-
L P Gaffney,
P A Butler,
M Scheck,
A B Hayes,
F Wenander,
M Albers,
B Bastin,
C Bauer,
A Blazhev,
S Bönig, [......],
P Thoele,
P Van Duppen,
M J Vermeulen,
M von Schmid,
D Voulot,
N Warr,
K Wimmer,
K Wrzosek-Lipska,
C Y Wu,
M Zielinska
[show abstract]
[hide abstract]
ABSTRACT: There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are 'octupole deformed', that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on (220)Rn and (224)Ra show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental studies of atomic electric-dipole moments that might reveal extensions to the standard model.
Nature 05/2013; 497(7448):199-204. · 36.28 Impact Factor
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N Warr,
J Walle,
M Albers,
F Ames,
B Bastin,
C Bauer,
V Bildstein,
A Blazhev,
S Bönig,
N Bree, [......],
R Wadsworth,
G Walter,
D Weißhaar,
F Wenander,
A Wiens,
K Wimmer,
B H Wolf,
P J Woods,
K Wrzosek-Lipska,
K O Zell
European Physical Journal A 03/2013; 49(3):1-32. · 2.19 Impact Factor
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N. Warr,
J. Van de Walle,
M. Albers,
F. Ames,
B. Bastin,
C. Bauer,
V. Bildstein,
A. Blazhev,
S. Bönig,
N. Bree, [......],
R. Wadsworth,
G. Walter,
D. Weißhaar,
F. Wenander,
A. Wiens,
K. Wimmer,
B. H. Wolf,
P. J. Woods,
K. Wrzosek-Lipska,
K. O. Zell
European Physical Journal A 03/2013; 49:40. · 2.19 Impact Factor
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M. G. Procter,
D. M. Cullen,
C. Scholey,
P. Ruotsalainen,
L. Angus,
T. Bäck,
B. Cederwall,
A. Dewald,
C. Fransen, T. Grahn, [......],
S. V. Rigby,
W. Rother,
M. Sandzelius,
J. Sarén,
J. Sorri,
M. J. Taylor,
J. Uusitalo,
P. Wady,
C. Qi,
F. R. Xu
-
M G Procter,
D M Cullen,
M J Taylor,
J Pakarinen,
K Auranen,
T Back,
T Braunroth,
B Cederwall,
A Dewald, T Grahn, [......],
P Peura,
P Rahkila,
P Ruotsalainen,
M Sandelius,
J Saren,
C Scholey,
J Sorri,
S Stolze,
J Uusitalo,
C Qi
Physical Review C. 01/2013; 87(1).
-
D. O'Donnell,
R. D. Page,
C. Scholey,
L. Bianco,
L. Capponi,
R. J. Carroll,
I. G. Darby,
L. Donosa,
M. Drummond,
F. Ertugral, [......],
P. Rahkila,
S. Rinta-Antila,
P. Ruotsalainen,
M. Sandzelius,
J. Saren,
B. Saygi,
J. Simpson,
J. Sorri,
A. Thornthwaite,
J. Uusitalo
[show abstract]
[hide abstract]
ABSTRACT: The a-decay chains originating from the s1/2 and h11/2 states in 173Au have
been investigated following fusion-evaporation reactions. Four generations of a
radioactivities have been correlated with 173Aum leading to a measurement of
the a decay of 161Tam. It has been found that the known a decay of 161Ta, which
was previously associated with the decay of the ground state, is in fact the
decay of an isomeric state. This work also reports on the first observation of
prompt g rays feeding the ground state of 173Au. This prompt radiation was used
to aid the study of the a-decay chain originating from the s1/2 state in 173Au.
Three generations of a decays have been correlated with this state leading to
the observation of a previously unreported activity which is assigned as the
decay of 165Reg. This work also reports the excitation energy of an a-decaying
isomer in 161Ta and the Q-value of the decay of 161Tag.
12/2012;
-
M. G. Procter,
D. M. Cullen,
C. Scholey,
P. Ruotsalainen,
L. Angus,
T. Bäck,
B. Cederwall,
A. Dewald,
C. Fransen, T. Grahn, [......],
S. V. Rigby,
W. Rother,
M. Sandzelius,
J. Sarén,
J. Sorri,
M. J. Taylor,
J. Uusitalo,
P. Wady,
C. Qi,
F. R. Xu
[show abstract]
[hide abstract]
ABSTRACT: Lifetime measurements have been made in the neutron-deficient nucleus 109Te using the coincident recoil distance Doppler-shift method. The experimental B(E2) values have been compared with state-of-the-art shell-model calculations using the monopole-corrected realistic charge-dependent Bonn nucleon-nucleon potential. Lifetimes in the νh11/2 band are consistent with an interpretation based on the deformation driving properties of a single valence neutron outside of the even-even tellurium core and highlight the unexpected presence of collective behavior as the N=50 shell closure is approached. Lifetime measurements for the low-lying positive-parity states also appear to correlate well with shell-model calculations. In addition, a comparison with the proton-unbound nucleus 109I suggests that the presence of a single decoupled valence proton affects the total measured B(E2) strengths in a manner that is not currently well understood.
Phys. Rev. C. 09/2012; 86(3).
-
P T Greenlees,
J Rubert,
J Piot,
B J P Gall,
L L Andersson,
M Asai,
Z Asfari,
D M Cox,
F Dechery,
O Dorvaux, [......],
P Ruotsalainen,
M Sandzelius,
J Sarén,
C Scholey,
D Seweryniak,
J Sorri,
B Sulignano,
Ch Theisen,
J Uusitalo,
M Venhart
[show abstract]
[hide abstract]
ABSTRACT: The rotational band structure of the Z=104 nucleus ^{256}Rf has been observed up to a tentative spin of 20ℏ using state-of-the-art γ-ray spectroscopic techniques. This represents the first such measurement in a superheavy nucleus whose stability is entirely derived from the shell-correction energy. The observed rotational properties are compared to those of neighboring nuclei and it is shown that the kinematic and dynamic moments of inertia are sensitive to the underlying single-particle shell structure and the specific location of high-j orbitals. The moments of inertia therefore provide a sensitive test of shell structure and pairing in superheavy nuclei which is essential to ensure the validity of contemporary nuclear models in this mass region. The data obtained show that there is no deformed shell gap at Z=104, which is predicted in a number of current self-consistent mean-field models.
Physical Review Letters 07/2012; 109(1):012501. · 7.37 Impact Factor
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R. -D. Herzberg,
S. Moon,
S. Eeckhaudt,
P. T. Greenlees,
P. A. Butler,
T. Page,
A. V. Afanasjev,
N. Amzal,
J. E. Bastin,
F. Becker, [......],
P. Reiter,
M. Sandzelius,
J. Saren,
Ch. Schlegel,
C. Scholey,
Ch. Theisen,
W. H. Trzaska,
J. Uusitalo,
A. Wiens,
H. J. Wollersheim
[show abstract]
[hide abstract]
ABSTRACT: In-beam gamma-ray and conversion electron spectroscopic studies have been performed on the 253
No nucleus. A strongly coupled rotational band has been identified and the improved statistics allows an assignment of the band
structure as built on the 9/2-[734]n\ensuremath 9/2^-[734]_{\nu} ground state. The results agree with previously known transition energies but disagree with the tentative structural assignments
made in earlier work.
European Physical Journal A 04/2012; 42(3):333-337. · 2.19 Impact Factor
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D. O'Donnell,
R. D. Page,
C. Scholey,
L. Bianco,
L. Capponi,
R. J. Carroll,
I. G. Darby,
L. Donosa,
M. Drummond,
F. Ertugral, [......],
P. Rahkila,
S. Rinta-Antila,
P. Ruotsalainen,
M. Sandzelius,
J. Saren,
B. Saygi,
J. Simpson,
J. Sorri,
A. Thornthwaite,
J. Uusitalo
[show abstract]
[hide abstract]
ABSTRACT: The neutron-deficient nucleus 173Hg has been studied following
fusion-evaporation reactions. The observation of gamma rays decaying from
excited states are reported for the first time and a tentative level scheme is
proposed. The proposed level scheme is discussed within the context of the
systematics of neighbouring neutron-deficient Hg nuclei. In addition to the
gamma-ray spectroscopy, the alpha decay of this nucleus has been measured
yielding superior precision to earlier measurements.
01/2012;
-
F. Ghazi Moradi,
T. Bäck,
B. Cederwall,
M. Sandzelius,
A. Atac,
A. Johnson,
C. Qi,
R. Liotta,
B. Hadinia,
K. Andgren, [......],
J. Sorri,
J. Uusitalo,
E. Ganioğlu,
J. Thomson,
D. T. Joss,
R. D. Page,
S. Ertürk,
J. Simpson,
M. B. Gomez Hornillos,
L. Bianco
[show abstract]
[hide abstract]
ABSTRACT: Excited states in the odd-odd neutron deficient nucleus 162Ta (Z=73, N=89) have been studied for the first time. The gamma spectroscopy analysis using γ−γ−γ coincidences revealed a strongly coupled rotational structure that was established up to large angular momentum states. The rotational band was assigned to the configuration πh11/2[514]9/2⊗νi13/2[660]1/2 based on its rotational and electromagnetic properties. The data are interpreted within the framework of total Routhian surface calculations, which suggests an axially symmetric shape with a γ-soft minimum at β2≈0.16 and γ≈6∘. The crossing of the signature partners observed in heavier (N⩾91) odd-odd nuclides in this mass region is found to be absent at N=89. This might be correlated with a change in S-band structure above the paired band crossing at these neutron numbers.
Phys. Rev. C. 12/2011; 84(6).
-
P. J. Sapple, R. D. Page, D. T. Joss, L. Bianco, T. Grahn,
J. Pakarinen,
J. Simpson and D. O’Donnell,
S. Ertürk,
P. T. Greenlees,
U. Jakobsson,
P. M. Jones,
R. Julin,
S. Juutinen,
S. Ketelhut,
M. Leino,
M. Nyman,
P. Peura,
A. Puurunen,
P. Rahkila,
P. Ruotsalainen,
J. Sarén,
C. Scholey,
J. Uusitalo
[show abstract]
[hide abstract]
ABSTRACT: Excited states have been identified in the isotones 74159W and 75160Re, which were produced in fusion-evaporation reactions of a beam of 310-MeV 58Ni ions with an isotopically enriched 106Cd target. The strongest γ-ray transitions in 159W and 160Re are interpreted as continuing the regular sequence of states identified in lighter N= 85 isotones that are built upon 9/2− and 10+ states, respectively. The half-life of 155Hf, the β-decaying daughter of the α decay of 159W, was measured with improved precision to be 840 ± 30 ms.
Phys. Rev. C. 11/2011; 84(5).
-
J. Piot,
O. Dorvaux,
B. J.-P. Gall,
P. T. Greenlees,
L. L. Andersson,
D. M. Cox,
F. Dechery, T. Grahn,
K. Hauschild,
G. Henning, [......],
J. Rubert,
P. Ruotsalainen,
M. Sandzelius,
J. Sarén,
C. Scholey,
D. Seweryniak,
J. Sorri,
B. Sulignano,
C. Theisen,
J. Uusitalo
[show abstract]
[hide abstract]
ABSTRACT: The structure of 246Fm has been investigated using in-beam
γ-ray spectroscopy. The experiment was performed at the University
of Jyväskylä using JUROGAM 2 coupled to RITU and GREAT. The
246Fm nuclei were produced using a 186 MeV beam of
40Ar impinging on a target of 208Pb. JUROGAM 2 was
fully instrumented with TNT2D digital acquisition cards. The use of
digital acquisition cards and a rotating target allowed for
unprecedented beam intensities up to 71 particle-nanoamperes for prompt
γ-ray spectroscopy. With all these major advances for spectroscopy
a rotational band is observed for the first time in 246Fm and
discussed here.
09/2011; 1377:301-305.
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R. D. Page,
A. N. Andreyev,
D. R. Wiseman,
P. A. Butler, T. Grahn,
P. T. Greenlees,
R.-D. Herzberg,
M. Huyse,
G. D. Jones,
P. M. Jones, [......],
P. Kuusiniemi,
M. Leino,
M. Muikku,
P. Nieminen,
P. Rahkila,
G. I. Rainovski,
C. Scholey,
J. Uusitalo,
K. Van de Vel,
P. Van Duppen
[show abstract]
[hide abstract]
ABSTRACT: Excited states in 180Hg were populated using the 147Sm(36Ar,3n)180Hg reaction and studied by in-beam conversion-electron spectroscopy. Conversion electrons emitted at the target position were measured using the Silicon Array for Conversion Electron Detection (SACRED) spectrometer and tagged through the characteristic α decays of 180Hg detected in a position-sensitive silicon strip detector located at the focal plane of the gas-filled recoil separator Recoil Ion Transport Unit (RITU). Electron conversion of transitions previously assigned to 180Hg through in-beam γ-ray spectroscopy studies was identified up to the 10+→8+ transition and the intensities of the conversion-electron transitions were found to be consistent with the previous multipolarity assignments. Evidence was also found for two highly converted transitions in 180Hg: a 167 keV transition is interpreted as the transition from the newly identified 22+ state at 601 keV to the 21+ state at 434 keV, while a 420 keV transition is assigned as the E0 decay from the 0+ bandhead of the prolate-deformed configuration to the weakly deformed ground state.
Phys. Rev. C. 09/2011; 84(3).
-
M. G. Procter,
D. M. Cullen,
P. Ruotsalainen,
T. Braunroth,
A. Dewald,
C. Fransen, T. Grahn,
P. T. Greenlees,
M. Hackstein,
K. Hauschild, [......],
W. Rother,
M. Sandzelius,
J. Sarén,
C. Scholey,
J. Sorri,
M. J. Taylor,
J. Uusitalo,
A. Vitturi,
Y. Shi,
F. R. Xu
[show abstract]
[hide abstract]
ABSTRACT: Lifetime measurements have been made in the ground-state band of the transitional nucleus 138Gd from coincidence recoil-distance Doppler-shift data. 138Gd nuclei were produced using the 106Cd (36Ar, 2p2n) reaction with a beam energy of 190 MeV. Reduced transition probabilities have been extracted from the lifetime data collected with the Köln plunger placed at the target position of the JUROGAM-II array. The B(E2) values have been compared with predictions from X(5) critical-point calculations, which describe the phase transition between vibrational and axially symmetric nuclear shapes, as well as with IBM-1 calculations at the critical point. While the excitation energies in 138Gd are consistent with X(5) predictions, the large uncertainties associated with the measured B(E2) values cannot preclude vibrational and rotational contributions to the low-lying structure of 138Gd. Although experimental knowledge for the low-lying γ and β-vibrational bands in 138Gd is limited, potential-energy surface calculations suggest an increase in γ softness in the ground-state band. In order to more fully account for the effects of γ softness, the X(5) and IBM-1 calculations need to be extended to include the γ degree of freedom for 138Gd.
Phys. Rev. C. 08/2011; 84(2).
-
I. G. Darby,
R. D. Page, D. T. Joss, L. Bianco, T. Grahn,
J. Simpson,
M. Nyman, P. Rahkila, J. Sarén, C. Scholey, A. N. Steer,
and M. Venhart J. Uusitalo,
S. Ertürk,
B. Gall,
B. Hadinia
[show abstract]
[hide abstract]
ABSTRACT: The decays of the πd3/2 ground states of 156Ta and 160Re have been studied in detail using the GREAT spectrometer. More than 7000 160Re nuclei were produced in reactions of 290- and 300-MeV 58Ni ions with an isotopically enriched 106Cd target and separated in flight using the RITU separator. The proton and α decays of the πd3/2 level were confirmed and the half-life and branching ratios of this state were determined with improved precision to be t1/2=611±7 μs and bp=89±1% and bα=11±1%, respectively. The α-decay branch populated the ground state of 156Ta, allowing improved values for the proton-decay energy and half-life to be obtained (Ep=1011±5 keV; t1/2=106±4 ms). The β decay of this level was identified for the first time and a branching ratio of bβ=29±3% was deduced. The spectroscopic factors deduced from these measurements are compared with predictions.
Phys. Rev. C. 06/2011; 83(6).
-
M. Scheck,
P. A. Butler,
L. P. Gaffney,
N. Bree,
R. J. Carrol,
D. Cox, T. Grahn,
P. T. Greenlees,
K. Hauschild,
A. Herzan, [......],
S. Rinta-Antila,
P. Ruotsalainen,
M. Sandzelius,
J. Saren,
C. Scholey,
J. Sorri,
J. Srebrny,
P. Van Duppen,
H. V. Watkins,
J. Uusitalo
[show abstract]
[hide abstract]
ABSTRACT: By exploiting the SAGE spectrometer a simultaneous measurement of conversion electrons and γ rays emitted in the de-excitation of excited levels in the neutron-deficient nuclei 184,186Hg was performed. The light Hg isotopes under investigation were produced using the 4n channels of the fusion-evaporation reactions of 40Ar and 148,150Sm. The measured K- and L-conversion electron ratios confirmed the stretched E2 nature of several transitions of the yrast bands in 184,186Hg. Additional information on the E0 component of the 22+→21+ transition in 186Hg was obtained.
Phys. Rev. C. 03/2011; 83(3).
-
D. M. Cullen,
P. J. R Mason,
C. Scholey,
S. Eeckhaudt, T. Grahn,
P. T. Greenlees,
U. Jakobsson,
P. M. Jones,
R. Julin,
S. Juutinen, [......],
J. Pakarinen,
P. Peura,
M. G. Procter,
P. Rahkila,
S. V. Rigby,
J. Sarén,
J. Sorri,
J. Uusitalo,
B. J. Varley,
M. Venhart
[show abstract]
[hide abstract]
ABSTRACT: Recoil-isomer tagging with the 54Fe+92Mo reaction was used to establish a 10(2)-μs isomeric state in 139Eu. Prompt versus delayed γ-ray coincidence data have revealed the presence of a prompt rotational band built upon the isomer. The alignment properties of the states in this band show that the isomer is based upon a proton g7/2 configuration. The decay of the isomer takes place through a single 26-keV E1 transition. The γ-ray transition strength for this decay is consistent with those established in the neighboring isomeric gamma-soft nuclei. In these nuclei, isomers are expected to form as a consequence of differences in nuclear shapes or configurations, and the natural hindrance associated with configuration-changing E1 transitions. The isomeric nature of the state in 139Eu is reasoned to be because of difference in shape of the proton g7/2 state and the proton h11/2 ground state to which it decays.
Phys. Rev. C. 01/2011; 83(1).
-
K. Lagergren,
D. T. Joss,
E. S. Paul,
B. Cederwall,
J. Simpson,
D. E. Appelbe,
C. J. Barton,
S. Eeckhaudt, T. Grahn,
P. T. Greenlees, [......],
P. Nieminen,
R. D. Page,
J. Pakarinen,
J. Perkowski,
P. Rahkila,
C. Scholey,
J. Uusitalo,
D. D. Warner,
D. R. Wiseman,
R. Wyss
[show abstract]
[hide abstract]
ABSTRACT: Excited states in the neutron-deficient odd-Z nuclide 161Ta were identified for the first time using the 106Cd(58Ni,3pγ) reaction at a beam energy of 270 MeV. The πh11/2 band, yrast at low spin, was observed up to (47/2-) and a further four strongly coupled bands have been established to high spin. Quasiparticle configuration assignments for the new band structures have been made on the basis of cranked shell model calculations. This work suggests that the negative-parity ν(f7/2,h9/2) orbitals are responsible for the first rotational alignment in the πh11/2 band.
Phys. Rev. C. 01/2011; 83(1).
-
K Lagergren,
D T Joss,
E S Paul,
B Cederwall,
J Simpson,
D E Appelbe,
C J Barton,
S Eeckhaudt, T Grahn,
P T Greenlees, [......],
P Nieminen,
R D Page,
J Pakarinen,
J Perkowski,
P Rahkila,
C Scholey,
J Uusitalo,
D D Warner,
D R Wiseman,
R Wyss
Phys.Rev. C. 01/2011; 83:014313.
