-
E Wilson, Zs Podolyák,
B Fornal,
R V F Janssens,
M Bowry,
M Bunce,
M P Carpenter,
C J Chiara,
N Cieplicka,
A Y Deo, [......],
R S Kempley,
F G Kondev,
G J Lane,
T Lauritsen,
M W Reed,
P H Regan,
C Rodríguez Triguero,
B Szpak,
P M Walker,
S Zhu
Zakopane Conference on Nuclear Physics “Extremes of the Nuclear Landscape”; 03/2013
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L Chen,
P M Walker,
H Geissel,
Yu. A Litvinov,
K Beckert,
P Beller,
F Bosch,
D Boutin,
L Caceres,
J J Carroll, [......],
C Scheidenberger,
E C Simpson,
M Shindo,
M Steck,
B Sun,
S J Williams,
H Weick,
M Winkler,
H -J Wollersheim,
T Yamaguchi
[show abstract]
[hide abstract]
ABSTRACT: Long-lived isomers in 212Bi have been studied following 238U projectile fragmentation at 670 MeV per nucleon. The fragmentation products were injected as highly charged ions into a storage ring, giving access to masses and half-lives. While the excitation energy of the first isomer of 212Bi was confirmed, the second isomer was observed at 1478(30) keV, in contrast to the previously accepted value of >1910 keV. It was also found to have an extended Lorentz-corrected in-ring half-life >30 min, compared to 7.0(3) min for the neutral atom. Both the energy and half-life differences can be understood as being due a substantial, though previously unrecognized, internal decay branch for neutral atoms. Earlier shell-model calculations are now found to give good agreement with the isomer excitation energy. Furthermore, these and new calculations predict the existence of states at slightly higher energy that could facilitate isomer deexcitation studies.
Physical Review Letters 03/2013; 110(12):122502. · 7.37 Impact Factor
-
Denis A M Bacelar,
A M Bruce, Zs. Podolyák,
N Al-Dahan,
M Górska,
S Lalkovski,
S Pietri,
M V Ricciardi,
A Algora,
N Alkhomashi, [......],
S J Steer,
K Steiger,
P Strmen,
T P D Swan,
I Szarka,
J J Valiente-Dobón,
S Verma,
P M Walker,
H Weick,
H J Wollersheim
[show abstract]
[hide abstract]
ABSTRACT: Isomeric ratios have been measured for high-spin states in Po-198,200,206,208, At-208,209,210,211,Rn-210,211,212,213,214, Fr-208,211,212,213,214, Ra-210,211,212,214,215, and Ac-215 following the projectile fragmentation of a 1 A GeV U-238 beam by a Be-9 target at GSI Helmholtzzentrum für Schwerionenforschung. The fragments were separated in the fragment separator (FRS) and identified by means of energy loss and time-of-flight techniques. They were brought to rest at the centre of the RISING gamma-ray detector array and intensities of gamma rays emitted in the decay of isomeric states with half-lives between 100 ns and 40 μs and spin values up to 55/2 ℏ were used to obtain the corresponding isomeric ratios. The data are compared to theoretical isomeric ratios calculated in the framework of the abrasion–ablation model. Large experimental enhancements are obtained for high-spin isomers in comparison to expected values.
Physics Letters B 01/2013; · 3.95 Impact Factor
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J. Kurcewicz,
F. Farinon,
H. Geissel,
S. Pietri,
C. Nociforo,
A. Prochazka,
H. Weick,
J.S. Winfield,
A. Estradé,
P. R. P. Allegro, [......],
P. Spiller,
J. Stadlmann,
P. Strmen,
B Sun,
I. Szarka,
J. Taïeb,
S. Terashima,
J. J. Valiente-Dobón,
M Winkler,
Ph. Woods
[show abstract]
[hide abstract]
ABSTRACT: With a new detector setup and the high-resolution performance of the fragment
separator FRS at GSI we discovered 57 new isotopes in the atomic number range
of 60$\leq Z \leq 78$: \nuc{159-161}{Nb}, \nuc{160-163}{Pm}, \nuc{163-166}Sm,
\nuc{167-168}{Eu}, \nuc{167-171}{Gd}, \nuc{169-171}{Tb}, \nuc{171-174}{Dy},
\nuc{173-176}{Ho}, \nuc{176-178}{Er}, \nuc{178-181}{Tm}, \nuc{183-185}{Yb},
\nuc{187-188}{Lu}, \nuc{191}{Hf}, \nuc{193-194}{Ta}, \nuc{196-197}{W},
\nuc{199-200}{Re}, \nuc{201-203}{Os}, \nuc{204-205}{Ir} and \nuc{206-209}{Pt}.
The new isotopes have been unambiguously identified in reactions with a
$^{238}$U beam impinging on a Be target at 1 GeV/u. The isotopic production
cross-section for the new isotopes have been measured and compared with
predictions of different model calculations. In general, the ABRABLA and COFRA
models agree better than a factor of two with the new data, whereas the
semiempirical EPAX model deviates much more. Projectile fragmentation is the
dominant reaction creating the new isotopes, whereas fission contributes
significantly only up to about the element holmium.
Physics Letters B 12/2012; 717:371-375. · 3.95 Impact Factor
-
A Gottardo,
J J Valiente-Dobón,
G Benzoni,
R Nicolini,
A Gadea,
S Lunardi,
P Boutachkov,
A M Bruce,
M Górska,
J Grebosz, [......],
P Strmen,
T P D Swan,
I Szarka,
C A Ur,
P M Walker,
O Wieland,
H-J Wollersheim,
F Nowacki,
E Maglione,
A P Zuker
[show abstract]
[hide abstract]
ABSTRACT: The neutron-rich lead isotopes, up to ^{216}Pb, have been studied for the first time, exploiting the fragmentation of a primary uranium beam at the FRS-RISING setup at GSI. The observed isomeric states exhibit electromagnetic transition strengths which deviate from state-of-the-art shell-model calculations. It is shown that their complete description demands the introduction of effective three-body interactions and two-body transition operators in the conventional neutron valence space beyond ^{208}Pb.
Physical Review Letters 10/2012; 109(16):162502. · 7.37 Impact Factor
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T Alharbi,
P J R Mason,
P H Regan,
N Mǎrginean, Zs Podolyák,
A Algora,
N Alazemi,
A M Bruce,
R Britton,
M R Bunce, [......],
O J Roberts,
S Rice,
J F Smith,
L Stroe,
T Sava,
C Townsley,
E Wilson,
V Werner,
M Zhekova,
N V Zamfir
[show abstract]
[hide abstract]
ABSTRACT: A study of intrinsic state halflife measurements in the N=80 nucleus 138Ce has been made using the 130Te(12C,4n)138Ce fusion evaporation reaction at beam energy of 56 MeV. The fast-timing gamma-ray coincidence method was used with a mixed LaBr3(Ce)-HPGe array to establish the lifetimes of the yrast 6+ state at 2294 keV, the Iπ=5− state at 2218 keV, the Iπ=11+ state at 3943 keV and the 14+ state at that at 5312 keV, all of which are in the sub nanosecond regime. Reduced transition probabilities have been calculated for the electromagnetic decays from these states.
Rutherford Centennial Conference on Nuclear Physics 8–12 August 2011, Manchester, UK; 09/2012
-
R. Caballero-Folch,
C. Domingo-Pardo,
J.L. Taín,
G. Cortés,
J. Agramunt,
A. Algora,
F. Ameil,
Y. Ayyad,
J. Benlliure,
M. Bowry, [......],
E. Sokol,
K. Steiger,
B. Sun,
D. Testov,
H. Weick,
E. Wilson,
J.S. Winfield,
R. Wood,
P. Woods,
A. Yeremin
[show abstract]
[hide abstract]
ABSTRACT: One of the main challenges for the better understanding of nucleosynthesis in the rapid neutron
capture process (r-process) concerns the enormous amount of very exotic neutron-rich nuclei
involved in this kind of cataclysmic scenario, and the scarce information available about their
nuclear properties. In particular, theoretical calculations in the mass region around N=126 are
difficult to validate on the basis only of the experimental information available close to stability
so far. Such information becomes relevant for a reliable interpretation of the third peak in the
r-process abundance distribution. Present and next generation radioactive-beam facilities (RIB)
will be instrumental towards the systematicmeasurement of such nuclei, for improving theoretical
nuclear models, and for enhancing the accuracy of the nuclear physics input in r-process model
calculations. Here we present an experiment carried out recently at Fragment Separator (FRS) at
the GSI Helmholtz Center for Heavy Ion Research in Darmstadt (Germany), which allowed us to
measure for the first time relevant nuclear properties of several neutron-rich isotopes in the region
around 211Hg and 215Tl. Preliminary results about the identified species and their implantation
statistics are reported in this contribution. The experimental setup was comprised of an array of
silicon implantation detectors (SIMBA) and the BEta deLayEd Neutron detector (BELEN). The
main advantage compared to previous experiments was due to an innovative self-triggered acquisition
system, which allowed us to enhance the neutron detection probability when compared
to conventional analogue acquisition systems. This setup has been developed in the framework
of the NuSTAR (Nuclear Structure, Astrophysics and Reactions) in the DESPEC (DEcay SPECtroscopy)
collaboration which will perform experiments at the future Super Fragment Separator
(SuperFRS) at FAIR (Facility for Antiproton and Ion Research).
XII International Symposium on Nuclei in the Cosmos, Cairns, Australia; 08/2012
-
T Alharbi,
P J R Mason,
P H Regan, Zs Podolyák,
N Mărginean,
M Nakhostin,
M Bowry,
D Bucurescu,
G Căta-Danil,
I Căta-Danil, [......],
P C Bender,
U Garg,
M N Erduran,
A Kusoglu,
M Bostan,
P Detistov,
N Alkhomashi,
A K Sinha,
R Chakrabarti,
S S Ghugre
[show abstract]
[hide abstract]
ABSTRACT: We report on a gamma-ray coincidence analysis using a mixed array of hyperpure germanium and cerium-doped lanthanum tri-bromide (LaBr3:Ce) scintillation detectors to study nuclear electromagnetic transition rates in the pico-to-nanosecond time regime in 33,34P and 33S following fusion-evaporation reactions between an 18O beam and an isotopically enriched 18O implanted tantalum target. Energies from decay gamma-rays associated with the reaction residues were measured in event-by-event coincidence mode, with the measured time difference information between the pairs of gamma-rays in each event also recorded using the ultra-fast coincidence timing technique. The experiment used the good full-energy peak resolution of the LaBr3:Ce detectors coupled with their excellent timing responses in order to determine the excited state lifetime associated with the lowest lying, cross-shell, Iπ=4- "intruder" state previously reported in the N=19 isotone 34P. The extracted lifetime is consistent with a mainly single-particle M2 multipolarity associated with a f7/2→d5/2 single particle transition.
Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine 07/2012; 70(7):1337-1339. · 1.09 Impact Factor
-
C B Hinke,
M Böhmer,
P Boutachkov,
T Faestermann,
H Geissel,
J Gerl,
R Gernhäuser,
M Górska,
A Gottardo,
H Grawe, [......],
A Procházka,
P H Regan,
C Rigollet,
H Schaffner,
C Scheidenberger,
S Schwertel,
P-A Söderström,
S J Steer,
A Stolz,
P Strmeň
[show abstract]
[hide abstract]
ABSTRACT: The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During β(+)-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of (100)Sn, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the β-decay of (100)Sn, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear β-decay, establishing the 'superallowed' nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, (100)In, are well reproduced by modern, large-scale shell model calculations.
Nature 06/2012; 486(7403):341-5. · 36.28 Impact Factor
-
E. A. Stefanova,
S. Lalkovski,
A. Korichi,
T. Kutsarova,
A. Lopez-Martens,
F. R. Xu,
H. L. Liu,
S. Kisyov,
A. Minkova,
D. Bazzacco,
M. Bergström,
A. Görgen,
F. Hannachi,
B. Herskind,
H. Hübel,
A. Jansen,
T. L. Khoo, Zs. Podolyák,
G. Schönwasser
[show abstract]
[hide abstract]
ABSTRACT: The neutron-rich nuclei $^{109}$Pd and $^{111}$Pd were produced as fission
fragments following the $^{30}$Si + $^{168}$Er reaction at 142 MeV. Using the
identification based on the coincidences with the complementary fission
fragments, the only positive-parity bands observed so far in $^{109}$Pd and
$^{111}$Pd emerged from this work. A band, built on top of the 5/2$^+$ ground
state exhibiting $\Delta I$ = 1 energy-level staggering, was observed in each
of these nuclei. Both nuclei of interest, $^{109}$Pd and $^{111}$Pd, are
suggested to lie in the transitional region of Pd isotopes of maximum
$\gamma$-softness. The ground states of both nuclei are predicted by TRS
calculations to be extremely $\gamma$-soft with shallow triaxial minima. The
first crossing in the new bands is proposed to be due to an alignment of
$h^2_{11/2}$ neutrons.
06/2012;
-
M Grieser,
Yu A Litvinov,
R Raabe,
K Blaum,
Y Blumenfeld,
P A Butler,
F Wenander,
P Woods,
M Aliotta,
A Andreyev, [......],
E Wildner,
N Winckler,
D F A Winters,
A Wolf,
H S Xu,
A Yakushev,
T Yamaguchi,
Y J Yuan,
Y H Zhang,
K Zuber
The European Physical Journal Special Topics 05/2012; 207:1-117. · 1.56 Impact Factor
-
N. Al-Dahan,
P. H. Regan, Zs. Podolyák,
P. M. Walker,
N. Alkhomashi,
G. D. Dracoulis,
G. Farrelly,
J. Benlliure,
S. B. Pietri,
R. F. Casten, [......],
Z. Liu,
P. J. Mason,
C. Mihai,
F. Molina,
D. Mücher,
B. Rubio,
A. Tamii,
S. Tashenov,
J. J. Valiente-Dobón,
P. J. Woods
[show abstract]
[hide abstract]
ABSTRACT: β decays from heavy, neutron-rich nuclei with A∼190 have been investigated following their production via the relativistic projectile fragmentation of an E/A=1 GeV 208Pb primary beam on a ∼2.5 g/cm2 9Be target. The reaction products were separated and identified using the GSI FRagment Separator (FRS) and stopped in the RISING active stopper. γ decays were observed and correlated with these secondary ions on an event-by-event basis such that γ-ray transitions following from both internal (isomeric) and β decays were recorded. A number of discrete, β-delayed γ-ray transitions associated with β decays from 194Re to excited states in 194Os have been observed, including previously reported decays from the yrast Iπ=(6+) state. Three previously unreported γ-ray transitions with energies 194, 349, and 554 keV are also identified; these transitions are associated with decays from higher spin states in 194Os. The results of these investigations are compared with theoretical predictions from Nilsson multi-quasiparticle (MQP) calculations. Based on lifetime measurements and the observed feeding pattern to states in 194Os, it is concluded that there are three β−-decaying states in 194Re.
Physical Review C 05/2012; 85(3):034301. · 3.31 Impact Factor
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Zs. Podolyák,
P. G. Bizzeti,
A. M. Bizzeti-Sona,
S. Lunardi,
D. Bazzacco,
A. Dewald,
A. Algora,
G. de Angelis,
M. De Poli,
E. Farnea, [......],
D. R. Kasemann,
T. Klug,
Th. Kröll,
S. Lenzi,
D. R. Napoli,
C. M. Petrache,
R. Peusquens,
C. Rossi Alvarez,
T. Martinez,
C. A. Ur
[show abstract]
[hide abstract]
ABSTRACT: The lifetime andthe γ-decay to the 0+ groundstate of the lowest 3− state in 148Gd has been determined. The reduced strength B(E3, 3− → 0+)=41 (6) W.u. agrees well with the theoretical value from empirical shell model calculations and can be directly compared
with the 12+ → 9− two-octupole-phonon → one-octupole-phonon strength obtained in the same Recoil Distance Method lifetime measurement. The
results of our search for a three octupole-phonon state built on the (νf
7/2)6+2 state is also reported.
European Physical Journal A 04/2012; 8(2):147-151. · 2.19 Impact Factor
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Zs. Podolyák,
S. J. Steer,
S. Pietri,
M. Górska,
P. H. Regan,
D. Rudolph,
A. B. Garnsworthy,
R. Hoischen,
J. Gerl,
H. J. Wollersheim, [......],
R. Krücken,
S. Lalkovski,
Z. Liu,
A. Maj,
S. Myalski,
S. Schwertel,
T. Shizuma,
P. M. Walker,
E. Werner-Malento,
O. Wieland
[show abstract]
[hide abstract]
ABSTRACT: Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a 20882Pb\ensuremath ^{208}_{\ 82}{\rm Pb} beam at E/A = 1\ensuremath E/A = 1 GeV on a 2.5 g/cm2\ensuremath 2.5 {\rm g/cm^2} thick Be target. The synthesised nuclei were selected and identified in-flight using the fragment separator at GSI. Approximately
300 ns after production, the selected nuclei were implanted in an ~ 8\ensuremath \sim 8 mm thick perspex stopper, positioned at the centre of the RISING g\ensuremath \gamma -ray detector spectrometer array. A previously unreported isomer with a half-life T1/2 = 163(5)\ensuremath T_{1/2} = 163(5) ns has been observed in the N = 126 closed-shell nucleus 20579Au\ensuremath ^{205}_{\ 79}{\rm Au} . Through g \gamma -ray singles and g \gamma -g \gamma coincidence analysis a level scheme was established. The comparison with a shell model calculation tentatively identifies
the spin-parity of the excited states, including the isomer itself, which is found to be Ip = (19/2+)\ensuremath I^{\pi} = (19/2^+) .
European Physical Journal A 04/2012; 42(3):489-493. · 2.19 Impact Factor
-
D. Rudolph,
R. Hoischen,
M. Hellström,
S. Pietri, Zs. Podolyák,
P. H. Regan,
A. B. Garnsworthy,
S. J. Steer,
F. Becker,
P. Bednarczyk, [......],
L. -L. Andersson,
L. Atanasova,
D. L. Balabanski,
M. A. Bentley,
A. Blazhev,
C. Brandau,
J. R. Brown,
C. Fahlander,
E. K. Johansson,
A. Jungclaus
[show abstract]
[hide abstract]
ABSTRACT: The fragmentation of a 550MeV/u primary beam of 58Ni on a 9Be target has been used to measure time- and energy-correlated γ decays following the implantation of event-by-event discriminated
secondary fragments into a 9Be stopper plate. A new isomeric γ decay with T
1/2 = 14(
6 4 \begin{smallmatrix}6 4\end{smallmatrix}
) ns and E
γ = 646.2(2) keV is observed and attributed to the decay of the yrast 3/2- state in 53
27Co26 . This short-lived isomeric state has been populated by means of nuclear reactions during the stopping process of the secondary
fragments. The experimental findings are discussed in the framework of large-scale spherical shell model calculations in conjunction
with isospin symmetry-breaking residual interactions for the A = 53 , T
z = ±1/2 mirror nuclei 53Co and 53Fe .
European Physical Journal A 04/2012; 36(2):131-138. · 2.19 Impact Factor
-
M. Kmiecik,
A. Maj,
J. Gerl,
G. Neyens,
L. Atanasova,
D. L. Balabanski,
F. Becker,
P. Bednarczyk,
G. Benzoni,
N. Blasi, [......],
N. Saito,
T. R. Saito,
A. Saltarelli,
G. S. Simpson,
J. Styczeń,
N. Vermeulen,
E. Werner-Malento,
O. Wieland,
H. J. Wollersheim,
M. Ziȩbliński
[show abstract]
[hide abstract]
ABSTRACT: The feasibility of measuring g -factors using the TDPAD method applied to high-energy, heavy fragmentation products is explored. The 2623keV Ip=12+\ensuremath I^{\pi}=12^+ isomer in 192Pb with t \tau = 1.57 μs has been produced using the fragmentation of a 1A GeV 238U beam. The results presented demonstrate for the first time that such heavy nuclei produced in a fragmentation reaction with
a relativistic beam are sufficiently well spin-aligned. Moreover, the rather large value of the alignment, 28(10)% of the
maximum possible, is preserved during the separation process allowing the determination of magnetic moments. The measured
values of the lifetime, t \tau = 1.54(9) μs, and the g -factor, g = - 0.175(20) , agree with the results of previous investigations using fusion-evaporation reactions.
European Physical Journal A 04/2012; 45(2):153-158. · 2.19 Impact Factor
-
M. Stanoiu,
D. Sohler,
O. Sorlin,
Zs. Dombrádi,
F. Azaiez,
B. A. Brown,
C. Borcea,
C. Bourgeois,
Z. Elekes,
Zs. Fülöp, [......],
F. Negoita,
Yu.-E. Penionzhkevich, Zs. Podolyák,
M. G. Porquet,
P. Roussel-Chomaz,
M. G. Saint-Laurent,
H. Savajols,
G. Sletten,
J. Timár,
C. Timis
[show abstract]
[hide abstract]
ABSTRACT: The structure of the weakly bound 926F17 odd-odd nucleus, produced from 27,28Na nuclei, has been investigated at GANIL by means of the in-beam γ-ray spectroscopy technique. A single γ-line is observed at 657(7) keV in 926F which has been ascribed to the decay of the excited J=2+ state to the J=1+ ground state. The possible presence of intruder negative parity states in 26F is also discussed.
Phys. Rev. C. 01/2012; 85(1).
-
[show abstract]
[hide abstract]
ABSTRACT: High-spin states in the 164 68 Er 96 region were studied using 9 Be + 160 Gd reactions. Pulsed beam conditions were exploited for enhanced sensitivity to delayed γ -ray transitions. New isomers were identified in 161 Dy, 163 Ho, 162 Er, and 165 Er. The 162 Er isomer is interpreted to decay by E1 transitions to the ground-state band with a reduced hindrance of f ν = 33. A plot of f ν values for all K = 7, E1 transitions from two-quasiparticle isomers to the ground-state bands of even-even nuclei reveals only a small influence from the dynamic to kinematic moment-of-inertia ratio, which provides a measure of Coriolis K mixing within the ground-state band. This is interpreted to imply that the relatively low hindrances are due to K mixing in the isomer, caused by a combination of Coriolis and octupole band mixing.
Physical Review C. 01/2012; 024313.
-
L. Chen,
W. R. Plaß,
H. Geissel,
R. Knöbel,
Kozhuharov,
Yu. A. Litvinov,
Z. Patyk,
C. Scheidenberger,
K. Siegień-Iwaniuk,
B. Sun, [......],
S. Rigby,
N. Saito,
T. Saito,
M. Shindo,
M. Steck,
P. M. Walker,
S. Williams,
M. Winkler,
H.-J. Wollersheim,
T. Yamaguchi
Nuclear Physics A 01/2012; 71:882. · 1.54 Impact Factor
-
T Alharbi,
P J R Mason,
P H Regan,
N Mǎrginean, Zs Podolyák,
A Algora,
N Alazemi,
A M Bruce,
R Britton,
M R Bunce, [......],
O J Roberts,
S Rice,
J F Smith,
L Stroe,
T Sava,
C Townsley,
E Wilson,
V Werner,
M Zhekova,
N V Zamfir
Journal of Physics Conference Series 01/2012; 381(012057).
