Measurement of electric quadrupole moment in neutron rich

The quadrupole moments of the excited levels in neutron rich iodine isotopes, viz., $$^{131}$$I (5/2$$_1^+$$) and $$^{132}$$I (3$$_1^+$$), have been measured with LaBr$$_3$$(Ce) detectors using Time Differential Perturbed Angular Correlation (TDPAC) spectroscopy. The excited levels were populated from $$\beta ^-$$ decay of the radiochemically separated tellurium (Te) fission products produced in $$^{nat}$$U($$^4$$He,f) reaction at E$$_{\alpha }$$(lab) = 40 MeV from K-130 cyclotron at VECC, Kolkata. The active tellurium fission products were radiochemically doped in metallic tellurium matrix to provide the necessary Electric Field Gradient (EFG) required for TDPAC measurement. The values of quadrupole moments for the 5/2$$_1^+$$ level of $$^{131}$$I and 3$$_1^+$$ level of $$^{132}$$I were determined to be $$(-)$$0.30(1) eb and (−)0.25(2) eb, respectively. The present measurement provides the first experimental determination on the electric quadrupole moment of 5/2$$_1^+$$ level of $$^{131}$$I