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Ghys, L.*; Andreyev, A. N.; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Capponi, L.*; Cocolios, T. E.*; Cubiss, J.*; Derkx, X.*; et al.
Physical Review C, 100(5), p.054310_1 - 054310_13, 2019/11
被引用回数:11 パーセンタイル:80.2(Physics, Nuclear)The aim of this work was to investigate the -decay properties of
Fr and daughter products. Neutron-deficient francium nuclei are produced at ISOLDE-CERN bombarding a UCx target with 1.4 GeV protons. Due to the very high statistics and the high beam purity, improved decay data for
Fr and its daughters were obtained. The observation of crossover transitions positioned the isomeric high-spin level of
At at an excitation energy of 265(3) keV. Half-life values of 4.47(5) s and 1.28(10) s were extracted for the ground state and isomeric state of
At and 52(3) ms for the ground-state decay of
Fr.
Barzakh, A. E.*; Cubiss, J. G.*; Andreyev, A. N.; Seliverstov, M. D.*; Andel, B.*; Antalic, S.*; Ascher, P.*; Atanasov, D.*; Beck, D.*; Biero, J.*; et al.
Physical Review C, 99(5), p.054317_1 - 054317_9, 2019/05
被引用回数:12 パーセンタイル:77.08(Physics, Nuclear)Hyperfine-structure parameters and isotope shifts for the 795-nm atomic transitions in At have been measured at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy technique. Magnetic dipole and electric quadrupole moments, and changes in the nuclear mean-square charge radii, have been deduced. A large inverse odd-even staggering in radii, which may be associated with the presence of octupole collectivity, has been observed. Namely, the radius of the odd-odd isotope
At has been found to be larger than the average.
Flavigny, F.*; Elseviers, J.*; Andreyev, A. N.; Bauer, C.*; Bildstein, V.*; Blazhev, A.*; 他31名*
Physical Review C, 99(5), p.054332_1 - 054332_6, 2019/05
被引用回数:7 パーセンタイル:60.44(Physics, Nuclear)The Ni isotope is known for exhibiting signs of shape coexistence at very low excitation energies. In this work, carried out at REX-Isolde, CERN, the
Ni(
,
) reaction in inverse kinematics was studied for the first time and used to assess directly the active neutrons orbitals responsible its shape coexistence. The main states populated were the
ground state, the second
state at 1604~keV, and the first excited 2
state at 2033 keV. The analysis of the differential transfer cross-sections and comparison with theoretical DWBA calculations permitted to quantify the contribution of neutron orbits below the
=40 gap in the structure of these states. This information is essential to better understand the phenomenon of shape coexistence in the region of medium-heavy nuclei.
Andel, B.*; Andreyev, A. N.; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; Elseviers, J.*; Fedorov, D. V.*; et al.
Physical Review C, 96(5), p.054327_1 - 054327_11, 2017/12
被引用回数:3 パーセンタイル:29.87(Physics, Nuclear)A detailed -decay spectroscopy study of
Tl has been performed at ISOLDE (CERN). Z-selective ionization by the Resonance Ionization Laser Ion Source (RILIS) coupled to mass separation provided a high-purity beam of
Tl. Fine-structure
decays to excited levels in the daughter
Au were identified and an
-decay scheme of
Tl was constructed based on an analysis of
-
and
-
-
coincidences. Multipolarities of several
-ray transitions deexciting levels in
Au were determined. Based on the analysis of reduced
-decay widths, it was found that all
decays are hindered, which signifies a change of configuration between the parent and all daughter states.
Truesdale, V. L.*; Andreyev, A. N.; Ghys, L.*; Huyse, M.*; Van Duppen, P.*; Sels, S.*; Andel, B.*; Antalic, S.*; Barzakh, A.*; Capponi, L.*; et al.
Physical Review C, 94(3), p.034308_1 - 034308_11, 2016/09
被引用回数:9 パーセンタイル:59.92(Physics, Nuclear)A nuclear-decay spectroscopy study of the neutron-deficient isotope At is reported where an isotopically pure beam was produced using the selective Resonance Ionization Laser Ion Source and On-Line Isotope Mass Separator (CERN). The fine-structure
decay of
At allowed the low-energy excited states in the daughter nucleus
Bi to be investigated. A
-delayed fission study of
At was also performed. A mixture of symmetric and asymmetric fission-fragment mass distributions of the daughter isotope
Po (populated by
decay of
At) was deduced based on the measured fission-fragment energies. A
DF probability
(
At) = 9(1)
10
was determined.
Nowak, K.*; Wimmer, K.*; Hellgartner, S.*; Mcher, D.*; Bildstein, V.*; Diriken, J.*; Elseviers, J.*; Gaffney, L. P.*; Gernh
user, R.*; Iwanicki, J.*; et al.
Physical Review C, 93(4), p.044335_1 - 044335_10, 2016/04
被引用回数:15 パーセンタイル:74.84(Physics, Nuclear)The Ar(
)
Ar two-neutron transfer reaction at 2.16 MeV/u was studied at CERN using a
Ar radioactive beam and a tritium loaded radioactive target. Angular distributions for three final states were measured and based on the shape of the differential cross section an excited state at 3695 keV was identified as the first excited 0
state. The differential cross-sections for the 0
-ground state, and first excited 2
and 0
states are compared to DWBA calculations including two-step reactions through the intermediate nucleus
Ar. By comparison large scale shell model calculations using state-of-the-art effective interactions, with and without the tensor components of the interactions, it was observed that the cross-shell proton-neutron tensor interaction has measurable effects on the observables at low excitation energy in
Ar.
Bottoni, S.*; Leoni, S.*; Fornal, B.*; Raabe, R.*; Rusek, K.*; Benzoni, G.*; Bracco, A.*; Crespi, F. C. L.*; Morales, A. I.*; Bednarczyk, P.*; et al.
Physical Review C, 92(2), p.024322_1 - 024322_8, 2015/08
被引用回数:19 パーセンタイル:78.42(Physics, Nuclear)An exploratory experiment was performed at REX-ISOLDE CERN to test the potential of cluster-transfer reactions at the Coulomb barrier as a mechanism to explore the structure of exotic neutron-rich nuclei. The transfer of triton and alpha particles in a reaction of a beam of Rb onto a
Li target were studied through particle-
coincidence measurements. The results indicate that such cluster transfer reactions can be an efficient method to investigate the structure of neutron-rich nuclei at medium-high excitation energies and spins.
Diriken, J.*; Patronis, N.*; Andreyev, A. N.; Antalic, S.*; Bildstein, V.*; Blazhev, A.*; Darby, I. G.*; De Witte, H.*; Eberth, J.*; Elseviers, J.*; et al.
Physical Review C, 91(5), p.054321_1 - 054321_15, 2015/05
被引用回数:8 パーセンタイル:52.89(Physics, Nuclear)Excited states up to an excitation energy of 5.8 MeV were populated in the neutron-rich isotope Ni via the
Ni(d,p) transfer reaction at REX-Isolde, CERN. In particular, single-neutron states above the N=40 sub-shell gap were populated, and the relative spectroscopic factors were extracted using distorted-wave Born approximation analysis. The positive parity g
, d
and s
neutron orbits above the shell closure are assumed to induce strong quadrupole collectivity in neutron-rich Fe and Cr isotopes. The extracted relative spectroscopic factors show that the strength of the d
orbit is mostly split over two states, hinting to substantial mixing of the neutron d
configuration with collective modes of the core. The size of the N=50 shell gap was also estimated, and found to be 2.6 MeV near
Ni, as also determined in lighter Ni isotopes.
Orlandi, R.; Mcher, D.*; Raabe, R.*; Jungclaus, A.*; Pain, S. D.*; Bildstein, V.*; Chapman, R.*; De Angelis, G.*; Johansen, J. G.*; Van Duppen, P.*; et al.
Physics Letters B, 740, p.298 - 302, 2015/01
被引用回数:24 パーセンタイル:82.28(Astronomy & Astrophysics)Single-neutron states in Zn have been populated using the reaction
Zn(d,p) at REX-Isolde, CERN. The analysis reveals that the lowest excited states in
Zn lie at approximately 1 MeV, and involve neutron orbits above the N=50 shell gap. A 5/2
configuration was assigned to the 983-keV state. Comparison with large-scale shell model calculations supports a robust neutron N=50 shell closure for
Ni. These data constitute an important step towards the understanding the magicity of
Ni and the structure of nuclei in the region.
Diriken, J.*; Patronis, N.*; Andreyev, A. N.*; Antalic, S.*; Bildstein, V.*; Blazhev, A.*; Darby, I. G.*; De Witte, H.*; Eberth, J.*; Elseviers, J.*; et al.
Physics Letters B, 736, p.533 - 538, 2014/09
被引用回数:17 パーセンタイル:74.35(Astronomy & Astrophysics)The neutron orbits , d
and s
are assumed to be responsible for the swift onset of collectivity observed in the region below
Ni. In order to gather information on the single-particle energies and spectroscopic factors of these orbitals, single-particle states in the nucleus
Ni were populated using the reaction
Ni(d,p), in inverse kinematics, at REX-ISOLDE, CERN. The new isotope was studied using combined particle-
spectroscopy. Comparison with DWBA calculations, permitted the identification of positive parity states with a substantial amount of
d
(1007 keV) and
d
(2207 and 3277 keV) single-particle strength. Comparisons with extended Shell-Model calculations was also performed to confirm the single-particle nature of these states, and to deduce general properties around
Ni.
Elseviers, J.*; Andreyev, A. N.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; et al.
Physical Review C, 88(4), p.044321_1 - 044321_13, 2013/10
被引用回数:37 パーセンタイル:89.4(Physics, Nuclear)The detailed analysis of the -delayed fission data of
Tl is presented. The experiment was performed by producing a pure beam of
Tl by means of highly selective resonance laser ionization followed by mass separation with the ISOLDE isotope separator. A surprising asymmetric mass distribution of fission fragments from
Hg, the daughter of
Tl
decays, was obtained. Here, the energy calibration of the silicon detectors, which is crucial for a proper determination of the fission fragments' energy and mass split, is presented and the total kinetic energy and its dependence on the mass split ratio is discussed. A more precise
-delayed fission probability of 3.2(2)
10
was deduced.
Andreyev, A. N.*; Liberati, V.*; Antalic, S.*; Ackermann, D.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Diriken, J.*; Elseviers, J.*; Fedorov, D.*; et al.
Physical Review C, 87(5), p.054311_1 - 054311_8, 2013/05
被引用回数:15 パーセンタイル:69.68(Physics, Nuclear)-decay studies of
Tl
and its dahghter products
Au
and
Ir
were carried out in two complementary experiments at the mass separator ISOLDE (CERN) and velocity filter SHIP (GSI). The nucluesu
Au
has
decay properties of half-life 207 ms and
-decay energy 6433 keV. The ground state spins and parities for
Au and
Ir were determined to be 1/2
.
Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; et al.
Physical Review Letters, 105(25), p.252502_1 - 252502_5, 2010/12
被引用回数:178 パーセンタイル:97.2(Physics, Multidisciplinary)A very exotic process of -delayed fission of
Tl is studied in detail by using resonant laser ionization with subsequent mass separation at ISOLDE (CERN). In contrast to common expectations, the fission-fragment mass distribution of the post-
-decay daughter nucleus
Hg (
/
= 1.25) is asymmetric. This asymmetry is more surprising since a mass-symmetric split of this extremely neutron-deficient nucleus would lead to two
Zr fragments, with magic
= 50 and semi-magic
= 40. This is a new type of asymmetric fission, not caused by large shell effects related to fragment magic proton and neutron numbers, as observed in the actinide region. The newly-measured branching ratio for
-delayed fission of
Tl is 3.6(7)
10
%.
西尾 勝久; Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; et al.
no journal, ,
陽子過剰な原子核Hgの低励起エネルギー核分裂を測定した。CERN-ISOLDEにおいて
Tlをアイソトープ分離し、このベータ崩壊によって娘核
Hgを励起さることで、この核分裂を観測した(ベータ崩壊遅延核分裂)。核分裂特性を調べたところ、中性子数50の閉殻を有する
Zr原子核は生成されず、質量数80と100に収率の最大を有する非対称な核分裂を示した。また、原子力機構タンデム加速器において、陽子過剰原子核のインビーム核分裂実験を行った。この結果、ウランなど従来の核分裂と異なり、励起エネルギーが増加しても質量非対称度が変化しないことがわかった。
Orlandi, R.; Mcher, D.*; Raabe, R.*; Jungclaus, A.*; Pain, S. D.*; Bildstein, V.*; Chapman, R.*; De Angelis, G.*; Johansen, J. G.*; Van Duppen, P.*; et al.
no journal, ,
Single-neutron states in the = 49 isotope
Zn were populated in the
Zn(d,p)
Zn transfer reaction at REX-ISOLDE, CERN. The combined detection of protons ejected in the reaction and of
rays emitted by
Zn permitted the identification of the lowest-lying 5/2
and 1/2
excited states. The analysis of proton angular distributions links these states to a significant amount of single-particle strength around 1 MeV, and specifically to the
d
and
s
neutron orbits, which lie above the
= 50 neutron shell gap. Comparison with large-scale-shell-model calculations supports a robust
= 50 shell-closure for
Ni. These data constitute a considerable step towards the understanding of the magicity of
Ni and of the structure of isotopes in the region.