[Triumf-seminars] TRIUMF ISAC Seminar today at 12:15

postmaster@admin.triumf.ca postmaster@admin.triumf.ca
Wed, 3 Dec 2003 05:00:01 -0800


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Date/Time: Wed 2003-12-03 at 12:15

Location:  Auditorium          

Speaker:   Christof Vockenhuber (University of Vienna)

Title:     182Hf, from the early Solar System to a possibly live supernova remnant on Earth.

Abstract: The presence of the now extinct radioisotope 182Hf (t1/2 = 9+/-2 Myrs) in the early Solar System is well established through isotopic anomalies of the stable daughter 182W. The high abundance of this neutron-rich hafnium isotope is the basis of the 182Hf-182W geochronometer, which offers an excellent way to determine the time scale of formation of objects in the early Solar System. However, both the understanding of the early Solar System abundance in terms of astrophysical models and the absolute time scale derived from the geochronometer were suffering from an imprecise knowledge of the half-life. For the first time after the discovery of 182Hf 40 years ago, we re-measured the half-life of 182Hf with high precision using two independent methods.
In addition, 182Hf may also complement a few other radionuclides in the million-year half-life range to trace relatively recent stellar events with high neutron fluxes in the vicinity of the Earth. This may be accomplished by finding minute traces of live 182Hf in suitable terrestial archives using Accelerator Mass Spectrometry. Here the big challenge is to find only a few 182Hf atoms out of gram size materials which requires sophisticated detection methods, particularly for the separation of the other hafnium isotopes and the stable isobar 182W.

Bring your lunch.

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