Quadrupole moment of the 8 + yrast state in Kr 84

The quadrupole moment of the 8(+) yrast state in Kr-84 was measured using the level-mixing spectroscopy technique to be Q= 36(4) e fm(2). The result is compared with predictions of the shell model using common sets of effective charges. The comparison of experimental quadrupole moments with calculated values for 8(+) states in Kr, Sr and Zr isotopes with N= 48, 50 and for 9/2(+) states in isotopes with N= 47, 49 suggests a modification of the effective charges used in this region.