$^{30}\mathrm{P}$ has been studied by in-beam \ensuremath{\gamma}-spectroscopy following the fusion-evaporation reaction $^{16}\mathrm{O}$($^{16}\mathrm{O}$,$\mathit{pn}$) at ${E}_{\mathrm{lab}}=40$ MeV, using the Indian National Gamma (Clover) Array (INGA) up to moderate spins ($I=5$). Polarization measurements of seven gamma rays have been performed for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental data have been compared with the results from large basis cross-shell shell model calculations. The results for the negative parity states are especially important in this respect. Positive parity states indicate an onset of collectivity, whereas the negative parity states are members of \ensuremath{\nu}-\ensuremath{\pi} multiplets.

The high spin states of 35Cl have been studied by in-beam γ-spectroscopy following the fusion–evaporation reaction 12C(28Si,αp)35Cl at Elab=70 and 88 MeV, using the Indian National Gamma (Clover) Array (INGA). Lifetimes of six new excited states have been estimated for the first time. To understand the underlying structure of the levels and transition mechanisms, experimental results have been compared with those from the large basis cross-shell shell model calculations. Involvement of orbitals from fp shell and squeezing of the sd–fp shell gap seem to be essential for reliable reproduction of high spin states.

The lifetime of the 3163 keV, 7/2$^-$ isomeric state in $^{35}Cl$ that decays by a stretched M2 transition to the $3/2^+$ ground state, has been re-measured using the Doppler Shift Attenuation Method, by gating on the 1185 keV transition which directly feeds this state. This eliminates the uncertainties in the measurement arising from the direct feedings from the continuum. A mean life of 0.6$^{+0.5}_{-0.2}$ ps has been obtained from the present work. This is considerably smaller than the adopted value 45.3(6) ps. Implication of this major reduction in the lifetime has been pointed out.

Medium spin states of Mo-95,Mo-97(Z=42,N=53,55) nuclei have been investigated through the Se-82(O-18,xn) reaction at E-b=60 MeV. In Mo-95, excited states upto 7.5 MeV have been studied in the present experiment. A significant modification of the existing level scheme has been suggested. The negative parity level sequence of Mo-97 has been extended to 8.6 MeV. The experimental data for both the nuclei have been compared with the theoretical results from shell model and particle rotor model calculations.

The Clover detectors in their addback mode are excellent tools for detecting high-energy gamma rays (⩾2MeV). The characteristics of these detectors, at energies above 2MeV, are usually determined from simulation data or from extrapolation of the empirical data. This is the first time that the characteristics of a Compton suppressed Clover germanium detector have been studied up to 5MeV using a radioactive 66Ga (T1/2=9.41h) source.

High-spin states of 95,97 Mo ( Z =42, N =53,55) nuclei have been investigated through 82 Se( 18 O, xn ) reaction at Eb =60 MeV. The level scheme in 95 Mo has been observed upto ≏ 10 MeV in the present experiment. The level structure shows mainly single particle character. In 97 Mo, the ground state level sequence has been extended to ≏ 4.5 MeV while the previous information had been up to 2.4 MeV. A negative parity band built on 1437 keV (11/2 − ) excited state has been extended to 5.5 MeV. The structure seems to show a coexistence of single particle and collective modes of excitation. Properties of both the nuclei have been compared with shell model calculations using OXBASH.

High-spin states of 96 Mo ( Z=42 , N=54 ) nucleus have been investigated through the 82 Se( 18O,4n ) reaction at Eb=60 MeV. The excited states have been extended upto 10 MeV and the levels with Jπ=20+ spins have been observed in the present experiment while the earlier information for the same was available only upto 4.8 MeV. A significant modification of the existing level scheme is also being proposed. The properties of the observed levels have been compared with shell-model calculations using OXBASH code. The analysis of the result shows that level structure exhibits mainly single particle character.

High-spin states of 79Br have been studied in the reaction 76 Ge( 7 Li , 4nγ) at 32 MeV. A gamma-detector array with twelve Compton-suppressed HPGe detectors was used. The positive-parity yrast states, interpreted as a rotationally aligned g 9 2 proton band, and the negative-parity ground state band have been extended to spins of ( 33 2 + ) and ( 25 2 − ), respectively. Lifetime measurements indicate that both bands have a similar quadrupole deformation of β2 ∼ 0.2. The positive-parity α = −1 2 band has been identified. Several new inter-band transitions are observed. A cranked-shell model analysis shows that the νg 9 2 alignments occur in the positive-parity and the negative-parity bands at rotational frequencies of ℏω ∼ 0.6 and 0.4 MeV, respectively. The level energies and the electromagnetic properties of the g 9 2 band can be well reproduced by a particle-rotor model calculation with an axially symmetric core.

A search for new isomers of nanosecond lifetimes were carried out in Eu-153 via the Nd-150(Li-7,xn gamma) reaction. The single particle angular momentum alignment and dynamical moment of inertia estimated from the experimental data indicate a configuration change at rotational energy (h) over bar w similar to 0.30 MeV. A decrease of B(E2) values is also observed at the same frequency. An isomeric level is identified at an excitation energy of 3100 keV (J(pi)=35/2(-)) which corresponds to this frequency. The lifetime of the level is found to be 8.6 +/- 1.3 nanosecond.

. A search for new isomers of nanosecond lifetimes were carried out in 153 Eu via the 150 Nd( 7 Li,xnγ) reaction. The single particle angular momentum alignment and dynamical moment of inertia estimated from the experimental data indicate a configuration change at rotational energy ħω∼ 0.30 MeV. A decrease of B(E2) values is also observed at the same frequency. An isomeric level is identified at an excitation energy of 3100 keV (J π =35/2 − ) which corresponds to this frequency. The lifetime of the level is found to be 8.6 ± 1.3 nanosecond.

The high-spin behavior of Eu-153 nucleus has been investigated via the Nd-150(Li-7,4n gamma) reaction. The level structures of the nucleus built on the 5/2(+) ground state and the 5/2(-) excited state have been established up to spins 39/2(+) and 43/2(-), respectively, and are observed to be interleaved through strong El transitions. From the B(E1)/B(E2) ratios of the high-spin region the intrinsic electric-dipole moment is deduced and is found to be 0.181+/-0.007 e fm and beta(3) thus obtained is similar to 0.03. The rotational features and magnetic moments indicate that an octupole correlated deformation has developed with the increasing spin. A theoretical study of the correlation between the beta(3) and the band crossing frequency supports the conjecture of octupole deformation at high spin.

High spin rotational bands in the odd–odd 150Eu nucleus, produced in the 148Nd(7Li,5n) reaction, were investigated by in-beam γ spectroscopy. Seven bands above the 588.8 keV (45 ns) isomeric level were observed. Probable single- and double-octupole-phonon coupling states were identified. Two positive parity bands are interpreted in terms of two quasiparticles (a proton and a neutron) coupled to an axially symmetric rotor core. Otherwise, the rest of the high spin levels are described by multiparticle–hole excitations.

An investigation of the high spin isomer in 151Sm was performed via the 150Nd(α, 3nγ) reaction at a projectile energy of 35 MeV. A new γ-transition, 693.6 keV was identified having an exponential delayed component. The transition feeds the 1912 keV state of the negative parity band built on the h11/2 state. This transition was also observed in coincidence with γ-rays belonging to 151Sm in the γ-γ coincidence experiment at E α =37 MeV. A new isomeric state having energy E x =2605.8 keV and half life T1/2=23.1±3.5 ns is proposed.

The \ensuremath{\beta} decay of the ${(11/2}_{1}^{\mathrm{\ensuremath{-}}}$ isomer of $^{141}\mathrm{Nd}$ to the odd parity states in $^{141}\mathrm{Pr}$ has been investigated by measurement of the \ensuremath{\gamma} rays of $^{141}\mathrm{Pr}$ in the radioactive decay of $^{141}\mathrm{Nd}^{\mathrm{m}}$ and the reaction $^{139}\mathrm{La}$(\ensuremath{\alpha},2n\ensuremath{\gamma}${)}^{141}$Pr. The half-life of the ${(11/2}_{1}^{\mathrm{\ensuremath{-}}}$ isomer of $^{141}\mathrm{Nd}$ is determined to be 60.9\ifmmode\pm\else\textpm\fi{}1.0 s. An upper limit of 0.010% for the \ensuremath{\beta} feeding to the 1117.6 keV (${(11/2}^{\mathrm{\ensuremath{-}}}$) state of $^{141}\mathrm{Pr}$ is deduced, in disagreement with earlier reports. No detectable \ensuremath{\beta} feeding to the 2000.8 keV (${(9/2}^{\mathrm{\ensuremath{-}}}$) and 2382.8 keV (${(11/2}^{\mathrm{\ensuremath{-}}}$) states of $^{141}\mathrm{Pr}$ is observed, and upper limits of 0.020% and 0.012%, respectively, are determined. The ratio of occupancies of protons in the 1${h}_{11/2}$ and 2${d}_{5/2}$ proton orbitals in $^{141}\mathrm{Nd}$ deduced from the \ensuremath{\beta}-decay data is compared with that from the spectroscopic factors for pickup and stripping reactions, and the results are discussed.

High spin states in the two nuclei $^{52}\mathrm{Cr}$ and $^{52}\mathrm{Mn}$, with ${J}^{\ensuremath{\pi}}$\ensuremath{\le}${11}^{+}$, have been studied via the reactions $^{51}\mathrm{V}$(\ensuremath{\alpha},p2n\ensuremath{\gamma}) and $^{51}\mathrm{V}$(\ensuremath{\alpha},3n\ensuremath{\gamma}), respectively, by in-beam \ensuremath{\gamma}-ray spectroscopy. Measurements of lifetimes of excited states by the Doppler shift attenuation and recoil distance techniques, \ensuremath{\gamma}-ray angular distributions, excitation functions, and \ensuremath{\gamma}\ensuremath{\gamma} coincidence, have been carried out in both the nuclei. New results obtained in $^{52}\mathrm{Cr}$ are the mean lifetime values of ${0.35}_{\mathrm{\ensuremath{-}}0.13}^{+0.25}$, ${0.23}_{\mathrm{\ensuremath{-}}0.11}^{+0.22}$, and <2.0 ps for the three highest observed states 8216.0 (${11}^{+}$), 7237.1 (${10}^{+}$), and 6453.4 keV (${9}^{+}$), and multipole mixing ratios ${\mathrm{\ensuremath{-}}0.10}_{\mathrm{\ensuremath{-}}0.05}^{+0.08}$, ${0.06}_{\mathrm{\ensuremath{-}}0.03}^{+0.05}$, and ${\mathrm{\ensuremath{-}}0.22}_{\mathrm{\ensuremath{-}}0.15}^{+0.08}$ for the 978.9, 784.7, and 629.1 keV \ensuremath{\gamma} rays depopulating these states, respectively. In $^{52}\mathrm{Mn}$, the lifetime of the 4163.4 keV (${10}^{+}$) state, hitherto unreported, has been measured to be ${0.20}_{\mathrm{\ensuremath{-}}0.16}^{+0.35}$ ps.Lifetimes of two other states in $^{52}\mathrm{Mn}$, at 870.1 (${7}^{+}$) and 2907.9 keV (${9}^{+}$), for which only the upper limits were known previously, have been measured in this work and are found to be ${0.07}_{\mathrm{\ensuremath{-}}0.04}^{+0.08}$ and 0.12\ifmmode\pm\else\textpm\fi{}0.08 ps, respectively. A comparison of the present experimental results on level lifetimes, multipole mixing ratios, and transition probabilities with the available theoretical calculations shows that most of the levels in $^{52}\mathrm{Cr}$ with excitation energies greater than 3.4 MeV are almost pure 1p5h states, while the lower lying states have a predominantly 0p4h configuration, with \ensuremath{\sim}20% 1p5h admixture. The observed M1 and E2 transition strengths between the high spin states in $^{52}\mathrm{Mn}$ favor interpretation of these states as having predominantly (${f}_{7/2}$${)}^{n}$ configuration and provide evidence for the existence of collective features in this nucleus.

A modified semiempirical expression for the LSS parameter ξe valid for ions with nuclear charge ⩽ 92 is presented and its applicability for predicting electronic stopping powers is discussed.

Lifetime measurements by the Doppler shift attenuation method for levels in the nuclei57Fe and57Co, populated via the reactions55Mn(α, pnγ)57Fe and55Mn(α, 2nγ)57Co, respectively, are reported. The relative γ-ray intensities and the branching ratios for levels in the two nuclei are also presented. In57Fe, mean lifetime values of τ=(0.20±0.09) ps and (0.26±0.10) ps are obtained for the levels at 1007.0 keV and 1356.8 keV, respectively, for which no lifetime information existed previously and values of τ=0.08±0.03, 0.54 −0.15 +0.30 and (0.16±0.06) ps are determined for the levels at 2355.7, 3269.1 and 6185.6 keV, respectively, for which only the limits of lifetimes were reported earlier. For the 2455.2 keV level in57Fe a lower limit of 2 ps is obtained for its mean life. In57Co lifetimes of eight levels withJπ≤19−/2 have been measured and compared with the earlier reported values. The results of lifetime measurements and reduced transition probabilities for both the nuclei are discussed and compared with the available shell model calculations.

The decay scheme of the 72.3d160Tb and γ-transitions in160Dy has been studied by γ-ray spectroscopy with high-efficiency Ge(Li) and HPGe detectors. The intensity of the 1004.8 keV γ-ray is measured to be 0.04±0.01 relative to 30 for the 879.353 keV γ-ray. Gamma-rays of energies 707.6 and 239.70 keV with relative intensities 0.010±0.005 and 0.002±0.001 are observed and assigned to160Dy. The energies and relative intensities of all other γ-rays are remeasured to remove anomalies in the previous reports. A new β-group of intensity (0.032±0.012)% and logft 11.2±0.2 is proposed to feed the 1288.6 keV level in160Dy. The total conversion coefficient of the 197.008 keV transition in160Dy is measured to be 0.22±0.08. The total andK-shell conversion coefficients of the 86.796 keV transition in160Dy are remeasured and the results obtained are 4.71±0.20 and 1.54±0.12, respectively. The results of the branching ratios of β and γ transitions are discussed. The band-mixing parametersz2 for160Dy is determined and it is observed that the measured γ-ray branching ratios do not lead to a unique value ofz2 for160Dy.