  We report the first observation of protons in the near (100--200 km from
surface) and deeper (near anti-subsolar point) lunar plasma wake when the
interplanetary magnetic field (IMF) and solar wind velocity ($v_{sw}$) are
parallel (aligned flow, angle between IMF and ($v_{sw} \le 10^\circ$). More
than 98% of the observations during aligned flow condition showed the presence
of protons in the wake. These observations are obtained by the SWIM sensor of
the SARA experiment on Chandrayaan-1. The observation cannot be explained by
the conventional fluid models for aligned flow. Back-tracing of the observed
protons suggests that their source is the solar wind. The larger gyro-radii of
the wake protons compared to that of solar wind suggest that they were part of
the tail of the solar wind velocity distribution function. Such protons could
enter the wake due to their large gyro-radii even when the flow is aligned to
IMF. However, the wake boundary electric field may also play a role in the
entry of the protons in to the wake.
