys. Pol. B 51, 333 (2020)

page 333 •


We study the nuclear deformation effects to the formation spectrum of the \(\eta '\)-mesic nucleus theoretically. We find that the deformation effects could significantly change the spectrum shape and the effects should be considered appropriately.

full authors' list

K. Kisielewicz, K. Rawojć, M. Tulik, A. Dziubińska, L. Mazur, B. Kiełtyka, J. Łukaszewska, D. Najberg-Pierzchała, M. Gądek, E. Łuczyńska, Z. Woś, J. Miszczyk, S. Heinze, A. Dziecichowicz

Comparison of Dose Received During Breast Cancer Diagnosis Performed by Using Two Different Imaging Modalities: Contrast-enhanced Spectral Mammography and Full-field Digital Mammography

Acta Phys. Pol. B 51, 339 (2020)

page 339 •


Breast cancer (BC) is strongly related to woman age. 95% of all BC cases affect women over 40 years of age. Mammography and ultrasound are the main diagnostic tools. Women with suspicious changes are referred to additional examination i.e. Magnetic Resonance Imaging (MRI). High progress in the development of new mammography devices i.e. new flat panel detectors, compression paddles, spectral modes and new type of X‑ray tubes gives a variety of new diagnostic modules available for clinical use. The aim of this study was to compare doses given to the patients during full-field digital mammography with doses obtained from dual-energy contrast-enhanced spectral mammography (CESM). The comparison of entrance surface air kerma (ESAK) and average glandular dose (AGD) values for both options are discussed in the paper. Our preliminary data show that CESM might be a new diagnostic tool allowing an accurate detection of malignant breast lesions, giving results similar to those received from MRI. However, due to higher levels of radiation exposure during CESM, one should take risk factor into account. Each method has its own benefits with respect to specific applications which are further discussed.

full authors' list

K. Kisielewicz, K. Rawojć, A. Dziubińska, L. Mazur, B. Kiełtyka, D. Najberg-Pierzchała, M. Gądek, E. Łuczyńska, Z. Woś, S. Heinze, A. Dziecichowicz

Patient Dose Evaluation in Digital Breast Tomosynthesis

Acta Phys. Pol. B 51, 345 (2020)

page 345 •


Breast cancer (BC), a most common women malignancy, is often screened by mammography (MG) and ultrasound exams. Patients, for whom MG study does not give a clear answer or is impossible to interpret, are often further diagnosed by additional modalities. MRI is currently regarded as the most sensitive BC detection technique. On the other hand, it is limited by higher costs and lower availability and it provides higher rates of false positive cases. Relatively new method applied in breast neoplasms detection is digital tomosynthesis (Digital Breast Tomosynthesis — DBT, 3D imaging), introduced in 2011. The aim of this study was to compare doses given to the patients during conventional digital mammography with doses obtained from digital breast tomosynthesis. The comparison of average glandular dose (AGD) values for both options are discussed in the paper, respectively. Data from 219 patients have been collected and analyzed in tomosynthesis mode. AGD for tomosynthesis was 30–60% higher depending on breast thickness, comparing with 2D examination (i.e. 1.36 vs. 1.75 mGy for 63–72 mm compressed breast thickness). The diagnostic benefits of 3D imaging compensate for the risk associated with increasing the glandular dose in patients, especially in groups where the breast thickness after compression does not exceed 63 mm.

Recent Results of the CKM Angle \(\gamma \) Measurement at the LHCb and Prospects for Run 3 and Run 4

Acta Phys. Pol. B 51, 351 (2020)

page 351 •


The Standard Model (SM) description of the CP violation can be tested by over-constraining the angles of the Unitary Triangle. Discrepancies between precise measurements of the Cabibbo–Kobayashi–Maskawa (CKM) angle \(\gamma \) in the tree-level and loop-dominated processes might provide evidence of physics beyond the Standard Model. Recent results of the CKM angle \(\gamma \) with special attention to decays from the \(B \rightarrow D K\) family and preliminary background studies for \(B^0_s \rightarrow D_s^* K^*\) decays are presented in this paper.

Reconstruction of the NEMA IEC Body Phantom from J-PET Total-body Scanner Simulation Using STIR

Acta Phys. Pol. B 51, 357 (2020)

page 357 •


The total-body positron emission tomography (PET) with its large field of view (FOV) brings many benefits i.a. scan time reduction, increase of the sensitivity and simultaneous imagining for multiple organs. However, introduction of oblique lines of response (LORs) can result in image quality degradation. In this paper, we provide a study of such effects based on simulations of two-meter long J-PET scanner. Simulation of a point source shows a degradation of the axial resolution due to parallax effect by factor of four. However, based on a simulation of the NEMA IEC-BODY phantom, we do not observe a significant reduction of image quality.

Search for the \(^{3}\)He–\(\eta \) Bound State via \(pd \to pd \pi ^{0}\) Reaction

Acta Phys. Pol. B 51, 361 (2020)

page 361 •


We present status and perspectives of the search for the \(\eta \)-mesic helium nuclei via \(pd\to pd\pi ^{0}\) reaction with the WASA-at-COSY. In this report, the experimental method is shortly described and preliminary excitation function is presented.

Search for the Charge Symmetry Forbidden Decays of Electron–Positron Bound State Using the J-PET Detector

Acta Phys. Pol. B 51, 365 (2020)

page 365 •


The Jagiellonian Positron Emission Tomograph (J-PET) is a multi-purpose device built out of plastic scintillators. With large acceptance and high angular resolution, it is suitable for the studies of various phenomena such as discrete symmetries in decay of positronium atom or entangled states of photons as well as medical imaging. J-PET enables the measurement of momenta together with photon polarization related observables. Large acceptance and high granularity of the J-PET detector enables measurement of ortho-positronium decays into three photons in the whole phase space. In this paper, we present the search of the C-forbidden decays of positronium with the J-PET detector.

Controlling Systematic Uncertainties in Search for an EDM in the Storage Ring

Acta Phys. Pol. B 51, 373 (2020)

page 373 •


Spin tracking simulations for the planned experiment for measurement of EDM in storage ring for fundamental particles are very important in order to check how to control the systematic uncertainties. Keeping in mind the sensitivity of experiment, various effects are important to be considered. One of the major factors are the interaction of particle’s magnetic dipole moment (MDM) and electric quadrupole moment (EQM) with electromagnetic field gradients that can produce an effect of a similar order of magnitude as that expected for EDM. Spin tracking is done by introducing realistic fields allowing to determine their gradients and extending the T-BMT equation in order to evaluate the real effect of interaction of MDM and EQM with field gradients. It is shown that the effects induced by field gradients do not affect the determination of EDM, but allow precise determination of magnitude of systematic uncertainty.

full authors' list

Z. Bura, K. Dulski, E. Kubicz, P. Małczak, M. Pędziwiatr, M. Szczepanek, E.Ł. Stępień, P. Moskal

Studies of the Ortho-positronium Lifetime for Cancer Diagnostics

Acta Phys. Pol. B 51, 377 (2020)

page 377 •


Positron Annihilation Lifetime Spectroscopy (PALS) is a technique based on the analysis of the lifetime of positronium emitted from implanted or delivered positronium donors. This technique employs the lifetime and intensity dependence on the structure of analyzed material. Due to this specific features, PALS might be used in further research protocols and clinical studies for cancer diagnostic purposes. This article reports the progress in the study design, main objectives of the study, protocols of measurements and data analysis and further perspective of this study. The main goal of this work was to show the effectiveness of this method and progress in its development. For this purpose, colorectal cancer was examined.

full authors' list

O. Melikhova, J. Čížek, P. Hruška, M.O. Liedke, M. Butterling, A. Wagner, M. Novotný, J. More-Chevalier

Study of Nanoscopic Porosity in Black Metals by Positron Annihilation Spectroscopy

Acta Phys. Pol. B 51, 383 (2020)

page 383 •


Black and smooth Al films were characterized by the variable energy positron annihilation spectroscopy (VEPAS). It was found that in smooth films positronium (Ps) is formed on the surface only while in black metal films, it is formed also in nanoscopic pores inside the film. The mean pore size increases from the substrate to the surface due to increasing film roughness.

The First Application of the Chiral SMS Nucleon–Nucleon Interaction to the Deuteron Photodisintegration Process

Acta Phys. Pol. B 51, 389 (2020)

page 389 •


A chiral nucleon–nucleon potential has been recently further improved by employing a semi-local regularization in momentum space. As such, a potential has not been tested yet in an electromagnetic process, we apply it to the deuteron photodisintegration reaction with photon energies up to 100 MeV. Results of our calculations show a weaker dependence of a selected observable on the cut-off parameter and a faster convergence with respect to the chiral expansion order compared to older chiral potentials.

full authors' list

Ł. Syrocki, K. Słabkowska, M. Polasik, E. Węder, J. Rzadkiewicz, J.J. Carroll, C.J. Chiara

Studies of Optimal Conditions for Depletion of the \(^{110m}\)Ag Isomer via Nuclear Excitation by Electron Capture in a Beam-based Scenario

Acta Phys. Pol. B 51, 393 (2020)

page 393 •


We have performed a theoretical study concerning the analysis of the nuclear and atomic resonance conditions for \(^{110m}\)Ag isomer depletion through nuclear excitation by electron capture (NEEC). This analysis includes selection of the relevant fusion–evaporation reaction for \(^{110m}\)Ag isomer production and calculation of its cross section. Moreover, using the relativistic multiconfiguration Dirac–Fock method, calculations of the dependence of the energy released by electron capture into specific atomic subshells (\(N\), \(O\) and \(P\)) on the \(^{110m}\)Ag ion charge state have been carried out. In addition, the potentially possible kinetic energy of the NEEC resonance and predictions of the mean equilibrium charge state for the \(^{110m}\)Ag recoil ions as a function of its kinetic energy in the C stopping medium have been evaluated.

The FAZIA Detector as a Powerful Tool to Investigate Isospin Dynamics Around 40 MeV/\(u\)

Acta Phys. Pol. B 51, 399 (2020)

page 399 •


The FAZIA (Forward \(A\) and \(Z\) Identification Array) is a charge- and mass-sensitive charged particle detector used mainly to investigate the evolution of isospin (\(N/Z\)) effects in heavy-ion collisions for excited quasi-projectiles (QP) formed in semi-peripheral collisions at Fermi energies. In the following text, there is a general discussion about FAZIA and plans for analysis and comparison of the data from \(^{48}\)Ca + \(^{27}\)Al at 40 MeV/\(u\) system from the recent FAZIA experiment performed at LNS (Catania) in February 2018 with the first assembled 6 FAZIA blocks.

Uncertainty of RBE Model in Proton Radiotherapy Based on \(\frac {\alpha }{\beta }\) Ratio and Linear Energy Transfer

Acta Phys. Pol. B 51, 405 (2020)

page 405 •


In proton radiotherapy, a constant value of the relative biological effect (RBE) is assumed in clinical practice. Many studies based on in vitro and in vivo experiments suggest that variable proton RBE would improve the treatment outcome. Several models based on data extracted from in vitro experiments relate RBE variations with linear energy transfer (LET) and \(\frac {\alpha }{\beta }\) ratio in linear-quadratic (LQ) model. In our study, we selected Wedenberg model and extended it by adding prediction of RBE statistical distribution. Such an approach propagates uncertainties of in vitro cell experiments into higher level quantities such as RBE and dose-volume-histograms. The model outcome was a skew RBE distribution. The mean value of predicted RBE distribution is in agreement of few percent with the original Wedenberg model. The introduced model predicts RBE distribution which enables more precise inter-model testing than a simple comparison of mean values.

Water Equivalence of Various 3D Printed Materials for Proton Therapy — Monte Carlo Simulation, Treatment Planning Modelling and Validation by Measurements

Acta Phys. Pol. B 51, 409 (2020)

page 409 •


In this article, Water Equivalent Ratio (WER) of three selected materials: Polylactic Acid (PLA), Acrylonitrilebutadiene Styrene (ABS) and Polyethylene Terephthalate Glycol (PETG) — commonly used in additive manufacturing technology — was measured on 60 MeV proton beam and compared with values predicted by Treatment Planning System (TPS) and Monte Carlo (MC) simulation. The agreement within 0.02–2.98% and 0.11–6.46% was found between results obtained from the measurement with comparison to the MC simulation and TPS, respectively. It was concluded that 3D printable materials can be safely used in proton therapy.

Application of 3D Model of Cancer Cells in Research on the Effectiveness of BNCT in the Treatment of Melanoma

Acta Phys. Pol. B 51, 413 (2020)

page 413 •


Melanoma is one of highly aggressive kinds of skin cancer with a metastatic potential. Currently, melanoma treatment has been improved by a combination of therapies with targeted kinase inhibitors and immunotherapies, with radiation therapy (RT) reserved to the most advanced melanoma stage. Among different RT options, the Boron Neutron Capture Therapy (BNCT) is a modality which selectively destroys tumor cells leaving healthy ones almost intact. Its therapeutic effect depends mainly on the boron concentration in a cancer. Therefore, there is a need to find a ligand which transfers sufficient amount of boron to cancer cells and study their potential therapeutic activity in preclinical studies. Spheroids, which are 3D cell models are proposed to test nucleic acids as a boron carrier for BNCT to mimic 3D structure and microenvironment of cancer.

Application of Silicon-polymer Composite Varistors to Protect Sensitive Medical Imaging Circuits and Performing Better Voltage Bias for SiPMs

Acta Phys. Pol. B 51, 421 (2020)

page 421 •


Nowadays, Silicon photomultipliers (SiPM) become a reasonable choice for Time-of-Flight Positron Emission Tomography (TOF-PET). To achieve the best performance of SiPMs, it is necessary to adjust a suitable voltage bias. In this article, we are using varistors which protect SiPM from voltage fluctuations. The silicon-polymer composite varistors prepared using hot press method have been investigated. Research on (current-voltage) characteristics of samples shows that by increasing silicon content in the mixture, the breakdown voltage decreases from 110 V to 70 V. The results also show that increasing silicon content decreases the potential barrier height from 0.29 eV to 0.26 eV, however, leakage current increases. Increasing silicon content increases nonlinear coefficient from 4.1 to 4.8. Using these techniques gives us ability to produce suitable surge protector for medical imaging modalities.

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