Abstract
The structure of the
11
/
2
1
+
state in
131
Sb was investigated at the LOHENGRIN spectrometer of Institut Laue-Langevin via neutron-induced fission of
235
U and lifetime measurements, ...yielding
T
1
/
2
=
3
(
2
)
, at the edge of the sensitivity of the experimental method. This first result for the
11
/
2
1
+
state half-life in neutron-rich Sb isotopes provides a quadrupole reduced transition probability to the ground state of
B
(
E
2
)
=
1.4
−
0.6
+
1.5
W.u., very close to the
B
(
E
2
;
2
1
+
→
0
1
+
)
in
130
Sn. Realistic shell-model calculations reproduce well both the experimental level scheme of
131
Sb and the
B
(
E
2
;
11
/
2
1
+
→
7
/
2
1
+
)
value, indicting a dominant
2
+
(
130
Sn
)
⊗
π
g
7
/
2
core-proton coupled configuration for the
11
/
2
1
+
state.
Lifetime measurements in 131Sb at LOHENGRIN Bottoni, S.; Gamba, E. R.; De Gregorio, G. ...
Journal of physics. Conference series,
09/2023, Letnik:
2586, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The neutron-rich 131Sb nucleus was studied at Institut Laue-Langevin, with the LOHENGRIN spectrometer, via neutron-induced fission of 235U and lifetime measurements using LaBr3(Ce) detectors. The ...lifetimes of the 11/21+ and 19/21+ states were measured with the generalized centroid difference and the decay slope methods, yielding T½=3(2) ps and T½=1347(171) ps, respectively. The measured value for the 11/21+ is at the limit of the fast-timing technique. The level scheme of 131Sb and the decay properties of the 11/21+ state were described by realistic shell-model calculations, which reproduce well both the experimental spin and energy sequences of 131Sb and the measured B(E2; 11/21+→7/21+) value, pointing to an almost pure 2+(130Sn) ⊗ πg7/2, core-proton coupled configuration for the 11/21+ state.
Lifetime of the ( 15 2 1 − ) state in 135Te Simpson, G; Regis, J M; Bettermann, L ...
Journal of physics. G, Nuclear and particle physics,
05/2019, Letnik:
46, Številka:
6
Journal Article
Recenzirano
The lifetime of the ( 15 2 1 − ) state of 135Te has been measured to be τ = 809(22) ps, corresponding to a reduced transition rate of B ( E 2 ; 15 2 1 − → 11 2 1 − ) =6.6(2) W.u. The experiment was ...performed at the focal point of the Lohengrin spectrometer and s-delayed γ rays from mass-selected A = 135 ions were detected by four LaBr3(Ce) scintillators. This allowed the fast-timing technique to be used to access lifetimes in the 10s-of-ps to ns time region. The B ( E 2 ; 15 2 1 − → 11 2 1 − ) value is typical of a vibrational transition, despite 135Te possessing only one valence neutron and two valence protons. Shell model calculations performed with the jj 56 pnb state-of-the-art effective interaction predict a B(E2) value close to the experimental one and show that contributions from the π(g7/2, d5/2) f7/2 couplings are coherent.
We report on the first measurement of the half-lives of Kπ=11− and 12+ four-quasiparticle states in the even-even nucleus 178W. The sub-nanosecond half-lives were measured by applying the centroid ...shift method to data taken with LaBr3(Ce) scintillator detectors of the NuBall array at the ALTO facility in Orsay, France. The half-lives of these states only became experimentally accessible by the combination of several experimental techniques - scintillator fast timing, isomer spectroscopy with a pulsed beam, and the event-by-event calorimetry information provided by the NuBall array. The measured half-lives are 476(44)ps and 275(65)ps for the Iπ=11− and 12+ states, respectively. The decay transitions include weakly hindered E1 and E2 branches directly to the ground-state band, bypassing the two-quasiparticle states. This is the first such observation for an E1 transition. The interpretation of the small hindrance hinges on mixing between the ground-state band and the t-band.
The neutron-rich nuclei 94,96Kr were studied via projectile Coulomb excitation at the REX-ISOLDE facility at CERN. Level energies of the first excited 2(+) states and their absolute E2 transition ...strengths to the ground state are determined and discussed in the context of the E(2(1)(+)) and B(E2;2(1)(+)→0(1)(+)) systematics of the krypton chain. Contrary to previously published results no sudden onset of deformation is observed. This experimental result is supported by a new proton-neutron interacting boson model calculation based on the constrained Hartree-Fock-Bogoliubov approach using the microscopic Gogny-D1M energy density functional.
We present the results from an experiment dedicated to measure the lifetime of the
2
2
+
state, candidate for the one-phonon mixed-symmetry state, of
208
Po. This nucleus was studied in the
α
...-transfer reaction
204
Pb(
12
C,
8
Be)
208
Po and the lifetime of the
2
2
+
state was determined by utilizing the Doppler-shift attenuation method. The experimental data show that the
2
2
+
state decays with a sizable
M
1 transition to the
2
1
+
state revealing its isovector nature.
The B(E2) excitation strength of the first excited 2(+) state in even-even nuclei should directly correlate with the size of the valence space and maximize at mid-shell. A previously found saturation ...of B(E2) strengths in well-deformed rotors at mid-shell is tested through high-precision measurements of the lifetimes of the lowest-lying 2(+) states of the Hf-168 and W-174 rare earth isotopes. Measurements were performed using fast LaBr3 scintillation detectors. Combined with the recently remeasured B(E2; 2(1)(+) -> 0(1)(+)) values for Hf and W isotopes the new data remove discrepancies observed in the differentials of B(E2) values for these isotopes.
Neutron-rich Ba isotopes are expected to exhibit octupolar correlations, reaching their maximum in isotopes around mass A = 146. The odd-A neutron-rich members of this isotopic chain show typical ...patterns related to non-axially symmetric shapes, which are however less marked compared to even-A ones, pointing to a major contribution from vibrations. In the present paper we present results from a recent study focused on 148-150Cs β-decay performed at the ISOLDE Decay Station equipped with fast-timing detectors. A detailed analysis of the measured decay half-lives and decay scheme of 149Ba is presented, giving a first insight in the structure of this neutron-rich nucleus.
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