Exploring Fundamental Issues in Nuclear Physics

The following sections are included:

• PREFACE

• CONTENTS

• PHOTOS OF THE SYMPOSIUM

The main aim of the present study is to evaluate the fusion probabilities and investigate competing quasifission process in the reactions with heavy ions leading to the formation of superheavy composite systems. The mass-energy distributions, as well as capture cross-sections of fission-like fragments for the reactions of ²²Ne, ²⁶Mg, ³⁶S, ⁴⁸Ca, ⁵⁸Fe and ⁶⁴Ni ions with actinides leading to the formation of superheavy compound systems with Z=102-120 at energies near the Coulomb barrier have been measured. The relative contribution of quasifission to the capture cross section becomes dominant for superheavy composite systems. Fusion-fission cross sections were estimated from the analysis of mass and total kinetic energy distributions.

An overview of present experimental investigation of superheavy elements is given. Using cold fusion reactions which are based on lead and bismuth targets, relatively neutron deficient isotopes of the elements from 107 to 112 were synthesized at GSI in Darmstadt, Germany, a neutron deficient isotope of element 113 at RIKEN in Wako, Japan. In hot fusion reactions of ⁴⁸Ca projectiles with actinide targets more neutron rich isotopes of element 112 and new elements up to 118 were produced at FLNR in Dubna, Russia. Recently, part of these data which represent the first identification of nuclei located on the predicted island of SHEs, was confirmed in independent experiments. The measured data combined with theoretical results were used for estimating cross-sections for production of element 120 isotopes. Also evaluated were their decay properties. An experiment for searching of isotopes of element 120 is planned at the GSI SHIP.

Prompt γ-γ-γ coincidence studies of neutron-rich nuclei populated in the spontaneous fission of ²⁵²Cf led to the discoveries of many important processes like neutron-less binary and ternary fragmentation in spontaneous fission, binary and ternary hot fission modes, hyper-deformation, cluster radioactivity and quasi-molecular states in ternary fission. The high statistics data, 5.7 × 10¹¹ triples and higher folds, opened up discoveries of new band structures and significant extensions of previously known bands. These data were used to measure the angular correlations of cascades of γ-rays from the excited states of neutron-rich fission fragments stopped in an unmagnetized iron foil. By using this γ-γ angular correlation technique, the single particle configurations of the known rotational bands were assigned and confirmed in the present work. In other words, the multipole mixing ratios of ΔI=1 transitions in the rotational bands were measured. These experimental mixing ratios are compred with the theoretical ones of particle and axial-rotor model. The configuration of the ground states in ^109,111Ru were, for the first time, assigned. And magnetic g-factors of excited states in even-even neutron-rich nuclei were meaured, too. Two sets of ΔI=1 alternating parity doublets with opposite parities were observed in Ba and Ce isotopes. The B(E1)/B(E2) branching ratios and D₀ values may indicate that the octupole correlations are strong in Ba and Ce isotopes because of the Z=56 and N=88 octupole shell gaps. High-spin, even-parity bands in neutron-rich ^108,110,112Ru nuclei indicate two-phonon quasi-gamma bands in ^110,112Ru.

It is well known that in fusion reactions one may get only neutron deficient superheavy nuclei located far from the island of stability. The multi-nucleon transfer reactions allow one to produce more neutron enriched new heavy nuclei but the corresponding cross sections are rather low. Neutron capture process is considered here as alternative method for production of long-lived neutron rich superheavy nuclei. Strong neutron fluxes might be provided by nuclear reactors and nuclear explosions in laboratory frame and by supernova explosions in nature. All these cases are discussed in the paper.

We have analyzed the XMM-Newton RGS spectral properties of a sample of the most prominent Narrow-Line Seyfert 1 (NLS1) galaxies observed so far with previous and present X-ray missions. We have fitted the merged RGS1/RGS2 first and second order spectra for all available observations from the XMM-Newton Science Archive to test the reflection model interpretation proposed by Ross & Fabian (2005). For objects with more than one observations a combined RGS1/RGS2 first and second order spectrum has been created, resulting in exposure times ranging between about 13 and 780 ks. For the maximum possible RGS statistics we work out the progress and limitations for the spectral fitting of those NLS1 galaxies most observed with XMM-Newton. The objects 1H 0707–495 and Ark 564 can be modelled with the relativistic reflection model by Ross & Fabian (2005). For 1H 0707–495, the reflection spectrum fit suggests an inner disc radius at about 3 R_G. Assuming a standard disc where the inner disc edge is equal to the marginally stable orbit we infer a rapidly rotating black hole with spin parameter of about 0.8. The emissivity index of the power law amounts to 6.3 suggesting a centrally peaked emission. The ionization parameter is about 1000. The soft X-ray lines are therefore strongly broadened by Compton broadening effects and the emission in the strong gravity field limit. Similar values are obtained for Ark 564. The FWHM of the additional soft X-ray lines required in the fit for 1H 0707-495 are much smaller, about 0.1c, which is consistent with an origination in the weaker field limit. We find that for the prototype objects 1H 0707–495 and for Ark 564 only the relativistic reflection model provides a statistically acceptable fit. The obtained parameters from the relativistic reflection model suggest that the observed emission originates from matter very close to the central supermassive black hole.

The design of sustainable energy systems is no longer only the domain of politics, economics and engineering. Mathematical physics is able to contribute with its generic understanding of everything. A new modelling approach is presented and applied to design a fully renewable European power system. This approach is based on weather data with good spatio-temporal resolution, which is first converted into wind and solar power generation and then used to derive estimates on the optimal mix between the renewable resources and the storage needs.

I discuss the phase diagram for QCD in the baryon chemical potential and temperature plane. I argue that there is a new phase of matter different from the deconfined Quark Gluon Plasma: Quarkyonic Matter. Quarkyonic Matter is confined and exists at densities parametrically large compared to the QCD scale, when the number of quark colors, N_c is large. I motivate the possibility that Quarkyonic Matter is in an inhomogeneous phase, and is surrounded by lines of phase transitions, making a Happy Island in the μB-T plane. I conjecture about the geography of Happy Island.

The dynamics of partons, hadrons and strings in relativistic nucleus-nucleus collisions is analyzed within the novel Parton-Hadron-String Dynamics (PHSD) transport approach, which is based on a dynamical quasiparticle model for partons (DQPM) matched to reproduce recent lattice-QCD results - including the partonic equation of state - in thermodynamic equilibrium. The transition from partonic to hadronic degrees of freedom is described by covariant transition rates for the fusion of quark-antiquark pairs or three quarks (antiquarks), respectively, obeying flavor current-conservation, color neutrality as well as energy-momentum conservation. In order to explore the space-time regions of ’partonic matter’ the PHSD approach is applied to nucleus-nucleus collisions from 20 A GeV up to RHIC energies of 21 A TeV.

In this paper we show how to compute the shear relaxation time from an underlying microscopic theory. We prove that the shear relaxation time in Israel-Stewart-type theories is given by the inverse of the pole of the corresponding retarded Green’s function, which is nearest to the origin in the complex energy plane. Consequently, the relaxation time in such theories is a microscopic, and not a macroscopic, i.e., fluid-dynamical time scale.

This talk consists of two parts. In the first part I discuss properties of hot stellar matter at sub-nuclear densities which is formed in supernova explosions. I present main steps of the statistical approach to the equation of state and nuclear composition, dealing with an ensemble of nuclear species instead of one “average” nucleus. The emphasis is put on possible formation of heavy and superheavy nuclei. In the second part of the talk I discuss the possibility of synthesizing heavy and superheavy elements by multiple neutron capture reactions in terrestrial experiments. The mass distributions of heavy isotopes are calculated by solving a chain of rate equations for consequtive neutron capture. High neutron fluxes which are needed to reach the “stability islend” of superheavy elements can be provided by multiple nuclear explosions.

The existence of collective dynamics and shock waves in nuclear collisions were predicted in the early ’70s by Greiner and colleagues. This was a revolutionary prediction, and it took a decade to prove it beyond doubt. Now at LHC this is the most dominant observable and the first heavy ion result from ALICE.

I would discuss some of the details of the recent advances in the field.

The Constituent Quark Number Scaling of the ν2, for different mesons and baryons is instinctively a proof for collective ow development in quark gluon plasma. Hybrid models with recombination into hadrons can account for the observed scaling, in a limited pt-range. However, the scaling is not obvious. We follow the rapid and simultaneous hadronization of QGP dynamically, where partons gain weight and the perturbative vacuum field disappears. This dynamical process inuences the ow observables and can reproduce the scaling. These studies may provide an insight into the features and dynamics of this intermediate phase between ideal QGP and Hadronic Matter.

Core-collapse supernova explosions give rise to the emission of a huge flux of neutrinos of all flavors. In this article we describe the phenomenon neutrino-neutrino interaction of these weakly interacting particles at the very high density central region of the stellar core giving rise to non-linear collective oscillations in both the neutrino and antineutrino sectors. The effect of the collective oscillations on the Diffuse Supernova Neutrino Background is elaborated with emphasis on its future detection and the connection of that to neutrino mass hierarchy.

Because the angular momentum in nuclear configurations is limited, most rotational bands will terminate. Examples of terminating bands in different mass regions are given and interpreted in the configuration-constrained Cranked Nilsson-Strutinsky (CNS) formalism. Important characteristics of the bands can be read out from the energy vs. angular momentum function but also from the (continuous) variation of the energy with respect to particle number.

A quarter of a century’s concerted international work in halo physics has resulted in an extended nuclear paradigm encompassing the limits of existence of cold nuclei and also structures beyond - continuum structures of open (nuclear) quantum systems. Realistic working models, based on cluster constituents, have sprung out of the very nature of halo phenomena, in particular from the three-body Borromean property of two-neutron halos; the lack of low-lying binary breakup channels. This has provided transparency and possibility for insight into new quantum behaviour, also in continua at driplines. Breakup spectra and progressively exclusive correlation cross sections can be computed and show, where relevant data exist, that general agreement is encouraging. Progress in studies of two-proton emitters has provided another pathway beyond driplines, where again few-body theory appears relevant.

We develop a unified model of hadrons and quarks. Within this approach we investigate the phase structure of the model as function of temperature and chemical potential. Computing the equation of state of cold matter we determine neutron and hybrid star masses and radii. In an extension of the investigation we consider the cooling behavior of the compact stars and derive a general relation between the star’s mass and rotation and its cooling behavior. Finally we study the effect of Δ resonances for star matter, especially with respect to possible solutions of stars with small radii.

For large baryochemical potential μB strongly interacting matter might undergo a first order phase transition at temperatures T ~ 100 – 200 MeV. Within standard cosmology, however, μB is assumed to be very small leading to a crossover. We discuss implications of a first order QCD transition at high μB being consistent with current observations. In this contribution we concentrate on effects on the gravitational wave spectrum. There are other interesting cosmological signals as a modification of the power spectrum of dark matter, the production of stellar black holes, and the seeds for the extragalactic magnetic fields which we briefly address also.

Massive neutron stars may harbor deconfined quark matter in their cores. I review some recent work on the microphysics and the phenomenology of compact stars with cores made of quark matter. This includes the equilibrium and stability of non-rotating and rapidly rotating stars, gravitational radiation from deformations in their quark cores, neutrino radiation and dichotomy of fast and slow cooling, and pulsar radio-timing anomalies.

The distance between the centers of gravity of two heavy colliding nuclei R(t) as function of time can be employed to describe the dynamical behavior of the di-nuclear system during the contact phase. In order to get information on this quantity, it was suggested by G. Soff, J. Reinhard, B. Müller and W. Greiner^1,2 many years ago to investigate the spectral shape of electrons emitted in dissipative heavy ion collisions. It has been shown that in the limit of lowest order adiabatic perturbation theory the δ−electron spectrum just reflects the Fourier transform of the function Ṙ(t)/R(t). With this tool nuclear contact times in the order of 1 zs = 1 · 10⁻²¹ s have been determined for the U+Au collision system at an uranium beam energy of 8.65 MeV/u.⁹ The δ electron spectra observed for the U+Pd (Z_u = 138) collision system at 6.1 MeV/u at impact parameters for which nuclear forces become important, most likely cannot anymore be analyzed within the framework of such a model because of its breakdown if time changes of Ṙ(t)/R(t) become too rapid.

The observation of atomic numbers Z that are 40% larger than that of Bi, the heaviest stable element, is an impressive extension of nuclear survival. Although the super heavy nuclei (SHN) are at the limits of Coulomb stability, shell stabilization lowers the ground-state energy, creates a fission barrier, and thereby enables the SHE to exist. The fundamentals of the modern theory concerning the mass limits of nuclear matter have been experimentally verified.

Note from publisher: This paper consists of In Memoriam: Irina Oganessian (1932–2010)

The twentieth century has thrown up exotic concepts — dark matter, gravity waves, Higgs Bosons, Magnetic Monopoles and so on. The sad truth is that even after several decades, these remain elusive to observation and experiment. Some are now questioning these conjectures. Their verification has become a matter more of hope than conviction. We will examine some alternatives in the light of the above pointing out that, on the other hand, an extra neutrino, recently predicted by the author may have just been discovered.

The energy dependence of hadron production in relativistic nucleus-nucleus collisions reveals the anomalies — kink, horn, and step. They were predicted as the signals of the deconfinement phase transition and observed by NA49 collaboration in Pb+Pb collisions at the CERN SPS. This indicates the onset of the deconfinement in nucleus-nucleus collisions at about 30 AGeV.

Using Hartree-Fock + BCS approach we analyze the behavior of the neutron drip line and predict the appearance of stability peninsulas. The conditions and mechanism for appearance of such peninsulas are analyzed and the properties of newly predicted stable isotopes are investigated.

Attempts to find superheavy elements in Nature started in the middle of sixties when predictions of the possible existence of longliving nuclei in the far transuranium region have been made. During following 15 years hundreds of geological samples, their processing products and probes of meteorites were studied. In all experiments only upper limits of the superheavy element concentration in the studied samples have been determined.

On October 4th, 2010, nine countries signed the international agreement on the construction of the Facility for Antiproton and Ion Research FAIR. The new facility is going to be constructed within the next eight years adjacent to the existing accelerator complex of the GSI Helmholtz Centre for Heavy Ion Research at Darmstadt/Germany, expanding the research goals and technical possibilities substantially. Providing a broad spectrum of unprecedented fore-front research at worldwide unique accelerator and experimental facilities, FAIR will open the way for a large variety of experiments in hadron, nuclear, atomic and plasma physics as well as applied sciences which will be briefly described in this article.

Based on results obtained with event generators we have launched the core-corona model. It describes in a simplified way but quite successfully the centrality dependence of multiplicity and < pt > of identified particles observed in heavy ion reaction at beam energies between and 200GeV. Also the centrality dependence of the elliptic flow, ν2, for all charged and identified particles could be explained in this model. Here we extend this analysis and study the centrality dependence of single particle spectra of K⁻ and measured by the PHENIX, STAR and BRAHMS collaborations. We find that also for these particles the analysis of the spectra in the core-corona model suffers from differences in the data published by the different experimental groups, notably for the pp collisions. As for protons and K⁺ for each experience the data agree well with the prediction of the core-corona model but the value of the two necessary parameters depends on the experiments. We show as well that the average momentum as a function of the centrality depends in a very sensitive way on the particle species and may be quite different for particle which have about the same mass. Therefore the idea to interpret this centrality dependence as a consequence of a collective expansion of the system, as done in blast way fits may be premature.

We present a brief overview of the multiscale approach towards the understanding of processes responsible for the radiation damage caused by energetic ions. This knowledge is important because it can be utilized in the ion-beam cancer therapy, which is one of the most advanced modern techniques to cure certain types of cancer. The central element of the multiscale approach is the theoretical evaluation and quantification of DNA damage within cell environment. We consider different pathways of DNA damage and focus on the the illustration of the thermo-mechanical effects caused by the propagation of ions through the biological environment and in particular on the possibility of the creation of the shock waves in the vicinity of the ion tracks. We demonstrate that at the initial stages after ion’s passage the shock wave is so strong that it can contribute to the DNA damage due to large pressure gradients developed at the distances of a few nanometers from the ionic tracks. This novel mechanism of the DNA damage provides an important contribution to the cumulative bio-damage caused by low-energy secondary electrons, holes and free radicals.

We implement a non-conventional statistical distribution, the canonical Tsallis distribution for lattice field theoretical calculations. We use a so called super-statistical approach: here the application of the Tsallis distribution is realized via introducing a fluctuating temperature. The fluctuations of the inverse temperature follow a Gamma distribution. We study the possibilities to evaluate expectation values in the superstatistical system and generalize the usual direct numerical method using a Metropolis algorithm. Our method is suitable for performing numerical calculations in order to investigate the thermodynamical properties of the strongly interacting superstatistical matter, or to derive the equation of state in this non-extensive approach.

Both bulk features of particle production and various correlations of particles in proton-proton collisions at energies are studied within the Monte Carlo quark-gluon string model. The model relies on Reggeon Field theory accomplished by string phenomenology. The available experimental data are reproduced quite well. Predictions are made for collisions at .

This symposium was very special. It was topical: Some of the most outstanding problems in Nuclear Physics were discussed: Superheavy elements; extremely neutron rich elements, as well as nuclei with strangeness and their possible creation in the cosmos and on earth; the nuclear equation of state has to be identified within strongly compressed and hot nuclear matter as it appears in nucleus-nucleus encounters; giant nuclear systems which are short lived (~ 10⁻¹⁹ − 10⁻²⁰ seconds) and extremely important for identifying the vacuum decay in overcritical electric fields (this is a very fundamental process - the most fundamental one in Quantum Electrodynamics!); astrophysical centers of extreme high density around which magnificent sun-like objects are Kepler-orbiting are discovered in our Galaxy by R. Genzel and colleagues (these centers are no black holes those don’t exist at all because repulsive gravitational forces may play an important role - the pseudocomplex general relativity eliminates the Schwarzschild singularity); network physics for distributing energy (nuclear, wind, sun, tides,…) all over Europe (and over the world) is basic for energy consumption now and even more so in future. We heard wonderful talks and I am grateful to all the friends and speakers (from Russia, America, Europe and India) for coming to Goa. It was a great symposium! Particular thanks go to Professor Bikash Sinha and especially to Professor Debades Bandyopadhyay from Calcutta who had the idea for and organized this Goa-symposium.…