Fusion should unleash a burst of neutrons, but Taleyarkhan detected only a few the last time around. Now, thanks to a better detector, he has measured an enormous neutron signal. Crum acknowledges the improvement, but remains skeptical: The neutrons used to start the reaction could be confused for the fusion products. Others are trying to reproduce the results, using laser stimulation to create the bubbles. Until then, most experts say they're not buying it.