ALMA [CII] 158 [mu]m Detection of a Redshift 7 Lensed Galaxy behind RX J1347.1?1145

We present the results of ALMA spectroscopic follow-up of a z= 6.766 Ly[alpha] emitting galaxy behind the cluster RX J1347.1?1145. We report the detection of [Cii] 158 [mu] m line fully consistent with the Ly[alpha] redshift and with the peak of the optical emission. Given the magnification of [mu]= 5.0 + or - 0.3, the intrinsic (corrected for lensing) luminosity of the [CII] line is L sub([CII])= (ProQuest: Formulae and/or non-USASCII text omitted), roughlt ~5 times fainter than other detections of z~ 7 galaxies. The result indicates that low L sub([CII]) in z~ 7 galaxies compared to the local counterparts might be caused by their low metallicities and/or feedback. The small velocity offset ([Delta] sub([nu])= (ProQuest: Formulae and/or non-USASCII text omitted)) between the Ly[alpha] and [CII] line is unusual, and may be indicative of ionizing photons escaping.