Nuclear physics activity in Institute for Nuclear Research and Nuclear Energy, Sofia. Ch. Protochristov, Ch. Stoyanov. Historical remarks. Prof. Dr. Elisabeth Kara – Michailova (1897-1968). obtained Ph.D at the Vienna University, Austria in 1923
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Nuclear physics activity inInstitute for Nuclear Research and Nuclear Energy,Sofia
Ch. Protochristov, Ch. Stoyanov
Kara – Michailova
(1897-1968)
Nuclear Physics, Neutron Physics and Nuclear Energy
University Dresden
Centroid Shift Method (GCSM)
He combined scientific investigations
in theoretical nuclear physics and
experimental nuclear spectroscopy.
In the seventies some 30% of the data of
lifetimes of high-spin states in deformed
rare-earth nuclei have been generated by the
group headed by acad. E. Nadjakov in close
collaboration with JINR-Dubna. Often citated
is his last work no nuclear charge radii.
Acad. Emil G.Nadjakov
(1929-1996)
The activity in the nuclear physics in INRNE is concentrated mainly in the Department of Nuclear Physics. There are 4 laboratories in the Department:
Experimental physics:
The basic facilities like accelerators are not available and the research reactor is under reconstruction. Because of that the main part of experimental work is done in collaboration with European research centers like CERN, GANIL, INFN, LNL-Legnaro, GSI-Darmstadt, IreS Strasbourg, JINR-Dubna etc.
The new direction of the experimental activity of the Lab is connected with nuclear waist transmutation problems. Spalation neutrons, produced by bombardment of heavy targets such as Pb, Pb-Bi, Hg etc. are used for transmutation of long-lived radioactive waste. The special design of the transmutation facilities depends on the neutron spectra and on details of nuclear reactions induced by neutrons, which can be studied by high-resolution gamma-ray spectroscopy. Therefore spallation spectra from massive lead targets (20 cm), irradiated with 1 GeV protons from the NUCLOTRON accelerator, have been investigated. The gamma-ray spectra emitted by decaying of residual nuclei produced by spallation neutrons in (n,xn), (n,xnyp), (n,p) and (n,n) reactions with activation threshold detectors 209-215 Bi were measured in the Laboratory of Nuclear Problems (LNP), JINR Dubna. The corresponding gamma-ray spectra have been analyzed with specialized software and the cross sections for the different reactions have been obtained.
The members of the Lab applied the method of high-resolution gamma-spectroscopy to study the environmental problems. The systematical investigations of the environmental radioactivity in the Bansko – Razlog region, carried out during the recent years, have been enlarged with investigations of Cs-137 concentration in soil, performed here for the first time. A total area of about 40 km2 has been investigated, by means of high-resolution gamma-ray spectroscopy, thereby the radio-nuclide content of the soil samples has been determined. The results gave us the opportunity to assess the total Cs-137 fallout in the region. The measured concentrations are compared with previous data obtained for other regions in Bulgaria. The Cs-137 fallout following the Chernobyl accident has been estimated and compared with the results obtained in other countries. The additional dose rate caused by this fallout has been estimated. `
The knowledge of the lifetimes of excited nuclear states allows the
derivation of absolute transition probabilities and of absolute
values of reduced transition matrix elements. These experimental
quantities represent a stringent test information for nuclear models
because they are very sensitive to the wave functions of the
initial and final states. Therefore the determination of lifetimes is
of importance for the understanding of nuclear structure.
Recently, some new topics are the focus of our collaboration as
a possible new region of X(5) nuclei around mass A=180, the application of the theoretical supersymmetry scheme to 195Pt and the isospin purity in Z=N nuclei (e.g. Ref.[20]) as well as experimental developments with the aim to perform RDDS measurements with beams of relativistic ions in exotic nuclei.
In this experimental field, since more than 20 years we have a
collaboration with the Institute fuer Kernphysik of the University
of Cologne, namely with the group of Prof. J. Jolie, Prof. P. von Brentano and Dr. A. Dewald. This collaboration resulted so far in more than 40 publications in refereed journals like Phys. Rev. C and Nucl. Phys. A.
Since few years, we have also a fruitful collaboration with the group of G. de Angelis from the Laboratori Nazionali di Legnaro, Italy, where operates the multidetector array GASP. The main topic studied within this collaboration is chirality in nuclear physics, concentrating on RDDS and DSAM data for 134Pr, which was considered to be the best example where the broken symmetry is realized. It was found that in this nucleus chirality exists only in a dynamical context.
Lifetime measurements in 154Gd were performed by means of the Recoil
Distance Doppler-shift method. Excited states of 154Gd were populated
via Coulomb excitation with a 32S beam at 110 MeV delivered by the FN
tandem accelerator of the University of Cologne. The data show that
154Gd is one of the good examples of the realization of the X(5) dynamical
symmetry. In addition, the experimental data are compared to fits in the
framework of the IBA and the General Collective Model (GCM). A comparison
of the model predictions and experimental data are shown in Fig. 2.
Several theoretical results have been obtained:
MICROSCOPIC DESCRIPTION OF THE STRUCTURE OF EXCITED STATES
Dipole excitations
Several theoretical results have been obtained:
MICROSCOPIC DESCRIPTION OF THE STRUCTURE OF EXCITED STATES
Dipole excitations
High-lying states
COLLABORATIONS
Department of Physics and Astronomy, Michigan State University,
National Superconducting Cyclotron Laboratory and
East Lansing, Michigan
SOME RECENT PUBLICATIONS:
Ch. Stoyanov, V. Zelevinsky.
High-lying single-particle modes, chaos, correlational
entropy, and doubling phase transition.
Phys. Rev. C v. 70 (2004) p. 014302, 7p.
Several theoretical results have been obtained:
MICROSCOPIC DESCRIPTION OF THE STRUCTURE OF EXCITED STATES
Dipole excitations
High-lying states
Mixed symmetry states
High-spin states in the neutron-rich
nuclei with
80 < A < 150
produced as fission fragments (FF)
by heavy ion reactions
collaboration betweenCNRS/Franceand BAS:
Contracts No 2937, 8198, 12531, 16946.
IPN Orsay; IreS Strasbourg; CEA/DSM/DAPNIA/SPhN Gif-sur-Yvette; IPNL, Uni Claude Bernard, Villeurbanne; IPN Lyon, France; Dep. of Phys., Dep.Phys.Astronomy University of Manchester, Manchester
Fission Fragments (FF)
106,107,108,109,110,111,112,113Rh (Z=45),
110,112,114,116Ag (Z=47), 115,117,119,121In (Z=49),121,123,125,127Sb (Z=51),
140Ba (Z=56),142,143,145,147Ce (Z=58),147,149Nd(Z=60)
“A new high-spin level scheme for 149Nd from a fusion-fission reaction”
Eur. Phys. J. A28, 147 (2006)
“New high-spin states of 147Nd and 145Ce: Octupole correlation in the N = 87 isotones”
Eur.Phys. J. A 26, 315 (2005)
High-spin structure of 121,123,125,127Sb nuclei: single proton and core-coupled states”
Eur. Phys. J. A 24, 39 (2005)
“High-spin study of odd-A49In isotopes beyond the neutron mid-shell”
Eur. Phys. J. A 15, 315 (2002)
“Evolution of the π g 9/2 ν h11/2 configuration in the neutron-rich 110,112Rh and 114,116Ag isotopes”
Eur. Phys. J. A 18, 25 (2003)
“High-spin structure of the neutron-rich odd-odd 106,108Rh and 110,112 Ag
isotopes”
Eur. Phys. J. A 15, 463 (2002)
“High-spin structure of the neutron-rich 109,111,113Rh isotopes”
Eur.Phys. J. A 15, 429 (2002)
”Beyond the N = 50 shell closure: High-spin excitations of 87Kr isotope and ground state spin of 87Br”
Eur. Phys. J. A 28, 153 (2006)
SUPERSCALING ANALYSIS OF INCLUSIVE ELECTRON SCATTERING AND ITS EXTENSION TO CHARGE- AND NEUTRAL-CURRENT NEUTRINO-NUCLEUS SCATTERING BEYOND THE RELATIVISTIC FERMI GAS MODEL
SUPERSCALING ANALYSIS OF INCLUSIVE ELECTRON SCATTERING AND ITS EXTENSION TO CHARGE- AND NEUTRAL-CURRENT NEUTRINO-NUCLEUS SCATTERING BEYOND THE RELATIVISTIC FERMI GAS MODEL
EFFECTS OF NUCLEON CORRELATIONS ON CHARACTERISTICS OF NUCLEAR STRUCTURE AND REACTIONS
MODELS OF COMPLEX DEFORMED NUCLEI, SYMMETRIES AND FINE STRUCTURE OF NUCLEAR SPECTRA
COLLABORATIONS
D. Bonatsos (Athens), W. Scheid (Giessen), R. Jolos (Dubna)
SOME RECENT PUBLICATIONS:
N. Minkov, P. Yotov, S. Drenska and W. Scheid,
J. Phys. G: Nucl. Part. Phys. 32, 497-509 (2006)
N. Minkov, P. Yotov, S. Drenska, W. Scheid, D. Bonatsos, D. Lenis
and D. Petrellis, Phys. Rev. C 73, 044315 (2006)
N. Minkov, P. Yotov, R. V. Jolos and W. Scheid,
J. Phys. G: Nucl. Part. Phys. 34 299-313 (2007)
EFFECTS OF NUCLEON CORRELATIONS ON CHARACTERISTICS OF NUCLEAR STRUCTURE AND REACTIONS
MODELS OF COMPLEX DEFORMED NUCLEI, SYMMETRIES AND FINE STRUCTURE OF NUCLEAR SPECTRA
APPLICATION OF THE ALGEBRAIC AND GEOMETRICAL ASPECTS OF DYNAMICAL SYMMETRIES IN THE DESCRIPTION OF CRITICAL PHENOMENA IN THE DEVELOPMENT OF NUCLEAR COLLECTIVITY.
APPLICATION OF THEALGEBRAIC AND GEOMETRICAL ASPECTS OF DYNAMICAL SYMMETRIES IN THE DESCRIPTION OF CRITICAL PHENOMENA IN THE DEVELOPMENT OF NUCLEAR COLLECTIVITY.
400
300
n
200
i
1.5
A=56
1
(n, i)
20
1f5/2 2p1/2 2p3/2 1g9/2
0.5
100
15
0
0
10
5
10
5
-10
-5
5
10
15
20
0
N–
-100
N+
-200
Sp(4) model and its q-deformed extension
Non-negligiblehigher-order many-body interactions (q) in regions of dominant pairing correlations
Local non-linear effects
(within individual nucleus)
Microscopic description of pairing-governed 0+ states in even A nuclei
Smooth dependence
on nuclear characteristics
U(2)
U(3)
U(6)
Negative and possitive parity bands
States withfixedL
Sp(12,R)
Sp(4,R)
SO(3)
6-D Davidson potential
O(6)
U(1,1)
SUpn(3)
O(2)
mixing of collective modes in the heavy even-even nuclei
Thank You
For Your
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