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Phys.Rev. C. 01/2011; 83:044326.
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M. Balodis,
J. Berzins,
L. Simonova,
V. Bondarenko,
T. Krasta,
J. Tambergs,
A. Jakimovics, I. Tomandl,
M. Jentschel,
P. Mutti,
H. Boerner
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ABSTRACT: Thermal neutron capture gamma-ray spectra for {sup 187}Re(n,{gamma}){sup 188}Re reaction were measured. Singles and coincidence spectra were detected in order to develop the level scheme. The evaluation is in progress, of which the first results are obtained from the analysis of coincidence spectra, allowing to check the level scheme below 500 keV excitation energy. Seven low-energy negative parity bands are developed in order to find better energies for rotational levels. With a good confidence, a few positive parity bands are developed as well. Rotor plus two quasiparticle model calculations, employing effective matrix element method are performed for the system of six negative parity rotational bands.
AIP Conference Proceedings 01/2009; 1090(1).
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ABSTRACT: Using the (n,γγ) reaction an extensive nuclear level scheme of 124Te was established, containing 694γ transitions between 210 levels. The level density and level population are investigated and compared with calculations. Various models are tested, in particular formulas for the γ strength function. The neutron binding energy was determined to be 9424.53(10) keV and the thermal neutron capture cross section of the 123Te(n,γ)124Te reaction to be 430(13) b.
Phys. Rev. C. 09/2006; 74(3).
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I. Tomandl,
J. Honzátko,
T. von Egidy,
H.-F. Wirth,
T. Belgya,
M. Lakatos,
L. Szentmiklósi,
Zs. Révay,
G. L. Molnár,
R. B. Firestone,
V. Bondarenko
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ABSTRACT: New values for thermal neutron capture cross sections of the tellurium isotopes 122Te,124Te,125Te,126Te,128Te, and 130Te are reported. These values are based on a combination of newly determined partial γ-ray cross sections obtained from experiments on targets contained natural Te and γ intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given.
Phys. Rev. C. 12/2003; 68(6).
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P. Prokofjevs,
L. I. Simonova,
M. Balodis,
J. Bērziņš,
V. Bondarenko,
H. F. Wirth,
T. von Egidy,
C. Doll,
J. Ott,
W. Schauer, [......],
R. F. Casten,
R. L. Gill,
J. Honzátko, I. Tomandl,
S. Boneva,
V. A. Khitrov,
A. M. Sukhovoj,
D. G. Burke,
J. Kvasil,
A. Macková
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ABSTRACT: The nucleus 166Ho was studied with thermal and average resonance neutron capture and with (d,p) and (d,3He) reactions. We have devoted a large effort to the measurements of γγ-coincidence spectra in the broad energy interval 50–6243 keV. From these data and those of previous studies, the level scheme has been developed containing levels grouped into 23 rotational bands below 1 MeV. Of these, six bands are new and several others, known previously, have been modified and expanded based upon our experimental data. In all, 32 new levels have been identified. Of particular note has been the identification of two rotational bands whose underlying structure consists of γ-vibrational states built upon the two lowest energy quasiparticle states in 166Ho. Two new Gallagher-Moszkowski matrix elements were determined: EGM(p7/2-[523]±n5/2-[523])=-108.5 keV and EGM{(p7/2-[523]±n7/2+[633])∓Q22}=+138.2 keV. The resultant level scheme is in good agreement with semiempirical and quasiparticle phonon models where residual interactions have been taken into account. Suggestions are given for further experimentation on 166Ho level structure using existing technology.
Phys. Rev. C. 02/2000; 61(4).
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ABSTRACT: The anomalously high activation yield of the 11/2- isomeric states in odd-A Te isotopes in the (n,γ), (γ,n), and (γ,γ′) reactions could be understood by the funneling of the initial gateway states through the lowest isolated 5/2- state. The peculiar deexcitation mode is governed by favored M1, E2 transitions inside the family of negative-parity states built in accordance with IBFM calculations by a coupling of the dominant 1h11/2 and 3p configurations to the neighboring bosonic even-even core.
Phys. Rev. C. 07/1999; 60(2).
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ABSTRACT: The125Te(n, )126Te reaction has been studied with thermal neutrons. Totally 113 lines in the -ray spectrum were assigned to radiative transitions in the126Te isotope. The neutron separation energy of126Te was evaluated to be 9113.80.1 keV. The experimental values of the partial cross sections of the primary E1-transitions were compared with predictions of the Lane-Lynn theory.
Czechoslovak Journal of Physics 12/1993; 44(1):11-18. · 0.42 Impact Factor
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V. Bondarenko,
J. Honzátko, I. Tomandl,
T. von Egidy,
H.-F. Wirth,
A.M. Sukhovoj,
L.A. Malov,
L.I. Simonova,
P. Alexa,
J. Bērziņš,
R. Hertenberger,
Y. Eisermann,
G. Graw
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ABSTRACT: The level structure of 185W has been studied using the prompt and delayed gamma–gamma coincidences from thermal neutron capture in 184W accompanied with the one-nucleon transfer reactions (d,p) and (d,t) with polarized beams. From these data and those of previous studies a total of 183 levels has been established for energies below 3 MeV. Many of these states have been grouped into rotational bands built on 28 intrinsic states of quasiparticle and quasiparticle-plus-phonon character. Although the DWBA analysis permitted definite spin–parity assignments for most of states a large number of particle transitions have ‘anomalous’ angular and asymmetry shapes with respect to the DWBA which indicate an influence of strong mixing between particle and hole states. The extra exchange of phonons and the significance of configurational ΔN=±2 mixing across the Fermi surface lead to a fine structure in the fragmentation of most single-particle strengths and at the same time has the effect of breakdown of the individual properties of Nilsson states. The accumulated l=1(d,p) sum is about a factor two smaller than the equivalent (d,t) strength. Thus, the previously observed loss of the (d,p) strength in the W nuclei with A=184,185 is presumably because of their redistribution amongst particle- and hole-type states. The observed states below 2 MeV are compared with predictions of the quasiparticle–phonon nuclear model.
Nuclear Physics A.
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J. Honzátko, I. Tomandl,
V. Bondarenko,
D. Bucurescu,
T. von Egidy,
J. Ott,
W. Schauer,
H.-F. Wirth,
C. Doll,
A. Gollwitzer,
G. Graw,
R. Hertenberger,
B.D. Valnion
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ABSTRACT: Levels in 125Te were investigated in the range up to 3.3 MeV excitation energy by the (n,γ), (d,p) and (3He,α) reactions. Over 160 levels and about 360 γ-transitions were established, most for the first time. The states below 2.3 MeV with the most complete spectroscopic information were interpreted in terms of the interacting boson-fermion model (IBFM). Unitary treatment of both positive- and negative-parity states is achieved with the same model parameter close to the intermediate case between O(6) and U(5) limits. Excitation energies, electromagnetic transition rates, γ-branchings and spectroscopic factors are discussed in connection with the possible structures. A family of low-spin negative-parity states has been identified and understood by the IBFM proving their antialigned origin.
Nuclear Physics A.
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ABSTRACT: Low–high and low–low energy γγ-coincidences, following the reaction with thermal neutrons, have been measured. Spectra have been recorded in the energy range from 50 to 2600 keV, and from 4500 to 6500 keV. The earlier known 188Re level scheme is corrected and extended up to ∼800 keV excitation energy and 62 levels by including 20 new levels. For 11 levels, the earlier interpretation has been changed. The complete level scheme is presented for up to ∼400 keV energy and spins ⩽5. Core plus two-quasiparticles model calculations have been performed. Some 188Re two-quasiparticle states display features indicating the nuclear shape phase transition from axial-deformation to γ-soft form.
Nuclear Physics A.
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D. Bucurescu,
T. von Egidy,
H.-F. Wirth,
N. Mărginean,
U. Köster,
W. Schauer, I. Tomandl,
G. Graw,
A. Metz,
R. Hertenberger,
Y. Eisermann
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ABSTRACT: The structure of the 121Te nucleus has been studied with the 122Te reaction at MeV. About 100 excited states have been observed up to an excitation energy of 2.65 MeV, and for most of them spin and parity values are proposed. A theoretical analysis based on the Interacting Boson–Fermion Model-1 is presented for the whole isotopic chain from 119Te to 129Te. The evolution of both positive and negative parity low-lying levels in these nuclei is reasonably well described with an essentially constant boson–fermion interaction. A detailed comparison of the calculations with experimental data is presented for 121Te. The level scheme up to about 1.5 MeV excitation is reasonably well accounted for. Possible indications of states with “intruder” character are discussed.
Nuclear Physics A.
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J. Honzatko, I. Tomandl,
V. Bondarenko J. Ott,
T. von Egidy,
W. Schauer,
Ch. Doll,
H.-F. Wirth,
A. Gollwitzer,
G. Graw,
R. Hertenberger,
B. Valnion
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ABSTRACT: Single g-ray spectra and gg-coincidences, following thermal neutron
capture in 124Te, were measured with semiconductor detectors
at the light-water reactor LWR-15 at e. Intensities of g transitions in
125Te were normalized using the absolute intensity of 7.8% of
the 6620keV line in 36Cl. The high resolution (d,p)
measurements were performed with 17 MeV deuterons, using the Q3D
spectrograph at two scattering angles of 15 ° and 30 °. Spectra
were recorded in the range up to 3.3 MeV and calibrated using the proton
peaks with l =1, and the corresponding level
energies were determined in the thermal neutron capture reaction. The
(3He,a) experiment was carried out with a 32 MeV He beam at
the angle of 10°. The spectrum was recorded in one run by means of a
large detector in a range up to approximately 4.7 MeV. The absolute
intensities were determined by measuring the total beam current.
Fizika B. 7:87-104.
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ABSTRACT: Levels in 123Te were investigated in the range up to 3 MeV excitation energy by (n,γ) and (d,p) reactions. Over 120 levels and about 140 γ-transitions were established most of them for the first time. The states below 2 MeV with the most complete spectroscopic information were interpreted in terms of the Interacting Boson–Fermion Model (IBFM). Unified treatment of both positive- and negative-parity states is achieved with constant parameters of the boson-fermion interaction for the whole chain of Te isotopes. Excitation energies, electromagnetic transition rates, γ-branchings and spectroscopic factors are discussed in connection with their possible structure. A family of low-spin negative-parity states has been identified and understood within the IBFM framework, thus proving their antialigned origin.
Nuclear Physics A.
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J. Honzátko,
V. Bondarenko, I. Tomandl,
T. von Egidy,
H.-F. Wirth,
D. Bucurescu,
V.Yu. Ponomarev,
N. Mărginean,
R. Hertenberger,
Y. Eisermann,
G. Graw,
L. Rubáček
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ABSTRACT: The nuclear structure of 127Te has been investigated with the reaction using thermal neutrons and with the reaction at Ed=20 MeV. About 190 levels were identified in a region to 4.1 MeV excitation energy, in most cases including spin, parity and γ-decay. The γ-decay scheme after neutron capture is essentially complete containing about 100% of the population of the 11/2− isomer and of the ground state. The thermal neutron capture cross section and isomer production of the 11/2− state at 88.3 keV were determined to be 0.44(6) b and 0.069(10) b, respectively. The neutron binding energy was determined to be 6287.6(1) keV. A significant number of the (d,p) angular distributions of cross section and asymmetry are anomalous with respect to the distorted-wave Born-approximation calculations and could be accounted for by inelastic multi-step mechanisms. The observed strong correlation of the (d,p) and primary (n,γ) strengths gives evidence for the direct neutron capture process which is mainly responsible for the primary population of 16 levels. The experimental level scheme is compared with predictions of the interacting boson–fermion model and of the quasiparticle phonon model.
Nuclear Physics A. 756:249-307.
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ABSTRACT: The level structure of 183W has been studied using gamma–gamma coincidences from thermal neutron capture in 182W accompanied with the reaction . From these data and those of previous studies a total of 76 levels and about 490 connecting γ-transitions have been established for energies below 2.4 MeV. An analysis based on the standard distorted-wave Born approximation (DWBA) provides the lj-angular momentum transfers and spectroscopic factors for 36 levels up to 2.2 MeV excitation energy. A large number of particle transitions indicate an influence of strong mixing between particle and probably hole states. The extra exchange of phonons across the Fermi surface leads to a fine structure in the fragmentation of most single particle strengths and at the same time has the effect of breakdown of the individual properties of Nilsson states. The extracted l=1 and 2 (d, p) sum below 2 MeV has about the same magnitude as in 185,187W. It comprises a rather small fraction of the expected strengths. The observed states below 2 MeV are compared with predictions of the quasiparticle–phonon model. Of particular interest is the identification of “quasi-bands” with inverse spin sequence based on the state 9/2+ at 622.8 keV; this indicates some transition aspects from rigid rotors of light W to γ-soft nuclei in the Os-Pt region.
Nuclear Physics A. 856(1):1-45.
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ABSTRACT: Levels of 166Ho were studied using thermal and average
resonance neutron capture and with the (d,p) and (d,3He)
reactions. We have devoted a large effort to the measurements of the
gg-coincidence spectra in the broad energy region 50 - 6243 keV. Based
on these data and those of earlier studies, the levels are grouped into
23 rotational bands. Among them are 6 new ones. The results are in good
agreement with the semiempirical and quasiparticle-phonon model, where
Coriolis and residual interactions are taken into account. Details of
model interpretation have been presented in a previously published
paper.
Fizika B. 9:97-110.
