Regular Series

XXXV Mazurian Lakes Conference on Physics Exotic Nuclei --- Laboratories for Fundamental Laws of Nature

Facets of Neutrino–Nucleus Interactions

Acta Phys. Pol. B 49, 221 (2018)

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abstract

Different approaches to the calculation of neutrino–nucleus cross sections are summarized. Potential impact of improving the nuclear physics input into neutrino interactions and cross-section calculations on uncovering new physics is discussed using the example of reactor anomaly. Importance of a thorough understanding of neutrino interactions in astrophysics and cosmology is highlighted.

all authors

P.E. Garrett, K.G. Leach, A.D. MacLean, G.C. Ball, P.C. Bender, V. Bildstein, B.A. Brown, C. Burbadge, A. Diaz Varela, R. Dunlop, T. Faestermann, B. Hadinia, R. Hertenberger, J.D. Holt, A.T. Laffoley, D.S. Jamieson, B. Jigmeddorj, A.J. Radich, E.T. Rand, S.R. Stroberg, C.E. Svensson, I.S. Towner, S. Triambak, H.-F. Wirth

Nuclear Structure Studied with Direct Reactions for Fundamental Symmetry Tests

Acta Phys. Pol. B 49, 229 (2018)

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abstract

Direct reaction studies provide crucial information on nuclear structure for nuclei that are used in weak interaction and fundamental symmetry tests. Motivated by the superallowed Fermi $\beta$-decay studies, we have investigated the structure of $^{50}$Cr and $^{62}$Zn, the daughters of the superallowed $\beta ^+$/EC emitters $^{50}$Mn and $^{62}$Ga, with $(p,t)$ reactions. For both nuclei, we reassigned the location of the first excited $0^+$ state. The data for these reassignments are reviewed and limits on the possible $L=0$ transfer to the previously assigned $0^+_2$ states are determined. For $^{50}$Cr, we find no evidence for the presence of a $0^+$ state at 3695 keV. For $^{62}$Zn, the data allow for a possible contribution of $L=0$ and $L=2$, indicating a possible $0^+/2^+$ doublet of states at 2342 keV. However, this relies on an enhanced cross section at only one data point, and thus the existence of a $0^+$ state at this energy is not clear. A preliminary result from a $\gamma$–$\gamma$ angular correlation measurement following the $\beta ^+$/EC decay of $^{62}$Ga weakly favours the existence of a $0^+$ state, but requires further study with increased statistics.

Quenching of the Weak Axial-vector Coupling Strength in $\beta$ Decays

Acta Phys. Pol. B 49, 237 (2018)

page 237 •

abstract

The quenching of the weak axial-vector coupling strength, $g_{\rm A}$, in nuclear $\beta$ decays is reviewed. The quenching is discussed for both the Gamow–Teller decays and the forbidden $\beta$ decays of different variants. Both the historical background and the present status are reviewed and compared with each other. Possible new measurements are urged, whenever relevant for determining the amount of $g_{\rm A}$ quenching.

Precision Measurements of $\beta$-energy Spectra in Nuclear Decays: Study of the Sensitivity to the Detector Calibration

Acta Phys. Pol. B 49, 249 (2018)

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abstract

A study of the detector calibration sensitivity for measurements of the shape of $\beta$-energy spectra is reported using Monte Carlo simulated spectra. An auto-calibration method is proposed which can be carried out simultaneously to the actual measurements. The statistical impact of such a procedure results in a 30% larger uncertainty on the Fierz term compared to a situation in which the detector calibration was exactly known.

all authors

M. Perkowski, K. Bodek, L. De Keukeleere, L. Hayen, A. Kozela, K. Łojek, D. Rozpędzik, N. Severijns

Initial Tests of MiniBETA Spectrometer Performance

Acta Phys. Pol. B 49, 261 (2018)

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abstract

MiniBETA is a new spectrometer incorporating a low-pressure multiwire drift chamber (MWDC). It is designed for beta spectrum shape measurements and to improve knowledge on electron backscattering in the about 100 keV to a few MeV region. After the commissioning phase, which we report on here, the spectrometer will first be used for the latter purpose. This will help reducing the systematic uncertainty in beta spectrum shape measurements. The performance of the trajectory recognition algorithm was investigated using cosmic muons as the source of the primary ionization. For the initial test, the chamber was filled with a mixture of helium–isobutane (50/50) at 600 mbar. A single cell efficiency $\eta$ higher than 0.98 within almost the entire cell was achieved and the single cell spatial resolution in the drift plane reached $\sigma =0.4$ mm for most of the cells in the chamber.

all authors

I. Mukul, M. Hass, O. Heber, T.Y. Hirsh, Y. Mishnayot, M.L. Rappaport, G. Ron, Y. Shachar, S. Vaintraub

Weak-interaction Studies with Light Radioactive Ions

Acta Phys. Pol. B 49, 269 (2018)

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abstract

We present an experimental plan to study the weak interaction by measuring the electron–neutrino angular correlation from radioactive $\beta$-emitter atoms, $^{6}$He being the first case. Radioactive atoms, produced by a neutron-induced reaction, will diffuse to an electron beam ion source that ionizes, bunches and then injects them into an electrostatic ion beam trap where the angular correlation will be measured. We have tested the trap with stable ions and found the storage time to be 0.6 to 1.2 s for different ions. We have also performed the production experiment for $^{6}$He with a production rate of $\sim 10^{5}$ atoms/s. We present the current status of this project and future plans.

all authors

S. Calabrese, F. Cappuzzello, D. Carbone, M. Cavallaro, C. Agodi, L. Acosta, D. Bonanno, D. Bongiovanni, T. Borello-Lewin, I. Boztosun, D. Calvo, E.R. Chàvez Lomeli, N. Deshmukh, P.N. de Faria, P. Finocchiaro, M. Fisichella, A. Foti, G. Gallo, A. Hacisalihoglu, F. Iazzi, R. Introzzi, G. Lanzalone, R. Linares, F. Longhitano, D. Lo Presti, N. Medina, A. Muoio, J.R.B. Oliveira, A. Pakou, L. Pandola, F. Pinna, S. Reito, G. Russo, G. Santagati, O. Sgouros, S.O. Solakci, V. Soukeras, G. Souliotis, A. Spatafora, D. Torresi, S. Tudisco, A. Yildirim, V.A.B. Zagatto

First Measurement of the $^{116}$Cd($^{20}$Ne,$^{20}$O)$^{116}$Sn Reaction at 15 $A$ MeV

Acta Phys. Pol. B 49, 275 (2018)

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abstract

The NUMEN Collaboration proposes an original experimental method to get information on the nuclear matrix elements involved in the neutrinoless double beta decay, exploring its connection with double charge-exchange nuclear reactions using heavy ions. The first results for the data reduction of the $^{116}$Cd($^{20}$Ne,$^{20}$O)$^{116}$Sn experiment at 15 $A$ MeV are presented.

Pairing Dynamics and Time-dependent Density Functional Theory

Acta Phys. Pol. B 49, 281 (2018)

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abstract

We discuss issues related to pairing dynamics in nuclear large amplitude collective motion. The examples of effects which are not properly described within BCS theory are presented. In the second part, we review properties of time-dependent density functional theory (TDDFT) and, in particular, we discuss the time-dependent superfluid local density approximation (TDSLDA) starting from the stationary action principle.

Time-dependent Method for Many-body Problems and Its Application to Nuclear Resonant Systems

Acta Phys. Pol. B 49, 293 (2018)

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abstract

The decay process of the schematic one-dimensional three-body system is considered. A time-dependent approach is used in combination with a one-dimensional three-body model, which is composed of a heavier core nucleus and two nucleons, with the aim of describing its evolution in two-nucleon emission. The process is calculated from the initial state, in which the three ingredient particles are confined. In this process, two different types of emission can be found: the earlier process includes the emission of spatially correlated two-nucleon pair, like a dinucleon, whereas, at a subsequent time, all the particles are separated from each other. The time-dependent method can be a suitable option to investigate the meta-stable and/or open-quantum systems, where the complicated many-body dynamics should necessarily be taken into account.

On the Multifragmentation and Phase Transition in the Perspectives of Different $n$-body Dynamical Models

Acta Phys. Pol. B 49, 301 (2018)

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abstract

We study central reactions of $^{40}$Ar+$^{45}$Sc in the energy range of 15–115 MeV/nucleon using two different $n$-body dynamical models. In particular, we use the Quantum Molecular Dynamics model and its modified isospin-dependent version. The charge distribution of emitted intermediate mass fragments $[3 \leq Z_{\rm f} \leq 12]$ is fitted using the power law function $[Y(Z_{\rm f}) = Y_0 Z_{\rm f}^{-\tau }]$. We discuss the differences in the results obtained using the two models for the critical point of the liquid–gas phase transition in nuclear matter.

Dynamics of Near-barrier Collisions of Statically Deformed Nuclei

Acta Phys. Pol. B 49, 307 (2018)

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abstract

Dynamics of collisions of heavy nuclei deformed at their ground states is considered within a multidimensional dynamical approach based on Langevin equations. The orientation effects and their energy dependence were investigated on example of the $^{160}$Gd + $^{186}$W reaction. Initial mutual orientations of colliding nuclei influence the distributions of reaction products at near-barrier energies. This should be taken into account when such combinations are used for production of new nuclei in multinucleon transfer reactions.

all authors

O.A. Ponkratenko, E.I. Koshchy, Val.M. Pirnak, A.A. Rudchik, A.T. Rudchik, K. Rusek, Yu.M. Stepanenko, V.V. Uleshchenko, Yu.O. Shyrma

Comparative Analysis of the Light Nuclei Diffractive Scattering on $^{12}$C

Acta Phys. Pol. B 49, 313 (2018)

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abstract

The diffractive structure of experimental differential cross sections of elastic scattering of 23 light nuclei with masses 3 $\le A \le 20$ on $^{12}$C was studied for collision energies from 1 up to 200 MeV/nucleon and transferred momenta up to $q \lt 3$–4 fm$^{-1}$. A common assumption of a diffractive nature of the interaction in these conditions is confirmed by a quantitative analysis of specific features of the differential cross section such as positions of maxima and minima. Their energy evolution as well as that of the corresponding diffraction radius are parameterized with smooth functions. The presented approximation provides an adequate description of experimental data and has a certain predictive power. The observed correlations between the diffraction radius parameters and the structure features of nuclei can be used as a source of information about internal nuclear structure and also as a base for a consistency check between different experimental studies.

Analysis of a Virtual State Using the Complex Scaling Method

Acta Phys. Pol. B 49, 319 (2018)

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abstract

We demonstrate that the complex scaling method (CSM) is a useful tool to study virtual states. We investigate it by applying the CSM to a simple schematic two-body model which simulates the $^8$Be$+n$ system. The pole position of the virtual state is obtained by using the continuum level density and the phase shift.

all authors

G. Khuukhenkhuu, M. Odsuren, Y. Gledenov, J. Munkhsaikhan, S. Davaa, C. Saikhanbayar, E. Sansarbayar, M. Sedysheva

Alpha Clustering in $(n,\alpha )$ Reactions Induced by Slow and Fast Neutrons

Acta Phys. Pol. B 49, 325 (2018)

page 325 •

abstract

Methods to derive $\alpha$-clustering factors from the analysis of experimental data for slow ($E_{n}\lesssim 30$ keV) and fast ($E_n=4$–6 MeV) neutron-induced $(n,\alpha )$ reactions using the statistical model are described. In this way, the dependence of the $\alpha$-clustering factor for the $(n,\alpha )$ reaction on the incident neutron energy can be followed. The resulting $\alpha$-clustering factors are compared with our previous results and those obtained using other approaches.

Skyrme N2LO Pseudo-potential for Calculations of Properties of Atomic Nuclei

Acta Phys. Pol. B 49, 331 (2018)

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abstract

We present recent developments obtained in the so-called N2LO extension of the usual Skyrme pseudo-potential. In particular, we discuss the isovector splitting mass in infinite nuclear matter and the pairing gaps of selected semi-magic even–even nuclei.

Towards Symmetry-unrestricted Skyrme–HFB in Coordinate-space Representation: The Example of Rotational Bands of the Octupole-deformed Nucleus $^{222}$Th

Acta Phys. Pol. B 49, 339 (2018)

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abstract

We report on the cranked Skyrme–HFB calculations of rotational bands of the octupole-deformed nucleus $^{222}$Th. A sudden change in configuration is observed, with the shape of the yrast state jumping from large octupole deformation at low spin to small octupole deformation at high spin.

Neutron–Proton Pairing Correlations in a Single $l$-shell Model

Acta Phys. Pol. B 49, 347 (2018)

page 347 •

abstract

The long-standing problem of neutron–proton pairing correlations is revisited by employing the Hartree–Fock–Bogoliubov formalism with neutron–proton mixing in both the particle–hole and particle–particle channels. We compare numerical calculations performed within this method with an exact pairing model based on the SO(8) algebra. The neutron–proton mixing is included in our calculations by performing rotations in the isospin space using the isocranking technique.

all authors

K. Rusek, N. Keeley, K.W. Kemper, J.L. Aguado-Casas, T. Garcia, I. Martel, A.M. Sánchez-Benítez

Pairing in Exotic He Isotopes

Acta Phys. Pol. B 49, 353 (2018)

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abstract

Data obtained in experiments with the exotic helium isotopes, $^{6,8}$He, are reanalyzed to learn about correlations between the valence neutrons. The results indicate strong pairing of the two valence neutrons in $^6$He, similar to that found in $^{18}$O. For $^8$He, the observed effect is still strong but weaker than that for $^6$He.

Bootstrap Technique to Study Correlation Between Neutron Skin Thickness and the Slope of Symmetry Energy in Atomic Nuclei

Acta Phys. Pol. B 49, 359 (2018)

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abstract

We examine the proposed correlation between the neutron skin thickness and the slope of the symmetry energy for two doubly-magic nuclei (${}^{100}$Sn and ${}^{132}$Sn) and find that a statistically significant correlation appears to exist for ${}^{132}$Sn whilst no such correlation appears to exist for ${}^{100}$Sn. Additionally, we present a new statistical tool based on random sampling to assess the confidence interval of Pearson’s and Spearman’s correlation coefficients in order to examine the aforementioned correlation. These estimators are then used to quantify the statistical correlations among the neutron skin thickness of atomic nuclei and the slope of the symmetry energy in the infinite nuclear medium.

all authors

K.L. Jones, C. Thornsberry, J. Allen, A. Atencio, D.W. Bardayan, D. Blankstein, S. Burcher, A.B. Carter, K.A. Chipps, J.A. Cizewski, I. Cox, Z. Elledge, M. Febbraro, A. Fijałkowska, R. Grzywacz, M.R. Hall, T.T. King, A. Lepailleur, M. Madurga, S.T. Marley, P.D. O'Malley, S.V. Paulauskas, S.D. Pain, W.A. Peters, C. Reingold, K. Smith, S. Taylor, W. Tan, M. Vostinar, D. Walter

Development of the $(d,n)$ Proton-transfer Reaction in Inverse Kinematics for Structure Studies

Acta Phys. Pol. B 49, 365 (2018)

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abstract

Transfer reactions have provided exciting opportunities to study the structure of exotic nuclei and are often used to inform studies relating to nucleosynthesis and applications. In order to benefit from these reactions and their application to rare ion beams (RIBs), it is necessary to develop the tools and techniques to perform and analyze the data from reactions performed in inverse kinematics, that is with targets of light nuclei and heavier beams. We are continuing to expand the transfer reaction toolbox in preparation for the next generation of facilities, such as the Facility for Rare Ion Beams (FRIB), which is scheduled for completion in 2022. An important step in this process is to perform the ($d,n$) reaction in inverse kinematics, with analyses that include $Q$-value spectra and differential cross sections. In this way, proton-transfer reactions can be placed on the same level as the more commonly used neutron-transfer reactions, such as ($d,p$), ($^9$Be,$^8$Be), and ($^{13}$C,$^{12}$C). Here, we present an overview of the techniques used in ($d,p$) and ($d,n$), and some recent data from ($d,n$) reactions in inverse kinematics using stable beams of $^{12}$C and $^{16}$O.

all authors

D. Carbone, J.L. Ferreira, F. Cappuzzello, J. Lubian, C. Agodi, M. Cavallaro, A. Foti, A. Gargano, S.M. Lenzi, R. Linares, G. Santagati

Microscopic Cluster Model for the Description of ($^{18}$O,$^{16}$O) Two-neutron Transfer Reactions

Acta Phys. Pol. B 49, 373 (2018)

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abstract

Excitation energy spectra and absolute cross-section angular distributions were measured for the $^{13}$C($^{18}$O,$^{16}$O)$^{15}$C two-neutron transfer reaction at 84 MeV incident energy. Exact finite-range coupled reaction channel calculations are used to analyse the data considering both the direct two-neutron transfer and the two-step sequential mechanism. For the direct calculations, two approaches are discussed: the extreme cluster and the newly introduced microscopic cluster. The latter makes use of spectroscopic amplitudes in the centre-of-mass reference frame, derived from shell-model calculations. The results describe well the experimental cross sections.

all authors

G. Santagati, B. Paes, R. Magana Vsevolodovna, F. Cappuzzello, D. Carbone, E.N. Cardozo, M. Cavallaro, H. Garcìa-Tecocoatzi, A. Gargano, J.L. Ferreira, S.M. Lenzi, R. Linares, E. Santopinto, A. Vitturi, J. Lubian

Study of the $^{18}$O + $^{64}$Ni Two-neutron Transfer Reaction at 84 MeV by MAGNEX

Acta Phys. Pol. B 49, 381 (2018)

page 381 •

abstract

A study of the two-neutron transfer reaction of the $^{18}$O + $^{64}$Ni system at 84 MeV incident energy to the ground and first 2$^{+}$ excited state of the residual $^{66}$Ni nucleus is presented. The experiment was performed at the INFN-LNS (Italy) by using the large acceptance MAGNEX spectrometer. Theoretical models are used in order to disentangle the competition between long-range and short-range correlations.

all authors

D. Wójcik, A. Trzcińska, E. Piasecki, M. Kisieliński, M. Kowalczyk, M. Wolińska-Cichocka, C. Bordeanu, B. Gnoffo, H. Jia, C. Lin, N.S. Martorana, M. Mutterer, E.V. Pagano, K. Piasecki, P. Russotto, L. Quatrocchi, W.H. Trzaska, G. Tiurin, R. Wolski, H. Zhang

Transfer Cross Sections at Near-barrier Energy for the $^{24}$Mg + $^{90,92}$Zr Systems

Acta Phys. Pol. B 49, 387 (2018)

page 387 •

abstract

We have tested the hypothesis that for systems $^{24}$Mg + $^{90,92}$Zr, the shape of the barrier height distribution is not influenced by transfers processes. The experiment was performed using the ICARE detector system at the Warsaw Cyclotron. Having measured the transfer cross sections of the near-barrier collisions of $^{24}$Mg + $^{90,92}$Zr, we have found them to be roughly half of the value obtained for the $^{20}$Ne + $^{90,92}$Zr systems. From that observation, we conclude that in the $^{24}$Mg + $^{90,92}$Zr case, the leading cause of washing out the barrier distribution structure is the partial dissipation of relative kinetic energy into the non-collective excitation of the system.

all authors

A. Trzcińska, E. Piasecki, M. Kowalczyk, G. Cardella, E. De Filippo, D. Dell’Aquila, S. De Luca, B. Gnoffo, G. Lanzalone, I. Lombardo, C. Maiolino, N.S. Martorana, S. Norella, A. Pagano, E.V. Pagano, M. Papa, S. Pirrone, G. Politi, L. Quattrocchi, F. Rizzo, P. Russotto, A. Trifiro, M. Trimarchi, M. Vigilante

Influence of Single Particle Excitations on Barrier Distributions: $^{24}$Mg+$^{90,92}$Zr

Acta Phys. Pol. B 49, 393 (2018)

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abstract

We present preliminary results of barrier height distribution measurements for $^{24}$Mg+$^{90,92}$Zr systems. The experiment was performed at LNS INFN in Catania with the CHIMERA detector system and a $^{24}$Mg beam accelerated by Tandem MP. The measurements were done at the near-barrier beam energies of 68–88.5 MeV. A discrepancy between experimental results and the predictions of Coupled Channels (CC) calculations was observed. We suggest that this discrepancy may be due to a cumulative effect of many individual weak channels such as non-collective excitations of the target, which cannot be fully implemented in practical CC calculations of a standard form.

Reactor $\overline {\nu }_e$ Properties from $\beta$-decay Study of Fission Fragments by Total Absorption Spectroscopy

Acta Phys. Pol. B 49, 399 (2018)

page 399 •

abstract

Total absorption spectroscopy is a unique technique that is highly efficient for detecting $\gamma$ radiation in a wide range of energies. Thanks to this feature, total absorption spectrometers are successfully used to study $\beta$ decay of unstable nuclei, allowing to determine $\beta$-feeding distributions over the entire decay energy window. Recent studies show the importance of total absorption spectroscopy measurements of the $\beta$ decay of fission product for the understanding of the reactor $\overline {\nu }_e$ spectra. This contribution focuses on the unique capabilities of Modular Total Absorption Spectrometer (MTAS) allowing us to obtain $\beta$ intensities and the de-excitation path of excited levels in daughter nucleus. These capabilities are applied to the analysis of decay data of $^{86}$Br, abundantly produced in nuclear reactors. MTAS results affecting the shape of the $\overline {\nu }_e$ spectrum associated with $^{86}$Br decay are presented.

Sensitivity Studies for the Decay Heat Calculation for $^{235}$U

Acta Phys. Pol. B 49, 409 (2018)

page 409 •

abstract

The sensitivity analysis for $^{235}$U decay heat calculation was performed. The simulations were carried out in SCALE/ORIGEN module using two different databases with fission yields (SCALE’s library and JEFF-3.1) and two databases with decay properties (SCALE’s library and ENDF/B-VII.1). Results obtained using different datasets were compared and the list of isotopes having the largest impact on the change in calculated decay heat was drawn up.

all authors

J.L. Tain, J. Agramunt, D.S. Ahn, A. Algora, J.M. Allmond, H. Baba, S. Bae, N.T. Brewer, R. Caballero Folch, F. Calvino, P.J. Coleman-Smith, G. Cortes, T. Davinson, I. Dillmann, C. Domingo-Pardo, A. Estrade, N. Fukuda, S. Go, C. Griffin, R. Grzywacz, J. Ha, O. Hall, L. Harkness-Brennan, T. Isobe, D. Kahl, M. Karny, G.G. Kiss, M. Kogimtzis, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, J. Lee, J. Liu, G. Lorusso, K. Matsui, K. Miernik, F. Montes, B. Moon, A.I. Morales, N. Nepal, S. Nishimura, R.D. Page, Z. Podolyak, V.F.E. Pucknell, B.C. Rasco, P.H. Regan, A. Riego, B. Rubio, K.P. Rykaczewski, Y. Saito, H. Sakurai, Y. Shimizu, J. Simpson, P.A. Söderström, D.W. Stracener, T. Sumikama, R. Surman, H. Suzuki, M. Takechi, H. Takeda, A. Tarifeno-Saldivia, S.L. Thomas, A. Tolosa-Delgado, V.H. Phong, P. Woods

The BRIKEN Project: Extensive Measurements of $\beta$-delayed Neutron Emitters for the Astrophysical r Process

Acta Phys. Pol. B 49, 417 (2018)

page 417 •

abstract

An ambitious program to measure decay properties, primarily $\beta$-delayed neutron emission probabilities and half-lives, for a significant number of nuclei near or on the path of the rapid neutron capture process, has been launched at the RIKEN Nishina Center. We give here an overview of the status of the project.

Underground Nuclear Astrophysics at LUNA

Acta Phys. Pol. B 49, 429 (2018)

page 429 •

abstract

Since 1991, LUNA (Laboratory for Underground Nuclear Astrophysics) has played a leading role in the direct measurement of nuclear cross sections relevant to astrophysics, producing several pioneering results. Thanks to the shielding provided by the Gran Sasso mountain, LUNA enables measuring very small cross sections of the nuclear reactions involved in stellar and Big Bang nucleosynthesis at (or very close to) the energy range at which they occur in astrophysical scenarios. The present accelerator is provided with two beamlines, respectively dedicated to a solid target and to a differential-pumping extended gas target. The most recent measurements are briefly presented, together with the experimental techniques used, and the astrophysical implications. The imminent installation of a new 3.5 MV accelerator paves the way for the study of a number of key reactions regarding helium and carbon burning.

Experimental Studies of Few-nucleon Systems. Dynamics of the $3N$ Interaction in Cross Sections

Acta Phys. Pol. B 49, 437 (2018)

page 437 •

abstract

Modern nucleon–nucleon ($NN$) interaction models are able to reproduce the bulk of all $NN$ data with an utmost precision. Their quality can be efficiently probed in the few-nucleon environment by comparing high quality theoretical predictions with the observables measured in precision experiments. The most common experimentally tested systems are those of three nucleons. Systematic studies of elastic nucleon–deuteron scattering and deuteron breakup reactions at intermediate energies show that a proper description of the experimental data cannot be achieved with the use of $NN$ forces alone and has to include additional dynamics like effects of suppressed degrees of freedom, introduced by means of genuine three-nucleon forces, Coulomb interaction between protons or relativistic effects. The most important results, concerning cross sections, of recent experimental studies of $3N$ systems at intermediate energies are discussed.

Reconstruction of the Neutron Momentum in the Deuteron Breakup Reaction

Acta Phys. Pol. B 49, 445 (2018)

page 445 •

abstract

Experiments devoted to studies of deuteron breakup reactions were carried out at KVI in Groningen with the use of the BINA detector. In this paper, a technique for direct neutron detection is presented. Time-of-flight information, signal amplitude and timing asymmetry measured at opposite sides of long scintillators were applied for direct neutron detection in kinematically complete three-body breakup experiments. The main motivation is to reach into phase-space regions, which have not been explored yet. The preliminary analysis of the $^2$H$(p,pn)p$ and $^2$H$(d,dn)p$ data measured at 160-MeV deuteron beam is presented.

Cross Section of Transfer Reactions in $d+d$ Collisions at the Deuteron Beam Energy of 160 MeV

Acta Phys. Pol. B 49, 451 (2018)

page 451 •

abstract

In this paper, we report on the $^2$H($d,^3$He)$n$ differential cross section, which was measured at the energy of 160 MeV. The data were collected at the KVI Groningen with the use of the BINA detector. The crucial steps of the data analysis are outlined. The results are presented in comparison to the existing world data set.

Towards an Explanation of the Space Star Anomaly

Acta Phys. Pol. B 49, 457 (2018)

page 457 •

abstract

One of the most intriguing discrepancies observed in the proton–deu-teron breakup reaction is known as the Space Star Anomaly. The effect was found to peak at the energies ranging from 7.5 to 13 MeV/nucleon, but due to scarcity of data at higher energies, it has not been explained yet. Recently, a new analysis has been started in order to fill the gaps in our understanding of the problem. As the first step, the differential cross sections were calculated on the basis of the CD-Bonn potential, including explicit ${\mit \Delta }$ excitation (coupled-channel potential) as well as the Coulomb force, in order to identify the effects that may contribute to the cross sections. The calculations were done for $d$(160 MeV)+$p$, $p$(108 MeV)+$d$ and $p$(135 MeV)+$d$ breakup reactions.

all authors

A. Rusnok, I. Ciepał, B. Jamróz, N. Kalantar-Nayestanaki, G. Khatri, St. Kistryn, B. Kłos, A. Kozela, J. Kuboś, P. Kulessa, A. Liptak, J. Messchendorp, W. Parol, I. Skwira-Chalot, E. Stephan, A. Wilczek, B. Włoch, J. Zejma

Experimental Study of Three-nucleon Dynamics in Proton–Deuteron Breakup Reaction

Acta Phys. Pol. B 49, 463 (2018)

page 463 •

abstract

Proton–deuteron breakup reaction can serve as a tool to test state-of-the-art descriptions of nuclear interactions. At intermediate energies, below the threshold for pion production, comparison of the data with exact theoretical calculations is possible and subtle effects of the dynamics beyond the pairwise nucleon–nucleon interaction, namely the three-nucleon force (3NF), are significant. Beside 3NF, Coulomb interaction or relativistic effects are also important to precisely describe the differential cross section of the breakup reaction. The data analysis and preliminary results of the measurement of proton-induced deuteron breakup at the Cyclotron Center Bronowice, Institute of Nuclear Physics, Polish Academy of Sciences in Kraków are presented.

Studies of Few-nucleon System Dynamics via Deuteron Breakup with the WASA Detector

Acta Phys. Pol. B 49, 469 (2018)

page 469 •

abstract

Relativistic treatment of the few-nucleon theoretical models has been recently developed for the deuteron breakup reaction. This ingredient can be quantitatively verified with the use of the deuteron breakup reaction at the intermediate energy region. The interplay of relativistic and three-nucleon force (3NF) effects can also be studied. For this purpose, an experiment investigating the $^{1}$H$(d,pp)n$ breakup cross section was performed in FZ-Jülich. The unpolarized deuteron beam of energies of 170, 190 and 200 MeV per nucleon was impinging on the hydrogen pellet target and the reaction products were registered with the use of the Wide Angle Shower Apparatus (WASA) detection system. Its almost 4$\pi$ geometrical acceptance gives unique possibility to study a variety of kinematic configurations. The main steps of the analysis, including PID, efficiency studies and normalization, and the preliminary results of the cross section are discussed.

all authors

N.S. Martorana, G. Cardella, E.G. Lanza, L. Acosta, M.V. Andrés, L. Auditore, F. Catara, E. De Filippo, S. De Luca, D. Dell' Aquila, B. Gnoffo, G. Lanzalone, I. Lombardo, C. Maiolino, S. Norella, A. Pagano, E.V. Pagano, M. Papa, S. Pirrone, G. Politi, L. Quattrocchi, F. Rizzo, P. Russotto, D. Santonocito, A. Trifirò, M. Trimarchi, M. Vigilante, A. Vitturi

Experimental Study of the Pygmy Dipole Resonance in the $^{68}$Ni Nucleus

Acta Phys. Pol. B 49, 475 (2018)

page 475 •

abstract

It is known that the low-energy E1 strength, known as the Pygmy Dipole Resonance (PDR), can be excited by both isovector and isoscalar probes. In this work, we report on the results of an experiment, carried out at the LNS-INFN in Catania, with the aim to study the Pygmy Dipole Resonance induced in the $^{68}$Ni nucleus through the interaction with a $^{12}$C isoscalar target. The CHIMERA multidetector and the FARCOS array were used to detect, respectively, $\gamma$ rays and charged particles. Details on the experimental set-up, data analysis and results are reported.

all authors

T. Ohnishi, A. Enokizono, M. Hara, M. Hori, S. Ichikawa, M. Wakasugi, M. Watanabe, K. Adachi, T. Fujita, T. Hori, K. Kurita, M. Togasaki, N. Uchida, K. Yamada, T. Suda, T. Tamae, K. Tsukada

The SCRIT Electron Scattering Facility Project at the RIKEN RI Beam Factory

Acta Phys. Pol. B 49, 483 (2018)

page 483 •

abstract

The SCRIT electron scattering facility has been constructed at the RIKEN RI Beam Factory. The commissioning experiment was performed and the properties of the ion trapping were studied. The first electron elastic scattering experiment of $^{132}$Xe was performed and the charge density distribution was obtained. The achieved luminosity in the experiment was $1.8\times 10^{27}$ cm$^{-2}$ s$^{-1}$ with a 250 mA electron beam current and the injection of 10$^8$ ions. The production of unstable nuclei has been started with a new online isotope separator (ISOL) system at the SCRIT facility, and developments of the ISOL system for increasing rates of unstable nuclei are underway. Electron scattering with unstable nuclei will be performed in the near future.

Study of Exotic Nuclei in the Flerov Laboratory of Nuclear Reactions at Joint Institute for Nuclear Research

Acta Phys. Pol. B 49, 495 (2018)

page 495 •

abstract

The fragment separator ACCULINNA-2 has been constructed, approved by the Programme Advisory Committee (PAC) and commissioned in the G.N. Flerov Laboratory of Nuclear Reactions (JINR, Dubna) in 2017. It was tested with the $^{15}$N beam at the energy of 49.7 MeV/nucleon. The secondary beams $^{6}$He and $^{12}$Be produced in the beryllium target were obtained with purities and intensities predicted by the code LISE++. Here, we list the most meaningful and challenging experiments on the light drip-line nuclei at ACCULINNA, which should be clarified at ACCULINNA-2: (i) the search for the minor $2p$-decay branch of the first excited state of $^{17}$Ne, the ${\mit \Gamma }_{2p}/{\mit \Gamma }_{\gamma }$ width ratio; (ii) study of break down of the shell closure in the doubly magic $^{10}$He in the $^3$H($^8$He,$p)^{10}$He reaction; (iii) study of the $\beta$-delayed proton emission in $^{26}$P and $^{27}$S, which offers insight into the structure of the initial and the final states of these exotic nuclei. Among the first-day experiments is a study of the low-energy resonance states of $^7$H anticipated for the $4n$ decay.

all authors

D. Kostyleva, O. Kiselev, A. Bezbakh, V. Chudoba, V. Eremin, A. Fomichev, A. Gorshkov, S. Krupko, I. Mukha, I. Muzalevskii, C. Scheidenberger, P. Sharov

Study of the Silicon Detectors for Time-of-Flight Measurements at the Super-FRS Facility and Expert Experiments at FAIR

Acta Phys. Pol. B 49, 503 (2018)

page 503 •

abstract

An important part of the beam diagnostics of the future superconducting Super-FRS fragment separator at FAIR will be the time-of-flight measurement. The tests of radiation-hard silicon detectors for such measurements at the Super-FRS and the EXPERT project within the Super-FRS Experiment Collaboration are presented. The main part of the current work is devoted to an investigation of the time characteristics of silicon detectors under the irradiation caused by intermediate energy Xe and C beams. The time resolution, obtained for the detector prototypes irradiated with Xe, reaches down to 20 ps, for C ions to 100 ps. These results are presented and discussed.

all authors

M. Ćwiok, M. Bieda, J.S. Bihałowicz, W. Dominik, Z. Janas, Ł. Janiak, J. Mańczak, T. Matulewicz, C. Mazzocchi, M. Pfützner, P. Podlaski, S. Sharma, M. Zaremba, D. Balabanski, A. Bey, D.G. Ghita, O. Tesileanu, M. Gai

A TPC Detector for Studying Photo-nuclear Reactions at Astrophysical Energies with Gamma-ray Beams at ELI–NP

Acta Phys. Pol. B 49, 509 (2018)

page 509 •

abstract

An active-target Time Projection Chamber (ELITPC) is being developed at the University of Warsaw to investigate the photo-disintegration reaction $^{16}$O($\gamma$,$\alpha$)$^{12}$C at energies relevant for nuclear astrophysics (down to $\sim 1$ MeV in the centre of mass). Selected results from ongoing R$\&$D activities are presented in this paper.

Extremely Small Isospin Impurity in the Lowest $T=2$ Isobaric Analogue State in $^{52}$Co

Acta Phys. Pol. B 49, 515 (2018)

page 515 •

abstract

Combining our newly measured masses of ground and $(2^+)$ isomeric states of $^{52}$Co with previous measurements of $^{52}$Ni $\beta$ decay, a remarkably different decay scheme of $^{52}$Ni is constructed. In the new scheme, the proton group with the highest intensity corresponds to the decay from the $1^+$ excited state in $^{52}$Co, and not from the $J^{\pi }=0^+, T = 2$ isobaric analog state (IAS) as it was commonly assumed. This finding indicates that the degree of isospin impurity in the lowest $T = 2$ IAS in $^{52}$Co is extremely small, thus leading to a negligibly weak proton emission from the IAS and a mistaken assignment. Effort to find an explanation for this phenomenon is highly called for.

all authors

M. Piersa, A. Korgul, L.M. Fraile, J. Benito, E. Adamska, R. Álvarez, A.E. Barzakh, G. Benzoni, T. Berry, M.J.G. Borge, M. Carmona, K. Chrysalidis, G. Correia, C. Costache, T. Day Goodacre, D.V. Fedorov, V.N. Fedosseev, G. Fernández-Martínez, M. Fila, D. Galaviz, R. Grzywacz, C. Henrich, A. Illana, Z. Janas, K. Johnston, V. Karanyonchev, M. Kicińska-Habior, R. Lică, M. Madurga, I. Marroquín, B. Marsh, C. Martínez, C. Mazzocchi, K. Miernik, R. Mihai, B. Olaizola, S. Paulaskalas, J.-M. Régis, S. Rothe, V. Sánchez-Tembleque, G. Simpson, Ch. Sotty, L. Stan, M. Stănoiu, M. Stryjczyk, A. Turturica, J.M. Udías, V. Vedia, A. Villa, W.B. Walters

Investigation of Low-lying States in $^{133}$Sn Populated in the $\beta$ Decay of $^{133}$In Using Isomer-selective Laser Ionization

Acta Phys. Pol. B 49, 523 (2018)

page 523 •

abstract

Excited states in the neutron-rich isotope $^{133}$Sn were studied via the $\beta$ decay of $^{133}$In. Isomer selective ionization using the ISOLDE RILIS enabled the $\beta$ decays of $^{133}$In$_{\rm gs}$ ($I^{\pi }=9/2^+$) and $^{133m}$In ($I^{\pi }=1/2^-$) to be studied independently for the first time. A description of the experimental setup at the ISOLDE Decay Station is presented together with preliminary results from the experiment.

all authors

C. Henrich, Th. Kröll, K. Arnswald, C. Berger, C. Berner, T. Berry, V. Bildstein, J. Cederkäll, D. Cox, G. de Angelis, H. De Witte, G. Fernández Martínez, L. Gaffney, G. Georgiev, S. Ilieva, A. Illana Sisón, R. Lozeva, M. Matejska-Minda, P.J. Napiorkowski, J. Ojala, J. Pakarinen, G. Rainovski, M. Ramdhane, P. Reiter, H.-B. Rhee, D. Rosiak, M. Seidlitz, B. Siebeck, G. Simpson, J. Snäll, V. Vaquero Soto, M. Thürauf, M. von Schmid, N. Warr, L. Werner, M. Zielińska

Coulomb Excitation of $^{142}$Xe

Acta Phys. Pol. B 49, 529 (2018)

page 529 •

abstract

The even–even nucleus $^{142}$Xe lies north-east of the doubly magic $^{132}$Sn on the neutron-rich side of the nuclear chart. In order to gain further information on the octupole collectivity and the evolution of quadrupole collectivity in this region, a “safe” Coulomb excitation experiment was carried out at the new HIE-ISOLDE facility (CERN) at the end of 2016. As the gamma-ray detector the Miniball spectrometer was used. Beam and target nuclei were detected using C-REX, i.e. an array of segmented Si detectors, covering forward as well as backward angles in the laboratory frame.

all authors

S. Dutt, M. Saxena, R. Kumar, A. Jhingan, A. Agarwal, A. Banerjee, R.K. Bhowmik, C. Joshi, J. Kaur, A. Kumar, M. Matejska-Minda, V. Mishra, I.A. Rizvi, A. Stolarz, H.J. Wollersheim, P.J. Napiorkowski

Re-measurement of Reduced Transition Probabilities in $^{132}$Ba

Acta Phys. Pol. B 49, 535 (2018)

page 535 •

abstract

Reduced transition probabilities between the low-lying states of $^{132}$Ba were measured using the Coulomb excitation technique. The experiment was performed at Inter University Accelerator Center (IUAC), New Delhi using a $^{58}$Ni beam of 175 MeV energy to Coulomb excite the $^{132}$Ba nuclei. In addition to the 2$_{1}^{+}$ state, other states in $^{132}$Ba, such as 2$_{2}^{+}$ and 4$_{1}^{+}$, were populated, the latter for the first time using Coulomb excitation. A set of matrix elements was extracted for the transitions between these levels. These values were determined relative to $^{134}$Ba excitations to minimize the systematic errors. A $B$(E2; 0$_{\rm gs}^{+}\rightarrow 2_1^{+}$) value of 1.088(85) $e^{2}$b$^{2}$ was determined, corresponding to $\sim 54.5$ single-particle units.

all authors

M. Saxena, P. Napiorkowski, R. Kumar, L. Próchniak, A. Stolarz, T. Abraham, S. Dutt, M. Kicińska-Habior, M. Kisieliński, M. Komorowska, M. Kowalczyk, M. Matejska-Minda, M. Palacz, J. Srebrny, K. Wrzosek-Lipska, H.-J. Wollersheim

Evidence of Rotational Behaviour in $^{120}$Te Isotope

Acta Phys. Pol. B 49, 541 (2018)

page 541 •

abstract

A multi-step Coulomb excitation experiment was performed to study the structure of stable $^{120}$Te nuclei using a $^{32}$S beam from the HIL cyclotron U-200P. The ground-state band up to the $4^{+}$ state was populated. In addition, the excitation of the $2_{2}^{+}$ and ${0_{2}^{+}}$ states was also observed. Magnitudes and relative signs of the transitional matrix elements between the low-lying states in $^{120}$Te were determined using the least-squares search code GOSIA. The diagonal matrix elements of the first $2^{+}$ and $4^{+}$ states were extracted.

all authors

J. Wiśniewski, W. Urban, T. Rząca-Urban, U. Köster, C. Michelagnoli, M. Jentschel, P. Mutti

Evolution of $\gamma$ Collectivity — $(n,\gamma )$ Spectroscopy of $^{98}$Mo with FIPPS

Acta Phys. Pol. B 49, 547 (2018)

page 547 •

abstract

Excited states in $^{98}$Mo have been populated in ($n,\gamma$) reaction and studied using $\gamma$-ray coincidences measured with Germanium Clover detectors of the new instrument FIPPS. The aim of the study is to investigate the evolution of $\gamma$ collectivity in Mo isotopes in its early-development stage. The ground state of $^{97}$Mo 5/2$^{+}$ should allow the observation of the $\gamma$ band in $^{98}$Mo up to spin 7$^{+}$. This is sufficient to measure interesting properties of the $\gamma$ band, such as mixing ratios.

all authors

E.R. Gamba, A.M. Bruce, M. Rudigier, S. Lalkovski, S. Bottoni, M.P. Carpenter, S. Zhu, A.D. Ayangeakaa, J.T. Anderson, T.A. Berry, I. Burrows, R.J. Carrol, P. Copp, M. Carmona Gallardo, D.M. Cullen, T. Daniel, G. Fernández Martínez, J.P. Greene, L.A. Gurgi, D.J. Hartley, R. Ilieva, S. Ilieva, R.V.F. Janssens, F.G. Kondev, T. Kröll, G.J. Lane, T. Lauritsen, I. Lazarus, G. Lotay, C.R. Niţă, Zs. Podolyák, V. Pucknell, M. Reed, P.H. Regan, J. Rohrer, J. Sethi, D. Seweryniak, C.M. Shand, J. Simpson, M. Smoleń, V. Vedia, E.A. Stefanova, O. Yordanov

Fast-timing Measurements in $^{100}$Zr Using LaBr$_{3}$(Ce) Detectors Coupled with Gammasphere

Acta Phys. Pol. B 49, 555 (2018)

page 555 •

abstract

In order to investigate the evolution of nuclear deformation in the region of the chart of nuclides around mass numbers $A\simeq 110$ and $A\simeq 150$, an experiment was performed at the Argonne National Laboratory where the gamma-decay radiation emitted from the fission fragments of $^{252}$Cf was measured using 51 Gammasphere detectors coupled with 25 LaBr$_{3}$(Ce) detectors. In this work, a short description of the experimental setup is presented together with some preliminary results from the fast-timing analysis of the $4^{+}$ state of the nucleus $^{100}$Zr. A lifetime value of $\tau = 50(28)$ ps was obtained using the Generalized Centroid Shift Method. This result agrees with the literature value of $\tau = 53(4)$ ps within one standard deviation.

all authors

N. Cieplicka-Oryńczak, C. Michelagnoli, S. Leoni, B. Fornal, G. Benzoni, A. Blanc, S. Bottoni, F.C.L. Crespi, Ł.W. Iskra, M. Jentschel, U. Köster, P. Mutti, N. Pietralla, E. Ruiz-Martinez, V. Werner

The Low-spin Structure of $^{206}$Tl Studied by $\gamma$-ray Spectroscopy from Thermal Neutron Capture Reaction

Acta Phys. Pol. B 49, 561 (2018)

page 561 •

abstract

The low-spin structure of the $^{206}$Tl nucleus has been investigated with the FIPPS prompt $\gamma$-ray spectrometer of ILL making use of the $^{205}$Tl($n,\gamma$)$^{206}$Tl reaction and the $\gamma$-coincidence technique. A large number of excitations up to the neutron binding energy (at 6.5 MeV) in $^{206}$Tl were observed. Preliminary results of the data analysis provided the information on the decay scheme of the capture state in $^{206}$Tl and on the multipolarities of a number of $\gamma$ rays. The comparison of the experimental data with shell-model calculations will help describing the proton–hole and neutron–hole couplings near the doubly magic core $^{208}$Pb, benchmarking single-particle levels and two-body matrix elements of the residual interaction in this important region of the nuclear chart.

all authors

M. Matejska-Minda, P.J. Napiorkowski, T. Abraham, P. Bednarczyk, A. Bezbakh, D.T. Doherty, K. Hadyńska-Klęk, J. Iwanicki, G. Kamiński, M. Kisieliński, M. Komorowska, M. Kowalczyk, M. Kicińska-Habior, R. Kumar, A. Maj, T. Marchlewski, P. Matuszczak, V. Nanal, A. Nannini, M. Palacz, L. Próchniak, M. Rocchini, M. Saxena, M. Siciliano, J. Srebrny, A. Stolarz, J. Styczeń, B. Wasilewska, K. Wrzosek-Lipska, M. Zielińska

Electromagnetic Properties of $^{45}$Sc Studied by Low-energy Coulomb Excitation

Acta Phys. Pol. B 49, 567 (2018)

page 567 •

abstract

A Coulomb excitation experiment to study electromagnetic properties of $^{45}$Sc was performed at the Heavy Ion Laboratory, University of Warsaw, using a 70 MeV $^{32}$S beam. Measured $\gamma$-ray intensities together with existing spectroscopic data were used to extract a set of matrix elements between the populated states. Upper limit on $B$(E3;$7/2^- \rightarrow 5/2^+)$ is given.

TDHF Investigations of the U+U Quasifission Process

Acta Phys. Pol. B 49, 573 (2018)

page 573 •

abstract

The use of actinide collisions have been suggested as a way to produce neutron-rich isotopes of high-$Z$ nuclei. The collision dynamics of these reactions can be studied using unrestricted time-dependent Hartree–Fock (TDHF) calculations. Here, we report on the recent studies of quasifission for the $^{238}$U+$^{238}$U system.

all authors

R.N. Sahoo, M. Kaushik, A. Sood, P. Kumar, V.R. Sharma, A. Yadav, M. Shuaib, D.P. Singh, P.P. Singh, U. Gupta, M.K. Sharma, R. Kumar, B.P. Singh, S. Aydin, H.J. Wollersheim, R. Prasad

Entrance Channel Effect on Incomplete Fusion

Acta Phys. Pol. B 49, 585 (2018)

page 585 •

abstract

In the present work, the onset and strength of incomplete fusion were studied in terms of various entrance channel parameters. Excitation functions for individual evaporation residues were measured in the $^{12}$C+$^{169}$Tm system at energies from 5 to 7.5 $A$ MeV, and analysed in the framework of the statistical model code PACE-IV to deduce the fraction of incomplete fusion. It was found that the probability of incomplete fusion increases with the incident energy as well as with the mass asymmetry of interacting partners for individual projectiles. Moreover, the critical value of the input angular momentum ($\ell _{\rm crit}$) obtained from the experimental cross sections was compared with that calculated using the Wilczyński formula and a slight difference has been found.

Accuracy of Fission Dynamics Within the Time-dependent Superfluid Local Density Approximation

Acta Phys. Pol. B 49, 591 (2018)

page 591 •

abstract

We investigate properties of the method based on time dependent superfluid local density approximation (TDSLDA) within an application to induced fission of $^{240}$Pu and surrounding nuclei. Various issues related to accuracy of time evolution and the determination of the fission fragment properties are discussed.

all authors

P. Chhetri, C.S. Moodley, S. Raeder, M. Block, F. Giacoppo, S. Götz, F.P. Heßberger, M. Eibach, O. Kaleja, M. Laatiaoui, A.K. Mistry, T. Murböck, Th. Walther

Investigation of the First Ionization Potential of Ytterbium in Argon Buffer Gas

Acta Phys. Pol. B 49, 599 (2018)

page 599 •

abstract

One of the most important atomic properties influencing elements chemical behaviour is the energy required to remove its outermost electron: the first ionization potential (IP). The determination of this basic atomic property is challenging for the transfermium elements with $Z\gt 100$. Recently, Rydberg states have been observed in nobelium (No, $Z=102$) inside a buffer gas cell. The buffer gas environment influences the energy of the Rydberg levels and thus the IP extracted from analysing the Rydberg series. Therefore, laser resonance ionization spectroscopy in a buffer gas cell was employed to determine the IP of its chemical homologue, ytterbium (Yb, $Z=70$) at different buffer gas pressures to characterize the systematics arising from the buffer gas environment.

all authors

P. Mošať, S. Antalic, F.P. Heßberger, D. Ackermann, B. Andel, M. Block, S. Hofmann, Z. Kalaninová, B. Kindler, I. Kojouharov, M. Laatiaoui, B. Lommel, A.K. Mistry, K. Nishio, J. Piot, B. Sulignano, M. Vostinar

Total Kinetic Energy Measurements for Spontaneous Fission of $^{255,\,256,\,258}$Rf

Acta Phys. Pol. B 49, 605 (2018)

page 605 •

abstract

Spontaneous fission of $^{255}$Rf, $^{256}$Rf and $^{258}$Rf was studied at SHIP in GSI Darmstadt. The isotopes were produced in fusion–evaporation reactions $^{50}$Ti + $^{207, 208}$Pb and $^{50}$Ti + $^{209}$Bi (compound nuclei $^{257}$Rf, $^{258}$Rf and $^{259}$Db, respectively) and implanted into the focal plane detector of the SHIP setup. The deficit in the measured fragments energies was evaluated as a function of implantation depth of evaporation residues in the silicon detector. This correction was applied to obtain the mean total kinetic energies of $^{255}$Rf, $^{256}$Rf and $^{258}$Rf.

all authors

A.K. Mistry, Z. Zhang, F.P. Heßberger, D. Ackermann, B. Andel, S. Antalic, M. Block, P. Chhetri, F. Dechery, C. Droese, Ch.E. Düllmann, F. Giacoppo, J. Hoffmann, O. Kaleja, J. Khuyagbaatar, N. Kurz, M. Laatiaoui, J. Maurer, P. Mošať, J. Piot, S. Raeder, M. Vostinar, A. Yakushev

Decay Spectroscopy of Heavy Isotopes at SHIP Using the COMPASS Focal Plane Detection Set-up

Acta Phys. Pol. B 49, 613 (2018)

page 613 •

abstract

The new COMPASS detection system designed and developed at GSI, Darmstadt was employed in the focal plane of the SHIP velocity filter on-line during a period of commissioning. The isotope $^{254}$No was initially measured for control purposes, following which the nuclei, $^{227,228,230}$U, $^{229}$Np, and $^{229,230}$Pu were synthesized. The obtained data from $\alpha$-decay spectroscopy is evaluated and compared with previous measurements.

Fission of SHN and Its Hindrance: Odd Nuclei and Isomers

Acta Phys. Pol. B 49, 621 (2018)

page 621 •

abstract

After shortly analysing data relevant to fission hindrance of odd-$A$ nuclei and high-$K$ isomers in super-heavy (SH) region, we point out the inconsistency of current fission theory and propose an approach based on the instanton formalism. A few results of this method, simplified by replacing selfconsistency by elements of the macro–micro model, are given to illustrate its features.

all authors

M. Thakur, B.R. Behera, R. Mahajan, N. Saneesh, G. Kaur, P. Sharma, R. Dubey, K. Kapoor, A. Yadav, N. Kumar, S. Kumar, K. Rani, P. Sugathan, A. Jhingan, A. Chatterjee, M.B. Chatterjee, S. Mandal, A. Saxena, S. Pal, S. Kailas

Fission Dynamics Studies of Near Super-heavy Compound Nucleus $^{256}$Rf

Acta Phys. Pol. B 49, 631 (2018)

page 631 •

abstract

To understand the fission dynamics of $^{256}$Rf, we performed neutron multiplicity measurements for the reaction $^{48}$Ti+$^{208}$Pb at an excitation energy of 57.4 MeV. The results confirmed the presence of quasi-fission processes in this system. The experimental neutron multiplicities have also been compared with the theoretical predictions from statistical model calculations. From this comparison, the value of reduced dissipation strength for the $^{256}$Rf nucleus is found to be $(7.6\pm 0.7)\times 10^{21}$ s$^{-1}$ and a fission delay time of $(39.6^{+4.6}_{-4.1})\times 10^{-21}$ s has been estimated.

all authors

Niyti, R. Singh, A. Deep, R. Kharab, S. Chopra, R.K. Gupta

Dynamical Cluster-decay Model Based on Skyrme Force KDE0(v1) and the Dynamics of $^{208,206,204}$Pb+$^{48}$Ca $\rightarrow ^{256,254,252}$No$^{*}$ Reaction

Acta Phys. Pol. B 49, 639 (2018)

page 639 •

abstract

Extending our earlier work on $^{48}$Ca + $^{204,206,208}$Pb reactions, based on the Dynamical Cluster-decay Model (DCM) using the pocket formula for nuclear proximity potential, we study the cross sections $\sigma _{xn}$ for the decay of the compound nuclei $^{252,254,256}$No$^{*}$, synthesized in $^{48}$Ca + $^{204,206,208}$Pb fusion reactions, via $1n$–$4n$ evaporation channels. For this study, we use the DCM with the Skyrme force KDE0(v1). Deformations $\beta _{2i}$ and hot-optimum orientations $\theta _i$ at various excitation energies $E^{*}$ from 19.6 to 43.6 MeV are included. Interestingly, for the use of a Skyrme force, the DCM reproduces the data very well with one parameter $\Delta R$ fitted to the measured data on fusion evaporation residues (ER).

all authors

R. Mahajan, B.R. Behera, M. Thakur, G. Kaur, P. Sharma, K. Kapoor, P. Sugathan, A. Jhingan, A. Chatterjee, N. Saneesh, R. Dubey, A. Yadav, N. Kumar, Hardev Singh, A. Kumar, A. Saxena, S. Pal

Fission Dynamics of $^{192,202,206,210}$Po Compound Nuclei by Neutron Multiplicity Measurements

Acta Phys. Pol. B 49, 645 (2018)

page 645 •

abstract

This paper reports a summary of the experimental results on pre- and post-scission neutron multiplicities ($M_{\rm pre}$ and $M_{\rm post}$) from $^{192,202}$Po compound nuclei populated by $^{48}$Ti+$^{144,154}$Sm systems at 72 MeV excitation energy, studied using the National Array of Neutron Detectors (NAND) at IUAC, New Delhi. The experimental neutron yields along with already existing data for $^{12}$C+$^{194}$Pt and $^{18}$O+$^{192}$Os are compared with predictions from the statistical model of compound nuclear decay including the strength of nuclear dissipation as a free parameter. $M_{\rm pre}$ values obtained from the present analysis do not show any specific dependence on the $(N-Z)/A$ values of the fissioning nuclei. In order to explain the experimental neutron multiplicities, the entrance channel effects are important.

all authors

G. Kaur, B.R. Behera, A. Jhingan, R. Dubey, T. Banerjee, M. Thakur, R. Mahajan, P. Sharma, Khushboo, N. Saneesh, A. Yadav, K. Kapoor, N. Kumar, K. Rani, P. Sugathan, N. Rowley

Quasi-elastic Scattering in the $^{48}$Ti+$^{232}$Th Reaction

Acta Phys. Pol. B 49, 651 (2018)

page 651 •

abstract

The barrier distribution (BD) for a system $^{48}$Ti+$^{232}$Th, leading to the super-heavy nucleus $^{280}$Cn$_{112}$ (copernicium) is obtained by measuring the flux reflected from the Coulomb barrier at large backward angles. The coupled-channel calculations are performed to study the effect of target and projectile excitation on the BD structure. Furthermore, from the BD study, the information on the fusion barrier is extracted.

Experimental Studies of Nuclear Reactions of Astrophysical Relevance by Means of the Trojan Horse Method Applied to Resonant Reactions

Acta Phys. Pol. B 49, 657 (2018)

page 657 •

abstract

Nuclear astrophysics aims at bringing together experimental and theoretical data necessary to understand, model and predict astrophysical phenomena, from energy production in the Sun to more exotic scenarios, such as supernovae. Nuclear physics plays a major role as fusion reactions are responsible for the energy generation as well as for the synthesis of elements. In this context, resonant reactions have a particular interest since resonances might significantly change the nucleosynthesis path and the energy production rate, modifying stellar evolution, including the last evolutionary stages. Such experimental studies are extremely difficult, since nuclear reactions in most astrophysical environments occur at energies well below the Coulomb barrier among charged particles, as large as a few MeV. This is why indirect methods have been introduced in recent years. Among them, the Trojan Horse Method has proven very effective for reactions induced by charged particles and neutrons. In this work, we will discuss two recent indirect measurements of reactions of astrophysical interest, having a resonant behaviour: the $^{19}$F$(p,\alpha ){}^{16}$O reaction that displays resonances at energies above the particle emission threshold and the $^{13}$C$(\alpha ,n){}^{16}$O, dominated by a near-threshold resonance due to the 6.356 MeV $^{17}$O level.

all authors

G.G. Rapisarda, C. Spitaleri, A. Cvetinović, R. Spartá, S. Cherubini, G.L. Guardo, M. Gulino, M. La Cognata, L. Lamia, S.M.R. Puglia, S. Romano, M.L. Sergi

Recent Results on the $^{10}$B$(p,\alpha )^{7}$Be Reaction Studied via THM at Low Energies

Acta Phys. Pol. B 49, 669 (2018)

page 669 •

abstract

The Trojan Horse Method has been applied to the $^{2}$H($^{10}$B,$\,\alpha ^{7}$Be)$n$ three-body reaction in order to study $^{10}$B($p,\,\alpha )^{7}$Be two-body interaction. Improvement in the experimental set-up allowed to obtain a better experimental resolution and to get for the first time separation between the $\alpha _{0}$ and $\alpha _{1}$ channels. Moreover, with respect to the previous THM experiment, an improvement of the energy resolution for the $^{10}$B($p,\,\alpha _{0})^{7}$Be excitation function has been achieved. For the first time, experimental data allowed the THM study of the $^{10}$B($p,\,\alpha _{1})^{7}$Be channel. Preliminary results will be discussed.

all authors

N. Targosz-Ślęczka, K. Czerski, M. Kaczmarski, D. Weissbach, A.İ. Kiliç, G. Ruprecht, A. Huke, S. Policastro

Electron Screening Effect in Nuclear Reactions in Metallic and Gaseous Targets

Acta Phys. Pol. B 49, 675 (2018)

page 675 •

abstract

The electron screening effect and its influence on enhanced $^2$H$(d,p)^3$H reaction cross section was investigated based on latest metallic (Zr) target data, as well as much older gaseous target data. The enhancement can result not only from the electron screening effect but also from a suggested $0^+$ resonance state in the $^4$He compound nucleus. This resonance state allows to explain the experimental enhancement factor energy dependence.

Measurement of Proton-induced Radiation in Animal Tissue

Acta Phys. Pol. B 49, 681 (2018)

page 681 •

abstract

Hadron therapy, because of the dosimetric and radiobiological advantages, is more and more often used in tumour treatment. This treatment method leads also to the radioactive effects induced by energetic protons on nuclei. Nuclear reactions may lead to the production of radioactive isotopes. In the present experiment, two animal (human-like) tissue samples were irradiated with 60 MeV protons. Gamma-ray spectroscopy and lifetime measurements allowed identifying isotopes produced during the irradiation, e.g. $^{18}$F and $^{34m}$Cl.

Systematic Investigation of Precompound Emission over Compound Evaporation in $\alpha +^{89}$Y Reaction

Acta Phys. Pol. B 49, 687 (2018)

page 687 •

abstract

The exciton model and the hybrid Monte-Carlo simulation method have been used to investigate the effect of pre-equilibrium emission over compound evaporation in the $\alpha +^{89}$Y reaction. The pre-equilibrium excitation functions of $^{92m,91m,90,89}$Nb, $^{89,88}$Zr and $^{88,87}$Y radionuclides populated via $xn$, $pxn$, and $\alpha$$xn$ channels, respectively, were evaluated over a wide energy range, starting from the threshold and up to 100 MeV. The results show that the inclusion of a precompound model is essential to reproduce the measured data. Our calculations are in a good agreement with the most of the experimental data reported earlier.

all authors

T.K. Zholdybayev, B.A. Duisebayev, B.M. Sadykov, M. Nassurlla, G. Ussabayeva, K.M. Ismailov

Emission of Light Charged Particles from Reaction of $^3$He Ions of Energy of 50.0 MeV with $^{59}$Co Nucleus

Acta Phys. Pol. B 49, 693 (2018)

page 693 •

abstract

This paper presents experimental double-differential and integral cross sections of reactions ($^{3}$He,$xp$), ($^{3}$He,$xd$) and ($^{3}$He,$x\alpha$) on the $^{59}$Co nucleus. The experiment with $^{3}$He ions, accelerated to the energy of 50.0 MeV, was performed at the isochronous cyclotron of the Institute of Nuclear Physics (Almaty, Kazakhstan). Theoretical analysis of the experimental results has been carried out in terms of a modified version of the exciton model. A satisfactory agreement between experimental and calculated values has been achieved.

Recent Results and the Future of the NA61/SHINE Strong Interactions Program

Acta Phys. Pol. B 49, 699 (2018)

page 699 •

abstract

NA61/SHINE is a fixed target experiment at the CERN Super-Proton-Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and to study the properties of the onset of deconfinement. In order to reach these goals, the collaboration studies hadron production properties in nucleus–nucleus, proton–proton and proton–nucleus interactions. In this paper, recent results on particle production in $p$+$p$ interactions, as well as Be+Be and Ar+Sc collisions in the SPS energy range, are reviewed. The results are compared with available world data. The future of the NA61/SHINE scientific program is also presented.

all authors

M. Skurzok, M. Cargnelli, C. Curceanu, Raffaele Del Grande, L. Fabbietti, C. Guaraldo, J. Marton, P. Moskal, K. Piscicchia, A. Scordo, M. Silarski, D.L. Sirghi, I. Tucakovic, O. Vazquez Doce, S. Wycech, E. Widmann, J. Zmeskal

Search for Deeply Bound Kaonic Nuclear States in the AMADEUS Experiment

Acta Phys. Pol. B 49, 705 (2018)

page 705 •

abstract

We briefly report on the search for Deeply Bound Kaonic Nuclear States with AMADEUS in the ${\mit \Sigma }^{0} p$ channel, and future perspectives.

all authors

A. Marcinek, A. Rybicki, A. Szczurek, M. Kiełbowicz, N. Davis, V. Ozvenchuk, S. Bhosale, I. Sputowska

Electromagnetic Effects in Pb+Pb Collisions at the SPS; from Nuclear Physics of the Spectator System to the Space-time Evolution of the QGP

Acta Phys. Pol. B 49, 711 (2018)

page 711 •

abstract

We review our studies of spectator-induced electromagnetic (EM) effects on charged pion emission in heavy-ion collisions at CERN SPS and RHIC BES energies. These effects are found to consist in the electromagnetic charge splitting of pion directed flow as well as very large distortions in spectra and ratios of produced charged particles. As it emerges from our analysis, they offer sensitivity to the actual distance $d_E$ between the pion formation zone at freeze-out and the spectator matter. As a result, this gives a new possibility of studying the space-time evolution of the dense and hot matter created in the course of the collision. A specific picture emerges, where the centrality dependence of pion rapidity spectra at CERN SPS energies may be interpreted as a pure consequence of local energy-momentum conservation. Furthermore, as follows from our analysis, EM effects also show sensitivity to the space-time scale of spectator breakup. We comment on a recent study of the dynamical evolution of the spectator system, which gives very different predictions for spectator excitation energy depending on the dynamical scenario assumed. In this context, we argue that EM effects in ultrarelativistic heavy-ion collisions can provide a unique, independent experimental input to test nuclear models in extreme conditions.

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