Structure of neutron-rich nuclei around the N = 126 closed shell; the yrast structure of 205Au126 up to spin-parity = (19/2+)

Zs. Podolyák; S. J. Steer; S. Pietri; M. Górska; P. H. Regan; D. Rudolph; A. B. Garnsworthy; R. Hoischen; J. Gerl; H. J. Wollersheim; H. Grawe; K. H. Maier; F. Becker; P. Bednarczyk; L. Cáceres; P. Doornenbal; H. Geissel; J. Grebosz; A. Kelic; I. Kojouharov; N. Kurz; F. Montes; W. Prokopowicz; T. Saito; H. Schaffner; S. Tashenov; A. Heinz; T. Kurtukian-Nieto; G. Benzoni; M. Pfützner; A. Jungclaus; D. L. Balabanski; C. Brandau; B. A. Brown; A. M. Bruce; W. N. Catford; I. J. Cullen; Zs. Dombrádi; M. E. Estevez; W. Gelletly; G. Ilie; J. Jolie; G. A. Jones; M. Kmiecik; F. G. Kondev; R. Krücken; S. Lalkovski; Z. Liu; A. Maj; S. Myalski; S. Schwertel; T. Shizuma; P. M. Walker; E. Werner-Malento; O. Wieland

doi:10.1140/epja/i2009-10794-5

2023 Impact factor 2.6

Hadrons and Nuclei

Eur. Phys. J. A (2009) 42: 489-493
https://doi.org/10.1140/epja/i2009-10794-5

Regular Article - Experimental Physics

Structure of neutron-rich nuclei around the N = 126 closed shell; the yrast structure of ²⁰⁵Au₁₂₆ up to spin-parity $I^{\pi}$ = (19/2⁺)

Zs. Podolyák¹^*, S. J. Steer¹, S. Pietri¹, M. Górska², P. H. Regan¹, D. Rudolph³, A. B. Garnsworthy¹^,4, R. Hoischen³, J. Gerl², H. J. Wollersheim², H. Grawe², K. H. Maier⁵^,6, F. Becker², P. Bednarczyk²^,5, L. Cáceres²^,7, P. Doornenbal²^,8, H. Geissel², J. Grebosz²^,5, A. Kelic², I. Kojouharov², N. Kurz², F. Montes², W. Prokopowicz², T. Saito², H. Schaffner², S. Tashenov², A. Heinz⁴, T. Kurtukian-Nieto⁹, G. Benzoni¹⁰, M. Pfützner¹¹, A. Jungclaus⁷, D. L. Balabanski¹², C. Brandau¹, B. A. Brown¹³^,1, A. M. Bruce¹⁴, W. N. Catford¹, I. J. Cullen¹, Zs. Dombrádi¹⁵, M. E. Estevez¹⁶, W. Gelletly¹, G. Ilie⁸, J. Jolie⁸, G. A. Jones¹, M. Kmiecik⁵, F. G. Kondev¹⁷, R. Krücken¹⁸, S. Lalkovski¹⁴, Z. Liu¹, A. Maj⁵, S. Myalski⁵, S. Schwertel¹⁸, T. Shizuma¹^,19, P. M. Walker¹, E. Werner-Malento² and O. Wieland¹⁰

¹ Department of Physics, University of Surrey, GU2 7XH, Guildford, UK
² GSI, Planckstrasse 1, D-64291, Darmstadt, Germany
³ Department of Physics, Lund University, S-22100, Lund, Sweden
⁴ WNSL, Yale University, 272 Whitney Avenue, 06520, New Haven, CT, USA
⁵ The Institute of Nuclear Physics, PL-31-342, Kraków, Poland
⁶ Department of Physics, University of the West of Scotland, PA1 2BE, Paisley, Scotland
⁷ Departmento de Fisica Teórica, Universidad Autonoma de Madrid, Madrid, Spain
⁸ IKP, Universität zu Köln, D-50937, Köln, Germany
⁹ Universidad de Santiago de Compostela, Santiago de Campostela, Spain
¹⁰ INFN, Università degli Studi di Milano, I-20133, Milano, Italy
¹¹ IEP, Warsaw University, Hoża 69, PL-00-681, Warsaw, Poland
¹² INRNE, Bulgarian Academy of Sciences, BG-1784, Sofia, Bulgaria
¹³ NSCL, Michigan State University, 48824-1321, East Lansing, MI, USA
¹⁴ School of Environment and Technology, University of Brighton, BN2 4GJ, Brighton, UK
¹⁵ Institute for Nuclear Research, H-4001, Debrecen, Hungary
¹⁶ Instituto de Fisica Corpuscular, Valencia, Spain
¹⁷ Nuclear Engineering Division, Argonne National Laboratory, 60439, Argonne, IL, USA
¹⁸ Physik Department E12, Technische Universität München, Garching, Germany
¹⁹ Japan Atomic Energy Agency, 619-0215, Kyoto, Japan

^* e-mail: Z.Podolyak@surrey.ac.uk

Received: 31 December 2008
Revised: 1 April 2009
Accepted: 9 April 2009
Published online: 17 May 2009

Abstract

Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a $\ensuremath ^{208}_{\ 82}{\rm Pb}$ beam at $\ensuremath E/A = 1$ GeV on a $\ensuremath 2.5 {\rm g/cm^2}$ 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 $\ensuremath \sim 8$ mm thick perspex stopper, positioned at the centre of the RISING $\ensuremath \gamma$ -ray detector spectrometer array. A previously unreported isomer with a half-life $\ensuremath T_{1/2} = 163(5)$ ns has been observed in the N = 126 closed-shell nucleus $\ensuremath ^{205}_{\ 79}{\rm Au}$ . Through $\gamma$ -ray singles and $\gamma$ - $\gamma$ 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 $\ensuremath I^{\pi} = (19/2^+)$ .