The interaction of the nuclear electric quadrupolemoment with an electric field gradient at the position of the nucleus changes the angular correlation of two successive y-rays and should also produce a circular polarization of the y-rays. By measuring this polarization it should be possible to distinguish between electric and magnetic attenuation of the y-cascade. In the electric case this measurement OE leads to determine not only the absolute value of the interaction product Q 9 --Oz but also the sign of it and therefore the sign of the nuclear quadrupolemoment. In the following paper the measurement of the circular polarization of the 247 key y-ray of Cadmium-tit is described. A polarization of P= (0.8 • 0.2)~o leads to the determination of the quadrupolemoment of the first excited state to Q = + 0"9 9 t 0 -24 cm 2.

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