  The IsoDAR sterile-neutrino search requires a very high intensity neutrino
source. For IsoDAR, this high intensity is produced using the high neutron flux
from a 60 MeV, 10 mA proton beam striking a beryllium target that floods a
sleeve of highly-enriched Li-7. Through neutron capture the Li-7 is transmuted
to Li-8, which beta-decays giving the desired high neutrino flux for very-short
baseline neutrino experiments. The target can be placed very close to can
existing large neutrino detector, which is typically located deep underground
to reduce backgrounds. With such a setup, it is necessary to design a shielding
enclosure for the target to prevent neutrons from causing unacceptable
activation of the rock walls close to the target. Various materials have been
studied including steel to thermalize the high energy neutrons and two new
types of concrete developed by Jefferson Laboratory, one very light with
shredded plastic aggregate, and the other one enriched with high quantities of
boron. The shielding is asymmetrical, having a larger thickness towards the
detector in order to suppress the neutron and gamma background in the neutrino
detector. Simulation results for rock activation and for detector backgrounds
are presented.
