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Author  |
PreSPEC and AGATA Collaborations (Ralet, D. et al); Domingo-Pardo, C.; Gadea, A.; Huyuk, T. |
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Title |
Lifetime measurement of neutron-rich even-even molybdenum isotopes |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physical Review C |
Abbreviated Journal |
Phys. Rev. C |
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Volume |
95 |
Issue |
3 |
Pages |
034320 - 11pp |
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Abstract |
Background: In the neutron-rich A approximate to 100 mass region, rapid shape changes as a function of nucleon number as well as coexistence of prolate, oblate, and triaxial shapes are predicted by various theoretical models. Lifetime measurements of excited levels in the molybdenum isotopes allow the determination of transitional quadrupole moments, which in turn provides structural information regarding the predicted shape change. Purpose: The present paper reports on the experimental setup, the method that allowed one to measure the lifetimes of excited states in even-even molybdenum isotopes from mass A = 100 up to mass A = 108, and the results that were obtained. Method: The isotopes of interest were populated by secondary knock-out reaction of neutron-rich nuclei separated and identified by the GSI fragment separator at relativistic beam energies and detected by the sensitive PreSPEC-AGATA experimental setup. The latter included the Lund-York-Cologne calorimeter for identification, tracking, and velocity measurement of ejectiles, and AGATA, an array of position sensitive segmented HPGe detectors, used to determine the interaction positions of the gamma ray enabling a precise Doppler correction. The lifetimes were determined with a relativistic version of the Doppler-shift-attenuation method using the systematic shift of the energy after Doppler correction of a gamma-ray transition with a known energy. This relativistic Doppler-shift-attenuation method allowed the determination of mean lifetimes from 2 to 250 ps. Results: Even-even molybdenum isotopes from mass A = 100 to A = 108 were studied. The decays of the low-lying states in the ground-state band were observed. In particular, two mean lifetimes were measured for the first time: tau = 29.7(-9.1)(+11.3) ps for the 4(+) state of Mo-108 and tau = 3.2(-0.7)(+ 0.7) ps for the 6(+) state of Mo-102. Conclusions: The reduced transition strengths B(E2), calculated from lifetimes measured in this experiment, compared to beyond-mean-field calculations, indicate a gradual shape transition in the chain of molybdenum isotopes when going from A = 100 to A = 108 with a maximum reached at N = 64. The transition probabilities decrease for Mo-108 which may be related to its well-pronounced triaxial shape indicated by the calculations. |
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Address |
[Ralet, D.; Cortes, M. L.; Gregor, E.; Guastalla, G.; Givechev, A.; Habermann, T.; Louchart-Henning, C.; Merchan, E.; Pietralla, N.; Reese, M.; Singh, P. P.; Stahl, C.] Tech Univ Darmstadt, Inst Kernphys, D-64289 Darmstadt, Germany, Email: ralet@csnsm.in2p3.fr |
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Publisher |
Amer Physical Soc |
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Language |
English |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9985 |
ISBN |
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Expedition |
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Conference |
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Notes |
WOS:000399143200002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3045 |
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Author |
PreSPEC and AGATA Collaborations (Ralet, D. et al); Gadea, A. |
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Title |
Data-flow coupling and data-acquisition triggers for the PreSPEC-AGATA campaign at GSI |
Type |
Journal Article |
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Year |
2015 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
786 |
Issue |
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Pages |
32-39 |
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Keywords |
AGATA; PreSPEC; MBS; NARVAL; DAQ; Trigger |
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Abstract |
The PreSPEC setup for high-resolution 'gamma-ray spectroscopy using radioactive ion beams was employed for experimental campaigns in 2012 and 2014. The setup consisted of the state of the art Advanced GAmma Tracking Array (AGATA) and the High Energy gamma cleteCTOR (HECTOR+) positioned around a secondary target at the final focal plane of the GSI FRagment Separator (FRS) to perform in-beam gamma-ray spectroscopy of exotic nuclei. The Lund York Cologne CAlorimeter (LYCCA) was used to identify the reaction products. In this paper we report on the trigger scheme used during the campaigns. The dataflow coupling between the Multi-Branch System (MBS) based Data AcQuisition (DAQ) used for FRS-LYCCA and the “Nouvelle Acquisition temps Reel Version 1.2 Avec Linux” (NARVAL) based acquisition system used for AGATA are also described. |
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Address |
[Ralet, D.; Pietralla, N.] Tech Univ Darmstadt, Inst Kernphys, Darmstadt, Germany, Email: D.Ralet@gsi.de |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Medium |
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Area |
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Conference |
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Notes |
WOS:000353068600006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
2203 |
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