Regular Series

Vol. 51 (2020), No. 3, pp. 517 - 904

XXXVI Mazurian Lakes Conference on Physics Probing Fundamental Laws of Nature with Exotic Nuclei and Atoms



Virtual Unfolding of Folded Papyri

Acta Phys. Pol. B 51, 541 (2020)

page 541 •


One of the best sources of information about our cultural origin are written texts. Often, texts are hidden, sometimes erased, faded away, or written over, sometimes not easily accessible in rolled or folded documents. Due to recent improvements in sensitivity and resolution, spectacular disclosures of rolled hidden texts were possible by X-ray tomography, most of them made out of parchment. However, revealing text on folded manuscripts is even more challenging. Due to the fragile condition of fragments, manual unfolding is often too risky, as it can lead to the total loss of the document. X-ray tomography allows for virtual unfolding and enables non-destructive access to hidden texts. Here, the progress in virtual unfolding is reviewed, focusing on papyri from Elephantine Island near Aswan. The project is a part of the European Research Council’s starting grant ELEPHANTINE. Results on unfolding ancient papyrus packages from the papyrus collection of the Musée du Louvre and of the Ägyptisches Museum und Papyrussammlung, Berlin are discussed.

Constraints on the High-density Equation of State from the Gravitational-wave Signal of Neutron Star Mergers

Acta Phys. Pol. B 51, 551 (2020)

page 551 •


We present a constraint on neutron star radii, which is derived from a multi-messenger interpretation of GW170817, the first unambiguously detected neutron star merger event. The optical and infrared emission of the electromagnetic counterpart was relatively bright compared to simulation results. We argue that the remnant of the merger did not undergo a prompt collapse to a black hole because this results in relatively dim electromagnetic transients. If this interpretation is correct, neutron star radii cannot be too small to prevent direct collapse. We find that the radius of a nonrotating neutron star with a mass of 1.6 \(M_\odot \) should be larger than about 10.7 km excluding very soft nuclear matter. We emphasize the potential of future multi-messenger observations to which the same arguments and procedures can be applied, and which can then yield more stringent radius limits. Furthermore, a prompt collapse event can place an upper bound on the maximum mass of nonrotating neutron stars.

full authors' list

P.G. Thirolf, B. Seiferle, L. v.d. Wense, I. Amersdorffer, D. Moritz, J. Weitenberg

‘Phase Transition’ in the ‘Thorium-Isomer Story’

Acta Phys. Pol. B 51, 561 (2020)

page 561 •


Given the drastic progress achieved during recent years in our knowledge on the decay and nuclear properties of the thorium isomer \(^{229m}{\mathrm {Th}}\), the focus of research on this potential nuclear clock transition will turn in the near future from the nuclear physics driven ‘search and characterization phase’ towards a laser physics driven ‘consolidation and realization phase’. This prepares the path towards the ultimate goal of the realization of a nuclear frequency standard, the ‘nuclear clock’. This article briefly summarizes our present knowledge, focusing on recent achievements, and points to the next steps envisaged on the way towards the nuclear clock.

full authors' list

V. Lagaki, P. Fischer, H. Heylen, F. Hummer, S. Lechner, S. Sels, F. Maier, P. Plattner, M. Rosenbusch, F. Wienholtz, R.N. Wolf, W. Nörtershäuser, L. Schweikhard, S. Malbrunot-Ettenauer

Stray-light Suppression for the MIRACLS Proof-of-principle Experiment

Acta Phys. Pol. B 51, 571 (2020)

page 571 •


The Multi-Ion Reflection Apparatus for Collinear Laser Spectroscopy (MIRACLS), currently under development at ISOLDE/CERN, aims to combine the high resolution of fluorescence-based collinear laser spectroscopy (CLS) with a high sensitivity. This will be achieved by confining 30-keV ion bunches in a Multi-Reflection Time-of-Flight (MR-ToF) device which allows laser spectroscopic probing for several thousand times. An MR-ToF setup operating at \(\sim 1.5\) keV beam energy has been adapted for a proof-of-principle experiment. Thus, efforts had to be undertaken to reduce the laser stray light as the leading source of background of this apparatus, not originally designed for CLS. These measures enabled CLS of \(^{24,26}{\mathrm {Mg}}^{+}\) ions in single-path mode, i.e. without ion trapping, which is the reference point to gauge the gain in sensitivity of the MIRACLS technique.

full authors' list

J. Giovinazzo, T. Goigoux, B. Blank, P. Ascher, M. Gerbaux, S. Grévy, T. Kurtukian-Nieto, C. Magron, P. Doornenbal, N. Fukuda, N. Inabe, G.G. Kiss, T. Kubo, S. Kubono, S. Nishimura, H. Sakurai, Y. Shimizu, C. Sidong, P.-A. Söderström, T. Sumikama, H. Suzuki, H. Takeda, P. Vi, J. Wu, D.S. Ahn, J. Agramunt, A. Algora, V. Guadilla, A. Montaner-Piza, A.I. Morales, S.E.A. Orrigo, B. Rubio, Y. Fujita, M. Tanaka, W. Gelletly, P. Aguilera, F. Molina, F. Diel, D. Lubos, G. de Angelis, D. Napoli, C. Borcea, A. Boso, R.B. Cakirli, E. Ganioglu, J. Chiba, D. Nishimura, H. Oikawa, Y. Takei, S. Yagi, K. Wimmer, G. de France, S. Go, B.A. Brown

Two-proton Radioactivity: the Interesting Case of \(^{67}\)Kr and Further Studies

Acta Phys. Pol. B 51, 577 (2020)

page 577 •


We report on the observation of \(^{67}\)Kr that has been produced in an experiment performed at the RIKEN/BigRIPS facility. The two-proton decay of \(^{67}\)Kr has been evidenced and this nucleus is thus the fourth observed long lived ground-state two-proton emitter, after \(^{45}\)Fe, \(^{48}\)Ni and \(^{54}\)Zn. In addition, the decay of several isotopes in the mass region has been investigated. While for previous cases of two-proton radioactivity, the theoretical models could reproduce the measured data, this is not the case anymore for \(^{67}\)Kr. Two interpretations have been proposed to explain this discrepancy: a transition between real two-proton and sequential decay or the influence of deformation. These hypotheses will be tested in future experiments by measuring the angular and energy correlations of the emitted protons.

full authors' list

A. Vitéz-Sveiczer, A. Algora, A.I. Morales, B. Rubio, G.G. Kiss, G. de Angelis, F. Recchia, S. Nishimura, J. Agramunt, V. Guadilla, A. Montaner-Pizá, S.E.A. Orrigo, A. Horváth, D. Napoli, S. Lenzi, A. Boso, V.H. Phong, J. Wu, P.-A. Söderström, T. Sumikama, H. Suzuki, H. Takeda, D.S. Ahn, H. Baba, P. Doornenbal, N. Fukuda, N. Inabe, T. Isobe, T. Kubo, S. Kubono, H. Sakurai, Y. Shimizu, S. Chen, B. Blank, P. Ascher, M. Gerbaux, T. Goigoux, J. Giovinazzo, S. Grévy, T. Kurtukián Nieto, C. Magron, W. Gelletly, Zs. Dombrádi, Y. Fujita, M. Tanaka, P. Aguilera, F. Molina, J. Eberth, F. Diel, D. Lubos, C. Borcea, E. Ganioglu, D. Nishimura, H. Oikawa, Y. Takei, S. Yagi, W. Korten, G. de France, P. Davies, J. Liu, J. Lee, T. Lokotko, I. Kojouharov, N. Kurz, H. Shaffner

Studying the Exotic Decay \(^{70}\)Kr \(\rightarrow {}^{70}\)Br

Acta Phys. Pol. B 51, 587 (2020)

page 587 •


Beta-decay of the very neutron-deficient Kr isotope, \(^{70}\)Kr, was studied at RIKEN-RIBF using the EURICA cluster array. The experiment significantly increased our knowledge of the beta-decay of this isotope. Namely, 16 new \(\gamma \)-ray transitions were identified and the half-life was derived from time correlations of the beta particles (\(t_{1/2}^{i \beta }=(44.99\pm 0.16)\) ms) and from the decay curves of the observed \(\gamma \)-ray transitions (\(t_{1/2}^{i \beta \gamma }=(45.16\pm 0.71)\) ms), respectively.

Properties of Spin-polarized Impurities — Ferrons, in the Unitary Fermi Gas

Acta Phys. Pol. B 51, 595 (2020)

page 595 •


A new excitation mode has been predicted to exist in the unitary Fermi gas. It has a form of a spin-polarized impurity, which was dubbed as ferron. It is characterized by a closed nodal surface of the pairing field surrounding a partially spin-polarized superfluid region, where the phase differs by \(\pi \). In this paper, we discuss the effect of temperature on the generation of the ferron and the adiabaticity of the spin-polarizing potential together with ferron’s ground-state properties.

full authors' list

M.C. Barton, S. Jin, P. Magierski, K. Sekizawa, G. Wlazłowski, A. Bulgac

Pairing Dynamics in Low-energy Nuclear Collisions

Acta Phys. Pol. B 51, 605 (2020)

page 605 •


Superfluidity is a generic feature of various quantum systems at low temperatures and it is in particular important for the description of dynamics of low energy nuclear reactions. The Time-Dependent Density Functional Theory (TDDFT) is, to date, the only microscopic method which takes into account in a consistent way far-from-equilibrium dynamics of pairing field and single-particle degrees of freedom. The local version of TDDFT, so-called TDSLDA, is particularly useful for the description of nuclear reactions and is well-suited for leadership class computers of hybrid (CPU+GPU) architecture. The preliminary results obtained for collisions involving both medium-mass and heavy nuclei at the energies around the Coulomb barrier are presented.

full authors' list

P. Bączyk, M. Konieczka, K.M.L. Martinez, S. Antić, P.A.M. Guichon, W. Satuła, J.R. Stone, A.W. Thomas

On Introducing Charge-Symmetry-Breaking Terms to Nuclear Energy Density Functionals

Acta Phys. Pol. B 51, 611 (2020)

page 611 •


The Charge-Symmetry-Breaking (CSB) character of the nucleon–nucleon interaction is well-established. This work presents two different ways of introducing such effects into a nuclear Energy Density Functional (EDF). CSB terms are either coming from the effective theory expansion or are derived from electromagnetic mixing of \(\rho ^0\) and \(\omega \) mesons. These terms are then introduced to Skyrme and Quark–Meson-Coupling EDFs, respectively.

Effect of \({\mit \Lambda }\) Particle Phonon Coupling on the Energy Spectra of \(^{5}_{\mit \Lambda }{\mathrm {He}}\) and \(^{17}_{\mit \Lambda }{\mathrm {O}}\)

Acta Phys. Pol. B 51, 617 (2020)

page 617 •


The energy spectra of the hypernuclei \(^{5}_{\mit \Lambda }{\mathrm {He}}\) and \(^{17}_{\;\mit \Lambda }{\mathrm {O}}\) were studied within a multiphonon scheme, where the \({\mit \Lambda }\) particle is coupled to particle–hole Tamm–Dancoff phonons describing the excitations of the core. A chiral interaction was used. The calculations show that the core excitations push considerably, through their coupling, the Hartree–Fock energies down in energy and enrich the low-energy spectrum in \(^{17}_{\;\mit \Lambda }{\mathrm {O}}\).

Natural Orbitals for the Equation of Motion Phonon Method

Acta Phys. Pol. B 51, 623 (2020)

page 623 •


We discuss the use of natural orbitals as single-particle basis states for the Equation of Motion Phonon Method (EMPM). They are obtained by computing a ground-state one-body density matrix in second-order many-body perturbation theory. We focus our attention on energy and proton point radius of \(^{16}\)O and show that, with respect to Hartree–Fock, the new basis improves drastically the convergence of the two-phonon correlation energy.

Neutron Sources in Early Stars

Acta Phys. Pol. B 51, 631 (2020)

page 631 •


Stellar abundance distributions in carbon enhanced metal poor carbon stars strongly suggest the existence of a third neutron-induced nucleosynthesis process beyond the s- and the r-processes, facilitating the build-up of elements in early star generations. This process is called the intermediate or i-process and is proposed to take place in a very dynamic stellar environment, driven by fast mixing and deep convection. This paper will summarize our understanding of neutron sources in stars and the sensitive role of macroscopic dynamics in the stellar environment, and the microscopic structure of the associated nuclei before discussing possible neutron sources that may emerge in an early or primordial stellar environment. It will present the current status of the experimental knowledge and the limits of the theoretical interpretation of the associated reaction rates.

Study of the \(^{22}{\mathrm {Ne}}(p,\gamma )^{23}{\mathrm {Na}}\) Reaction at LUNA

Acta Phys. Pol. B 51, 641 (2020)

page 641 •


The \(^{22}\mathrm {Ne}(p,\gamma )^{23}\mathrm {Na}\) reaction, part of the neon–sodium cycle of hydrogen burning, may explain the observed anticorrelation between sodium and oxygen abundances in globular cluster stars. At the astrophysical energies, the presence of many resonances dominates the rate. The LUNA Collaboration measured for the first time three of them: \(E_p = 156.2\), 189.5, and 259.7 keV. Recently, by using a high-efficiency setup, the uncertainties related to those three states have been lowered drastically and the direct component of the cross section was also measured. As a result, at a temperature of 0.1 GK, the error bar of the \(^{22}\mathrm {Ne}(p,\gamma )^{23}\mathrm {Na}\) reaction rate is now reduced by three orders of magnitude. The new high-efficiency setup provides also a possibility to investigate the branching cascades, despite the limited resolution of the BGO detector.

Deuteron–Deuteron Reaction Cross Sections at Very Low Energies

Acta Phys. Pol. B 51, 649 (2020)

page 649 •


Recent studies of the deuteron–deuteron nuclear reactions in metallic targets, at projectile energies below the Coulomb barrier, show a significant enhancement of cross sections due to the electron screening effect and the threshold resonance contribution. Both effects are sensitive to the crystal lattice defects of the target material which increases the effective electron mass. Based on experimental results and the atomic deuteron–deuteron potential, we could calculate here the cross section of the \(^2{\mathrm {H}}(d,p)^3{\mathrm {H}}\) reaction down to energies corresponding to room temperature where the enhancement effects are of crucial importance.

full authors' list

F. Pinna, V. Capirossi, F. Delaunay, F. Iazzi, O. Brunasso, D. Calvo, M. Fisichella

Tests of a Cooling System for Thin Targets Submitted to Intense Ion Beams for the NUMEN Experiment

Acta Phys. Pol. B 51, 655 (2020)

page 655 •


The NUMEN experiment, hosted at LNS (Catania, Italy), aims to determine the Nuclear Matrix Elements (NMEs) involved in \(0\nu \beta \beta \) decay via heavy-ion induced Double Charge Exchange (DCE) reactions. High intensity beams of about 50 \(\mu \)A and of energies ranging from 15 to 60 MeV/\(u\) are necessary, due to the low DCE cross sections and the use of very thin targets (several hundreds of nm) needed to reach the required energy resolution. These intense beams produce a considerable amount of heat inside the target, which can be dissipated by depositing the targets on a highly thermally conductive substrate, HOPG (Highly Oriented Pyrolytic Graphite), and coupling it with a suitable designed target-cooler system. The heat transfer from the beam spot to the cold region has been studied by solving numerically the heat equation to determine the evolution in space and time of the temperature inside the target. According to calculations, the temperatures of most of the target isotopes remain under the melting points. Experimental tests with a laser were initiated to validate the whole cooling system and the calculations.

full authors' list

V. Capirossi, F. Delaunay, F. Iazzi, F. Pinna, D. Calvo, M. Fisichella, V. Rigato

Thickness and Uniformity Characterization of Thin Targets for Intense Ion Beam Experiments

Acta Phys. Pol. B 51, 661 (2020)

page 661 •


The NUMEN Experiment aims to get information on the Nuclear Matrix Elements of the Neutrinoless Double Beta Decay, by measuring heavy-ion induced Double Charge Exchange (DCE) reactions cross sections. A good energy resolution is needed to clearly distinguish energy states of DCE products. To measure the energy of reaction products with the required resolution, the target must be thin and uniform to minimise dispersion and straggling effects on the ejectile energy. Few hundreds of nanometers of the target isotope are deposited on a Highly Oriented Pyrolytic Graphite substrate a few micrometers thick. The results of the characterisation of the first target prototypes of tin and tellurium are presented. The Scanning Electron Microscopy was used to qualitatively analyse the samples surface. A setup to study Alpha Particle Transmission has been assembled to measure thickness and uniformity of the targets; the thickness results have been verified by the Rutherford Backscattering measurements. To evaluate the effects of the thickness on the resolution of the DCE products energy, a Monte Carlo code has been implemented, using the measured thickness and uniformity as input data for the simulation.

Experimentally Constrained (\(n,\gamma \)) Reaction Rates Relevant to r- and i-Process Nucleosynthesis

Acta Phys. Pol. B 51, 667 (2020)

page 667 •


The element distribution that we observe in the Universe today tells a fascinating story of nucleosynthesis events that have taken place throughout the 13.7-billion-years-long history starting with the Big Bang. It has been known for a long time that radiative neutron-capture reactions play a major role in synthesizing elements heavier than iron. However, many questions remain when it comes to our understanding of neutron-capture processes in extreme stellar environments. In particular, the intermediate and rapid neutron-capture processes are very challenging to describe, as there exist little or no data on the much-needed neutron-capture rates. In this work, we discuss possibilities to obtain indirect, experimental constrains on these rates by means of the Oslo and the \(\beta \)-Oslo methods.

full authors' list

B. Wasilewska, M. Kmiecik, M. Ciemała, A. Maj, J. Łukasik, P. Pawłowski, B. Sowicki, M. Ziębliński, J. Grębosz, F.C.L. Crespi, P. Bednarczyk, A. Bracco, S. Brambilla, I. Ciepał, N. Cieplicka-Oryńczak, B. Fornal, K. Guguła, M.N. Harakeh, M. Jeżabek, M. Kicińska-Habior, M. Krzysiek, P. Kulessa, M. Lewitowicz, M. Matejska-Minda, K. Mazurek, P. Napiorkowski, Ch. Schmitt, Y. Sobolev

Measurement of the \(\gamma \) Decay from the Energy Region of the Pygmy Dipole States Excited in the \(^{208}\)Pb\((p,p'\gamma )\) Reaction at CCB

Acta Phys. Pol. B 51, 677 (2020)

page 677 •


For a few years, the medical cyclotron Proteus C-235 at the Cyclotron Centre Bronowice in Kraków, Poland has been regularly used for nuclear structure experiments. One of the ongoing studies is focused on the \(\gamma \) decay of collective states populated in \((p,p'\gamma )\) reactions. In a recent experiment, \(\gamma \) decays of excited states in the energy region of the Pygmy Dipole States in \(^{208}{\mathrm {Pb}}\) have been observed. Good efficiency and energy resolution provided by the PARIS clusters and LaBr\(_3\):Ce scintillators facilitate a comparison of the obtained energy spectra with previous measurements of pygmy states in this nucleus.

full authors' list

G. Gosta, S. Ceruti, A. Mentana, M. Ciemała, F. Camera, A. Bracco, G. Benzoni, N. Blasi, G. Bocchi, S. Brambilla, F.C.L. Crespi, A. Giaz, S. Leoni, B. Million, O. Wieland, M. Kmiecik, A. Maj, B. Wasilewska, M. Ziębliński, D. Filipescu, D. Ghita, V. Zamfir, J.J. Valiente-Dobón, G. de Angelis, F. Galtarossa, A. Goasduff, G. Jaworski, D.R. Napoli, D. Testov, M. Siciliano, T. Marchi, D. Mengoni, D. Bazzacco, A. Boso, P.R. John, F. Recchia, R. Raabe, O. Poleshchuk, J. Yang

Isospin Symmetry in the \(^{60}\)Zn Nucleus

Acta Phys. Pol. B 51, 683 (2020)

page 683 •


The “isospin mixing” phenomenon was measured by the study of the Isovector Giant Dipole Resonance (IVGDR) in \(^{60}\)Zn at two different excitation energies \(E^*=47\) MeV and \(E^*=58\) MeV. A fusion–evaporation reaction, with a beam of \(^{30}\)S and a target of \(^{28}\)Si, was used to produce the nucleus of interest. A second target of \(^{30}\)Si was used to produce \(^{62}\)Zn. For this nucleus, the mixing effect does not strongly appear in the gamma decay of the GDR and for this reason, the second reaction is necessary as reference. The experimental setup was composed of the GALILEO array (germanium detectors) coupled to large-volume LaBr\(_{3}\)(Ce) detectors for the \(\gamma \)-ray measurements. An overview of the ongoing analysis and the preliminary results are presented.

Electromagnetic Transitions in Near-threshold Resonances

Acta Phys. Pol. B 51, 689 (2020)

page 689 •


Near-threshold collectivization of continuum shell model eigenstates is investigated in \(^{20}{\mathrm {O}}\) on the example of \(B({\mathrm {E}}\lambda )\) decays of 4\(^+\) states in the vicinity of elastic and inelastic neutron threshold. Changes of the electromagnetic transition probabilities as a function of the continuum-coupling strength are explained by the corresponding evolution of the double poles of the scattering matrix.

full authors' list

M. Ciemała, S. Ziliani, F. Crespi, S. Leoni, B. Fornal, A. Maj, P. Bednarczyk, G. Benzoni, A. Bracco, C. Boiano, S. Bottoni, S. Brambilla, M. Bast, M. Beckers, T. Braunroth, F. Camera, N. Cieplicka-Oryńczak, E. Clément, O. Dorvaux, S. Erturk, G. de France, C. Fransen, A. Goldkuhle, J. Grębosz, M.N. Harakeh, Ł.W. Iskra, B. Jacquot, A. Karpov, M. Kicińska-Habior, Y. Kim, M. Kmiecik, A. Lemasson, S.M. Lenzi, M. Lewitowicz, H. Li, I. Matea, K. Mazurek, C. Michelagnoli, M. Matejska-Minda, B. Million, C. Müller-Gatermann, V. Nanal, P. Napiorkowski, D.R. Napoli, R. Palit, M. Rejmund, Ch. Schmitt, M. Stanoiu, I. Stefan, E. Vardaci, B. Wasilewska, O. Wieland, M. Zielińska, M. Ziębliński

Short-range Lifetime Measurements for Deep-inelastic Reaction Products: the \(^{19}\)O Test Case

Acta Phys. Pol. B 51, 699 (2020)

page 699 •


An experiment, aiming at measuring lifetimes of excited states in neutron-rich C and O isotopes, was performed at the GANIL laboratory with the use of the AGATA segmented HPGe tracking array, coupled to the PARIS scintillator array and to the VAMOS\(++\) magnetic spectrometer. The nuclei of interest were populated in transfer and deep-inelastic processes induced by an \(^{18}\)O beam at 126 MeV (7.0 MeV/\(u\)) on a \(^{181}\)Ta target. This paper contains a brief description of a novel implementation of a Monte-Carlo technique, which allowed us to obtain excited states lifetimes in the range from tens to hundreds femtoseconds for a reaction with complex initial velocity distribution, making use of the Doppler-shift attenuation method (DSAM). As a test case, we present here the analysis for two states in \(^{19}\)O: 2371-keV \(9/2^+\) and 2779-keV \(7/2^+\), for which lifetimes of \(\tau \gt 400 \) fs and \(\tau =140^{+50}_{-40}\) fs were obtained, respectively, in agreement with literature values. This newly developed approach will be essential for short lifetimes measurements in neutron-rich systems, exploiting intense ISOL-type beams, currently under development.

full authors' list

S. Ziliani, M. Ciemała, F.C.L. Crespi, S. Leoni, B. Fornal, A. Maj, P. Bednarczyk, G. Benzoni, A. Bracco, C. Boiano, S. Bottoni, S. Brambilla, M. Bast, M. Beckers, T. Braunroth, F. Camera, N. Cieplicka-Oryńczak, E. Clément, S. Coelli, O. Dorvaux, S. Erturk, G. de France, C. Fransen, A. Goldkuhle, J. Grębosz, M.N. Harakeh, Ł.W. Iskra, B. Jacquot, A. Karpov, M. Kicińska-Habior, Y. Kim, M. Kmiecik, A. Lemasson, S.M. Lenzi, M. Lewitowicz, H. Li, I. Matea, K. Mazurek, C. Michelagnoli, M. Matejska-Minda, B. Million, C. Müller-Gatermann, V. Nanal, P. Napiorkowski, D.R. Napoli, R. Palit, M. Rejmund, Ch. Schmitt, M. Stanoiu, I. Stefan, E. Vardaci, B. Wasilewska, O. Wieland, M. Ziębliński, M. Zielińska

Spectroscopy of Neutron-rich Nitrogen Isotopes with AGATA+PARIS+VAMOS

Acta Phys. Pol. B 51, 709 (2020)

page 709 •


Excited states of \(^{17}{\mathrm {N}}\), \(^{18}{\mathrm {N}}\) and \(^{19}{\mathrm {N}}\) were investigated through the measurement of gamma rays, following their population via deep-inelastic reactions induced by an \(^{18}{\mathrm {O}}\) beam (7 MeV/\(u\)) on a thick \(^{181}{\mathrm {Ta}}\) target. The experimental setup comprised the AGATA+PARIS detection system, coupled to the VAMOS\(++\) magnetic spectrometer. In the \(^{17}{\mathrm {N}}\) nucleus, the analysis of gamma-ray transitions de-exciting two states around 4–5 MeV clearly pointed to discrepancies with the lifetime values reported in literature. Three new gamma rays were observed in \(^{18}{\mathrm {N}}\) at the energies of 1662.3 (3) keV, 2073.4 (8) keV and 2300.9 (8) keV, and hints for other two new transitions around 1566 keV and 1720 keV were found. In addition, a new transition with energy of 2489.7 (8) keV was observed in \(^{19}{\mathrm {N}}\).

full authors' list

S. Viñals, E. Nácher, O. Tengblad, J. Benito, M.J.G. Borge, P. Figuera, L.M. Fraile, H.O.U. Fynbo, A. Gad, J. Jensen, B. Jonson, R. Lica, I. Marroquín, M. Munch, T. Nilsson, J.D. Ovejas, A. Perea, K. Riisager, S. Smain, C. Sotty

The Most Accurate Determination of the \(^8\)B Half-life

Acta Phys. Pol. B 51, 717 (2020)

page 717 •


Beta decay is a primary source of information of the structure of a nucleus. An accurate measurement of the half-life of a nucleus is essential for the proper determination of the reduced Gammow–Teller transition probability \(B\)(GT). In this work, we present an experiment using a compact set-up of Si-telescope detectors to measure the half-life of the \(^8\)B nucleus. Three independent measurements have been analysed, obtaining the values 771.9(17) ms, 773.9(18) ms, and 770.9(27) ms. The value of the half-life obtained as the weighted averaged with the previous published measures is 771.17(94) ms which is a factor 3.2 of improvement in the uncertainty of the half-life.

full authors' list

P. Wojtowicz, K. Miernik, A. Korgul, M. Piersa, M. Siłkowski, T. Rogiński

Warsaw Time-of-flight Neutron Detector

Acta Phys. Pol. B 51, 725 (2020)

page 725 •


A set of neutron time-of-flight detectors, based on the design of the VANDLE detector, is currently being built at the University of Warsaw. The objective is to construct mobile, small form-factor detectors, suitable for use as auxiliary extension in the existing beta-decay spectroscopy decay stations in cases where beta-delayed neutron emission is an important decay path. The detectors are based on \(15\times 15\times 200\) mm\(^3\) plastic bars read from one end using silicon photomultipliers equipped with the custom-designed electronic front-ends and a fully digital electronic acquisition system. Preliminary results of time resolution and detector response to radiation measured with gamma-ray sources are presented.

full authors' list

J.D. Ovejas, A. Knyazev, I. Martel, O. Tengblad, M.J.G. Borge, J. Cederkäll, N. Keeley, K. Rusek, C. García-Ramos, L.A. Acosta, A.A. Arokiaraj, M. Babo, T. Cap, N. Ceylan, G. de Angelis, A. Di Pietro, J.P. Fernández, P. Figuera, L. Fraile, H. Fynbo, D. Galaviz, J.H. Jensen, B. Jonson, R. Kotak, T. Kurtukian, M. Madurga, G. Marquínez-Durán, M. Munch, A.K. Orduz, R. Honório, A. Pakou, T. Pérez, L. Peralta, A. Perea, R. Raabe, M. Renaud, K. Riisager, A.M. Sánchez-Benítez, J. Sánchez-Segovia, O. Sgouros, V. Soukeras, P. Teubig, S. Viñals, M. Wolińska-Cichocka, R. Wolski, J. Yang

Halo Effects in the Low-energy Scattering of \(^{15}\)C with Heavy Targets

Acta Phys. Pol. B 51, 731 (2020)

page 731 •


The neutron-rich carbon isotope \(^{15}\)C was postulated to be a halo nucleus (\(S_{n}=1215\) keV, \(S_{2n}=9395\) keV) according to different high-energy experiments. If so, it would be the only halo nucleus exhibiting a “pure” s-wave structure of the ground state. At low collision energies, the effect of this halo structure should manifest as a strong absorption pattern in the angular distribution of the elastic cross section, with a total suppression of the nuclear rainbow due to the large neutron transfer and breakup probabilities, enhanced by the halo configuration. The IS619 experiment, carried out at the HIE-ISOLDE facility at CERN (Switzerland), is the first dynamical study of this nucleus at energies around the Coulomb barrier. It aims to probe the halo structure via the measurement of the elastic cross section on a high-\(Z\) \(^{208}\)Pb target. Preliminary results of the elastic cross section are discussed and compared to Optical Model calculations.

full authors' list

O. Sgouros, V. Soukeras, A. Pakou, F. Cappuzzello, L. Acosta, C. Agodi, N. Alamanos, S. Calabrese, D. Carbone, M. Cavallaro, A. Foti, N. Keeley, I. Martel, K. Rusek, D. Torresi

Study of the \(^6{\mathrm {Li}}+p\) and \(^7{\mathrm {Li}}+p\) Systems in the Continuum Discretized Coupled Channels Approach

Acta Phys. Pol. B 51, 737 (2020)

page 737 •


A complete study of the \(^{6,7}{\mathrm {Li}}+p\) reactions was performed by measuring the complete net of reaction channels at the energy range of \(\sim 2\) to 5 MeV/nucleon. The experiments were performed at the MAGNEX facility of the Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud (INFN-LNS) in Catania. The breakup channel was identified by means of a new algorithm, MULTIP, which gives the possibility of following up the decay of the nucleus into two or more constituent particles from the rest frame of the nucleus itself to the laboratory frame. Angular distributions were obtained for all reaction products and were considered within the Continuum Discretized Coupled Channels (CDCC) framework. The results of the CDCC calculations were found in a very good agreement with the experimental data presenting a strong evidence for the important influence of coupling to breakup on the elastic channel.

full authors' list

D.M. Janseitov, N. Burtebayev, Zh. Kerimkulov, D. Alimov, M. Nassurlla, B. Mauyey, D.S. Valiolda, A.S. Demyanova, A. Danilov, Sh. Hamada, A. Aimaganbetov

Investigation of Deuteron Scattering from \(^{13}\)C at Low Energy

Acta Phys. Pol. B 51, 745 (2020)

page 745 •


We measured differential cross sections for the elastic scattering of deuterons on a \(^{13}\)C target using the U-150M cyclotron at INP, Republic of Kazakhstan. The beam energy of deuterons was 14.5 MeV. As a result, we obtained new experimental data for the \(d+^{13}\)C elastic scattering. Those were combined with literature data and analyzed within the framework of the optical model using the Woods–Saxon and the double folding potentials.

full authors' list

M. Nassurlla, N. Burtebayev, D.M. Janseitov, Zh. Kerimkulov, D. Alimov, A.K. Morzabayev, K. Talpakova, Y. Mukhamejanov, L.I. Galanina, A.S. Demyanova, A.N. Danilov, V. Starastsin

Study of Elastic and Inelastic Scattering of Deuterons by \(^{9}\)Be at Energy \(E=14.5\) MeV

Acta Phys. Pol. B 51, 751 (2020)

page 751 •


Differential cross sections have been measured for the elastic and inelastic scattering of deuterons on \(^{9}\)Be at \(E_{d}=14.5\) MeV. As a result, we obtained new experimental data for the \(d+^{9}\)Be elastic and inelastic scattering leading to the 2.43 MeV (\(5/2^{-}\)) excited state of the \(^{9}\)Be nucleus. The experimental results on elastic scattering were analyzed within the framework of the optical model using the Woods–Saxon and double folding potentials. The theoretical calculations for the relevant excited states were performed using the coupled channel (CC) method. The optimal deformation parameters for the excited states of the \(^{9}\)Be nucleus were extracted.

full authors' list

N. Amangeldi, N. Burtebayev, S.B. Sakuta, M. Nassurlla, J. Burtebayeva, M. Nassurlla, G. Yergaliuly, A. Sabidolda, K. Rusek, A. Trzcińska, M. Wolińska-Cichocka, B. Mauyey

Study of Elastic Scattering of \(^{10}{\mathrm {B}}\) Ions on \(^{12}{\mathrm {C}}\) Nuclei at the Energy of 17.5 MeV

Acta Phys. Pol. B 51, 757 (2020)

page 757 •


Elastic scattering angular distribution was measured for the \(^{10}\mathrm {B}+^{12}\)C system at \(E_{\mathrm {lab}}=17.5\) MeV in the angular range of \(\theta _{\mathrm {cm}}=15^\circ \)–\(165^\circ \). The analysis of the experimental data was carried out in the framework of the optical model and the distorted-wave method (FRDWBA) using the FRESCO code. The optical model describes well the experimental cross sections in the region of the angles of the forward hemisphere, but it is not able to reproduce the observed rise of the cross sections at large angles. Only accounting for the exchange mechanism with a deuteron transfer allows us to describe the experiment in the full angular range. Spectroscopic amplitude has been extracted from the analysis for the \(^{12}\mathrm {C}\rightarrow {}^{10}\mathrm {B}+d\) configuration.

full authors' list

A. Szadziński, A. Wilczek, E. Stephan, B. Włoch, N. Kalantar-Nayestanaki, St. Kistryn, B. Kłos, A. Kozela, P. Kulessa, A. Łobejko, J. Messchendorp, W. Parol, I. Skwira-Chalot, J. Zejma

Simulation of Star Configurations in the BINA Detector

Acta Phys. Pol. B 51, 763 (2020)

page 763 •


Star Anomaly is one of the most intriguing and unsolved discrepancies between theoretical calculations and experimental data observed in the domain of few-nucleon systems at low energies. Previous and upcoming measurements of the breakup reaction with the use of the BINA detector enable systematic studies of the Star configurations at intermediate energies. A dedicated simulation was developed to study feasibility of registering such events with the required accuracy and to support the future data analysis. An additional rotation angle \(\beta \) has been introduced to parametrise the Star configurations. First results concerning the acceptance of certain segments of BINA for registering the Star configurations are presented.

full authors' list

G. Colucci, G. Montagnoli, A.M. Stefanini, K. Hagino, A. Caciolli, P. Čolović, L. Corradi, E. Fioretto, F. Galtarossa, A. Goasduff, J. Grębosz, M. Mazzocco, D. Montanari, C. Parascandolo, F. Scarlassara, M. Siciliano, E. Strano, S. Szilner, N. Vukman

Study of Sub-barrier Fusion of \(^{36}\)S+\(^{50}\)Ti,\(^{51}\)V Systems

Acta Phys. Pol. B 51, 769 (2020)

page 769 •


A detailed comparative study of the sub-barrier fusion of the two near-by systems \(^{36}\)S+\(^{50}\)Ti,\(^{51}\)V was performed at the National Laboratories of Legnaro (INFN). The experiment aimed to evidence possible effects of the non-zero spin of the ground state of the \(^{51}\)V nucleus on the sub-barrier excitation function and on the shape of the barrier distribution. The comparison of both excitation functions and barrier distributions showed a very similar behavior, down to the level of 20–30 \(\mu \)b. Coupled-channels calculations have been performed including the low-energy excitations of both projectile and the two targets, and the results are in very good agreement with the data. This indicates that the low-lying levels in \(^{51}\)V can be interpreted in the weak-coupling scheme and that the extra proton in the \(f_{7/2}\) shell does not have a significant influence on sub-barrier fusion.

full authors' list

Arshiya Sood, Pawan Kumar, R.N. Sahoo, Pushpendra P. Singh, Abhishek Yadav, Vijay R. Sharma, Manoj K. Sharma, R. Kumar, R.P. Singh, S. Muralithar, B.P. Singh, R.K. Bhowmik

Evidence of Narrow Range High Spin Population in Incomplete Fusion

Acta Phys. Pol. B 51, 775 (2020)

page 775 •


Particle (\(p,\alpha \))–\(\gamma \)-coincidence experiment has been performed to probe incomplete fusion dynamics in the \(^{12}\)C+\(^{169}\)Tm system at 5–7.5 MeV/\(A\). Spin distributions of different reaction products populated via \(xn\) and \(\alpha /2\alpha xn\) channels have been measured to acquire information about the involved reaction mechanism on the basis of their experimentally observed de-excitation patterns. The spin distributions of direct-\(\alpha \) (incomplete fusion) and fusion–evaporation (complete fusion) channels are found to be distinct from each other, substantiating their origin in entirely different reaction dynamics. It has been found that CF products span a broad spin range, while ICF products are confined to a narrow spin range localized in the higher spin states. Findings of the present work comprehensively demonstrate that incomplete fusion reactions can be used as a sensitive tool to populate high-spin states in final reaction products, which are not otherwise accessible.

full authors' list

Y. Mukhamejanov, G. Alieva, D. Alimov, G.D. Kabdrakhimova, M. Nassurlla, N. Saduyev, B.M. Sadykov, T.K. Zholdybayev, K.M. Ismailov, Y. Kucuk

Investigation of \((p,xp)\) and \((p,x\alpha )\) Reactions of 30-MeV Protons with the \(^{103}\)Rh Nucleus

Acta Phys. Pol. B 51, 783 (2020)

page 783 •


Double-differential and integral cross sections of the (\(p,xp\)) and (\(p,x\alpha \)) reactions on the \(^{103}\)Rh nucleus were measured at \(E_p = 30\) MeV using a proton beam delivered by the U-150M cyclotron of the Institute of Nuclear Physics (Almaty, Kazakhstan). A self-sustaining \(^{103}\)Rh foil of 3 \(\mu \)m thickness was used as a target. The obtained experimental results were compared with the TENDL-2019 nuclear data library, which provides the output of the TALYS nuclear model code. We assert that the TENDL-2019 evaluations provide a valid description of the obtained experimental data.

full authors' list

K. Wrzosek-Lipska, L. Próchniak, P.E. Garrett, S.W. Yates, J.L. Wood, P.J. Napiorkowski, T. Abraham, J.M. Allmond, F.L. Bello Garrote, H. Bidaman, V. Bildstein, C. Burbadge, M. Chiari, A. Diaz Varela, D.T. Doherty, S. Dutt, K. Hadyńska-Klęk, M. Hlebowicz, J. Iwanicki, B. Jigmeddorj, M. Kisieliński, M. Komorowska, M. Kowalczyk, R. Kumar, T. Marchlewski, M. Matejska-Minda, B. Olaizola, F. Oleszczuk, M. Palacz, E. Pasquali, E.E. Peters, M. Rocchini, E. Sahin, M. Saxena, J. Srebrny, A. Tucholski

Quadrupole Deformation of \(^{110}\)Cd Studied with Coulomb Excitation

Acta Phys. Pol. B 51, 789 (2020)

page 789 •


The low-energy electromagnetic structure of \(^{110}\)Cd was studied using safe-energy Coulomb excitation at the Heavy Ion Laboratory, University of Warsaw. The preliminary results on the quadrupole deformation of low-lying 0\(^+\) states in \(^{110}\)Cd are presented and compared to the recent beyond-mean-field and General Bohr Hamiltonian calculations.

full authors' list

P.E. Garrett, L. Makhathini, R.A. Bark, T.R. Rodríguez, S. Valbuena, V. Bildstein, T.D. Bucher, C. Burbadge, R. Dubey, T. Faestermann, R. Hertenberger, M. Kamil, E.A. Lawrie, K.G. Leach, A.D. MacLean, C. Malotana, C. Mehl, S.H. Mthembu, J. Mukwevho, C. Ngwetsheni, S.S. Ntshangase, J. Ondze, J.N. Orce, B. Rebeiro, B. Singh, S. Triambak, E.C. Vyfers, H.-F. Wirth

Shape Coexistence in the Ru Isotopes; Multi-spectroscopic Study of \(^{98}\)Ru and Beyond-mean-field Calculations

Acta Phys. Pol. B 51, 799 (2020)

page 799 •


The level structure of \(^{98}\)Ru was investigated via \(\gamma \)-ray spectroscopy following the \(\beta ^+\)/electron capture decay of \(^{98}\)Rh and with the \(^{100}\)Ru(\(p,t\))\(^{98}\)Ru reaction. Additional \(\gamma \)-ray transitions from low-lying levels were observed and spin-parity assignments of some key states were clarified, permitting the assignment of the \(0^+_2\) band and the \(\gamma \) band. The energies of the states in these bands fit well into the systematic trends observed in the heavier isotopes. The results are interpreted with the aid of beyond-mean-field calculations performed within the self-consistent configuration mixing method.

full authors' list

S. Leoni, B. Fornal, N. Marginean, C. Michelagnoli, J. Wilson, M. Sferrazza, Y. Tsunoda, T. Otsuka

Shape-coexistence Studies in the Ni Isotopic Chain by Using the Selectivity of Different Reaction Mechanisms

Acta Phys. Pol. B 51, 807 (2020)

page 807 •


We report on the investigation of the shape coexistence phenomenon in the Ni isotopic chain, from \(A=62\) to \(A=66\), by using \(\gamma \)-ray spectroscopy techniques and different reaction mechanisms, such as sub-Coulomb barrier transfer reactions and thermal-neutron capture. Our aim is to understand, from the microscopic point of view, the appearance of nuclear deformation in Ni isotopes at low excitation energy. A series of experiments was performed at the Tandem Accelerator Laboratory in Bucharest, at ALTO IPN-Orsay and at the ILL reactor in Grenoble. Various mean-field theoretical approaches, as well as recent state-of-the-art Monte Carlo Shell Model (MCSM) calculations, predict in \(^{66}{\mathrm {Ni}}\) a deep secondary prolate minimum in the nuclear potential energy surface at spin zero, resulting in a hindered electromagnetic decay towards the spherical ground state (i.e. , with an E2 transition probability less than 1 W.u.). This has been confirmed in the first experiment performed in Bucharest. Less pronounced prolate minima, at higher excitation energies, are also expected in lighter neutron-rich Ni isotopes, from state-of-the-art Monte Carlo Shell Model (MCSM) calculations. Preliminary results are discussed for \(^{62}{\mathrm {Ni}}\) and \(^{64}{\mathrm {Ni}}\), in comparison with theory predictions.

full authors' list

A. Spătaru, D.L. Balabanski, O. Beliuskina, P. Constantin, T. Dickel, C. Hornung, A. Kankainen, A.V. Karpov, D. Nichita, W. Plass, S. Purushothaman, A. Rotaru, V.V. Saiko, A. State, J.S. Winfield, A. Zadvornaya

Production of Exotic Nuclei via MNT Reactions Using Gas Cells

Acta Phys. Pol. B 51, 817 (2020)

page 817 •


The use of multi-nucleon transfer (MNT) reactions to produce neutron-rich nuclei in the heavy region has received an increased attention in the last decade. The feasibility of employing such reactions at the FRS Ion Catcher facility at GSI and the IGISOL facility at JYFL is studied using a combination of theoretical calculations and experiment simulations. The reactions are computed within a Langevin-type model, and the Geant program is used to simulate the transport of the resulting products within the experimental setups of the above-mentioned facilities. The angular distribution of ion release, possible target choices and target-to-beam-dump distances are discussed.

Lifetime Measurements in \(^{105}\)Sn: the Puzzle of \(B\)(E2) Strengths in Sn Isotopes

Acta Phys. Pol. B 51, 823 (2020)

page 823 •


Information on the doubly-magic nature of the \(N=Z=50\) \(^{100}\)Sn nucleus can be extracted from systematic studies of the tin isotopic chain. In this context, the lifetimes of the neutron deficient \(^{105}\)Sn have been investigated with the coincidence Recoil Distance Doppler Shift (RDDS) technique through the reaction \(^{50}\)C\((^{58}{\mathrm {Ni}},2pn)^{105}\)Sn. The experimental technique has been validated by comparing the preliminary results with known lifetimes in \(^{105}\)In.

full authors' list

M. Matejska-Minda, P.J. Napiorkowski, R. Kumar, M. Saxena, S. Dutt, A. Agarwal, I. Ahmed, S. Bhattacharya, A. Jhingan, J. Kaur, M. Kicińska-Habior, M. Kumar, S. Kumar, D. Kumar, V. Nanal, R. Palit, N.K. Rai, M. Shuaib, A. Sood, A. Stolarz, T. Trivedi, A.K. Tyagi, R.K. Bhowmik, H.J. Wollersheim

Revised Lifetime of the \(11/2^-\) State in \(^{45}\)Sc via Coulomb Excitation

Acta Phys. Pol. B 51, 829 (2020)

page 829 •


A Coulomb-excitation measurement to study low-energy electromagnetic properties of \(^{45}{\mathrm {Sc}}\) has been performed at the IUAC facility in New Delhi, India using a 70 MeV \(^{32}{\mathrm {S}}\) projectile from the 15UD tandem accelerator. The preliminary value of the reduced transition probability \(B({\mathrm {E2}}; 11/2^- \rightarrow 7/2^-)\) and the resulting lifetime for the \(11/2^-\) state at 1237 keV were determined using the GOSIA code.

full authors' list

T. Milanović, I. Čeliković, C. Michelagnoli, G. de France, A. Boso, T. Braunroth, E. Clément, A. Dewald, G. Georgiev, E. Ideguchi, B. Jacquot, W. Królas, D. Napoli, N. Lalović, K.Y. Lee, A. Lemasson, H. Li, J. Ljungvall, A. Navin, A. Nori, R. Pérez-Vidal, M. Rejmund, P. Ujić, D. Wilmsen, Y. Yamamoto, M. Zielińska

Lifetime Measurements of Low-lying States in \(^{73}\)Ga and \(^{70,72,74}\)Zn Isotopes

Acta Phys. Pol. B 51, 837 (2020)

page 837 •


Lifetimes of low-lying states in \(^{73}\)Ga and \(^{70,72,74}\)Zn were measured using the Recoil Distance Doppler Shift (RDDS) method. These nuclei were produced in deep-inelastic reactions in inverse kinematics with a \(^{208}\)Pb beam impinging on a \(^{76}\)Ge target. Prompt \(\gamma \) rays were detected using the AGATA tracking array coupled to the VAMOS\(++\) spectrometer. Lifetime of the \(5/2^-\) state in \(^{73}\)Ga, measured for the first time, provides additional evidence for the existence of a \(1/2^-\), \(3/2^-\) ground-state doublet. The lifetimes of the \(4^+\) states in \(^{70,72,74}\)Zn were remeasured in an attempt to understand the discrepancies observed between earlier measurements. Our results are in agreement with those of previous plunger experiments.

full authors' list

E. Adamska, A. Korgul, A. Fijałkowska, K. Miernik, M. Piersa, R. Canavan, D. Etasse, N. Jovančević, M. Lebois, M. Rudigier, D. Thisse, J.N. Wilson, P. Adsley, A. Algora, M. Babo, K. Belvedere, J. Benito, A. Blazhev, G. Benzoni, A. Boso, S. Bottoni, M. Bunce, R. Chakma, N. Cieplicka-Oryńczak, M. Ciemała, S. Collins, L. Cortés, P. Davies, C. Delafosse, M. Fallot, B. Fornal, L.M. Fraile, R.-B. Gerst, D. Gjestvang, A. Gottardo, V. Guadilla, G. Hafner, K. Hauschild, M. Heine, C. Henrich, I. Homm, F. Ibrahim, Ł.W. Iskra, P. Koseoglou, T. Kröll, T. Kurtukian-Nieto, L. Le-meur, S. Leoni, J. Ljungvall, A. Lopez-Martens, R. Lozeva, I. Matea, J. Nemer, S. Oberstedt, W. Paulsen, Y. Popovitch, L. Qi, D. Ralet, P.H. Regan, D. Reygadas Tello, K. Rezynkina, V. Sánchez-Tembleque, C. Schmitt, P.-A. Söderström, C. Surder, G. Tocabens, V. Vedia, D. Verney, N. Warr, B. Wasilewska, J. Wiederhold, M. Yavahchova, F. Zeiser

\(\gamma \)-ray Spectroscopy of \(^{85}\)Se Produced in \(^{232}\)Th Fission

Acta Phys. Pol. B 51, 843 (2020)

page 843 •


Excited states in the neutron-rich \(^{85}\)Se nucleus have been studied using for the first time a fast neutron-induced fission of \(^{232}\)Th. The experiment was performed at the ALTO facility of the IPN Orsay. Coupling of the LICORNE directional neutron source with the \(\nu \)-ball high-resolution \(\gamma \)-ray spectrometer provided unique access to high-spin states in neutron-rich fission fragments from the \(^{232}\)Th(\(n,f\)) reaction. A preliminary level scheme of \(^{85}\)Se was established by the analysis of prompt \(\gamma \)–\(\gamma \)–\(\gamma \) coincidences. Identification of the all known yrast states in \(^{85}\)Se is the first step towards studies of more neutron-rich Se isotopes.

full authors' list

P. Mosat, S. Antalic, F.P. Heßberger, D. Ackermann, B. Andel, M. Block, Z. Kalaninova, B. Kindler, M. Laatiaoui, B. Lommel, A.K. Mistry, J. Piot, M. Vostinar

Isomeric States in \(^{255}\)Rf, \(^{256}\)Rf and \(^{257}\)Rf

Acta Phys. Pol. B 51, 849 (2020)

page 849 •


In this work, we present results from the investigations of high-\(K\) isomers in \(^{255}\)Rf, \(^{256}\)Rf and \(^{257}\)Rf isotopes produced in \(^{50}\)Ti\(+^{207}\)Pb and \(^{50}\)Ti\(+^{208}\)Pb reactions. The method of time and position correlation search was used to identify ER–CE–\(\alpha \)/SF events in the data. Previously known high-\(K\) states in \(^{256}\)Rf and \(^{257}\)Rf were confirmed. A search for high-\(K\) isomer in \(^{255}\)Rf was performed for the first time. Observation of ER–CE correlations with a lifetime of \(\approx 30~\mu \)s indicates the presence of isomeric states also in this isotope.

\({\mit \Lambda }(1520)\) and \(\phi \) as Potential Sources of \(K^{-}\) Meson Emission in Heavy-ion Collisions Around Kaon Threshold

Acta Phys. Pol. B 51, 855 (2020)

page 855 •


In the context of search for in-medium modifications of negatively charged kaons emitted from hot and dense nuclear medium, we extracted efficiencies for the measurement of \(\phi \) and \({\mit \Lambda }(1520)\) from \(\mathrm {Ag}+\mathrm {Ag}\) collisions at beam energy of 1.58 \(A\) GeV by the HADES apparatus. Whereas about 18% contribution to \(K^-\) spectra results from \(\phi \rightarrow K^+K^-\) decays, calculations within statistical model suggest the contribution from \({\mit \Lambda }(1520)\rightarrow pK^-\) to be very similar. We found reconstruction efficiencies for \(\phi \) meson and \({\mit \Lambda }(1520)\) to be about 2% and 3%, respectively. We also estimate that the signal from the latter particle may be too weak to be observed by the HADES \(\mathrm {Ag}+\mathrm {Ag}\) experiment.

full authors' list

J. Jastrzębski, N. Zandi, J. Choiński, M. Sitarz, A. Stolarz, A. Trzcińska, M. Vagheian

Investigation of the Production of the Auger Electron Emitter \(^{135}{\mathrm {La}}\) Using Medical Cyclotrons

Acta Phys. Pol. B 51, 861 (2020)

page 861 •


Possible reactions leading to the production of \(^{135}{\mathrm {La}}\) are discussed in this study and corresponding theoretical yields calculated using Monte-Carlo (MCNPX) code are presented. The pilot \(^{135}{\mathrm {La}}\) production was performed employing the 16 MeV protons provided by a PETtrace cyclotron and a \(^{\mathrm {nat}}{\mathrm {BaCO}}_3\) target.

full authors' list

N. Młyńczyk, A. Konefał, A. Orlef, M. Sokół, J. Rostocka, W. Lniak, B. Gawełczyk

Innovatory Production of Radioisotopes \(^{117m}{\mathrm {Sn}}\), \(^{186}{\mathrm {Re}}\) and \(^{188}{\mathrm {Re}}\) for Laboratory Tests and the Future Application in Nuclear Medicine

Acta Phys. Pol. B 51, 867 (2020)

page 867 •


In this work, innovatory production of three radioisotopes \(^{117m}{\mathrm {Sn}}\), \(^{186}{\mathrm {Re}}\) and \(^{188}{\mathrm {Re}}\), which can be used in nuclear medicine, is described. The natural tin and rhenium targets were irradiated by a high-energy 20 MV X-ray therapeutic beam from a medical linear accelerator. Additionally, the targets were in the photoneutron field. The radioisotopes were obtained in photonuclear and neutron reactions. A special lead-PMMA system was used to increase the slowed-down neutron flux in the target volume. The specific activities of \(^{117m}{\mathrm {Sn}}\), \(^{186}{\mathrm {Re}}\) and \(^{188}{\mathrm {Re}}\) are 11 kBq/g, 2.6 MBq/g and 0.26 MBq/g in the saturation state, respectively. The produced amounts of the radioisotopes of tin and rhenium are sufficient for various laboratory tests in nuclear medicine.

Nuclear Reactions in Human-like Tissues During Proton Therapy

Acta Phys. Pol. B 51, 873 (2020)

page 873 •


During particle therapy, the beam of protons or heavier ions can induce secondary particles, like neutrons, or produce radioisotopes, which decay with emission of \(\beta \) and \(\gamma \) radiation. These provide information about the beam or the tissues and are at the origin of an additional dose to surrounding tissues. This work is mainly focused on secondary neutrons that can interact with a tissue by indirect ionization or induce different nuclear reactions, e.g. \(^{12}\)C(\(n,n2\alpha \))\(^4\)He, which may result in high biological effectiveness. The neutron flux induced by a proton beam was estimated using a GATE/Geant4 simulation for the calculation of neutron energy spectrum, and the Neutron Activation Analysis (NAA) method. Additionally, the cross sections for the \(^{12}\)C(\(p,np\))\(^{11}\)C reaction were measured.

full authors' list

W. Pereira, A. Kowalska, K. Czerski, E. Nasonova, P. Kustalo, L.E. Valerievich

Deviations from Poisson Statistics Observed in Chromosome Aberrations Induced by \(^{252}\)Cf Neutrons

Acta Phys. Pol. B 51, 881 (2020)

page 881 •


Biological efficiency of ion beams and neutral particles can be determined by studying the number of chromosome aberrations induced in irradiated cells. In the present investigation, we studied Relative Biological Efficiency (RBE) and statistical distributions of chromosome aberrations induced in human peripheral blood lymphocytes exposed to 0.23 Gy and 0.47 Gy of \(^{252}\)Cf neutrons. Due to the possible cell cycle delay, the aberrations were scored at two different sampling times. Data were fitted using Poisson and Generalized Poisson distributions. In all cases, experimentally measured distributions significantly deviate from theoretical expectations.

full authors' list

N.O. Saduyev, O.A. Kalikulov, A.N. Sedov, Y.S. Mukhamejanov, V.V. Oskomov, S.K. Shinbulatov, N.O. Yerezhep, A.I. Zhumabayev, Sh.B. Utey, A.Y. Baktoraz

Development of an Automated System for the Determination of the Snow Water Equivalent and Soil Moisture by the Neutron Component of Cosmic Rays

Acta Phys. Pol. B 51, 887 (2020)

page 887 •


A method for determination of snow water equivalent and soil moisture is proposed. The method is based on measurements of the fluxes of cosmic-ray neutrons. Global fluxes of various components of cosmic rays are attenuated exponentially, depending on the thickness of the atmosphere and on the thickness of the absorber (water). Thus, the moisture content can be determined from two measurements: one without snow and the second with snow.

full authors' list

D. Böhm, K. Czerski, A. Huke, J.-C. Lewitz, D. Weißbach, S. Gottlieb, G. Ruprecht

New Methods for Nuclear Waste Treatment of the Dual Fluid Reactor Concept

Acta Phys. Pol. B 51, 893 (2020)

page 893 •


The Dual Fluid Reactor (DFR) is a new fast-neutron, high temperature, liquid fuel nuclear reactor concept which is able to utilize Used Nuclear Fuel (UNF) of previous nuclear reactor generations. The DFR features an integrated Pyroprocessing Unit (PPU) which separates transuranium elements as well as fission products when distillation of chlorinated liquid fuel is applied. Simplified calculations performed here show that the distillation process with maximum 12 stages is sufficient to obtain separation of corresponding chlorides to a very high precision level. Furthermore, insoluble metallic and non-chlorinated solid materials can be removed by simple crystallization techniques.

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Acta Phys. Pol. B 51, 903 (2020)

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