[en] This issue of the SSDL Newsletter contains the report of the 12th SSDL Scientific Committee (SSC) Meeting held at the IAEA Headquarters from 7-10 March 2006. The SSC conducts biennial reviews and evaluations of the Dosimetry and Medical Radiation Physics activities. Following each meeting, the report of the SSC is addressed to the Directors General of the IAEA and WHO and circulated subsequently to Member States through this Newsletter. The report is pending acceptance by the IAEA and WHO. The second article is a brief note on the polarity of electrometers. The IAEA has received many queries from SSDLs on the definitions used by manufacturers of ionization chambers concerning the sign of the polarity of the chamberelectrometer connecting systems. The lack of clarity has also induced mistakes in some dosimetry comparison exercises where inconsistent polarities were used by some participants. It is hoped that this note will help clarify the issue. The readers were informed in the SSDL Newsletter No. 51 on the extension of the calibration facilities at Seibersdorf. It is a pleasure to announce that less than one year later, the construction of the new wing was completed. The inauguration ceremony was held on June 1 2006