Advances at TRIUMF-ISAC and decay of neutron-rich Cd studied with GRIFFIN

¹ Department of Physics, University of Guelph, Guelph, ON N1G2W1 Canada
² Department of Physics and Astronomy, University of the Western Cape, Belleville 7441, South Africa
³ TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T 2A3, Canada
⁴ Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T1Z4, Canada
⁵ Instituto de Estructura de la Materia, CSIC, E-28006 Madrid, Spain
⁶ Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A1S6, Canada
⁷ Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom
⁸ Department of Physics, Colorado School of Mines, Golden, Colorado 80401, USA
⁹ Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
¹⁰ Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares, AP 70-543, México City 04510, DF, México
¹¹ Centre de Sciences Nucléaires et Sciences de la Matière, CNRS/IN2P3, Université Paris-Saclay, 91405 Orsay, France
¹² Department of Physics, Florida State University, Tallahassee, Florida 32306, USA

^* e-mail: pgarrett@physics.uoguelph.ca

Published online: 14 November 2018

Abstract

The β-decay half lives of nuclei near the r-process path are critical information required for abundance calculations, especially those near neutron number N = 82. Specifically, the nuclei below doubly-magic ¹³²Sn are key, and play an important role in the formation and shape of the second r-process abundance peak. The half lives in this region are challenging to measure due to the significant β-delayed neutron decay branches and the population of isomeric states with half lives comparable to the ground states. However, by measuring the time distribution of γ rays, these complications can be eliminated. This requires, however, a very effcient γ-ray spectrometer since the production of isotopes in this region is very limited. The new GRIFFIN array at TRIUMF-ISAC provides the high effciency required for these measurements. Recent improvements in the quality of the beams produced at TRIUMF, employing the IG-LIS device, are outlined, as well as the current status of the ARIEL facility. The GRIFFIN spectrometer and its use are briefly described. The experiment to measure the half lives of ^128-130Cd is outlined and the results given, and some examples of the power of GRIFFIN to expand decay schemes, specifically for the decay of ¹²⁸Cd to ¹²⁸In, are given.