  In this review we will present the results of recent beta-decay studies using
the total absorption technique that cover topics of interest for applications,
nuclear structure and astrophysics. The decays studied were selected primarily
because they have a large impact on the prediction of a) the decay heat in
reactors, important for the safety of present and future reactors and b) the
reactor electron antineutrino spectrum, of interest for particle/nuclear
physics and reactor monitoring. For these studies the total absorption
technique was chosen, since it is the only method that allows one to obtain
beta decay probabilities free from a systematic error called the Pandemonium
effect. The measurements presented and discussed here were performed mainly at
the IGISOL facility of the University of Jyvaskyla (Finland) using isotopically
pure beams provided by the JYFLTRAP Penning trap. Examples are presented to
show that the results of our measurements on selected nuclei have had a large
impact on predictions of both the decay heat and the anti-neutrino spectrum
from reactors. Some of the cases involve beta delayed neutron emission thus one
can study the competition between gamma- and neutron-emission from states above
the neutron separation energy. The gamma-to-neutron emission ratios can be used
to constrain neutron capture (n,gamma)cross sections for unstable nuclei of
interest in astrophysics. The information obtained from the measurements can
also be used to test nuclear model predictions of half-lives and Pn values for
decays of interest in astrophysical network calculations. These comparisons
also provide insights into aspects of nuclear structure in particular regions
of the nuclear chart.
