John A Simpson Lectures

The John A. Simpson Lectures honor the late University of Chicago physicist, John Alexander Simpson.  Simpson Lecturers are scientists who have achieved distinction in fields within the physical sciences.

Learn more about John A. Simpson

october 30, 2018 at 4pm
PHysics research center, room 201
933 east 56th Street
chicago IL 60637

2018-2019 John A. Simpson Lecture
What Rare Isotopes and Rare Elements Tell Us About the Origin of Cosmic Rays
Martin H. Israel, Washington University, St. Louis

The Cosmic Ray Isotope Spectrometer (CRIS) on the ACE spacecraft uses instrumentation pioneered by John Simpson.  The long working life of this instrument, now over 21 years, has enabled identification of extremely rare components of the cosmic rays, notably 60Fe.  The short half-life of this isotope, just 2.6 million years, points to cosmic rays originating from relatively recent and nearby supernovae.  Measurements of the rare elements with atomic number Z > 30, both with CRIS and with a large instrument (SuperTIGER) on high-altitude balloon flights give further constraints on where in our Galaxy cosmic rays are accelerated.

event poster