  DaRveX stands for "Decay at Rest $\nu_e$-Pb cross (X) section measurement".
So far, there has not been good target to detect low energy $\nu_e$. Lead is
expected to be an excellent $\nu_e$ target because the cross section is
expected to be very large and the delayed coincidence technique can be used
using final state neutron(s). However, the cross section have not been measured
yet. If it is measured, it opens a new window to the future neutrino research
field, such as low energy $\nu_e$ oscillation measurements, flavor specific
detection of the supernova explosion $\nu_e$ and understanding of
$\nu_e$-nucleus interactions. This report explains a conceptual design of
DaRveX experiment, which measures cross section of $\nu_e$+Pb charged current
interaction, $\nu_e$(E~30MeV)+Pb $\to$ $e^-$+$xn$+Bi; ($x$=1 or 2), using
$\nu_e$ from $\mu^+$ decay at rest at J-PARC MLF. The energy and direction of
the final state $e^-$ will be measured by using 1-ton scale lead-scintillator
sandwich detector. With two years of data taking, the cross section is expected
to be measured with 20% of precision.
