Search

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.

The GALILEO array is a high-efficiency γ -ray spectrometer, resident at the Legnaro National Laboratory (LNL)in Italy, and it is currently used in combination with the Si-ball EUCLIDES for the detection of charged-particles. The combined setup was used in the 6 Li+89Y experiment with incident energies of 22 MeV and 34 MeV to investigate the influence of breakup and transfer of weakly bound projectile on the fusion process. Using the coincidence by the charged particles and γ -rays, the different reaction channels can be clearly identified and the different reaction mechanisms can be clearly studied. It is shown that this facility can be used well to explore the fusion reaction mechanisms induced by weakly bound nuclei.

Gamma-ray angular distributions in oriented $$^{92}$$ Mo produced via the $$^{6}$$ Li+ $$^{89}$$ Y reaction were studied in this work. The characteristic $$\gamma $$ rays in $$^{92}$$ Mo were measured by means of the GALILEO array, which is composed of 25 Compton-suppressed HPGe detectors arranged in a nearly 2 $$\pi $$ geometry. A detailed analysis of the spin-alignment attenuation factors ( $$\alpha _2$$ ) for different excited states in $$^{92}$$ Mo was performed, by analyzing the measured angular distribution coefficients of several pure-E2 transitions. The relationship between $$\alpha _2$$ and the spin was established in $$^{92}$$ Mo and the 244-keV transition between the 5 $$^-_1$$ and 4 $$^+_1$$ states resulted to have a E1 + M2 character with a mixing ratio ( $$\delta $$ ) of $$-0.05^{+0.05}_{-0.06}$$ , consistent with shell model calculations.

The high-spin structure of $$^{109}\hbox {In}$$ was investigated with the $$^{100}\hbox {Mo}(^{14}\hbox {N},\, 5\hbox {n})^{109}\hbox {In}$$ fusion-evaporation reaction at CIAE, Beijing. Eleven new $$\gamma $$-rays of $$^{109}\hbox {In}$$ were identified, by which the bandheads of the $$\varDelta \textit{I}$$ = 2 rotational bands were confirmed. The configurations were assigned with the help of the systematic discussion. Furthermore, the rotational bands are compared with the tilted-axis cranking calculations based on a relativistic mean-field approach. The rotational bands involving the 1p1h excitation to the $$\pi d_{5/2}$$ and $$\pi g_{7/2}$$ orbitals are suggested as candidates for antimagnetic rotation based on the theoretical results.

Aydın, Sezgin ( Aksaray, Yazar ), Level structures of Rn212 have been studied by in-beam γ-ray spectroscopic methods using the Bi209(Li6,3n)Rn212 reaction at beam energies of 28, 30, and 34 MeV. A number of new nonyrast states based on πh9/24 and πh9/23f7/2 configurations have been identified. A 3(-) collective state is also proposed at 2121 keV, which is most likely formed by mixing the octupole vibration with the 3- member of the πh9/23i13/2 multiplet. The level scheme is compared with large-scale shell model calculations and discussed in terms of excitations of valence protons and without contributions from the Pb208 core. An overall excellent agreement is obtained for states that can be described in this model space.

Adenosine triphosphate (ATP) borate ester as a new boron agent for boron neutron capture therapy was tested. It was synthesized via a dehydration reaction induced by heating adenosine triphosphate disodium with boric acid. Next, ATP borate ester pretreatments were assessed to study their effects on cell sensitization from exposure to thermal neutron irradiation emitted by a nuclear reactor. Using cell viability assays (CCK8), survival rates of A549 cells pretreated with or without boron-containing agents, including ATP borate ester and 4-dihydroxyborylphenylalanine (BPA), were measured. One week after feeding an ATP borate ester solution to tumor-bearing nude mice, elemental B content values of tumor muscle and blood were measured using inductively coupled plasma mass spectrometry (ICP-MS). Meanwhile, other tumor tissue samples were placed in a culture medium, subjected to a 3-min neutron irradiation exposure, and then fixed in formalin 24 h later for the terminal-deoxynucleotidyl transferase (TDT)-mediated dUTP nick end labeling (TUNEL) immunohistochemical staining analysis. Results showed that A549 cell irradiation sensitization (irradiation dose of 0.33 Gy) varied with pretreatment. Sensitization values of the ATP borate ester pretreatment group were 1.3–14.1 with boron agent concentrations of 0.3–4.5 mM. Within 1.1–3.4 mM, ATP borate ester showed significantly higher sensitization values than BPA. Meanwhile, TUNEL results demonstrated that apoptosis rates of tumor tissue cells exposed to irradiation after ATP borate ester pretreatment significantly exceeded the corresponding rates for BPA-pretreated cells. In animal experiments, although the distribution ratio of ATP borate ester (tumor tissue/normal muscle, T/N) of 1.2 was not significantly different compared with that of BPA (1.3), the total ATP borate ester concentration in the tumor tissue (0.79 ± 0.05 μg/g) significantly exceeded that of BPA (0.58 ± 0.05 μg/g). Thus, compared with BPA, the greater enrichment of ATP borate ester in tumor tissues permits preferential targeting toward tumor cells for radiation sensitization. Therefore, ATP borate ester is superior to BPA for use in boron neutron capture therapy.

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 heavy ion fusion–evaporation reaction study for the high-spin spectroscopy of 75As has been performed via the reaction channel 70Zn(9Be, 1p3n)75As at a beam energy of 42 MeV. The collective structure especially a dipole band in 75As is established for the first time. The properties of this dipole band are investigated in terms of the self-consistent tilted axis cranking covariant density functional theory. Based on the theoretical description and the examination of the angular momentum components, this dipole band can be interpreted as a novel stapler band, where the valence neutrons in ( 1 g 9 / 2 ) orbital rather than the collective core are responsible for the closing of the stapler of angular momentum.

High-spin states in $^{92}\mathrm{Nb}$ have been investigated by using in-beam $\ensuremath{\gamma}$ ray spectroscopy with the $^{82}\mathrm{Se}(^{14}\mathrm{N},4\mathrm{n})^{92}\mathrm{Nb}$ reaction at a beam energy of 54 MeV. The positive-parity decay sequences above the previously known state ${13}^{+}$ have been extended to ${I}^{\ensuremath{\pi}}\ensuremath{\ge}({20}^{+})$ by adding nineteen new $\ensuremath{\gamma}$ rays. The level structures in $^{92}\mathrm{Nb}$ have been interpreted in terms of the shell model calculations performed in the configuration space $\ensuremath{\pi}(1{f}_{5/2},2{p}_{3/2},2{p}_{1/2},1{g}_{9/2})$ for the protons and $\ensuremath{\nu}(2{p}_{1/2},1{g}_{9/2},1{g}_{7/2},2{d}_{5/2})$ for the neutrons. The calculated results show that the inclusion of proton core excitation relative to the $Z=38$ subshell closure and neutron particle-hole excitation for the $N=50$ shell closure are essential to adequately describe the experimental high-spin states at $I\ensuremath{\approx}(18--20)\ensuremath{\hbar}$ with excitation energies above 8.5 MeV.

This short paper presents the investigation of reaction mechanism induced by 6Li through a particle­γ coincidence measurement. The data have been taken from a 6Li+89Y experimentwhich is performed inINFN-LNL, Italy. In this experiment, the light charged particles are detected by a Si­ball, named EUCLIDES, and the γ rays are collected by a HPGe detector array, called GALILEO. In this contribution, scientific motivations, experimental details and some results, such as α­γ analysis, are presented.

Excited states of odd-odd nucleus 92Nb and odd-A nucleus 93Nb were populated in the 6Li+ 89Y reaction with an incident energy of 34 MeV. The processes that produce 92,93Nb and can be measured by a combination of light charged particle and gamma ray measurements are discussed. Twenty new transitions are observed and eight new levels are constructed in 92Nb, and in addition two new transitions are added to the level scheme of 93Nb. Using shell model calculations, the low-lying structure of 92Nb is investigated and compared with the experimental results.

Experimental elastic scattering angular distributions of 11B, 12C, and 16O + heavy-ions are used to study the Woods-Saxon potential parameters. Best fitted values of the diffuseness parameters are found for each system, and a linear relationship is expressed between the diffuseness parameters and . The correlation of the potential depth and radius parameters with is also revealed within the limitations of the diffuseness parameter formula. Because the incident energies of most of the analyzed reactions are below or around the Coulomb barrier, the energy dispersion relation between the real and imaginary potentials is considered in order to investigate the ratio between the imaginary and real potential well depths, resulting in an expression of . Within the limitation of the volume integrals calculated with the S o Paulo potential, parameterized formulas for the depth and radius parameters are obtained. The systematic Woods-Saxon potential parameters derived in the present work can reproduce not only the experimental data of elastic scattering angular distributions induced by 11B, 12C, and 16O but also some elastic scattering induced by other heavy-ions.

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.

The high-spin structure of $^{109}\mathrm{In}$ has been investigated with the $^{100}\mathrm{Mo}(^{14}\mathrm{N}$, $5n)^{109}\mathrm{In}$ reaction at a beam energy of 78 MeV using the in-beam $\ensuremath{\gamma}$ spectroscopic method. The level scheme of $^{109}\mathrm{In}$ has been modified considerably and extended by 46 new $\ensuremath{\gamma}$ rays to the highest excited state at 8.980 MeV and ${J}^{\ensuremath{\pi}}=(45/{2}^{+})$. The new level scheme consists of eight bands, six of which are identified as dipole bands. The configurations have been tentatively assigned with the help of the systematics of neighboring odd-$A$ indium isotopes and the experimental aligned angular momenta. The dipole bands are then compared with the titled axis cranking calculation in the framework of covariant density function theory. The results of theoretical calculations based on the configurations, which involve one proton hole at the ${g}_{9/2}$ orbital and two or four unpaired neutrons at the ${g}_{7/2}$, ${d}_{5/2}$, and ${h}_{11/2}$ orbitals, show that the shape of $^{109}\mathrm{In}$ undergoes an evolution on both $\ensuremath{\beta}$ and $\ensuremath{\gamma}$ deformations, and possible chirality is suggested in $^{109}\mathrm{In}$.

Several zirconium isotopes are in the path of slow neutron capture (s) process, and the direct components of ($n,\ensuremath{\gamma}$) reactions can be derived from their neutron spectroscopic factors. In the present work, the angular distributions of ($^{12}\mathrm{C},^{13}\mathrm{C}$) and ($^{13}\mathrm{C},^{12}\mathrm{C}$) reactions on targets $^{90,92,94,96}\mathrm{Zr}$ were obtained using the high-precision Q3D magnetic spectrograph at the Beijing HI-13 tandem accelerator in China Institute of Atomic Energy. The distorted-wave Born approximation calculations were performed to extract the spectroscopic factors, using three different sets of Woods-Saxon potential parameters for these heavy-ion systems. The neutron spectroscopic factors for the ground state of $^{90--97}\mathrm{Zr}$ have been obtained and compared with other experimental data.

Background: The fusion reaction 12C+30Si is a link between heavier cases studied in recent years, and the light heavy-ion systems, e.g., 12C+12C, 16O+16O that have a prominent role in the dynamics of stellar evolution. 12C+30Si fusion itself is not a relevant process for astrophysics, but it is important to establish its behavior below the barrier, where couplings to low-lying collective modes and the hindrance phenomenon may determine the cross sections. The excitation function is presently completely unknown below the barrier for the 12C+30Si reaction, thus no reliable extrapolation into the astrophysical regime for the C+C and O+O cases can be performed. Purpose: Our aim was to carry out a complete measurement of the fusion excitation function of 12C+30Si from well below to above the Coulomb barrier, so as to clear up the consequence of couplings to low-lying states of 30Si, and whether the hindrance effect appears in this relatively light system which has a positive Q value for fusion. This would have consequences for the extrapolated behavior to even lighter systems. Methods: The inverse kinematics was used by sending 30Si beams delivered from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro onto thin 12C (50μg/cm2) targets enriched to 99.9% in mass 12. The fusion evaporation residues (ER) were detected at very forward angles, following beam separation by means of an electrostatic deflector. Angular distributions of ER were measured at Ebeam=45, 59, and 80 MeV, and they were angle integrated to derive total fusion cross sections. Results: The fusion excitation function of 12C+30Si was measured with high statistical accuracy, covering more than five orders of magnitude down to a lowest cross section ≃3μb. The logarithmic slope and the S factor have been extracted and we have convincing phenomenological evidence of the hindrance effect. These results have been compared with the calculations performed within the model that considers a damping of the coupling strength well inside the Coulomb barrier. Conclusions: The experimental data are consistent with the coupled-channels calculations. A better fit is obtained by using the Yukawa-plus-exponential potential and a damping of the coupling strengths inside the barrier. The degree of hindrance is much smaller than the one in heavier systems. Also a phenomenological estimate reproduces quite closely the hindrance threshold for 12C+30Si, so that an extrapolation to the C+C and O+O cases can be reliably performed.

The measurement of one-neutron stripping cross sections for the $^{89}\mathrm{Y}(^{6}\mathrm{Li},^{5}\mathrm{Li})^{90}\mathrm{Y}^{*}$ reaction at 22 MeV and 34 MeV is reported, using both in-beam and off-beam $\ensuremath{\gamma}$-ray spectroscopy methods. Characteristic $\ensuremath{\gamma}$ lines of $^{90}\mathrm{Y}$ are clearly identified by both the $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ and proton-$\ensuremath{\gamma}$ coincidence methods. The obtained cross section of one-neutron stripping at 34 MeV is found to be much smaller than that at 22 MeV. The one-neutron stripping cross sections measured for this system have the same order of magnitude as the one measured for the same reaction for the $^{6}\mathrm{Li}+^{96}\mathrm{Zr}$ system at energies around the Coulomb barrier. Parameter-free coupled reaction channel calculations agree quite well with the experimental data. Theoretical study of the effect of the one-neutron transfer on the elastic total fusion cross section is performed.

Investigation of the breakup and transfer effect of weakly bound nuclei on the fusion process has been an interesting research topic in the past several years. In comparison with radioactive ion beam (RIB), the beam intensities of stable weakly bound nuclei such as 6,7Li and 9Be, which have significant breakup probability, are orders of magnitude higher. Precise fusion measurements induced by these nuclei have already been performed. However, the conclusion of reaction dynamics was not clear and has contradiction. In order to have a proper understanding of the influence of breakup and transfer of weakly bound projectiles on the fusion process, the 6Li+89Y experiment with incident energies of 22 MeV and 34 MeV was performed on Galileo array in combination with Si-ball EUCLIDES at Legnaro National Laboratory (LNL) in Italy. Using the coincidence by the charged particles and γ-rays, the different reaction channels can be clearly identified.

Excited states of the odd–odd nucleus 74 As have been investigated via heavy ion fusion evaporation reaction Zn 70 ( Li 7 , 3 n ) As 74 at beam energy of 30 MeV. The properties of the positive- and the negative- parity bands can be interpreted in terms of the Cranked Nilsson–Strutinsky (CNS) model calculations which show that the observed bands are built on the triaxial deformed shape. The inversion of the favored and unfavored signature branches observed in the positive-parity bands presents at high spins rather than normal signature inversion occurs at low spins. This phenomenon may be explained as the origin of unpaired band crossing in a highly rotating triaxial nucleus.

The semimagic nucleus $^{89}\mathrm{Y}$ has been investigated using the $^{82}\mathrm{Se}(^{11}\mathrm{B},4n)$ reaction at beam energies of 48 and 52 MeV. More than 24 new transitions have been identified, leading to a considerable extension of the level structures of $^{89}\mathrm{Y}$. The experimental results are compared with the large-basis shell model calculations. They show that cross-shell neutron excitations play a pivotal role in high-spin level structures of $^{89}\mathrm{Y}$. The systematic features of neutron-core excitations in the $N=50$ isotones are also discussed.

High spin states of 114In were investigated via the reaction Pd 110 ( Li 7 , 3 n ) at beams energy of 26 and 28 MeV. The newly observed magnetic dipole bands of 114In in the experiment have been investigated employing the self-consistent tilted axis cranking relativistic mean-field theory based on a point-coupling interaction. A large backbend in the yrast band has been reproduced by the theory based on configuration involving alignment of a pair of positive-parity g 7 / 2 / d 5 / 2 neutrons. According to the experimental characteristics and theoretical calculations, the positive-parity dipole band has been assigned as a magnetic rotation band. In addition, the experimental results are also compared with a semiclassical geometric model that employs effective interactions between the proton holes and neutrons as an alternate interpretation for the shears mechanism.

The perception of bitter taste, as a defensive mechanism against ingestion of toxins, plays a very vital role in animal’s life because it can help animals avoid intake of poisonous substances. The ability of bitter taste detecting is extremely differential among vertebrates, which may mainly be due to their diverse living environment and dissimilar food preference. The bitter taste perception is initially mediated by the interaction between bitter tastants and their receptors. Thus, the studies of bitter taste genes ( T2R ) provide us an opportunity to understand the molecular basis of bitter taste perception. More recently, more and more ligands of bitter taste receptors were described in vitro functional assays. On the other hand, with the available of many vertebrate genome sequences, the study on the evolution of bitter taste receptor gene has got great progress. Studying evolutionary force can trace the change patterns of the function of bitter taste receptors in different species which can help us find more ligands of bitter taste receptors. In this review, we focus on the latest advances on the function and evolution of T2R gene family in vertebrates. Then, we propose some visions on the future studies of T2R gene family.

Excited states of the odd-odd nucleus $^{158}\mathrm{Tb}$ have been studied via the $^{154}\mathrm{Sm}(^{7}\mathrm{Li},3n)^{158}\mathrm{Tb}$ reaction at a beam energy of 27 MeV. The new level scheme of $^{158}\mathrm{Tb}$ involving a positive parity rotational band is established up to excitation energy $\ensuremath{\sim}2.3\phantom{\rule{4.pt}{0ex}}\mathrm{MeV}$ and spin $\ensuremath{\sim}17\ensuremath{\hbar}$. By comparing with the rotational bands in the neighboring nuclei $^{157}\mathrm{Tb}$ and $^{157}\mathrm{Gd}$, the configuration was tentatively assigned as $\ensuremath{\pi}{d}_{5/2}\ensuremath{\bigotimes}\ensuremath{\nu}{i}_{13/2}$, and the phenomenon of signature inversion is discussed.

Measurements of complete and incomplete fusion cross sections for $^{6}\mathrm{Li}+^{154}\mathrm{Sm}$ have been performed at energies above the Coulomb barrier by the online $\ensuremath{\gamma}$-ray method, to investigate the effect of breakup and inelastic couplings on the complete fusion (CF) of this weakly bound system. We show that inelastic excitation couplings have non-negligible effects, when compared with the breakup effect, for deformed nuclei at energies very close to the Coulomb barrier. The average CF suppression corresponding to dynamic breakup effects was found to be around 35%. The total fusion cross section is not affected by the breakup coupling. A comparison between the $^{6}\mathrm{Li}$-induced CF suppression for three different samarium isotopes shows that the breakup effect is larger for the more spherical isotope.

The measurements of complete fusion cross sections for $^{6}\mathrm{Li}+^{96}\mathrm{Zr}$ have been performed at energies around the Coulomb barrier by the online $\ensuremath{\gamma}$-ray method. The complete fusion cross sections at above-barrier energies were found to be suppressed by $\ensuremath{\sim}25%$. A comparison of the systematics of complete fusion suppression with the existing data for $^{6}\mathrm{Li}$+ heavy targets with the present results shows that the systematics of the suppression factor observed for $^{6}\mathrm{Li}$-induced fusion in the heavy mass region may not be consistent in lighter target mass region.

Investigation of the breakup and transfer effect of weakly bound nuclei on the fusion process has been an interesting research topic in the past several years. However, owing to the low intensities of the presently available radioactive ion beam (RIB), it is difficult to clearly explore the reaction mechanisms of nuclear systems with unstable nuclei. In comparison with RIB, the beam intensities of stable weakly bound nuclei such as 6,7 Li and 9 Be, which have significant breakup probability, are orders of magnitude higher. Precise fusion measurements have already been performed with those stable weakly bound nuclei, and the effect of breakup of those nuclei on the fusion process has been extensively studied. Those nuclei indicated large production cross sections for particles other than the α + x breakup. The particles are originated from non-capture breakup (NCBU), incomplete fusion (ICF) and transfer processes. However, the conclusion of reaction dynamics was not clear and has the contradiction.In our previous experiments we have performed 6 Li+96 Zr and 154 Sm at HI-13 Tandem accelerator of China Institute of Atomic Energy (CIAE) by using HPGe array. It is shown that there is a small complete fusion (CF) suppression on medium-mass target nucleus 96 Zr different from about 35% suppression on heavier target nucleus 154 Sm at near-barrier energies. It seems that the CF suppression factor depends on the charge of target nuclei. We also observed one neutron transfer process. However, the experimental data are scarce for medium-mass target nuclei.In order to have a proper understanding of the influence of breakup and transfer of weakly bound projectiles on the fusion process, we performed the 6 Li+89 Y experiment with incident energies of 22 MeV and 34 MeV on Galileo array in cooperation with Si-ball EUCLIDES at Legnaro National Laboratory (LNL) in Italy. Using particle-particle and particle-γ coincidences, the different reaction mechanisms can be clearly explored.

The lifetime of the ${2}_{1}^{+}$ state in $^{178}\mathrm{Pt}$ was measured by using fast-timing techniques with the high-purity Ge and ${\mathrm{LaBr}}_{3}:\mathrm{Ce}$ array using the $^{154}\mathrm{Gd}$(${}^{28}\mathrm{Si},4n$) reaction at a beam energy of 146 MeV. The deduced $B(E2,{2}_{1}^{+}\ensuremath{\rightarrow}{0}_{1}^{+})$ strength is discussed in relation to the systematics of the previously reported $B(E2,{2}_{1}^{+}\ensuremath{\rightarrow}{0}_{1}^{+})$ strengths in the light even-even ${}^{176--184}\mathrm{Pt}$ isotopes and compared with calculations of the generator coordinate method. The present results support a configuration-mixing interpretation for low-spin states in these light Pt isotopes.

The high-spin spectroscopy of ${}^{144}\mathrm{Tb}$ has been studied via ${}^{116}$Sn(${}^{32}S$, $3n1p$)${}^{144}\mathrm{Tb}$ fusion-evaporation reaction at a beam energy of 156 MeV. A dipole band built on the $\ensuremath{\pi}{h}_{11/2}^{3}\ensuremath{\bigotimes}\ensuremath{\nu}{h}_{11/2}^{\ensuremath{-}1}$ configuration is newly observed in ${}^{144}\mathrm{Tb}$. Together with similar observation in neighboring nuclei, the properties of dipole bands in $N=79$ isotones are investigated in terms of the self-consistent tilted-axis-cranking covariant density functional theory. Based on systematic comparison and examination of the shears mechanism, the dipole band in ${}^{144}\mathrm{Tb}$ can be interpreted as a magnetic rotational band.

The high-spin states in 86Sr have been investigated by using in-beam $ \gamma$ -ray spectroscopy with the 82Se(9Be, 5n)86Sr reaction at a beam energy of 53 MeV. The level scheme of 86Sr has been extended considerably, four decay sequences have been established. The observed level schemes are compared with shell-model calculations using the recently developed residual interaction “jun45”, and a good agreement is shown.

The high-spin level structure of the semi-magic nucleus $^{91}\mathrm{Nb}$ has been investigated via the ${}^{82}$Se(${}^{14}$N,$5n$)$^{91}\mathrm{Nb}$ reaction at a beam energy of 60 MeV. Based on these experimental results, a new level scheme is established that modifies and extends earlier schemes. Shell-model calculations have been carried out to interpret the level structure of $^{91}\mathrm{Nb}$. The calculated results show that the inclusion of neutron particle-hole excitation across the $N=50$ shell gap is essential to adequately describe states above $I=(21/2\phantom{\rule{0.16em}{0ex}}--\phantom{\rule{0.16em}{0ex}}23/2)\ensuremath{\hbar}$, with excitation energies above $\ensuremath{\sim}$6.0 MeV.

The excited states in ${}^{107}$Ag were populated through the heavy-ion fusion evaporation reaction ${}^{100}$Mo (${}^{11}$B, 4$n$) ${}^{107}$Ag at a beam energy of 46 MeV. Lifetimes of high-spin states in ${}^{107}$Ag have been measured through the Doppler shift attenuation method. The deduced $B(M1)$ values, gradually decreasing with increasing spin, clearly demonstrate that both the yrast positive-parity band and the yrast negative-parity band in ${}^{107}$Ag are magnetic rotation bands. Furthermore, experimental deduced $B(M1)$ values for the yrast positive-parity band are compared with the predictions of the particle rotor model. The approximate agreement between theoretical calculations and experimental results further confirms the mechanism of magnetic rotation for the yrast positive-parity band. In addition, a systematic investigation shows the evolution of the magnetic rotation mechanism in the $A\ensuremath{\approx}110$ mass region.

The high-spin level structure of the doubly odd nucleus ${}^{104}$Ag has been investigated via the ${}^{97}$Mo(${}^{11}$B, 4n)${}^{104}$Ag reaction at a beam energy of 50 MeV. The newly established level scheme includes lower-lying two-quasiparticle states and several higher-lying bands. Two positive-parity bands associated with the $\ensuremath{\pi}{g}_{9/2}^{\ensuremath{-}1}\ensuremath{\bigotimes}\ensuremath{\nu}{d}_{5/2}$ and $\ensuremath{\pi}{g}_{9/2}^{\ensuremath{-}1}\ensuremath{\bigotimes}\ensuremath{\nu}{g}_{7/2}$ configurations are extended significantly. Based on the comparison with the analogous structures in neighboring nuclei and the features of nuclear chirality, the negative parity bands are suggested as candidate chiral doublet bands with the $\ensuremath{\pi}{g}_{9/2}^{\ensuremath{-}1}\ensuremath{\bigotimes}\ensuremath{\nu}{h}_{11/2}$ configuration.

The low spin states of ${}^{138}$Nd have been reinvestigated via the ${}^{124}$Te(${}^{19}$F,$4n1p$) reaction at a beam energy of 103 MeV. The quasi-one-phonon $\ensuremath{\gamma}$-vibrational band based on the 1013.7 keV level has been expanded and the quasi-two-phonon $\ensuremath{\gamma}$-vibrational band built on the 1842.7 keV level has been proposed. A systematic comparison supports our assignments for multiphonon $\ensuremath{\gamma}$-vibrational bands in ${}^{138}$Nd. The characteristics of $\ensuremath{\gamma}$ softness in ${}^{138}$Nd have been discussed. Triaxial projected shell model calculations can well describe the rotational feature of the bands, but they fail to reproduce simultaneously the bandhead energies of the two $\ensuremath{\gamma}$-vibrational bands if a fixed triaxial deformation is assumed.

The asymptotic normalization coefficients (ANCs) of the virtual decay 16N → 15N + n are extracted from the 15N(7Li, 6Li)16N reaction populating the ground and first three excited states in 16N. The root-mean-square (rms) radii of the valence neutron in these four low-lying 16N states are then derived by using the ANCs. The probabilities of the valence neutron staying out of the core potentials are found to be 31% ± 8%, 58% ± 12%, 32% ± 8%, and 60% ± 12%. The present results support the conclusion that a one-neutron halo may be formed in the 16N first and third excited states, while the ground and second excited states do not have a one-neutron halo structure. However, the core excitation effect has a strong influence on the one-neutron halo structure of the ground and first excited states in 16N.

High-spin states in doubly odd ${}^{88}$Y have been investigated using the ${}^{82}$Se(${}^{11}$B, 5$n$) reaction at beam energies of 48 and 52 MeV. On the basis of the $\ensuremath{\gamma}$-$\ensuremath{\gamma}$ coincidence relationships, the level scheme of ${}^{88}$Y has been extended up to an excitation energy of 9.5 MeV at spin 21$\ensuremath{\hbar}$. About 20 new levels and 30 new transitions have been added into the level scheme, and spin-parity assignments have been made to most of the newly proposed levels. In order to better understand the nuclear structure of ${}^{88}$Y, semiempirical shell-model calculations were carried out considering a valence space formed by the proton 1${p}_{1/2}$, 1${p}_{3/2}$, 0${f}_{5/2}$, 0${g}_{9/2}$ and neutron 0${g}_{9/2}$ orbitals.

Background: ${}^{139}$Pr is located in a transitional region of neutron number close to the $N=82$ shell. The study of its high-spin states and collective bands is important for systematically understanding the nuclear structural characteristics in this region.Purpose: To investigate the high-spin levels and to search for oblate bands in ${}^{139}$Pr.Methods: The high-spin states of ${}^{139}$Pr have been studied via the reaction ${}^{124}$Sn(${}^{19}$F,4$n$) at a beam energy of 80 MeV. The experiment was carried out at the HI-13 Tandem Accelerator at the China Institute of Atomic Energy (CIAE). The data analysis was done by using the $\ensuremath{\gamma}$-$\ensuremath{\gamma}$ coincidence method.Results: The level scheme of ${}^{139}$Pr has been expanded with spin up to 45/2$\ensuremath{\hbar}$. A total of 39 new levels and 45 new transitions are identified. Four collective band structures at high-spin states have been newly established. From systematic analysis, one of the bands is proposed as a double decoupled band; two bands are proposed as oblate bands with $\ensuremath{\gamma}\ensuremath{\sim}\ensuremath{-}{60}^{\ensuremath{\circ}}$; another band is suggested as an oblate-triaxial band with $\ensuremath{\gamma}\ensuremath{\sim}\ensuremath{-}{90}^{\ensuremath{\circ}}$. The other characteristics for these bands are discussed.Conclusions: A new level scheme in ${}^{139}$Pr has been established and the collective bands at high spin have been identified. The result shows that the strong oblate shape-driving effect is caused by neutrons at the high-spin states in ${}^{139}$Pr.

High-spin states in 114In were populated using the reaction 110Pd(7Li, 3n)114In at a beam energy of 26MeV. The level scheme of 114In consisting of six bands is established up to excitation energy ∼ 5MeV and spin ∼ 17 ℏ with the addition of 58 new transitions and their configurations are discussed. The intense positive-parity dipole cascade may be interpreted as shears band based on $ \pi$ [(g 9/2)-1] ⊗ $ \nu$ [(g 7/2/d 5/2)(h 11/2)2] configuration. The $ \Delta$ I = 2 bands based on proton excitation have been observed in 114In for the first time.

High spin states of the odd-A 87Sr were populated by the fusion-evaporation reaction 82Se(9Be,4n) 87Sr at a beam energy of 46 MeV. Excited levels of 87Sr have been extended up to an excitation energy of 7.4 MeV at spin 31/2ħ. The coupling of a g9/2 neutron hole to the yrast states of the 88Sr core can account for the low-lying states in 87Sr. The structure of the higher spin states is discussed by analogy with those of the neighboring odd-A N = 49 isotones and possible configurations are proposed.

High spin states of the odd-odd nucleus 92Nb are investigated using the 82Se (14N, 4n)92Nb reaction at a beam energy of 54 MeV. The level scheme of the 92Nb was extended up to Jπ =(16+) at about 7.3 MeV and Jπ=(21−) at about 9.7 MeV. According to systematic analyses and a comparison with the neighboring nucleus, the higher spin states could be interpreted by the multi-particle excitations in the π(f5/2,p3/2,p1/2,g9/2)⊗ν(p1/2,g9/2,d5/2, g7/2) configuration space.