It took 250 days to make enough berkelium, shown here (in dissolved state), to synthesize element 117.
ORNL, Department of Energy
between circa 2009 and circa 2010 <div style="display: none;">date QS:P,+2050-00-00T00:00:00Z/7,P1319,+2009-00-00T00:00:00Z/9,P1326,+2010-00-00T00:00:00Z/9,P1480,Q5727902</div>
<a rel="nofollow" class="external free" href="http://www.sciencemag.org/news/2010/04/finally-element-117-here">http://www.sciencemag.org/news/2010/04/finally-element-117-here</a>