On the basis of conversion electron and y-angular distribution measurements new spin and parity assignments in 138Ce have been made. They lead together with the already known lifetime of the 10 + yrast state whose parity was unclear to an extremely low transition probability of the 10 +--.8 + transition. A comparison with neighbouring even isotopes is made.Nuclear Reactions: 136Ba(c~,2n7) E,=24MeV, 139La(p, 2n7) Ep=16MeV, measured E~, 1~, Iv(E), I~(0), ICC, deduced J, re. Ge(Li), miniorange with Si(Li), enriched a36Ba target.The nucleus 13sc,~ is situated near the neutron 58~80 shell closure at N = 82 and has 8 protons above the closed proton shell at Z=50. It is interesting to obtain detailed spectroscopic information about its low-lying states as it represents a good example of the interplay of collective and single-particle degrees of freedom. An in-beam study of this nucleus has been performed at the Cologne FN tandem accelerator and at the Milan cyclotron using the 139La(p, 2n7) and 136Ba(~,2nT) reactions. In the present short note we shall focus on the information obtained on the parities of the levels in the groundstate sequence which is based mainly on the measurement of conversion electrons following the 139La(p, 2n) reaction. This measurement was performed using a spectrometer of the miniorange type. An electron spectrum and a gamma-ray spectrum were taken simultaneously at Ep= 16 MeV. Figure 1 shows the conversion coefficients of transitions in 138Ce which were obtained using an internal transmission calibration for the spectrometer. Figure 2 shows the levelscheme of 138Ce. The levels up to the 5 state at 2,217keV are well established from radioactive-decay and in-beam work [-1-4].The 2,294keV state was already identified in I38Ba(~, 4nv) studies [5,6] and a spin of I=6h was assigned to it. Our angular distribution data obtained in a 136Ba(7 ' 2n?) experiment at 24 MeV fully confirm this spin assignment. The parity of this state however was assigned only tentatively on the basis of intensity considerations. Our conversion coefficient of the 467 keV transition (Fig. 2) indicates an E2 multipolarity and gives a strong support for a positive parity assignment. The 3,109keV level, which decays by an 815keV transition to the so established 6 + level at 2,294 keV and by a 980keV transition to the 7-level at 2,129 keV, was also identified previously by Ludziejewski and Arnold [5] and by Miiller-Veggian et al.[6] and a spin of I = 8h but no parity was assigned.Our angular distribution and excitation-function measurements confirm this spin assignment. The conversion coefficients clearly establish E2 and E1 multipolarities respectively for the 815keV and 980keV transitions, which means that the parity of the 3,109 keV state is positive. The isomeric state at 3,539 keV decays by a 430 keV transition to the 3,109 keV level. The lifetime of this
