A long-wavelength ( approximately 10- mu m) quantum-well (QW) infrared detector with normal incident detection was fabricated using p-type Si1-xGex/Si multiple QWs. Photocurrent is measured as a function of the incident beam polarization. With a beam polarized parallel to the growth plane (90 degrees polarization, normal incidence), a photocurrent peak is observed at near 7.2 mu m with a full width at half maximum (FWHM) of about 80 meV. On the other hand, when the beam is polarized along the growth direction (0 degrees polarization), a peak is observed at near 8.6 mu m with FWHM of about 80 meV. With the non-optimized detector, the peak photoresponsivity of 0.3 A/W and detectivity of D∗ approximately 1.0 109cm square root Hz/W at 77 K are obtained for both polarizations. The results of normal incident detection demonstrate the feasibility of Si-based long-wavelength IR detectors and focal plane arrays with the advantage of monolithic integration with Si integrated circuits.