Polarized diffuse emission observations at 2.3 GHz in a high Galactic latitude area are presented .
The 2 \degr \times 2 \degr field , centred in ( \alpha = 5 ^ { h } , \delta = -49 ^ { \circ } ) , is located in the region observed by the BOOMERanG experiment .
Our observations has been carried out with the Parkes Radio telescope and represent the highest frequency detection done to date in low emission areas .
Because of a weaker Faraday rotation action , the high frequency allows an estimate of the Galactic synchrotron contamination of the Cosmic Microwave Background Polarization ( CMBP ) that is more reliable than that done at 1.4 GHz .
We find that the angular power spectra of the E – and B –modes have slopes of \beta _ { E } = -1.46 \pm 0.14 and \beta _ { B } = -1.87 \pm 0.22 , indicating a flattening with respect to 1.4 GHz .
Extrapolated up to 32 GHz , the E –mode spectrum is about 3 orders of magnitude lower than that of the CMBP , allowing a clean detection even at this frequency .
The best improvement concerns the B –mode , for which our single-dish observations provide the first estimate of the contamination on angular scales close to the CMBP peak ( about 2 degrees ) .
We find that the CMBP B –mode should be stronger than synchrotron contamination at 90 GHz for models with T / S > 0.01 .
This low level could move down to 60–70 GHz the optimal window for CMBP measures .