The decay of¹³¹ gTe and¹³¹ mTe to¹³¹I levels

Abstract

The gamma rays emitted in the decay of¹³¹ gTe and¹³¹ mTe to levels in¹³¹I were investigated by means of a Ge(Li) spectrometer. The energies and intensities of 78 gamma-rays were determined from the gamma-ray singles spectra. Of these, 21 gamma-transitions reported for the first time in the present work, are identified to¹³¹I. A new level not reported before has been proposed at 1854 keV excitation energy.

Two-parameter gamma-gamma coincidence experiments with Ge(Li) and NaI(Tl) detectors have been performed. The resolving time of the fast coincidence circuit was 50 nsec. A level scheme has been constructed for¹³¹I on the basis of energy, intensity and coincidence measurements. The most probable spins and parities, values of mixing parameters and multipolarities of gamma rays were determined from gamma-gamma directional angular correlation measurements and log ft values. The results of spin assignment to some levels in¹³¹I from the present work are summarised in the following, where the level energy is in keV followed by the spin and parity as (J^π):

590 (3/2⁺, 5/2⁺); 603 (5/2⁺); 773.7 (9/2⁺); 877((1/2⁺); 1065 (9/2⁺); 1188 (1/2⁺); 1315 (9/2⁺); 1556.4 (9/2⁺); 1596.5 (11/2⁺); 1646 (9/2⁻); 1797 (11/2⁻, 13/2⁻); 1854 (9/2⁻, 11/2⁻, 13/2⁻); 1888 (9/2⁻, 11/2⁻); 1899 (9/2⁻); 1980 (11/2⁻); 2001 (9/2⁻); 2118 (9/2⁻; 11/2⁻, 13/2⁻); 2231 (13/2⁻); 2240 (9/2⁻, 11/2⁻) and 2330 (9/2⁻, 11/2⁻).