DOI 10.1140/epja/i2002-10157-x Eur. Phys. J. A 17, 153–157 (2003) T HE EUROPEAN P HYSICAL JOURNAL A Short Note Investigations of low- and high-spin states of 132 La Vinod Kumar 1 , Pragya Das 1, a , R.P. Singh 2 , S. Muralithar 2 , and R.K. Bhowmik 2 1 Physics Department, Indian Institute of Technology-Bombay, Powai, Mumbai-400076, India 2 Nuclear Science Centre, Aruna Asaf Ali Marg, New Delhi-110067, India Received: 12 August 2002 / Revised version: 28 February 2003 / Published online: 7 May 2003 – c  Societ` a Italiana di Fisica / Springer-Verlag 2003 Communicated by W. Henning Abstract. The fusion evaporation reaction 122 Sn( 14 N, 4n) 132 La was used to populate the high-spin states of 132 La at the beam energy of 60 MeV. A new band consisting of mostly E2 transitions has been discovered. This band has the interesting links to the ground state 2 − and the isomeric state 6 − . A new transition of energy 351 keV connecting the low-spin states of the positive-parity band based on the πh 11/2 ⊗ νh 11/2 particle configuration, has been found. This has played a very important role in resolving the existing ambiguities and inconsistencies in the spin assignment of the band head. PACS. 23.20.Lv Gamma transitions and level energies – 23.20.En Angular distribution and correlation measurements – 23.20.Gq Multipole mixing ratios – 27.60.+j 90 ≤ A ≤ 149 1 Introduction In the recent past, there has been a tremendous interest in the spectroscopic studies of odd-odd nuclei in the mass re- gion ∼ 130 because of the newly recognized phenomenon of chirality in nuclear rotation [1–8]. Two nearly degener- ate bands based on the same particle configuration, called as chiral bands, were first found in 134 Pr [7]. We began our investigation of 132 La with the motiva- tion of understanding the nuclear structure at both the low, as well as high spins. Very few energy levels of 132 La were known earlier [9] and their spin assignments were mostly tentative. Starosta et al. [1–3] later reported the existence of a chiral partner of the πh 11/2 ⊗ νh 11/2 band by identifying a series of M 1 and E2 transitions. Though very weakly populated, our data has confirmed the chiral partner bands in 132 La. With our discovery of a transition of energy 351 keV, the band head has been reassigned to a new state 8 + leading to a consistent picture among the earlier experimental [1,9] and theoretical works [1,10]. Owing to the isomeric nature of 6 − state (T 1/2 = 24.3 min), the interconnecting transitions to the ground state 2 − were completely missed in the earlier prompt coincidence measurement [9]. On the other hand, the in- terconnecting transitions of energy values 53 keV (M 3), 135 keV (M 1) and 188 keV (E4) were present in the elec- tron conversion spectroscopic measurements [11,12]. With a e-mail: pragya@phy.iitb.ac.in the identification of 3 new transitions namely, 96 keV, 129 keV and 160 keV, the spin difference of 4 units be- tween the known ground state as 2 − and the isomeric state as 6 − has further been confirmed from our data. The transitions 515 keV, 699 keV, 841 keV and 975 keV, constituting another band, have also been dis- covered. 2 Experiment and data analysis The experiment using the fusion evaporation reaction 122 Sn( 14 N, 4n) 132 La, was performed at the Nuclear Sci- ence Centre, New Delhi, with the 15 UD Pelletron accel- erator. The experimental set up consisted of 8 Compton suppressed HPGe detectors and a 14-element BGO mul- tiplicity filter. The HPGe detectors were placed at angles of 50 ◦ , 98 ◦ and 144 ◦ with respect to the beam direction. The 122 Sn target of thickness 1.2 mg/cm 2 was rolled onto the 10 mg/cm 2 of Pb. The Pb thickness was chosen so as to stop the recoiling nuclei. The energy calibration and the efficiency determina- tion of individual HPGe detectors were done using the 133 Ba and 152 Eu radioactive sources. In order to measure the excitation function, the energy spectra of individual HPGe detectors were taken at the various beam energies. After matching the gains, the energy spectra from all the detectors were added to minimize the effect of the angu- lar correlation of γ -rays. A comparison of the intensities