### Regular Series

#### XXXIII Mazurian Lakes Conference on Physics Frontiers in Nuclear Physics

Pear-shaped Nuclei: Nuclear Models and the Standard Model

Acta Phys. Pol. B 45, 127 (2014)

page 127 •

abstract

For certain combinations of protons and neutrons, there is a theoretical expectation that the shape of nuclei can assume octupole deformation, which would give rise to reflection asymmetry or a “pear shape” in the intrinsic frame, either dynamically (octupole vibrations) or statically (permanent octupole deformation). In this paper, I will briefly review the historic evidence for reflection asymmetry in nuclei, describe how recent experiments carried out at REX-ISOLDE are constraining nuclear theory and how they contribute to tests of extensions of the Standard Model, and look at future prospects for this field.

Studying Stars by Going Underground: The LUNA Experiment at Gran Sasso Laboratory

Acta Phys. Pol. B 45, 137 (2014)

page 137 •

abstract

One of the main ingredients of nuclear astrophysics is the knowledge of the thermonuclear reactions responsible for powering the stellar engine and for the synthesis of the chemical elements. At astrophysical energies, the cross section of nuclear processes is extremely reduced by the effect of the Coulomb barrier and often extrapolations are needed. The Laboratory for Underground Nuclear Astrophysics (LUNA) is placed under the Gran Sasso mountain. Thanks to the environmental background reduction provided by its position, many reactions involved in hydrogen burning has been measured directly at astrophysical energies. Based on this progress, currently there are efforts in several countries to construct new underground accelerators. The exciting science that can be probed with these new facilities will be highlighted.

Nuclear Structure Studies with the AGATA Array at Legnaro

Acta Phys. Pol. B 45, 147 (2014)

page 147 •

abstract

Results of three selected AGATA Demonstrator experiments performed at Legnaro National Laboratory of INFN (Italy), aiming at studying collective modes of excitations, such as rotation and vibration, under extreme conditions, are reported. Firstly, the $K$-hindrance to the $\gamma$ decay is investigated in the warm rotating $^{174}$W nucleus, focusing on the weakening of the selection rules of the $K$ quantum number with excitation energy. A strong hindrance to the E1-decay between low-$K$ and high-$K$ rotational bands is found, giving evidence that $K$-mixing due to temperature effects is the leading phenomenon, contributing, for all discrete excited bands, to the progressive erosion of the $K$-quantum number with excitation energy. The second experiment concerns the study of the pygmy dipole resonance in the neutron rich $^{208}$Pb nucleus, by inelastic scattering of $^{17}$O at 20 MeV/$u$. The $\gamma$ decay is measured with the AGATA Demonstrator coupled to an array of large volume LaBr$_{3}$:Ce scintillators. A preliminary comparison with ($\gamma$,$\gamma$’) data indicate that states in the 5–8 MeV energy interval belong to two different groups, one with an isoscalar character and the other with an isovector nature. Finally, the breaking of isospin symmetry is studied in the hot compound $N=Z$ nucleus $^{80}$Zr, by comparing the $\gamma$ decay of the Giant Dipole Resonance from the fusion reactions $^{40}$Ca+$^{40}$Ca at $E_{\mathrm {beam}} = 136$ MeV and $^{37}$Cl+$^{44}$Ca at $E_{\mathrm {beam}} = 95$ MeV. Preliminary results show that the yield associated with the Giant Dipole Resonance is different in the two reactions because in self-conjugate nuclei the E1 selection rules forbid the decay between states with isospin $I=0$. The experiment aims at providing information on the degree of isospin mixing at temperature around $\approx 2$ MeV and to extrapolate the zero-temperature value, which is then compared with the latest predictions.

all authors

C.E. Mertin, D.D. Caussyn, A.M. Crisp, N. Keeley, K.W. Kemper, O. Momotyuk, B.T. Roeder, A. Volya

Separation Between $d_{5/2}$ and $s_{1/2}$ Neutron Single Particle Strength in $^{15}$N

Acta Phys. Pol. B 45, 159 (2014)

page 159 •

abstract

The separation between single particle levels in nuclei plays the dominant role in determining the location of the neutron drip line. The separation also provides a test of current crossed shell model interactions if the experimental data is such that multiple shells are involved. The present work uses the $^{14}$N($d,p)^{15}$N reaction to extract the $2s_{1/2}$, and $1d_{5/2}$ total neutron single particle strengths and then compares these results with a shell model calculation using a $p$–$sd$ crossed shell interaction to identify the $J^\pi$ of all levels in $^{15}$N up to 11 MeV in excitation.

Isospin Mixing Within the Symmetry Restored Density Functional Theory and Beyond

Acta Phys. Pol. B 45, 167 (2014)

page 167 •

abstract

We present results of systematic calculations of the isospin-symmetry-breaking corrections to the superallowed $I=0^+$, $T=1\rightarrow I=0^+$, $T=1$ $\beta$-decays, based on the self-consistent isospin- and angular-momentum-projected nuclear density functional theory (DFT). We discuss theoretical uncertainties of the formalism related to the basis truncation, parametrization of the underlying energy density functional, and ambiguities related to determination of Slater determinants in odd–odd nuclei. A generalization of the double-projected DFT model towards a no core shell-model-like configuration-mixing approach is formulated and implemented. We also discuss new opportunities in charge-symmetry- and charge-independence-breaking studies offered by the newly developed DFT formalism involving proton–neutron mixing in the particle–hole channel.

all authors

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

From Nuclei to Stars with a Trojan Horse

Acta Phys. Pol. B 45, 181 (2014)

page 181 •

abstract

Nuclear reactions are responsible for the energy production in stars and related nucleosynthesis processes. For this reason, an accurate knowledge of their rates at the energies of interest is required. The Trojan Horse Method has been introduced to overcome the experimental difficulties arising from the small cross sections involved in reactions induced by charged particles at astrophysical energies. This is done by measuring the quasi-free cross section of an appropriate three body process. The basic theory of the Trojan Horse Method will be presented together with a review of some recent experimental results.

all authors

N. Benouaret, J. Beller, J. Isaak, J.H. Kelley, H. Pai, N. Pietralla, V.Yu. Ponomarev, R. Raut, C. Romig, G. Rusev, D. Savran, M. Scheck, L. Schnorrenberger, K. Sonnabend, A.P. Tonchev, W. Tornow, H.R. Weller, M. Zweidinger

Photoexcitation of the Stable Tl Isotopes Below the Neutron Separation Energy

Acta Phys. Pol. B 45, 193 (2014)

page 193 •

abstract

Although the systematics of the Pygmy Dipole Resonance was established in several stable even–even nuclei, the collectivity of this mode, explained in a macroscopic picture as an oscillation of a neutron skin against an isospin symmetric proton–neutron core, is still not well understood. In order to guide the theoretical models, we investigated the heavy odd mass, stable isotopes $^{203,205}$Tl using unpolarized bremsstrahlung photon beams at the S-DALINAC facility at TU Darmstadt. The NRF experiments were complemented by measurements at the High Intensity $\gamma$-ray Source (HI$\gamma$S) at the Triangle Universities Nuclear Laboratory (TUNL) in Durham, NC, USA, with a fully linearly polarized quasi-monoenergetic photon beam. Between 4 and 7 MeV, a concentration of dipole strength is observed in the odd-mass nuclide $^{205}$Tl. For the $^{203}$Tl isotope, two ground-state transitions around 5 MeV could be resolved in the spectra. In this report, the obtained results will be presented. The results for the proton-odd nuclide $^{205}$Tl will be compared to the ones for the neighbouring even–even nucleus $^{206}$Pb.

all authors

S. Calinescu, L. Cáceres, S. Grévy, O. Sorlin, D. Sohler, M. Stanoiu, F. Negoita, E. Clément, R. Astabatyan, C. Borcea, R. Borcea, M. Bowry, W. Catford, Z. Dombradi, S. Franchoo, R. Garcia, R. Gillibert, H. Guerin, J.C. Thomas, I. Kuti, S. Lukyanov, A. Lepailleur, V. Maslov, P. Morfouace, J. Mrazek, M. Niikura, L. Perrot, Z. Podolyak, C. Petrone, Y. Penionzhkevich, T. Roger, F. Rotaru, I. Stefan, Z. Vajta, E. Wilson

Study of the Neutron-rich Isotope $^{46}$Ar Through Intermediate Energy Coulomb Excitation

Acta Phys. Pol. B 45, 199 (2014)

page 199 •

abstract

The preliminary value of the reduced transition probability $B$(E2; 0$^+ \rightarrow$ 2$^+_1$) in $^{46}$Ar has been determined using the Coulomb excitation technique at intermediate energy. The $^{46}$Ar was produced in the fragmentation of a $^{48}$Ca beam at GANIL. The $\gamma$-rays following the Coulomb excitation of the 2$^+_1$ were emitted in-flight and detected by the 64 BaF$_2$ detectors of the Château de Cristal array. The relatively low $B$(E2) value of $^{46}$Ar reported in this article supports the semi-magic character of this nucleus due to the persistence of the $N=28$ shell closure at $Z=18$.

all authors

N. Cieplicka, B. Fornal, K.H. Maier, B. Szpak, R. Broda, W. Królas, T. Pawłat, J. Wrzesiński, R.V.F. Janssens, M.P. Carpenter, C.J. Chiara, C.R. Hoffman, F.G. Kondev, T. Lauritsen, S. Zhu, Zs. Podolyák, M. Bowry, M. Bunce, W. Gelletly, R. Kempley, M. Reed, P. Regan, P. Walker, E. Wilson, A.Y. Deo, G. Dracoulis, G. Lane, C. Rodriguez-Triguero

Angular Distributions of $\gamma$ Rays from $^{210}$Bi Produced in $^{208}$Pb+$^{208}$Pb Deep-inelastic Reactions

Acta Phys. Pol. B 45, 205 (2014)

page 205 •

abstract

The high-spin yrast structure of the $^{210}$Bi nucleus was investigated using $\gamma$-ray coincidence spectroscopy following deep-inelastic reactions in the $^{208}$Pb+$^{208}$Pb system. Cascades of $\gamma$ rays following the decay of a new isomer were identified. Spin-parity assignments to the states known from previous studies as well as to newly located excitations were made based on the measured angular distributions of $\gamma$ rays combined with a transition conversion coefficient analysis.

all authors

D. Gorelov, J. Hakala, A. Jokinen, V. Kolhinen, J. Koponen, I. Moore, H. Penttilä, I. Pohjalainen, M. Reponen, S. Rinta-Antila, V. Sonnenschein, A. Voss, A. Al-Adili, M. Lantz, A. Mattera, S. Pomp, V. Rakopoulos, V. Simutkin, A. Solders, J. Äystö

Isomeric Yield Ratios of Fission Products Measured with the JYFLTRAP

Acta Phys. Pol. B 45, 211 (2014)

page 211 •

abstract

Experimental methods to determine isomeric yield ratios usually apply $\gamma$-spectroscopic techniques. In such methods, ground and isomeric states are distinguished by their decays. In the present work, several isomeric yield ratios of fission products have been measured by utilizing capabilities of the double Penning-trap mass spectrometer JYFLTRAP, where isomeric and ground state were separated by their masses. To verify the new experimental technique, the results were compared to those from $\gamma$-spectroscopy measurements.

all authors

R. Grzywacz, K.P. Rykaczewski, C.J. Gross, M. Madurga, K. Miernik, D.T. Miller, S.V. Paulauskas, S.W. Padgett, C. Rasco, M. Wolińska-Cichocka, E.F. Zganjar

Hybrid-3Hen — New Detector for Gammas and Neutrons

Acta Phys. Pol. B 45, 217 (2014)

page 217 •

abstract

Recently, a unique detector system for beta-delayed neutron spectroscopy, Hybrid-3Hen, was constructed and used in an experiment. This detector is a modification of the neutron detector 3Hen array, which uses $^3$He-filled tubes at 10 atm and high density polyethylene moderator. In Hybrid-3Hen the gamma-ray detection capability was implemented by adding two large HPGe clover-type detectors from the CLARION/CARDS array. This modification of 3Hen enabled efficient studies of beta-delayed neutron emission by using neutron–gamma coincidences. The system is equipped with full-digital readout for easy implementation of the slow and fast coincidences between various parts of the entire detection system. This new array was used in measurements at the Holifield Radioactive Ion Beam Facility and proven to be an essential tool to measure the large beta delayed two neutron emission branching ratio from the exotic isotope $^{86}$Ga.

Structure of Neutron-rich Nuclei Beyond $N=50$

Acta Phys. Pol. B 45, 223 (2014)

page 223 •

abstract

The measurement of the $\beta$-decay scheme of $^{85}$Ga triggered questions on the properties of the low-lying states in $^{85}$Ge. In order to inspect the sensitivity of the results to the neutron $d_{5/2}$ and $s_{1/2}$ single-particle states, we performed an analysis of the level structure in the $N=51$ $^{83}$Ge and $N=53$ $^{85}$Ge isotopes.

all authors

J. Marganiec, F. Wamers, F. Aksouh, Y. Aksyutina, H. Alvarez Pol, T. Aumann, S. Beceiro, C. Bertulani, K. Boretzky, M.J.G. Borge, M. Chartier, A. Chatillon, L. Chulkov, D. Cortina-Gil, I. Egorova, H. Emling, O. Ershova, C. Forssén, L.M. Fraile, H. Fynbo, D. Galaviz, H. Geissel, L. Grigorenko, M. Heil, D.H.H. Hoffmann, J. Hoffmann, H. Johansson, B. Jonson, M. Karakoç, C. Karagiannis, O. Kiselev, J.V. Kratz, R. Kulessa, N. Kurz, C. Langer, M. Lantz, K. Larsson, T. Le Bleis, R. Lemmon, Yu.A. Litvinov, K. Mahata, C. Müntz, T. Nilsson, C. Nociforo, G. Nyman, W. Ott, V. Panin, Yu. Parfenova, S. Paschalis, A. Perea, R. Plag, R. Reifarth, A. Richter, K. Riisager, C. Rodríguez Tajes, D. Rossi, G. Schrieder, N. Shulgina, H. Simon, J. Stroth, K. Sümmerer, J. Taylor, O. Tengblad, E. Tengborn, H. Weick, M. Wiescher, C. Wimmer, M. Zhukov

Study of the $^{15}$O$(2p,\gamma )^{17}$Ne Cross Section by Coulomb Dissociation of $^{17}$Ne for the $rp$ Process of Nucleosynthesis

Acta Phys. Pol. B 45, 229 (2014)

page 229 •

abstract

The $^{15}$O$(2p,\gamma )^{17}$Ne cross section has been studied by the inverse reaction, the Coulomb dissociation of $^{17}$Ne. The experiment has been performed at the GSI. The $^{17}$Ne excitation energy prior to decay has been reconstructed by using the invariant-mass method. The preliminary differential and integral Coulomb dissociation cross sections ($\sigma _{\rm Coul}$) have been extracted, which provide a photoabsorption ($\sigma _{\rm photo}$) and a radiative capture cross section ($\sigma _{\rm cap}$). Additionally, important information about the $^{17}$Ne nuclear structure will be obtained. The analysis is in progress.

all authors

M. Matejska-Minda, P. Bednarczyk, B. Fornal, M. Ciemała, M. Kmiecik, M. Krzysiek, A. Maj, W. Męczyński, S. Myalski, J. Styczeń, M. Ziębliński, G. de Angelis, T. Huyuk, C. Michelagnoli, E. Sahin, S. Aydin, E. Farnea, R. Menegazzo, F. Recchia, C. Ur, S. Brambilla, S. Leoni, D. Montanari, G. Jaworski, M. Palacz, R. Wadsworth, F. Xu, W. Liang

Lifetime Measurements of Short Lived States in $^{69}$As

Acta Phys. Pol. B 45, 235 (2014)

page 235 •

abstract

Lifetimes of high-spin states in $^{69}$As have been measured using Doppler shift attenuation technique with the GASP and RFD set-up. The nucleus of interest was populated in the $^{40}$Ca($^{32}$S, $3p$)$^{69}$As reaction at beam energy of 95 MeV. Extracted lifetimes for the $33/2^+$ state at 7897 keV and $37/2^+$ state at 9820 keV are 72 ($-45$, $+55$) fs and 25($-25$, $+50$) fs, respectively. The transition quadrupole moment resulting from the measurement can serve as a test of the TRS calculations.

all authors

P. Morfouace, S. Franchoo, M. Assié, F. Azaiez, N. De Séréville, J. Guillot, F. Hammache, B. Le Crom, L. Lefebvre, I. Matea, A. Mutschler, I. Stefan, D. Suzuki, D. Napoli, D. Mengoni, C. Borcea, R. Borcea, C. Petrone, F. Rotaru, M. Stanoiu, L. Grassi

Single-particle Strength in Neutron-rich $^{69}$Cu

Acta Phys. Pol. B 45, 243 (2014)

page 243 •

abstract

The nuclear structure of $^{69}$Cu has been investigated by means of the ($d$,$^3$He) transfer reaction at the Orsay tandem in direct kinematics using a deuteron beam at $E_d=27$ MeV and a target of $^{70}$Zn isotopically enriched to 95.4%. The $^3$He of interest from the transfer reaction were detected with the split-pole spectrometer at different angles in the laboratory frame in order to perform angular distributions and assign the angular momentum for each populated state in $^{69}$Cu. In this paper, the transferred angular momenta of the populated states will be presented.

Properties of Localized Protons in Neutron Star Matter at Finite Temperatures

Acta Phys. Pol. B 45, 249 (2014)

page 249 •

abstract

We study properties of the proton component of neutron star matter for realistic nuclear models. Vanishing of the nuclear symmetry energy implies proton–neutron separation in dense nuclear matter. Protons which form admixture tend to be localized in potential wells. Here, we extend the description of proton localization to finite temperatures. It appears that the protons are still localized at temperatures typical for hot neutron stars. That fact has important astrophysical consequences. Moreover, the temperature inclusion leads to unexpected results for the behavior of the proton localized state.

all authors

A. Zwolińska, T.W. Bao, T. Batsch, I. Britvitch, J.Y. Chai, Y.W. Dong, N. Gauvin, W. Hajdas, K. Jędrzejczak, J. Karczmarczyk, M.N. Kong, C. Lechanoine-Leluc, Lu Li, J.T. Liu, X. Liu, R. Marcinkowski, S. Orsi, M. Pohl, N. Produit, D. Rapin, A. Rutczyńska, D. Rybka, H.L. Shi, J.C. Sun, J. Szabelski, T. Tymieniecka, R.J. Wang, X. Wen, B.B. Wu, H.L. Xiao, H.H. Xu, Li Zhang, L.Y. Zhang, S.N. Zhang, Y.J. Zhang

POLAR: the Space Experiment to Study the Origin of Gamma Ray Bursts

Acta Phys. Pol. B 45, 255 (2014)

page 255 •

abstract

Measurements of polarisation of $\gamma$-rays emitted in Gamma-Ray Burst (GRB) will provide a new parameter in collected data. This parameter is sensitive to predictions of different models of poorly known $\gamma$-ray emission processes. Here, we present the POLAR experiment — a compact space detector dedicated to the measurement of polarisation of GRB $\gamma$-rays prompt emission. The flight model of POLAR will be ready in 2014, for launch in space by 2015 on the Chinese Spacelab TG-2. Expected lifetime of experiment is 3 years.

all authors

D. Rudolph, U. Forsberg, P. Golubev, L.G. Sarmiento, A. Yakushev, L.-L. Andersson, A. Di Nitto, Ch.E. Düllmann, J.M. Gates, K.E. Gregorich, C.J. Gross, R.-D. Herzberg, F.P. Heßberger, J. Khuyagbaatar, J.V. Kratz, K. Rykaczewski, M. Schädel, S. Åberg, D. Ackermann, M. Block, H. Brand, B.G. Carlsson, D. Cox, X. Derkx, K. Eberhardt, J. Even, C. Fahlander, J. Gerl, E. Jäger, B. Kindler, J. Krier, I. Kojouharov, N. Kurz, B. Lommel, A. Mistry, C. Mokry, H. Nitsche, J.P. Omtvedt, P. Papadakis, I. Ragnarsson, J. Runke, H. Schaffner, B. Schausten, P. Thörle-Pospiech, T. Torres, T. Traut, N. Trautmann, A. Türler, A. Ward, D.E. Ward, N. Wiehl

Alpha-Photon Coincidence Spectroscopy Along Element 115 Decay Chains

Acta Phys. Pol. B 45, 263 (2014)

page 263 •

abstract

Produced in the reaction $^{48}$Ca+$^{243}$Am, thirty correlated $\alpha$-decay chains were observed in an experiment conducted at the GSI Helmholzzentrum für Schwerionenforschung, Darmstadt, Germany. The decay chains are basically consistent with previous findings and are considered to originate from isotopes of element 115 with mass numbers 287, 288, and 289. A set-up aiming specifically for high-resolution charged particle and photon coincidence spectroscopy was placed behind the gas-filled separator TASCA. For the first time, $\gamma$ rays as well as X-ray candidates were observed in prompt coincidence with the $\alpha$-decay chains of element 115.

Theoretical Survey of Superheavy Elements

Acta Phys. Pol. B 45, 273 (2014)

page 273 •

abstract

Half lives of superheavy elements are discussed. Energies were obtained in the framework of Skyrme Hartree–Fock–Bogoliubov (HFB) theory and the mass parameters in adiabatic time dependent HFB (ATDHFB) cranking approximation. The SkM* energy density functional (EDF) was used in the particle–hole channel and density dependent delta interaction (DDDI) in a mixed form in the particle–particle channel. Ground state energies were estimated on the semi-classical WKB formula resembling the Bohr–Sommerfeld (BS) quantization rule. The results for spontaneous fission, alpha and beta decays are presented and discussed. The most stable superheavy nuclei are located in the vicinity of $Z=112$, $N=182$.

all authors

Z. Majka, M. Barbui, F. Becchetti, G. Chubaryan, M. Cinausero, D. Fabris, G. Giuliani, H. Griffin, K. Hagel, J. Kallunkathariyil, E-J. Kim, S. Kowalski, P. Lasko, M. Lunardon, T. Materna, S. Moretto, R. Murthy, J. Natowitz, G. Nebbia, T. O'Donnel, S. Pesente, R. Planeta, G. Prete, L. Quin, V. Rizzi, P. Sahu, K. Schmidt, G. Souliotis, Z. Sosin, G. Viesti, R. Wada, J. Wang, A. Wieloch, S. Wuenschel, H. Zheng

Experimental Search for Super and Hyper Heavy Nuclei at Cyclotron Institute Texas A&M University

Acta Phys. Pol. B 45, 279 (2014)

page 279 •

abstract

The question “How heavy can an atomic nucleus be?” is a fundamental problem in nuclear physics. The possible existence of island(s) of stable super-heavy nuclei has been an inspiring problem in heavy ion physics for almost four decades. This paper is focused on the experimental search of Super/Hyper Heavy Elements (SHE/HHE) conducted at the Cyclotron Institute, Texas A&M University. A novel experimental idea and experimental set up introduced for this research will be presented.

Synthesis of Superheavy Nuclei: Nearest and Distant Opportunities

Acta Phys. Pol. B 45, 291 (2014)

page 291 •

abstract

There are only 3 methods for the production of heavy and superheavy (SH) nuclei, namely, a sequence of neutron capture and beta($-$) decay, fusion reactions, and multinucleon transfer reactions. A macroscopic amount of the long-living SH nuclei located at the island of stability may be produced by using the pulsed nuclear reactors of the next generation only if the neutron fluence per pulse will be increased by about three orders of magnitude. Low values of the fusion cross sections and very short half-lives of nuclei with $Z\gt 120$ also put obstacles in synthesis of new elements. At the same time, an important area of SH isotopes located between those produced in the cold and hot fusion reactions remains unstudied yet. This gap could be filled in fusion reactions of $^{48}$Ca with available lighter isotopes of Pu, Am, and Cm. New neutron-enriched isotopes of SH elements may be produced with the use of a $^{48}$Ca beam if a $^{250}$Cm target would be prepared. In this case, we get a real chance to reach the island of stability owing to a possible beta(+) decay of $^{291}$114 and $^{287}$112 nuclei formed in this reaction with a cross section of about 0.8 pb. Multinucleon transfer processes look quite promising for the production and study of neutron-rich heavy nuclei located in the upper part of the nuclear map not reachable by other reaction mechanisms. Reactions with actinide beams and targets are of special interest for synthesis of new neutron-enriched transfermium nuclei and not-yet-known nuclei with closed neutron shell $N=126$ having the largest impact on the astrophysical r-process. The estimated cross sections for the production of these nuclei allows one to plan such experiments at currently available accelerators.

Alpha Decay Half-lives for Super-heavy Nuclei Within a Gamow-like Model

Acta Phys. Pol. B 45, 303 (2014)

page 303 •

abstract

The simple two-free-parameter phenomenological formula derived in A. Zdeb, M. Warda, K. Pomorski, Phys. Rev. C87, 024308 (2013) for alpha and cluster decays is applied to predict alpha radioactivity half-lives of super-heavy isotopes. Nuclei with proton number $100 \le Z \le 122$ and neutron number $150 \le N \le 192$ are considered.

Test of Modern Theoretical Approaches Using Modern Experimental Methods

Acta Phys. Pol. B 45, 309 (2014)

page 309 •

abstract

Resonance scattering induced by rare isotope beams provides new possibilities for testing ab initio nuclear structure calculations. We discuss such tests involving resonance reactions populating $^{14}$F and $^8$B levels.

Acta Phys. Pol. B 45, 321 (2014)

page 321 •

abstract

Studies of neutron radioactivity, a spontaneous break-up of atomic nucleus by emission of one or more neutrons are reviewed. Theoretical predictions of this still un-observed phenomenon and the recent experimental activity are presented. For example, the case of two-neutron decay of $^{26}$O isotope is discussed. Prospective candidates for observation of neutron radioactivity and the related novel experimental methods are introduced. In particular, the fragment correlation method applied to neutron decays in-flight at intermediate energies is argued to be sensitive to decay energies down to 1 keV provided the corresponding neutron detector has sufficiently fine angular resolution. The design of such a neutron detector is suggested.

Near-threshold Correlations of Neutrons

Acta Phys. Pol. B 45, 331 (2014)

page 331 •

abstract

The emergence of charged-particle clustering in near-threshold configuration is a phenomenon which can be explained in the Open Quantum System (OQS) description of the atomic nucleus. In this work, we apply the realistic Shell Model Embedded in the Continuum (SMEC) to elucidate emergence of neutron correlations in near-threshold many-body states coupled to $\ell =1,2$ neutron decay channels. Consequences of continuum coupling for spectra and the emergence of complex multi-neutron correlations are briefly discussed.

all authors

S. Bottoni, S. Leoni, B. Fornal, R. Raabe, G. Benzoni, A. Bracco, F.C.L. Crespi, A. Morales, B. Bednarczyk, N. Cieplicka, W. Królas, A. Maj, B. Szpak, M. Callens, J. Bouma, J. Elseviers, F. Falvigny, R. Orlandi, K. Rusek, P. Reiter, M. Seidlitz, S. Klupp, D. Mücher, G. Georgiev, D. Balabanski, M. Sferrazza, M. Kowalska, E. Rapisarda

$\gamma$ Spectroscopy of Neutron-rich Nuclei with $A\approx 100$ Produced by Cluster Transfer Reactions at REX-ISOLDE

Acta Phys. Pol. B 45, 343 (2014)

page 343 •

abstract

In this work, we present an exploratory experiment performed at REX-ISOLDE to investigate neutron-rich Sr, Y and Zr nuclei around mass $A=100$ by cluster transfer reactions of radioactive $^{98}$Rb/$^{98}$Sr beams on a $^{7}$Li target. The goal of the experiment is to test the potential of cluster-transfer mechanism to study the low-lying structure of neutron-rich nuclei, performing, as a first case, a $\gamma$-spectroscopy study of the structure in deformed nuclei beyond $N=60$ populated, so far, only via $\beta$ decay and spontaneous fission experiments.

Relative Population of $^6$Be and $^8$Be Clusters in the Decay of Excited Compound Nucleus $^{124}$Ce* Using the Dynamical Cluster-decay Model

Acta Phys. Pol. B 45, 349 (2014)

page 349 •

abstract

The decay of proton-rich compound nucleus $^{124}$Ce$^*\!$, formed in $^{32}$S+$^{92}$Mo reaction at an above barrier laboratory energy of 150 MeV, is studied within the dynamical cluster-decay model (DCM) with effects of deformations up to hexadecapole and “compact” orientations of nuclei included in it. Treating the experimental data on the statistical code PACE4 shows large deviations in all cases of proton clusters $2p$, $3p$ and $4p$, constituting evaporation residue (ER), and $^6$Be, the intermediate mass fragment (IMF). Though the data is observed up to $^{10}$C, the $^8$Be decay is not observed in this experiment. Using the DCM, for the best fitted cross-sections of two ERs ($2p, 3p$) and two IMFs ($^5$Li, $^6$Be), the relative cross-section of $^8$Be is found to be bigger than that of $^6$Be. The only parameter of the model is the neck-length $\Delta R$, related to “barrier lowering” parameter.

all authors

S.E.A. Orrigo, B. Rubio, J. Agramunt, A. Algora, F. Molina, Y. Fujita, B. Blank, P. Ascher, M. Gerbaux, J. Giovinazzo, S. Grévy, T. Kurtukian-Nieto, W. Gelletly, B. Bilgier, R.B. Cakirli, E. Ganioğlu, H.C. Kozer, L. Kucuk, G. Susoy, L. Cáceres, O. Kamalou, C. Stodel, J.C. Thomas, H. Fujita, T. Suzuki, A. Tamii, L. Popescu, A.M. Rogers

Beta Decay of the Exotic $T_z = -2$, $^{56}$Zn Nucleus and Half-life of Various Proton-rich $T_z = -1$ Nuclei

Acta Phys. Pol. B 45, 355 (2014)

page 355 •

abstract

Preliminary results of an experimental study of the $\beta$-decay of the exotic $T_z = -2$, $^{56}$Zn nucleus and other proton-rich $T_z = -1$ nuclei are presented. The ions were produced at GANIL using fragmentation reactions, separated by the LISE3 spectrometer and implanted in a double-sided silicon strip detector surrounded by Ge detectors. The half-lives of $^{56}$Zn and four $T_z = -1$ nuclei in the $fp$-shell have been measured. While the decay of the $T_z = -1$ nuclei proceeds essentially by $\beta$-delayed gamma emission, in the case of $^{56}$Zn $\beta$-delayed proton emission is also observed. Moreover, the exotic $\beta$-delayed gamma-proton decay is seen for the first time. The information from the decay study has been used to determine the absolute Fermi and Gamow–Teller transition strengths. The results for $^{56}$Zn have been compared with the mirror Charge Exchange process, the ($^{3}$He,$t$) reaction on the $T_z = +2$, $^{56}$Fe target nucleus. This comparison is important for understanding the $^{56}$Zn decay data.

all authors

M. Mazzocco, D. Torresi, L. Acosta, A. Boiano, C. Boiano, N. Fierro, T. Glodariu, A. Guglielmetti, N. Keeley, M. La Commara, I. Martel, C. Mazzocchi, P. Molini, A. Pakou, C. Parascandolo, V.V. Parkar, N. Patronis, D. Pierroutsakou, M. Romoli, K. Rusek, A.M. Sanchez-Benitez, M. Sandoli, C. Signorini, R. Silvestri, F. Soramel, E. Stiliaris, E. Strano, L. Stroe, K. Zerva

Direct and Compound Nucleus Reactions for the System $^7$Be + $^{58}$Ni at Near-barrier Energies

Acta Phys. Pol. B 45, 363 (2014)

page 363 •

abstract

The interaction of the Radioactive Ion Beam $^7$Be with the closed proton shell target $^{58}$Ni was investigated at two energies around the Coulomb barrier. $^7$Be scattered ions as well as $^{3,4}$He reaction products were measured in a rather wide angular range. The elastic scattering angular distributions were analyzed within the framework of the optical model to extract the total reaction cross section. Extensive theoretical and kinematical calculations were performed to disentangle the origin of $^{3,4}$He ions between direct and compound nucleus reactions.

all authors

V. Pesudo, M.J.G. Borge, A.M. Moro, E. Nacher, L. Acosta, M. Alcorta, M.A.G. Alvarez, G.C. Ball, P.C. Bender, R. Braid, M. Cubero, A. di Pietro, J.P. Fernandez-Garcia, P. Figuera, M. Fisichella, B.R. Fulton, A.B. Garnsworthy, J. Gomez-Camacho, G. Hackman, O.S. Kirsebom, K. Kuhn, R. Krüecken, M. Lattuada, J.A. Lay, G. Marquínez-Durán, I. Martel, D. Miller, M. Moukaddam, P.D. O'Malley, A. Perea, M.M. Rajabali, A.M. Sánchez-Benítez, F. Sarazin, V. Scuderi, C.E. Svensson, O. Tengblad, C. Unsworth, Z.M. Wang

Reaction of the Halo Nucleus $^{11}$Be on Heavy Targets at Energies Around the Coulomb Barrier

Acta Phys. Pol. B 45, 375 (2014)

page 375 •

abstract

New data for the reaction $^{11}$Be on $^{197}$Au at $E_{\mathrm {lab}}= 31.9$ MeV are presented. The angular distributions of the inelastically scattered $^{11}$Be and the $^{10}$Be fragments coming from the $^{11}$Be dissociation have been extracted and compared with semiclassical and coupled-channels calculations in an angular range $\theta _{\mathrm {lab}} =13^\circ$–$46^\circ$ for the detected Be fragment.

all authors

A. Trzcińska, E. Piasecki, W. Czarnacki, P. Decowski, N. Keeley, M. Kisieliński, S. Kliczewski, P. Koczoń, A. Kordyasz, M. Kowalczyk, S. Khlebnikov, E. Koshchiy, T. Krogulski, B. Lommel, T. Loktev, M. Mutterer, K. Piasecki, I. Strojek, W.H. Trzaska, S. Smirnov, A. Stolarz, G. Tiourin

Barrier Height Distributions — the Influence of Weak Channels

Acta Phys. Pol. B 45, 383 (2014)

page 383 •

abstract

We present a review of barrier height distribution studies performed at the Heavy Ion Laboratory (HIL) of the Warsaw University using $^{20}$Ne beams. The barrier height distributions for the $^{20}$Ne+$^{58,60,61}$Ni, $^{90,92}$Zr, $^{118}$Sn and $^{208}$Pb systems were experimentally determined. In some cases, a discrepancy between experimental results and the predictions of Coupled-Channels (CC) calculations was observed. We suggest that this discrepancy could be due to the cumulative effect of many individually weak channels, such as non-collective excitations of the target or transfer reactions, which cannot be implemented fully in practical CC or CRC calculations of standard form.

Study of Deformation Effects on Fusion Probabilities with Skyrme Interaction and Other Proximity Based Potentials

Acta Phys. Pol. B 45, 391 (2014)

page 391 •

abstract

The Skyrme energy density formalism (SEDF) is used to study the effect of deformation on the fusion barriers and fusion cross-sections. Proximity based potentials like AW 95, Bass 80 and Denisov DP are also used for a comparative analysis. In this paper, deformation enters via deformed Coulomb potential between the two colliding nuclei. Our detailed study reveals that the deformed Coulomb potential alone can affect interaction potential significantly in the inner region as well as fusion probabilities at below barrier energies.

Direct Reaction Mechanisms for Exotic Nuclei

Acta Phys. Pol. B 45, 397 (2014)

page 397 •

abstract

Since the first measurements in the 80s of total reaction cross sections from radioactive beams up to the most recent and advanced exclusive experiments for dripline unbound nuclei, our understanding of exotic nuclei has greatly evolved. This has been possible through a joint effort in the description of the reaction mechanisms and of the underlying nuclear structure. Most exotic nuclei are weakly bound due to the excess of either neutrons or protons and they breakup easily in peripheral reactions. We will discuss in this paper the mechanism responsible for nuclear breakup and the way it influences elastic scattering and total reaction cross section measurements. Some open problems will be discussed in detail, such as kinematical effects on core parallel momentum distributions and the possibility and consequences that such cores be themselves weakly bound. A general framework for the reaction theory will be used, based on a time dependent perturbation theory approach. Its eikonal limit will be also mentioned.

all authors

M. Bondí, F. Cappuzzello, C. Agodi, D. Carbone, M. Cavallaro, A. Cunsolo, M. De Napoli, A. Foti, V.N. Garcia, A. Gargano, S.M. Lenzi, R. Linares, J. Lubian, D. Nicolosi, B. Paes, S. Tropea

Natural Parity States Excited via ($^{18}$O,$^{16}$O) Two-neutron Transfer Reaction

Acta Phys. Pol. B 45, 411 (2014)

page 411 •

abstract

The $^{12}$C($^{18}$O,$^{16}$O)$^{14}$C and $^{13}$C($^{18}$O,$^{17}$O)$^{14}$C reactions were studied at INFN-LNS laboratory in Catania. The experiments were performed using an $^{18}$O Tandem beam at 84 MeV incident energy. Charged ejectiles produced in the reactions were momentum analyzed and identified by the MAGNEX spectrometer. $Q$-value spectra were extracted with a remarkable energy resolution (FWHM $\sim$ 150 keV) and several known bound and resonant states were identified. In particular, states with relevant 1p–3h configuration with respect to the $^{16}$O core are mainly populated by the reaction ($^{18}$O,$^{17}$O) while states with known 2p–4h configuration are excited by the ($^{18}$O,$^{16}$O) one. Exact Finite Range Coupled Reaction Channel calculations based on a parameter free double-folding optical potential were performed to reproduce the measured absolute cross-section angular distributions. The ($^{18}$O,$^{16}$O) is found to be an important probe to study pair configurations in nuclear states.

Sensitivity of Transverse Flow and Its Disappearance Towards Density-dependent Cross-section

Acta Phys. Pol. B 45, 419 (2014)

page 419 •

abstract

We study the relative role of density-dependent reduction and constant reduction of the cross-section on the mass dependence of balance energy throughout the mass range for two isobaric series corresponding to different neutron to proton contents using isospin-dependent quantum molecular dynamics model. Our study indicates that mass-dependent analysis of balance energy for semi-central collisions is almost insensitive to the choice of reduction in the cross-section. This insensitivity remains preserved for static as well as momentum-dependent soft equation of state.

all authors

S. Barlini, S. Piantelli, G. Casini, P.R. Maurenzig, A. Olmi, M. Bini, S. Carboni, G. Pasquali, G. Poggi, A.A. Stefanini, E. Scarlini, R. Bougault, O. Lopez, N. Le Neindre, M. Parlog, E. Vient, E. Bonnet, A. Chbihi, J.D. Frankland, D. Gruyer, M.F. Rivet, B. Borderie, E. Rosato, G. Spadaccini, M. Vigilante, M. Bruno, L. Morelli, M. Cinausero, M. Degerlier, F. Gramegna, T. Marchi, T. Kozik, T. Twarog, R. Alba, C. Maiolino, D. Santonocito

Isospin Transport in $^{84}$Kr + $^{112,124}$Sn Collisions at Fermi Energies with the FAZIA Detector

Acta Phys. Pol. B 45, 425 (2014)

page 425 •

abstract

Isotopically resolved fragments up to $Z\approx 20$ have been studied in a test experiment by the FAZIA Collaboration with a three-stage telescope. The reactions $^{84}$Kr+$^{112}$Sn ($n$-poor) and $^{84}$Kr+$^{124}$Sn ($n$-rich) at 35 MeV/nucleon were measured. The telescope was located near the grazing angle, so the detected fragments are mainly emitted from the phase-space region of the projectile. In the following, evidences for isospin diffusion and drift will be discussed.

all authors

D. Carbone, A. Bonaccorso, C. Agodi, M. Bondì, F. Cappuzzello, M. Cavallaro, A. Cunsolo, M. De Napoli, A. Foti, D. Nicolosi, S. Tropea

The Continuum of $^{11}$Be Populated by the ($^{18}$O,$^{16}$O) Two-neutron Transfer Reaction

Acta Phys. Pol. B 45, 431 (2014)

page 431 •

abstract

A study of the continuum of $^{11}$Be populated by the $^{9}$Be($^{18}$O,$^{16}$O)$^{11}$Be reaction at 84 MeV incident energy has been performed. The ejectiles have been momentum analysed at forward angles by the MAGNEX magnetic spectrometer and $^{11}$Be energy spectra have been obtained up to about 13 MeV. The scattering of two neutrons independently removed from the projectile as it passes the target nucleus has been described by means of an optical potential with a semiclassical approximation for the relative motion.

all authors

M. De Napoli, M. Cavallaro, J.A. Scarpaci, F. Cappuzzello, C. Agodi, M. Assie, F. Azaiez, M. Bondí, D. Carbone, A. Cunsolo, A. Foti, E. Khan, S. Franchoo, R. Linares, D. Nicolosi, I. Stefan, S. Tropea

High Excitation Energy Modes in $^{118}$Sn Populated by the $^{120}$Sn($p$,$t$)$^{118}$Sn Reaction at 35 MeV

Acta Phys. Pol. B 45, 437 (2014)

page 437 •

abstract

The $^{120}$Sn($p,t$)$^{118}$Sn reaction was investigated at 35 MeV incident energy. The $^{118}$Sn excitation energy spectrum was reconstructed up to about 16 MeV. Preliminary results show the presence of a broad resonance at high excitation energy, compatible with the predicted population of the Giant Pairing Vibration (GPV).

Reconstruction of Primary Fragments of Heavy Ion Collisions at Intermediate Energies

Acta Phys. Pol. B 45, 443 (2014)

page 443 •

abstract

For intermediate energies in the range of 20–100 MeV/$A$, multifragmentation is the one of the nuclear mechanisms which determine variety of reaction products. Moreover, emission of secondary fragments is strongly dependent on excitation energy of hot nuclear sources. As a results of heavy ion collisions at intermediate energies, high excited nuclear matter is produced. Time evolution of such system is a very dynamic process, so experimental detection of primary nuclear fragments is impossible at this stage. De-excitation of this matter, through the secondary decays produces a variety of stable fragments which can be measured in the experiments. This phenomenon causes that information about the original nucleus from which are formed secondary particles can be lost. We propose a reconstruction procedure based on correlations between intermediate mass fragments and multiplicities of light particles like: $n$, $p$, $d$, $t$, $^3$He, $^4$He. Secondary products of heavy ion reaction have been obtained by predictions given by the GEMINI model. A combination of theoretical knowledge with experimental data, especially information about secondary fragments and average excitation energy, allows to obtain a reaction products formed directly after heavy ion collision.

Analyzing the Role of Fragment Charge on Nuclear Stopping for Symmetric Colliding Nuclei

Acta Phys. Pol. B 45, 451 (2014)

page 451 •

abstract

We study the role of fragment charge on nuclear stopping using Isospin-dependent Quantum Molecular Dynamics model. The analysis is carried out for the reactions of $_{20}^{40}{\rm Ca} \,+\,_{20}^{40}$Ca, $_{28}^{58}{\rm Ni}\, +\,_{28}^{58}$Ni, $_{54}^{129}{\rm Xe} \,+\, _{54}^{129}$Xe, and $_{79}^{197} {\rm Au} \,+\, _{79}^{197}$Au, at an incident energy between 90 MeV/nucleon and 1.5 GeV/nucleon. For fragment formation, we use three different clusterization algorithms namely minimum spanning tree, minimum spanning tree with momentum constraint, isospin-dependent minimum spanning tree. We conclude that the influence of various clusterization algorithms is small on nuclear stopping for the fragments having charge $Z = 1, 2, 3$ and 4 and shows small influence only at lower incident energies. Moreover, minimum spanning tree algorithm yields higher stopping compared to other clusterization techniques. The theoretical calculations follow the similar trend given by experimental findings.

The NA61/SHINE Experiment at the CERN SPS

Acta Phys. Pol. B 45, 457 (2014)

page 457 •

abstract

The aim of the NA61/SHINE ion programme is to explore the QCD phase diagram within the range of thermodynamical variables accessible by the SPS. In addition, the experiment provides precision hadron production measurements for description of the neutrino beam of the T2K experiment at J-PARC and for simulation of cosmic-ray showers for the Pierre Auger Observatory, KASCADE-Grande and KASCADE experiments. The main physics goals of the NA61/SHINE ion programme are the study of the properties of the onset of deconfinement and the search for signatures of the critical point of strongly interacting matter. These goals are pursued by performing an energy (beam momentum 13 $A$–158 $A$ GeV/$c$) and system size ($p+p$, $p$+Pb, Be+Be, Ar+Ca, Xe+La) scan. The architecture and performance of the detector will be discussed. Moreover, an overview of the recent NA61/SHINE status, results and plans will be presented.

Isospin Effects on the Transverse Momentum Spectra of Protons and Neutrons

Acta Phys. Pol. B 45, 463 (2014)

page 463 •

abstract

We present a theoretical study to see the effect of isospin degree of freedom and system size on the behavior of transverse momentum spectra, $dN/p_{\rm t}dp_{\rm t}$, of protons and neutrons. We find that most of the nucleons suffer soft collisions. In the Fermi energy region, transverse momentum spectra of both protons and neutrons show sensitivity towards the density dependence of symmetry energy.

Accessing Dynamical Emissions with Two-particle Correlations in Heavy-ion Collisions

Acta Phys. Pol. B 45, 469 (2014)

page 469 •

abstract

In this work, we present a study of two-proton correlation functions measured in Xe+Au collisions at $E/A=50$ MeV. The main goal of the analysis consists of understanding the space-time properties of the two-proton emitting source. In order to answer this question, we study transverse momentum gated correlations, guided by indications provided by BUU transport model simulations. The source profiles extracted by imaging techniques are studied to understand to what extent information on the space-time properties of pre-equilibrium stages can be explored. These studies are key to address open problems such as the density dependence of the symmetry energy that affects significantly the dynamical pre-equilibrium neutron/proton emission in heavy-ion collisions.

Freeze-out Configuration Properties in the $^{197}$Au+${}^{197}$Au Reaction at 23 $A$MeV

Acta Phys. Pol. B 45, 475 (2014)

page 475 •

abstract

We present the results of the experiment performed by the CHIMERA Collaboration with the $4\pi$ CHIMERA array, for the system $^{197}$Au+$^{197}$Au at 23 $A$MeV. Conclusions related to the shape of the freeze-out configuration are drawn.

all authors

D.L. Balabanski, G. Cata-Danil, D. Filipescu, S. Gales, O. Tesileanu, C.A. Ur, I. Ursu, N.V. Zamfir

The Extreme Light Infrastructure Nuclear Physics Facility: Towards Experiments with Brilliant $\gamma$-Ray Beams

Acta Phys. Pol. B 45, 483 (2014)

page 483 •

abstract

The Extreme Light Infrastructure Nuclear Physics (ELI-NP) facility which is being built at Bucharest–Magurele aims at utilizing extreme electromagnetic fields for nuclear physics and quantum electrodynamics studies. Two ten pentawatt high-power laser systems and a brilliant $\gamma$ beam are the main research tools of the facility. Here, we present the current status and the perspectives for experiments with intense $\gamma$ rays at ELI-NP.

all authors

F. Gramegna, M. Manzolaro, S. Corradetti, D. Scarpa, M. Rossignoli, A. Monetti, M. Lollo, M. Calderolla, J. Vasquez, A. Andrighetto, D. Zafiropoulos, L. Sarchiapone, D. Benini, P. Favaron, E. Brezzi, R. Pegoraro, D. Maniero, M. Rigato, M. Maggiore, A. Lombardi, L. Piazza, A.M. Porcellato, C. Roncolato, G. Bisoffi, A. Pisent, A. Galatá, M. Poggi, M. Giacchini, G. Bassato, S. Canella, M. Bellato, J. Valiente, J. Bermudez, T. Marchi, G. Prete, L. Calabretta

SPES: the INFN Exotic Beam ISOL Facility at the LNL and Its First Day Scientific Program

Acta Phys. Pol. B 45, 491 (2014)

page 491 •

abstract

SPES (Selective Production of Exotic Species) is the INFN project for the construction of a Radioactive Ion Beam (RIB) facility based on the ISOL method. The SPES facility is under development at the Legnaro National Laboratories site and it will provide mostly neutron-rich exotic beams produced through the proton induced fission on a direct UC$_x$ target. The expected SPES beam intensities, quality and energies (up to 11 MeV/$A$ for $A=130$) together with the up-to-date experimental apparatuses, which are at present and will be in the near future available at the LNL, will permit performing forefront research to study nuclear structure and nuclear dynamics in a region of the nuclear chart far from stability.

ARIEL: TRIUMF’s Advanced Rare IsotopE Laboratory

Acta Phys. Pol. B 45, 503 (2014)

page 503 •

abstract

TRIUMF, Canada’s National Laboratory for particle and nuclear physics, is constructing ARIEL, the Advanced Rare IsotopE Laboratory. The centerpiece of the new laboratory is a 500 kW, 50 MeV electron accelerator to drive production of exotic isotopes by photoreactions. The first phase will produce $^8$Li for material and subatomic science, followed by neutron-rich fission fragments for nuclear structure approaching the postulated astrophysical $r$-process. ARIEL will levarage existing infrastructure at TRIUMF, including the existing suite of ISAC experimental equipment and the cyclotron proton beamline for spallation. By 2020 it is envisioned that, with a fully instrumented ARIEL and the existing ISAC complex, it will be routine to perform three simultaneous experiments in nuclear structure, fundamental interactions, and nuclear astrophysics with rare isotope beams from three separate production stations.

all authors

M. Kaczmarski, A.I. Kilic, K. Czerski, A. Kowalska, D. Weissbach, N. Targosz-Sleczka, A. Huke, G. Ruprecht

New Accelerator Facility for Measurements of Nuclear Reactions at Energies Below 1 keV

Acta Phys. Pol. B 45, 509 (2014)

page 509 •

abstract

Nuclear reactions at very low energies can be strongly enhanced due to screening of the Coulomb barrier by surrounding electrons. In the past decade, this effect was intensively studied for the $d+d$ reactions taking place in metallic environments as a model for dense astrophysical plasmas, where the reaction rates can be increased even by many orders of magnitude. The experimentally determined screening energies corresponding to the reduction of the Coulomb barrier height are, however, much larger than the theoretical predictions. New experimental data obtained under ultra high vacuum conditions additionally increases this discrepancy, the origin of which remains still unknown. One of a possible explanation is the excitation of a hypothetical threshold resonance in the $^4$He nucleus. As the energy dependence of the resonant reaction cross section differs to that of the electron screening effect, one can distinguish between both processes expanding measurements down to the deuteron energies of 1 keV. Because of very high enhancement factors (of the order of $10^6$) a new high current accelerator facility, being now under construction at the University of Szczecin, will make it possible to measure for the first time the reaction cross sections at so low energies.

all authors

G. Kaminski, R.S. Slepnev, A.A. Bezbakh, V. Chudoba, A.S. Fomichev, M.S. Golovkov, A.V. Gorshkov, V.A. Gorshkov, A.N. Isadykov, D.M. Janseitov, S.A. Krupko, M. Mentel, P. Plucinski, S.V. Stepantsov, G.M. Ter-Akopian

Neutron Detector Array Based on Stilbene Crystals for the ACCULINNA and ACCULINNA-2 Separators

Acta Phys. Pol. B 45, 519 (2014)

page 519 •

abstract

The investigation of light neutron-rich nuclei is planned by means of the ACCULINNA separator and at the newly constructed ACCULINNA-2 separator. Fast neutron detection techniques in presence of $\gamma$-rays background play an important role in such investigations. Therefore, a prototype of the neutron detector array based on stilbene crystals has been designed for further studies. Stilbene scintillators have excellent $n$–$\gamma$ discrimination, competitive to the liquid scintillators, used in the past experiments at ACCULINNA. The first results of $n$–$\gamma$ separation obtained with stilbene crystals are presented.

all authors

W. Parol, I. Ciepał, K. Bodek, St. Kistryn, G. Khatri, A. Magiera, D. Rozpędzik, A. Wrońska, J. Zejma, B. Kłos, E. Stephan, A. Kozela, P. Kulessa, N. Kalantar-Nayestanaki, J. Messchendorp, I. Mazumdar, I. Skwira-Chalot

Investigation of Three Nucleon Force Effects in Deuteron–Proton Breakup Reaction

Acta Phys. Pol. B 45, 527 (2014)

page 527 •

abstract

Experiments devoted to study subtle ingredients of nuclear dynamics were carried out at KVI in Groningen with the use of the $^1$H$(d,pp)n$ breakup reaction at the deuteron beam energy of 80 MeV/nucleon. The aim of the work is to determine the breakup cross sections and confront them with the set of modern calculations which model forces acting between nucleons. Elastic scattering process was also measured for the purpose of the cross section normalization. This paper presents preliminary results of the data analysis including geometry cross check, energy calibration, particles identification and sample distributions of the unnormalized breakup cross sections.

Novel Coincidence Techniques, Detectors and Concepts for Safety, Security and Safeguards

Acta Phys. Pol. B 45, 533 (2014)

page 533 •

abstract

Research and development (R&D) projects are used to maintain and improve STUK’s ability to act and advice other competent authorities correctly in conditions involving nuclear and other radioactive materials. Examples from recent or ongoing in-field and laboratory R&D projects are given. All projects introduced are related to passive detection of alpha particle emitting nuclides or neutron sources.

all authors

A. Fijałkowska, M. Karny, K.P. Rykaczewski, M. Wolińska-Cichocka, R. Grzywacz, C.J. Gross, J.W. Johnson, B.C. Rasco, E.F. Zganjar, D.W. Stracener, L. Cartegni, K.C. Goetz, R. Goans, C. Jost, M. Madurga, K. Miernik, D. Miller, S.W. Padgett, S.V. Paulauskas, M. Al-Shudifat, E. Spejewski, J.H. Hamilton, A.V. Ramayya

First Results from the Modular Total Absorption Spectrometer at the HRIBF

Acta Phys. Pol. B 45, 545 (2014)

page 545 •

abstract

A Modular Total Absorption Spectrometer (MTAS) has been recently constructed and commissioned at the Holifield Radioactive Ion Beam Facility (HRIBF) at the Oak Ridge National Laboratory (ORNL). The main goal of MTAS is to determine the true beta-decay feeding and following gamma radiation pattern for the decays of fission products. In this contribution, we would like to present the results of the measurement of $^{86}$Br. The preliminary analysis yields an average energy of emitted $\gamma$-radiation of about 4110 keV. It represents an increase of over 26% (850 keV), when compared to the average EM energies deduced using the ENSDF database.

all authors

U. Kaźmierczak, D. Banaś, J. Braziewicz, I. Buraczewska, J. Czub, M. Jaskóła, Ł. Kaźmierczak, A. Korman, M. Kruszewski, A. Lankoff, H. Lisowska, Z. Szefliński, M. Wojewódzka

Analysis of the Biological Response in CHO-K1 Cells to High LET Radiation

Acta Phys. Pol. B 45, 553 (2014)

page 553 •

abstract

The impact of irradiated cells and their progeny on non-irradiated cells was investigated. The experimental set up with a horizontal heavy ion beam designed for radiobiological research at the Heavy Ion Laboratory of the University of Warsaw (HIL) was used. Chinese Hamster Ovary (CHO-K1) cells were irradiated in the dose range 0.1 Gy–4 Gy of high Linear Energy Transfer (LET) $^{12}$C ions and X rays. To examine the bystander effect, irradiated and non-irradiated cells were co-cultured in special Petri dishes with inserts. The cells shared medium but could not touch each other. To assess the biological response in individual cells a micronucleus assay was performed.

Dependence Between the Size of the Treatment Room and the Fluence of Neutrons Undesirable in Radiotherapy for the High-energy Therapeutic X-rays Generated by the Linear Medical Accelerator

Acta Phys. Pol. B 45, 559 (2014)

page 559 •

abstract

The medical linear accelerator is a very commonly used therapeutic equipment in modern radiotherapy. The high-energy X-ray beams generated by such accelerators induce neutrons undesirable in the radiotherapy treatment. The neutron radiation is produced mainly in ($\gamma$,$n$) and ($\gamma$,$2n$) reactions. The problem of induced neutron radiation during emission of high-energy X-ray beams is known but it is still unsolved. The undesirable neutrons induce radioactivity inside the treatment room as well as they are the factor of the additional total body dose to patients. The induced radioactivity gives its contribution to the dose to staff operating an accelerator. The influence of sizes of the treatment room on the neutron fluence in the vicinity of the accelerator was investigated in the presented studies. Two methods were applied. The main one was the Monte Carlo computer simulations based on the Geant4 code. These Monte Carlo calculations were verified by means of the neutron activation method with the use of the indium foil and cadmium in the range of thermal and resonance energies. The performed studies are indicative that there is a sensitive dependence between the treatment room size and the neutron level. The greater neutron fluence was observed for a less treatment room.

all authors

S. Tropea, M. De Napoli, C. Agodi, A.A. Blancato, M. Bondì, F. Cappuzzello, D. Carbone, M. Cavallaro, G.A.P. Cirrone, G. Cuttone, F. Giacoppo, D. Nicolosi, L. Pandola, G. Raciti, E. Rapisarda, F. Romano, D. Sardina, V. Scuderi, C. Sfienti

Measurement of Fragment Production Cross Sections in the $^{12}$C+$^{12}$C and $^{12}$C+$^{197}$Au Reactions at 62 $A$ MeV for Hadrontherapy and Space Radiation Protection

Acta Phys. Pol. B 45, 565 (2014)

page 565 •

abstract

Over the last twenty years, there has been a renewed interest in nuclear fragmentation studies for both hadrontherapy applications and space radiation protection. In both fields, fragmentation cross sections are needed to predict the effects of the ions nuclear interactions within the patient’s and the astronaut’s body. Indeed, the Monte Carlo codes used in planning tumor treatments and space missions must be tuned and validated by experimental data. However, only a limited set of fragmentation cross sections are available in literature, especially at Fermi energies. Therefore, we have studied the production of secondary fragments in the $^{12}$C+$^{12}$C and $^{12}$C+$^{197}$Au reactions at 62 $A$ MeV. In this work, the measured $^{4}$He cross sections angular distributions at four selected angles are presented and compared.

Nuclear Physics Methods in Cultural Heritage Research — Accelerators for Art

Acta Phys. Pol. B 45, 571 (2014)

page 571 •

abstract

A review will be given on the use of nuclear physics techniques in non-destructive investigations on our cultural heritage objects. It focuses on making use of the production and detection of X-rays as a tool for micro analysis. At ‘small accelerators’, a versatile approach to determine elemental compositions as major constituents or as trace elements is the proton induced X-ray emission (PIXE), especially when combined with Rutherford backscattering spectroscopy (RBS), a powerful technique for near-surface investigations with micrometer resolution, and nowadays, with the use of improved detection sensitivities, set up for elemental mapping of large areas in a reasonable time for data taking. Such ‘small accelerator’ installations are well complemented by larger facilities, synchrotron radiation sources as well as medium energy ion accelerators for high energy PIXE. When high energy protons are used as inducing particles — with energies between about 20 and 100 MeV — elements deeply buried under several hundreds of micrometer of corrosion layers, can easily be identified, too. These techniques are complemented by X-ray fluorescence, which have recently been developed into a 3-dimensional micro analytical technique with a resolution of around 30 micrometers by employing multi capillary X-ray guiding lenses. The state-of-the-art methodology will be illustrated on examples from painted glass windows and luster ceramics closely related to basic research on nanometer sized metallic inclusions in glasses for plasmonics in photonics. Finally, an outlook will be given for a new generation under way of almost mono-energetic high-energy and high-intensity X-ray sources being developed as ‘table-top’ instrumentation with MeV-electron LINACS rather than GeV-electron synchrotrons.

top

ver. 2022.08.08 • we use cookies and MathJax