Lifetime measurement of neutron-rich even-even molybdenum isotopes

Research output: Contribution to journalArticle

Abstract

Background: In the neutron-rich A≈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 γ 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 γ-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: τ=29.7-9.1+11.3 ps for the 4+ state of Mo108 and τ=3.2-0.7+0.7 ps for the 6+ state of Mo102. 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 Mo108 which may be related to its well-pronounced triaxial shape indicated by the calculations.

Details

Authors
  • D. Ralet
  • S. Pietri
  • T. Rodríguez
  • M. Alaqeel
  • T. Alexander
  • N Alkhomashi
  • F. Ameil
  • T. Arici
  • A. Ataç
  • R. Avigo
  • Torbjörn Bäck
  • D Bazzacco
  • B. Birkenbach
  • P. Boutachkov
  • B. Bruyneel
  • A. M. Bruce
  • F. Camera
  • B. Cederwall
  • S. Ceruti
  • E. Clément
  • M.L. Cortes
  • D. Curien
  • G de Angelis
  • P. Désesquelles
  • M. Dewald
  • F. Didierjean
  • C. Domingo-Pardo
  • M. Doncel
  • G. Duchêne
  • J Eberth
  • A Gadea
  • J Gerl
  • F. Ghazi Moradi
  • H. Geissel
  • T. Goigoux
  • N. Goel
  • P. Golubev
  • V. González
  • M Górska
  • A. Gottardo
  • E. Gregor
  • G. Guastalla
  • A. Givechev
  • T. Habermann
  • M. Hackstein
  • L. Harkness-Brennan
  • G. Henning
  • Natasa Lalovic
  • D. Rudolph
  • L. G. Sarmiento
  • (PreSPEC and AGATA Collaborations)
Organisations
External organisations
  • Autonomous University of Madrid
  • Imam Muhammad ibn Saud Islamic University
  • King Abdulaziz City for Science and Technology
  • Justus Liebig University Giessen
  • KTH Royal Institute of Technology
  • Ankara University
  • University of Brighton
  • GANIL Grand Accelerateur National d'Ions Lourds
  • INFN Laboratori Nazionali di Legnaro
  • Technical University of Darmstadt
  • GSI Helmholtz Centre for Heavy Ion Research
  • University of Paris-Saclay
  • University of Surrey
  • INFN Section of Milano
  • INFN Section of Padova
  • University of Cologne
  • Institut de Recherche sur les Lois Fondamentales de l'Univers
  • University of Strasbourg
  • University of Valencia
  • University of Liverpool
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Subatomic Physics

Keywords

  • gamma-ray spectroscopy, relativistic projectile fragmentation, secondary fragmentation
Original languageEnglish
Article number034320
Number of pages11
Journal Physical Review C: covering nuclear physics
Volume95
Issue number3
Publication statusPublished - 2017 Mar 27
Publication categoryResearch
Peer-reviewedYes

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Related research output

Ralet, D., Pietri, S., Aubert, Y., Bellato, M., Bortolato, D., Brambilla, S., Camera, F., Dosme, N., Gadea, A., Gerl, J., Golubev, P., Grave, X., Johansson, H. T., Karkour, N., Korichi, A., Kurz, N., Lafay, X., Legay, E., Linget, D., Pietralla, N. & 5 othersDirk Rudolph, Schaffner, H., Stezowski, O., Travers, B. & Wieland, O., 2015, In : Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. 786, p. 32-39 8 p.

Research output: Contribution to journalArticle

Golubev, P., Wendt, A., Scruton, L., Taprogge, J., Rudolph, D., Reiter, P., Bentley, M. A., Avdeichikov, V., Boutachkov, P., Fox, S. P., Gerl, J., Goergen, C., Hoischen, R., Kurz, N., Singh, B. S. N., Pascovici, G., Pietri, S., Schaffner, H., Taylor, M. J., Thiel, S. & 1 othersWollersheim, H. J., 2013, In : Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. 723, p. 55-66

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Related projects

Dirk Rudolph, Pavel Golubev & Luis Sarmiento Pico

Crafoord Foundation, Swedish Research Council, Kungliga Fysiografiska Sällskapet i Lund

2010/03/122030/12/31

Project: Research

Dirk Rudolph, Claes Fahlander, Pavel Golubev, Luis Sarmiento Pico, Anton Såmark-Roth, Daniel Cox, Ulrika Forsberg, Christian Lorenz, Natasa Lalovic, Natasa Lalovic, Ulrika Forsberg, Jnaneswari Gellanki, Robert Hoischen, Emma Johansson, Lise-Lotte Andersson, Rickard du Rietz, Jörgen Ekman & Corina Andreoiu

Kungliga Fysiografiska Sällskapet i Lund, Swedish Research Council

2002/01/012021/12/31

Project: Research

View all (2)

Related activities

Rudolph, D. (Chair)
20122014

Activity: Consultancy, expert advice and membershipsMember of board/committee/council etc

Rudolph, D. (Member)
20092015

Activity: Consultancy, expert advice and membershipsMember of board/committee/council etc

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