High-spin states in 217Ac are reported up to 3.9-MeV excitation energy and I pi = 41/2+ where 22 transitions are newly observed. The structure of the yrast and near-yrast states below the 29/2+ isomer is revisited. The level structure above the 29/2+ isomer is established with firm spin and parity assignments. Large-basis shell-model calculations with the Kuo-Herling particle effective interaction are performed to compare the experimentally observed level energies with the theoretical predictions. A comparison with the systematics of the N = 128 isotones suggests that the yrast structures result from a weak coupling of the odd proton to the even-even 216Ra core, which is consistent with the shell-model configurations.

High-spin states in the transitional ^217Ac nucleus are established up to 3.8 MeV excitation energy and I^π = 41/2^+ with the addition of around 20 new transitions. The structure of the yrast and near-yrast states below the 29/2^+ isomer is revisited. The inconsistencies in the level schemes reported earlier are resolved. The level structure above the 29/2^+ isomer is established for the first time. Large-basis shell-model calculations with the KHPE interaction are performed to compare the experimentally observed level energies with the theoretical predictions. A comparison with the systematics of the N = 128 isotones suggests that the yrast structures result from a weak coupling of the odd proton to the even-even 216Ra core, which is consistent with the shell-model configurations. Furthermore, alpha decay of the 29/2^+ isomer is revisited and the decay scheme established from this work is discussed in the framework of the shell model.

Excited states of the molybdenum isotopes 97,99,101 42 Mo have been populated in two experiments which used fusion-fission and binary grazing reactions to populate yrast states of the nuclei of interest. In the first experiment, the GASP array of escape-suppressed Ge detectors was used to detect gamma rays from fusion-fission products initiated by the interaction of a 230-MeV beam of 36S ions with a thick target of 176Yb. In the multinucleon transfer experiment, a 530-MeV beam of 96Zr ions was incident on a thin 124Sn target; projectile-like ejectiles were detected and identified using the PRISMA magnetic spectrometer and their associated gamma rays were detected using the CLARA array of escape-suppressed Ge detectors. In 99Mo, the previously known positive-parity vd5/2 decay sequence was extended to spin (25/2+) while, in 101Mo, a similar, but hitherto unobserved vg7/2 positive-parity decay sequence was established to spin (27/2+). In 99Mo and in 101Mo, previously observed vh11/2 negative-parity decay sequences were also observed to spin 27/2-. Although the observed decay sequences in 97Mo have not been extended beyond the results of earlier work, a disagreement in the published level structure of the h11/2 band has been resolved. The observed positive-parity decay sequences have been compared with the results of state-of-the-art shell-model calculations; the general features of the energy spectrum of excited states of 97Mo, 99Mo, and 101Mo are reproduced, but not in detail. The experimental energies of the negative-parity states of 99Mo and 101Mo are reasonably well reproduced in particle-rotor (PRM) calculations. For 97Mo, better agreement with the high-spin states was obtained when the core in the PRM calculations was treated in a variable moment of inertia approach. For the vh11/2 negative-parity decay sequences of the three isotopes studied here, model-dependent evidence is presented for nuclear shape changes with increasing neutron number.

An investigation using the 27 Al( 28 Si, 3 p 1 n ) reaction and the high -efficiency Indian National Gamma Array has yielded an enriched level scheme for the 51 Cr nucleus. Multiple new gamma rays, including high-energy feeders to the yrast states, have been observed. The yrast K pi = 15 - three-quasiparticle band structure has been extended 2 beyond band termination. Angular correlation and polarization measurements have yielded unambiguous spins and parities to most of the observed yrast states. Unambiguous measurements of mean lifetimes for the yrast states in the K pi = 15 - band, leading to and even beyond band termination, have been carried out for the 2 first time in this nucleus. This, coupled with the clear identifications of weak intraband crossover transitions, have facilitated profiling of the evolution of B ( E 2) values along the yrast sequence. Large-scale shell model calculations in the full fp valence space, with no restriction on the occupancy of the valence orbitals, have been performed. The results from such calculations have been found to be consistent with the experimental observations.

The region of the nuclear chart with atomic number Z = 80–83 (Hg-Bi) and neutron number N = 118–126, which is the subject of many recent investigations, has revealed the presence of quite long-lived states at high excitation energy and spin. Some noteworthy results include the 8-ms, spin (51/2) isomer at about 8 MeV in 205 Bi, and the 60-ns, spin 28 level at 13.67 MeV in 208 Pb. The states in 205 Bi and 208 Pb have the longest half-life and the highest excitation energy of isomers above 7 MeV identified across the nuclear chart yet. The recently discovered isomers are exceptional in terms of half-life, excitation energy or spin, and are built on excitations of the 208 Pb core, which is the heaviest doubly-magic nucleus. The properties of these isomers with multi-quasiparticle configurations, involving nucleons in predominantly high- j orbitals below and above the Z = 82 and N = 126 shell gaps, are challenging to reproduce through large-scale shell-model calculations owing to the constraints imposed by the large model space. These metastable states constitute the means to discriminate between and serve to improve the available nuclear effective interactions.

Excited states of the neutron-rich niobium isotopes 96,97,98,99 41Nb have been populated in two experiments which used fusion-fission and multinucleon binary grazing reactions to populate high-spin yrast states. In the multinucleon-transfer experiment, a 530-MeV beam of 96Zr ions was incident on a thin 124Sn target; projectile-like ejectiles were detected and identified using the PRISMA magnetic spectrometer and the associated gamma rays were detected using the CLARA array of Ge detectors. In the second experiment, the GASP array of escape-suppressed Ge detectors was used to detect gamma rays from fusion-fission products formed following the interaction of a 230-MeV beam of 36S ions with a thick target of 176Yb. Level schemes of 96,97,99Nb were established up to excitation energies of 4545, 5409, and 3814 keV, respectively; states with proposed spin values up to about 15 h over bar were populated. Gamma-ray photopeaks corresponding to transitions in 98Nb were also observed in the PRISMA-CLARA experiment; however, it was not possible, in this case, to produce a level scheme based on gamma-ray coincidence data from the GASP experiment. For 96Nb and 97Nb, the level schemes are in agreement with the results of earlier publications. Two new decay sequences have been populated in 99Nb; tentative J pi values of the hitherto unobserved states have been assigned through comparisons with J pi values of neighboring nuclei. In contrast with earlier published studies of the high-spin spectroscopy of 96Nb and 97Nb, the present work provides an unambiguous association of the observed gamma rays with the A and Z of the excited nucleus. The structure of the yrast states of 96,97,99Nb is discussed within the context of shell-model calculations. The experimental results, supported by model calculations, indicate the first observation of shape coexistence at low spin and low excitation energy in the N = 58 nucleus 99Nb. The results of TRS calculations indicate that the 9/2+ ground state is triaxial, tending to oblate shapes with a transition to a more deformed prolate shape beyond the 17/2+ member of the decay sequence; here the sequence has been observed to (29/2+). On the other hand, the previously unobserved decay sequence based on the 5/2- state at 631 keV exhibits the characteristics of a rotational sequence and has been assigned Nilsson quantum numbers 5/2-[303]. TRS calculations indicate that the 5/2-[303] band is gamma soft and this is consistent with the inability of the particle-rotor model to reproduce the observed behavior of the signature-splitting function.

The level structure of the transitional nucleus $\mathrm{^{217}Ra}$ has been extended with the addition of around 20 new transitions. The discrepancies between the placements of several transitions reported in the earlier studies are resolved. The newly-established negative-parity sequence at low excitation energies hints at the expected parity-doublet structures in this nucleus. The properties of the observed simplex bands are compared with that of similar bands in neighboring nuclei. Since the presence of parity-doublet structures reflect octupole correlations, theoretical calculations using reflection-asymmetric triaxial particle rotor model (RAT-PRM) have been performed. A comparison of the observed features of the simplex bands with the predictions of the RAT-PRM calculations suggests that $\mathrm{^{217}Ra}$ exhibits an intermediate the behavior between the extremes of spherical and octupole-deformed nuclei. The termination of the simplex bands at intermediate energies and the structures lying above reflect the dominance of the single-particle excitations at higher excitation energies.

Yrast and near-yrast states above the known 25/2$^{+}$ isomer in $^{207}$At are established for the first time. The level scheme is extended up to 47/2$\hbar$ and 6.5 MeV with the addition of about 60 new $\gamma$-ray transitions. The half-life of the 25/2$^{+}$ isomer is revisited and a value of $T_{1/2}$ = 107.5(9) ns is deduced. Evidence of a hitherto unobserved 29/2$^{+}$ isomer in $^{207}$At is presented. A systematic study of $B(E3)$ values for the transitions de-exciting the 29/2$^{+}$ isomer in the neighboring odd-$A$ At isotopes suggests a half-life in the 2$-$4.5 $\mu$s range for this state in $^{207}$At. The experimental results are compared with large-scale shell-model calculations performed using the KHM3Y effective interaction in the $Z$ = 50$-$126, $N$ = 82$-$184 model space and an overall good agreement is noted between the theory and the experiment. A qualitative comparison of the excited states and the isomers with analogous states in neighboring nuclei provides further insight into the structure of $^{207}$At.

Excited states of the neutron-rich niobium isotopes $_{\phantom{96,97,98,}41}^{96,97,98,99}\mathrm{Nb}$ have been populated in two experiments which used fusion-fission and multinucleon binary grazing reactions to populate high-spin yrast states. In the multinucleon-transfer experiment, a 530-MeV beam of $^{96}\mathrm{Zr}$ ions was incident on a thin $^{124}\mathrm{Sn}$ target; projectile-like ejectiles were detected and identified using the PRISMA magnetic spectrometer and the associated $\ensuremath{\gamma}$ rays were detected using the CLARA array of Ge detectors. In the second experiment, the GASP array of escape-suppressed Ge detectors was used to detect $\ensuremath{\gamma}$ rays from fusion-fission products formed following the interaction of a 230-MeV beam of $^{36}\mathrm{S}$ ions with a thick target of $^{176}\mathrm{Yb}$. Level schemes of $^{96,97,99}\mathrm{Nb}$ were established up to excitation energies of 4545, 5409, and 3814 keV, respectively; states with proposed spin values up to about 15 $\ensuremath{\hbar}$ were populated. Gamma-ray photopeaks corresponding to transitions in $^{98}\mathrm{Nb}$ were also observed in the PRISMA-CLARA experiment; however, it was not possible, in this case, to produce a level scheme based on $\ensuremath{\gamma}$-ray coincidence data from the GASP experiment. For $^{96}\mathrm{Nb}$ and $^{97}\mathrm{Nb}$, the level schemes are in agreement with the results of earlier publications. Two new decay sequences have been populated in $^{99}\mathrm{Nb}$; tentative ${J}^{\ensuremath{\pi}}$ values of the hitherto unobserved states have been assigned through comparisons with ${J}^{\ensuremath{\pi}}$ values of neighboring nuclei. In contrast with earlier published studies of the high-spin spectroscopy of $^{96}\mathrm{Nb}$ and $^{97}\mathrm{Nb}$, the present work provides an unambiguous association of the observed $\ensuremath{\gamma}$ rays with the $A$ and $Z$ of the excited nucleus. The structure of the yrast states of $^{96,97,99}\mathrm{Nb}$ is discussed within the context of shell-model calculations. The experimental results, supported by model calculations, indicate the first observation of shape coexistence at low spin and low excitation energy in the $N=58$ nucleus $^{99}\mathrm{Nb}$. The results of TRS calculations indicate that the $9/{2}^{+}$ ground state is triaxial, tending to oblate shapes with a transition to a more deformed prolate shape beyond the $17/{2}^{+}$ member of the decay sequence; here the sequence has been observed to ($29/{2}^{+}$). On the other hand, the previously unobserved decay sequence based on the $5/{2}^{\ensuremath{-}}$ state at 631 keV exhibits the characteristics of a rotational sequence and has been assigned Nilsson quantum numbers $5/{2}^{\ensuremath{-}}[303]$. TRS calculations indicate that the $5/{2}^{\ensuremath{-}}[303]$ band is gamma soft and this is consistent with the inability of the particle-rotor model to reproduce the observed behavior of the signature-splitting function.

Isomers with three- and five-nucleon-hole configurations have been established in 203Tl. These include newly identified levels with a three-nucleon-hole structure: Ig = (15/2???) with T1/2 = 7.9(5) ns and Ig = (35/2???) with T1/2 = 4.0(5) ns. In addition, five-nucleon-hole states have also been established: Ig = (39/2???) with T1/2 = 1.9(2) ns and Ig = (49/2+) with T1/2 = 3.4(4) ns. The previously determined long-lived decay, T1/2 = 6.6(3) ??s from this work, is associated with isomerism of the Ig = (29/2+) state. Levels above this long-lived isomer have been identified through a delayed-prompt ?? ??? ?? coincidence measurement. Five-nucleon-hole states with excitation energies Ex ??? 7 MeV have been established as well as possible octupole excitations of the 208Pb core built on these levels. The level scheme of 203Tl is extended up to Ex ??? 11 MeV with the inclusion of 25 new transitions. Empirical and shell-model calculations have been performed to aid in the description of the observed states which are found to be of intrinsic character.

The negative-parity band structure built on the proton h(9/2) state in Tl-199 has been established up to an excitation energy of 7 MeV and spin of (51/2)h. The level scheme has been extended with the inclusion of fourteen new transitions de-exciting levels at high spin. The Delta I=1 gamma rays are found to be more prominently visible in the spectra when comparing to Delta I=2 transitions. Rotation alignments are evident at frequencies of 0.22 and 0.30 MeV with both being attributed to the breaking of pairs of neutrons in the i(13/2) subshell. Since Tl-199 is expected to have weak oblate deformation, and lies in a transitional region where competing contributions to the spin are expected from collective rotation and the angular momentum of high-j nucleons, calculations using both the principal axis cranking (PAC) and tilted axis cranking (TAC) formalisms have been performed to understand its structure. Both the PAC and TAC calculations are found to provide a satisfactory description of the evolution of excitation energies with spin. The PAC calculations give a good account of the experimental crossing frequencies and associated spins. The structure of the yrast, negative-parity band in Tl-199 may be primarily understood in terms of the collective rotation of a moderately deformed oblate nucleus, along with contributions to the angular momentum from two pairs of rotation-aligned i(13/2) neutrons.

The level scheme of Fr-215 is extended up to 55/2 h and 4.8 MeV excitation energy with the addition of 52 new gamma-ray transitions. Previously established isomers and their half-lives, except for the 47/2(+) state, are revisited. The discrepancy in the half-life of the 39/2(-) state is resolved, and its half-life is revised to 11.4(14) ns. An overall good agreement is observed between the experimental results and the shell-model calculations performed using the CD-Bonn NN interaction derived from the V-l(ow)-k renormalization approach. A weak coupling of the odd proton to the even-even core is observed to account for the level structure at lower energies, which strongly resembles a decoupled nonrotational band. A new positive-parity sequence is also established which is observed to originate from the coupling of the i(13/12) proton at low excitation energy.

Metastable states with T1/2 = 8(2) ms in 205Bi and T1/2 = 0.22(2) ms in 204Pb, with ≈ 8 MeV excitation energy and angular momentum ≥ 22 ħ, have been established. These represent, by up to two orders of magnitude, the longest-lived nuclear states above an excitation energy of 7 MeV, ever identified in the nuclear chart. Additionally, the half-life of the 10.17 MeV state in 206Bi has been determined to be 0.027(2) ms, the next highest value in this highly excited regime. These observations indicate the emergence of an island of extreme nuclear isomerism arising from core-excited configurations at high excitation in the vicinity of the doubly closed-shell nucleus 208Pb. These results are expected to provide discriminating tests of the effective interactions used in current large-scale shell-model calculations.

Three new isomers have been identified in the transitional odd-odd Fr-216 nucleus. The properties of the (11(+)) isomer with T-1/2 = 9.6(14) ns are compared with those of the similar isomeric states in neighboring doubly-odd nuclei. The experimental results are compared with predictions of shell-model calculations and a fair agreement is observed between the experimental and calculated excitation energies of the (11(+)) isomeric state and the states to which it decays. The deviation between the measured and calculated reduced transition probabilities suggests contribution from effects other than the single-particle degrees of freedom in these states. Evidence of two high-spin [J(pi) > (18(+))] isomers above 2.2 MeV excitation energy with T-1/2 = 7.8(14) and 89(9) ns is also presented. These isomers at high excitation energies reflect a pronounced change in the structure above the previously established level scheme, where moderate quadrupole collectivity and octupole correlations were evident.

The elemental composition of about 60 items of precious and non‐precious jewelry in the Indian retail market has been explored through x‐ray fluorescence (XRF) measurements using silicon drift and high‐purity germanium detectors. The proportions of various elements have been established through the use of Gaussian fitting and background subtraction routines, along with corrections for photopeak detection efficiencies at different energies. Tabulated XRF yields were accounted for in the determination of proportions however matrix correction and absorption enhancement effects, if present, could not be included. The non‐destructive characterization and quantification allowed by x‐ray spectrometric methods indicate the presence of significant amounts of toxic bromine and antimony in fashion jewelry. A disturbing trend observed in many items of non‐precious, metal imitation jewelry is that carcinogenic cadmium is the predominant constituent (around 80% w/w) which poses a significant health hazard for a large section of the population. The proportion of cadmium is found to be far greater than the minor fractions reported earlier. It has been determined that cadmium continues to be added to precious jewelry, albeit in smaller amounts, though its use is restricted by existing regulations. This pan‐Indian study underscores the urgent necessity to inspect and regulate, particularly the metal imitation and fashion jewelry business, in order to mitigate the harmful effects of some of the constituent elements on human health and the environment.

Isomeric states and associated collective structures have been studied up to high spin in $^{198,200,202}\mathrm{Hg}$ using multinucleon transfer reactions and the Gammasphere array. A coupled rotational band, with possible four-quasiparticle character, is established in $^{198}\mathrm{Hg}$. Sequences built on two-quasiparticle, positive- and negative-parity levels are assigned to $^{202}\mathrm{Hg}$. New isomers in $^{202}\mathrm{Hg}$ with ${I}^{\ensuremath{\pi}}=({7}^{\ensuremath{-}})$ and $({9}^{\ensuremath{-}})$, and ${T}_{1/2}$ = 10.4(4) ns and 1.4(3) ns, respectively, have been identified. A half-life of 1.0(3) ns is established for the ${I}^{\ensuremath{\pi}}={12}^{+}$ state in $^{200}\mathrm{Hg}$. $B(E2)$ values deduced from isomeric transitions in Hg isotopes indicate that, while collectivity near the ground state gradually diminishes from $N$ = 112 to $N$ = 124, it is found to increase for the ${12}^{+}$ and ${9}^{\ensuremath{-}}$ states up to $N$ = 118, followed by a reduction for higher neutron numbers. Calculations using the ultimate cranker code provide insight into the variation of deformation with spin and allow for an understanding of observed band crossings. The evolution of collectivity with spin, and along the isotopic chain, is described.

Nonyrast, excited states in neutron-rich W-186 were populated via inelastic-scattering reactions using beams of Xe-136 nuclei accelerated to 725 and 800 MeV. Levels populated in the reactions were investigated via particle-lambda coincidence techniques using the Gammasphere array of high-purity germanium detectors and the compact heavy-ion counter, CHICO2. The K-pi = 2(+) (gamma), K-pi = 0(+) and K-pi = 2(-) (octupole) rotational side bands were extended to spins 14 (h) over bar, 12 (h) over bar, and 13 (h) over bar, respectively. A staggering pattern observed in the energies of levels in the K-pi = 2(+) band was found to be consistent with a potential that gets softer to vibration in the gamma degree of freedom with increasing spin. The odd-even staggering of states in the K-pi = 2(-) band was found to exhibit a phase opposite to that seen in the. band; an effect most probably associated with Coriolis coupling to other, unobserved octupole vibrational bands in 186W.

Lifetimes of states in the negative-parity band, based on the $$\nu (h_{11/2})$$ orbital in $$^{103}\hbox {Pd}$$ , have been measured in the spin range from 27/2 to 39/2 using the Doppler-Shift Attenuation Method. The inferred B(E2) values are observed to decrease with increasing angular momentum and $${\mathcal {J}}^{\text {(}2\text {)}}/$$ B(E2) values are found to be large (> 300 $$\hbar ^2\hbox {MeV}^{-1}\hbox {(eb)}^{-2}$$ ). These observations along with calculations based on the semiclassical particle-rotor model approach suggest that antimagnetic and collective rotation, along with gradual neutron alignment are responsible for angular momentum generation in the band under consideration.

Madhu1,∗ A. Y. Deo1,† Pragati1, Khamosh Yadav1, S. K. Tandel2, S. S. Bhattacharjee3, S. Chakraborty4, S. Rai5, S. G. Wahid2, S. Kumar6, S. Muralithar3, R. P. Singh3, Indu Bala3, Ritika Garg3, and A. K. Jain1,7 1Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, INDIA 2UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Mumbai 400098, INDIA 3Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, INDIA 4Dept. of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005, INDIA 5Department of Physics, Visva-Bharati, Santiniketan 731235, INDIA 6Dept. of Physics and Astrophysics, University of Delhi, New Delhi 110007, INDIA and 7Amity Inst. of Nucl. Sci. & Tech., Amity University, Noida 201303, INDIA