Potential of present-day experiments for determining the parameters of the gamma decay of compound states of heavy nuclei in a model-independent way

Collisions of heavy nuclei at (ultra-)relativistic energies provide a fascinating opportunity to re-create various forms of matter in the laboratory. For a short extent of time (10-22 s), matter under extreme conditions of temperature and density can exist. In dedicated experiments, one explores the microscopic structure of strongly interacting matter and its phase diagram. In heavy-ion reactions at SIS18 collision energies, matter is substantially compressed (2–3 times ground-state density), while moderate temperatures are reached (T < 70 MeV). The conditions closely resemble those that prevail, e.g., in neutron star mergers. Matter under such conditions is currently being studied at the High Acceptance DiElecton Spectrometer (HADES). Important topics of the research program are the mechanisms of strangeness production, the emissivity of matter, and the role of baryonic resonances herein. In this contribution, we will focus on the important experimental results obtained by HADES in Au+Au collisions at 2.4 GeV center-of-mass energy. We will also present perspectives for future experiments with HADES and CBM at SIS100, where higher beam energies and intensities will allow for the studies of the first-order deconfinement phase transition and its critical endpoint.

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Modeling and design of role engineering in development of access control for dynamic information systems

Bulletin of the Polish Academy of Sciences Technical Sciences ◽

10.2478/bpasts-2013-0058 ◽

2013 ◽

Vol 61 (3) ◽

pp. 569-579 ◽

Cited By ~ 2

Author(s):

A. Poniszewska-Marańda

Keyword(s):

Information Systems ◽

Dynamic Information ◽

Minimal Set ◽

Distributed Information ◽

Heterogeneous Information ◽

System Protection ◽

Level Model ◽

Model Independent ◽

Role Concept ◽

High Level

Abstract Nowadays, the growth and complexity of functionalities of current information systems, especially dynamic, distributed and heterogeneous information systems, makes the design and creation of such systems a difficult task and at the same time, strategic for businesses. A very important stage of data protection in an information system is the creation of a high level model, independent of the software, satisfying the needs of system protection and security. The process of role engineering, i.e. the identification of roles and setting up in an organization is a complex task. The paper presents the modeling and design stages in the process of role engineering in the aspect of security schema development for information systems, in particular for dynamic, distributed information systems, based on the role concept and the usage concept. Such a schema is created first of all during the design phase of a system. Two actors should cooperate with each other in this creation process, the application developer and the security administrator, to determine the minimal set of user’s roles in agreement with the security constraints that guarantee the global security coherence of the system.

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POSSIBILITY OF FORMING A LARGE DCC IN ULTRA-RELATIVISTIC HEAVY-ION COLLISIONS

International Journal of Modern Physics A ◽

10.1142/s0217751x0000094x ◽

2000 ◽

Vol 15 (15) ◽

pp. 2269-2288

Author(s):

SANATAN DIGAL ◽

RAJARSHI RAY ◽

SUPRATIM SENGUPTA ◽

AJIT M. SRIVASTAVA

Keyword(s):

Three Dimensional ◽

Thermal Fluctuations ◽

Heavy Ion ◽

High Energy ◽

Chiral Condensate ◽

Relativistic Heavy Ion Collisions ◽

Maximum Temperature ◽

Chiral Field ◽

Heavy Nuclei ◽

True Vacuum

We demonstrate the possibility of forming a single, large domain of disoriented chiral condensate (DCC) in a heavy-ion collision. In our scenario, rapid initial heating of the parton system provides a driving force for the chiral field, moving it away from the true vacuum and forcing it to go to the opposite point on the vacuum manifold. This converts the entire hot region into a single DCC domain. Subsequent rolling down of the chiral field to its true vacuum will then lead to emission of a large number of (approximately) coherent pions. The requirement of suppression of thermal fluctuations to maintain the (approximate) coherence of such a large DCC domain, favors three-dimensional expansion of the plasma over the longitudinal expansion even at very early stages of evolution. This also constrains the maximum temperature of the system to lie within a window. We roughly estimate this window to be about 200–400 MeV. These results lead us to predict that extremely high energy collisions of very small nuclei (possibly hadrons) are better suited for observing signatures of a large DCC. Another possibility is to focus on peripheral collisions of heavy nuclei.

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A model-independent adaptive sequential sampling technique based on response nonlinearity estimation

Structural and Multidisciplinary Optimization ◽

10.1007/s00158-019-02404-6 ◽

2019 ◽

Vol 61 (3) ◽

pp. 1051-1069 ◽

Cited By ~ 2

Author(s):

Andrea Garbo ◽

Brian J. German

Keyword(s):

Sequential Sampling ◽

Sampling Technique ◽

Model Independent ◽

Nonlinearity Estimation

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Formation of α clusters in dilute neutron-rich matter

Science ◽

10.1126/science.abe4688 ◽

2021 ◽

Vol 371 (6526) ◽

pp. 260-264 ◽

Cited By ~ 1

Author(s):

Junki Tanaka ◽

Zaihong Yang ◽

Stefan Typel ◽

Satoshi Adachi ◽

Shiwei Bai ◽

...

Keyword(s):

Cross Sections ◽

Cluster Formation ◽

Reaction Cross ◽

Skin Thickness ◽

Neutron Skin ◽

Heavy Nuclei ◽

Α Decay ◽

Neutron Skin Thickness ◽

Reaction Cross Sections ◽

Α Particles

The surface of neutron-rich heavy nuclei, with a neutron skin created by excess neutrons, provides an important terrestrial model system to study dilute neutron-rich matter. By using quasi-free α cluster–knockout reactions, we obtained direct experimental evidence for the formation of α clusters at the surface of neutron-rich tin isotopes. The observed monotonous decrease of the reaction cross sections with increasing mass number, in excellent agreement with the theoretical prediction, implies a tight interplay between α-cluster formation and the neutron skin. This result, in turn, calls for a revision of the correlation between the neutron-skin thickness and the density dependence of the symmetry energy, which is essential for understanding neutron stars. Our result also provides a natural explanation for the origin of α particles in α decay.

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