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Lifetimes of the 2 $$_1^{+}$$ , 4 $$_1^{+}$$ , 7 $$_2^{-}$$ , 10 $$_2^{+}$$ , 12 $$_2^{+}$$ , and 14 $$_1^{+}$$ states in $$^{138}$$ Nd populated via the $$^{123}$$ Sb( $$^{19}$$ F, 4n) $$^{138}$$ Nd fusion–evaporation reaction were measured with the recoil distance Doppler shift technique in combination with the differential decay curve method. The $$B(E2; 2_{1}^{+} \rightarrow 0_{1}^{+})$$ value fit well with the systematic trend in the Nd isotope chain and Grodzins rule, which proved that $$^{138}$$ Nd is a transitional nucleus.

Excited states in the odd-A nucleus 71Ga have been studied via the 70Zn(7Li, )71Ga fusion-evaporation reaction with incident beam energies of 30 and 35 MeV. The level scheme is established up to spin = (29/2+) and an excitation energy 6.6 MeV. A previously known sequence built on the 9/2+ state is extended as a novel rotational band originating from the alignment. Furthermore, a negative-parity sequence is also reported. The observed energy levels of 71Ga have been interpreted in the framework of the nuclear shell model (SM).

The lifetime of the state in Cd populated via the Zr ( O, 4n) Cd reaction has been measured with the Recoil Distance Doppler Shift technique in combination with the Differential Decay Curve Method. By subtracting the contamination in the data, the mean lifetime of the =2 633 keV state was determined as 9.9 (12) ps. The value calculated in this study is in good agreement with the experimental systematics and was compared to the shell model calculations.

A new development of indirect gating case in the differential decay curve method used for lifetime measurement has been introduced. The gate region was extended from partial shifted peak to both shifted and unshifted components. The statistics of flight and stop peaks in gating spectra was improved obviously. The reliability of this change has been tested by reanalysing the lifetime of $$2^{+}$$ state in $$^{134} \hbox {Ce}$$ . The result of 32.2(33) ps was fit well with the previous published values within the experimental uncertainty. The developed method was also used to analyse the lifetime of $$2_1^{+}$$ state in $$^{138} \hbox {Nd}$$ .

A Mini-Orange spectrometer used for in-beam measurements of internal conversion electrons, which consists of a Si(Li) detector and different sets of SmO$_5$ permanent magnets for filtering and transporting the conversion electrons to the Si(Li) detector, has been developed at China Institute of Atomic Energy. The working principle and configuration of the Mini-Orange spectrometer are described. The performance of the setup is illustrated by measured singles conversion electron spectra using the Mini-Orange spectrometer.