The Belle II experiment searches for beyond-the-standard-model physics using the Belle II detector and SuperKEKB collider. The silicon vertex detector (SVD) is crucial for particle tracking. After the 1.5-year shutdown from June 2022, Run 2 began in January 2024; Run 2 operation shows stable noise levels, high signal-to-noise ratios, and hit efficiency over 99%. To manage higher beam background from increased luminosity, new techniques such as hit-time selection and cluster grouping are being developed. These methods increase the acceptable level of occupancy by distinguishing hits from triggered collisions and other sources.

To understand the break-up fusion reaction dynamics, the forward recoil range distribution (FRRD) measurements of 12C + 165Ho system at the incident projectile energy of approximate to 88 MeV has been performed. The recoil catcher activation technique followed by the off-line gamma ray spectroscopy was implemented. It is observed that the FRRD measurements of the evaporation residues (ERs) populated via xn and pxn channels have a single Guassian peak at large cumulative thickness. This is attributed to complete momentum transfer from the projectile to the target nucleus. However, in case of the FRRD measurements of the ERs populated via alpha xn, alpha pxn and 2 alpha xn emitting channels, in addition to peak corresponding to complete momentum transfer, the Gaussian peaks at lower cumulative thicknesses are also observed. This is accredited to the breakup fusion. Moreover, the effect of projectile breakup on complete fusion cross section is also studied. The suppression in fusion cross section is observed when compared with the universal fusion function, thus indicating the breakup probability of 12C projectile.

This present study explores the role of incomplete fusion in heavy-ion reactions alongside complete fusion, examining recoil ranges of populated residues. An attempt has been made to distinguish between complete and incomplete fusion contributions by analyzing linear momentum transfer from the projectile to the target nucleus. Employing the recoil-catcher activation technique, forward recoil range distributions for the 19F + 169Tm system at energies around 96 and 106 MeV have been measured. Analysis of these recoil range distributions reveals characteristics of complete and incomplete fusion processes. Complete fusion reactions show larger recoil ranges, signifying comprehensive linear momentum transfer. On the other hand, residues exhibiting smaller recoil ranges result from partial linear momentum transfer due to incomplete fusion of the projectile. The forward recoil range distributions indicate an admixture of full and partial linear momentum transfer components in reactions with a particles in the exit channels. This behavior suggests projectile breakup caused by the Coulomb effect, offering valuable insights into fusion process dynamics.

The fusion excitation functions of evaporation residues, populated through complete fusion and/or incomplete fusion, were measured in the ^18 O+ ^146 Nd system at an incident beam energy of ≈ 3–7 MeV/nucleon. These results were then compared with those obtained from the previously reported ^16 O+ ^148 Nd system. This comparison is particularly relevant since both systems lead to the population of the same compound nucleus, ^164 Er*, in the case of complete fusion, and the same intermediate composite system, ^160 Dy*, in the case of incomplete fusion. Significant enhancements in the measured excitation functions of evaporation residues populated via α -emitting channels indicate the population of such residues via incomplete fusion in addition to complete fusion. Further, a comparison of the measured data for ^18 O+ ^146 Nd and ^16 O+ ^148 Nd systems shows interesting results. The complete fusion and incomplete fusion cross-sections, reduced by three different procedures, are found to satisfactorily match each other, despite the major difference in the α - breakup threshold values of the projectiles ^18 O (6.23 MeV) and ^16 O (7.16 MeV). The effect of different α -breakup threshold values of the projectiles ^18 O and ^16 O was not observed in the comparison of incomplete fusion data for the systems ^18 O+ ^146 Nd and ^16 O+ ^148 Nd. This may be attributed to the fact that the residues populated in the exit channel are emitted from the same intermediate composite system ^160 Dy* and also there is a high resemblance in the entrance channel mass asymmetry and other structural properties of these systems.

Abstract We report results from a study of B±→ DK± decays followed by D decaying to the CP-even final state K+K− and CP-odd final state $$ {K}_S^0{\pi}^0 $$ K S 0 π 0 , where D is an admixture of D0 and $$ {\overline{D}}^0 $$ D ¯ 0 states. These decays are sensitive to the Cabibbo-Kobayashi-Maskawa unitarity-triangle angle ϕ3. The results are based on a combined analysis of the final data set of 772 × 106$$ B\overline{B} $$ B B ¯ pairs collected by the Belle experiment and a data set of 198 × 106$$ B\overline{B} $$ B B ¯ pairs collected by the Belle II experiment, both in electron-positron collisions at the Υ(4S) resonance. We measure the CP asymmetries to be $$ \mathcal{A} $$ A CP+ = (+12.5 ± 5.8 ± 1.4)% and $$ \mathcal{A} $$ A CP− = (−16.7 ± 5.7 ± 0.6)%, and the ratios of branching fractions to be $$ \mathcal{R} $$ R CP+ = 1.164 ± 0.081 ± 0.036 and $$ \mathcal{R} $$ R CP− = 1.151 ± 0.074 ± 0.019. The first contribution to the uncertainties is statistical, and the second is systematic. The asymmetries $$ \mathcal{A} $$ A CP+ and $$ \mathcal{A} $$ A CP− have similar magnitudes and opposite signs; their difference corresponds to 3.5 standard deviations. From these values we calculate 68.3% confidence intervals of (8.5° < ϕ3 < 16.5°) or (84.5° < ϕ3 < 95.5°) or (163.3° < ϕ3 < 171.5°) and 0.321 < rB < 0.465.

Background: The involvement of noncompound nuclear reactions in light and medium-heavy compound nuclei is not fully understood. In this regime, breakup fusion is regarded as the predominant reaction mode among all noncompound nuclear processes and has not been much explored explicitly. Purpose: : A systematic study of the compound nucleus fusion probability of various compound nuclei populated through different target-projectile systems is undertaken to investigate its dependence on various entrance channel parameters. The study provides better insight to determine the onset of noncompound nucleus fusion, due to which compound nucleus fusion probability reduces. Method: In the present investigations, excitation functions of evaporation residues of 40 reactions leading to the formation of the compound nucleus in the mass region approximate to 64-195 have been taken into account from the literature. The compound nucleus fusion probability of these systems was calculated as the ratio of the compound nucleus fusion to the total fusion cross sections. Results: Reduction in compound nucleus fusion probability was observed with an increase in parameters such as the projectile energy, the charge of the target, the total asymmetry, and the critical angular momentum of the different systems. Moreover, the alpha - Q value of the projectiles was found to affect and trigger the noncompound nuclear fusion processes more than other entrance channel parameters. It was also observed from the present analysis that the values of maximum angular momenta are slightly larger than the values of critical angular momenta as extracted from the measured cross sections for the studied systems. Conclusions: The present study reveals the presence of noncompound nuclear fusion reactions in light- and medium-mass compound nuclei. This is mainly because of the loss in the flux of the compound nuclear fusion reaction and the subsequent gain in the flux of the noncompound nuclear fusion reaction. The observations further show that these processes are significantly influenced by the alpha - Q value of the projectiles. These results indicate that noncompound nuclear fusion processes occur in peripheral collisions.

We present a measurement of |V_ub| from a simultaneous study of the charmless semileptonic decays B^0→π^- ℓ^+ ν_ℓ and B^+→ρ^0 ℓ^+ν_ℓ, where ℓ = e, μ. This measurement uses a data sample of 387 million BB meson pairs recorded by the Belle II detector at the SuperKEKB electron-positron collider between 2019 and 2022. The two decays are reconstructed without identifying the partner B mesons. We simultaneously measure the differential branching fractions of B^0→π^- ℓ^+ ν_ℓ and B^+→ρ^0 ℓ^+ν_ℓ decays as functions of q^2 (momentum transfer squared). From these, we obtain total branching fractions B(B^0→π^- ℓ^+ ν_ℓ) = (1.516 ± 0.042 (stat) ± 0.059 (syst)) × 10^-4 and B(B^+→ρ^0 ℓ^+ν_ℓ) = (1.625 ± 0.079 (stat) ± 0.180 (syst)) × 10^-4. By fitting the measured B^0→π^- ℓ^+ ν_ℓ partial branching fractions as functions of q^2, together with constraints on the non-perturbative hadronic contribution from lattice QCD calculations, we obtain |V_ub| = (3.93 ± 0.09 ± 0.13 ± 0.19) × 10^-3. Here, the first uncertainty is statistical, the second is systematic, and the third is theoretical.

An outstanding problem in the heavy-ion (HI)-induced nuclear reactions is understanding the role of incomplete fusion (ICF) and its dependence on various entrance channel parameters relatively at energies slightly above the Coulomb barrier. For this purpose, the excitation functions (EFs) of reaction residues populated in ^14 N+ ^51 V system have been measured at energies ≈ 3–6 MeV/nucleon. The stacked foil activation technique followed by an off-line γ -ray spectrometer with a high-resolution HPGe detector has been employed. The measured excitation functions are compared with the theoretical predictions, obtained from statistical model codes PACE4 and ALICE-91. The analysis of the present work suggests that the experimental excitation functions for xn and/or pxn channels are grossly reproduced by the theoretical predictions. However, for α -emitting-channels, the measured EFs are found to be underestimated by the statistical predictions which may be attributed to the breakup fusion of the projectile with the target nucleus. For a better understanding of ICF reaction dynamics, the percentage of ICF fraction has been deduced. The present study in light of the literature data provides insight into the dependence of ICF processes on the projectile structure. Further, some physical parameters such as mass asymmetry of interacting partners, Coulomb interaction between projectile and target ( Z_P Z_T ), and the target deformation parameter ( β _2 ) are also found liable for projectile breakup prior to fusion.

High spin states of 40K populated through the 27Al(19F, alpha np) 40K reaction at 68 MeV beam energy were studied using the Indian National Gamma Array (INGA) facility. Six new levels and fourteen new transitions were added to the existing level scheme. The spins and parities of most of the levels were assigned, modified, or confirmed from RDCO, RADO, and linear polarization measurements. The multipole mixing ratios (8) for most of the transitions were measured. Large -basis shell -model calculations were performed to understand the microscopic origin of the levels. Different particle restrictions in sd and pf shell orbitals were used to explain the experimental results.

An experimental investigation of collisionless shock ion acceleration is presented using a multicomponent plasma and a high-intensity picosecond duration laser pulse. Protons are the only accelerated ions when a near-critical-density plasma is driven by a laser with a modest normalized vector potential. The results of particle-in-cell simulations imply that collisionless shock may accelerate protons alone selectively, which can be an important tool for understanding the physics of inaccessible collisionless shocks in space and astrophysical plasma.

We report the result of a search for the rare decay B0→γγ using a combined dataset of 753×106 BB¯ pairs collected by the Belle experiment and 387×106 BB¯ pairs collected by the Belle II experiment from decays of the ϒ(4S) resonance produced in e+e− collisions. A simultaneous fit to the Belle and Belle II data sets yields 11.0−5.5+6.5 signal events, corresponding to a 2.5σ significance. We determine the branching fraction B(B0→γγ)=(3.7−1.8+2.2(stat)±0.5(syst))×10−8 and set a 90% credibility level upper limit of B(B0→γγ)<6.4×10−8. Published by the American Physical Society 2024

The emission of auger electrons from 161Ho makes it as a potential candidate for Auger electronic therapy. Despite several methods for its production are proposed, it remains scarcely available. Most of the direct methods using low-energy protons and deuterons beams result in a high content of radionuclidic impurities. Hence, an alternative method for the production of 161Ho has been proposed. Experimental excitation functions in 16O induced reactions were measured with the activation method in the 69–100 MeV energy range on 154Sm targets. To measure the cross-section data for producing 161Ho, the stacked foil irradiation method along with high-resolution gamma-ray spectrometry was employed. The experimental data are compared with results of PACE4 and EMPIRE-3.2.2 theoretical codes. It was observed that the 161Ho radioisotope is produced via incomplete fusion. The production route suggested has no impurities of Holmium isotopes.

During the first half of the fourth observing run (O4a) of the International Gravitational Wave Network (IGWN), the Zwicky Transient Facility (ZTF) conducted a systematic search for kilonova (KN) counterparts to binary neutron star (BNS) and neutron star-black hole (NSBH) merger candidates. Here, we present a comprehensive study of the five high-significance (FAR < 1 per year) BNS and NSBH candidates in O4a. Our follow-up campaigns relied on both target-of-opportunity observations (ToO) and re-weighting of the nominal survey schedule to maximize coverage. We describe the toolkit we have been developing, Fritz, an instance of SkyPortal, instrumental in coordinating and managing our telescope scheduling, candidate vetting, and follow-up observations through a user-friendly interface. ZTF covered a total of 2841 deg$^2$ within the skymaps of the high-significance GW events, reaching a median depth of g~20.2 mag. We circulated 15 candidates, but found no viable KN counterpart to any of the GW events. Based on the ZTF non-detections of the high-significance events in O4a, we used a Bayesian approach, nimbus, to quantify the posterior probability of KN model parameters that are consistent with our non-detections. Our analysis favors KNe with initial absolute magnitude fainter than -16 mag. The joint posterior probability of a GW170817-like KN associated with all our O4a follow-ups was 64%. Additionally, we use a survey simulation software, simsurvey, to determine that our combined filtered efficiency to detect a GW170817-like KN is 36%, when considering the 5 confirmed astrophysical events in O3 (1 BNS and 4 NSBH), along with our O4a follow-ups. Following Kasliwal et al. (2020), we derived joint constraints on the underlying KN luminosity function based on our O3 and O4a follow-ups, determining that no more than 76% of KNe fading at 1 mag/day can peak at a magnitude brighter than -17.5 mag.

In the present investigation, the thermomechanical fatigue (TMF) behavior of Timetal 834 alloy was studied under clockwise diamond (CWD) and counter clockwise diamond (CCD) loading conditions. These tests were conducted within 723 K <-> 873 K temperature range at the strain amplitudes of Delta epsilon m/2 = +/- 0.6% and +/- 1.0%. The cyclic softening behavior observed under CWD-TMF condition at both strain amplitudes, is attributed to shearing of coherent Ti3Al precipitates. Contrarily, the alloy exhibits both cyclic hardening and softening responses under the CCD-TMF conditions. This additional hardening response is attributed to the occurrence of dislocation-dislocation interactions coupled with dynamic strain aging. The present study reveals that both phase angle and strain amplitude affect the TMF life. The alloy exhibited relatively lower fatigue life under CCD-TMF condition than under CWD-TMF condition, at both strain amplitudes. Transmission electron microscopy analyses of the post-deformed specimens reveal that the dislocation arrangements are similar in both loading conditions at Delta epsilon m/2 = +/- 0.6%, while being distinctively different at Delta epsilon m/2 = +/- 1.0%. At higher strain amplitude, the fatigue life is significantly reduced under CCD-TMF condition. Fractographic analyses indicate the involvement of oxidation damage during both the TMF loading conditions. However, its effect is more pronounced under CCDTMF than under CWD-TMF condition.

We measure the branching fraction of the decay $B^- \to D^0 \rho(770)^-$ using data collected with the Belle II detector. The data contain 387 million $B\overline{B}$ pairs produced in $e^+e^-$ collisions at the $\Upsilon(4S)$ resonance. We reconstruct $8360\pm 180$ decays from an analysis of the distributions of the $B^-$ energy and the $\rho(770)^-$ helicity angle. We determine the branching fraction to be $(0.939 \pm 0.021\mathrm{(stat)} \pm 0.050\mathrm{(syst)})\%$, in agreement with previous results. Our measurement improves the relative precision of the world average by more than a factor of two.

The electromagnetic structure of Sc-45 at low excitation energy was investigated via low-energy Coulomb excitation at the Heavy Ion Laboratory (HIL) of the University of Warsaw and at the Inter-University Accelerator Centre (IUAC) in New Delhi. A set of reduced E2, E3, and M1 matrix elements was extracted from the collected data using the GOSIA code. The reduced transition probability B(E2; 11/2(-) -> 7/2(-)) has been determined, allowing us to deduce the lifetime of the 11/2(-) state at 1237 keV. In addition, the upper limit on the reduced transition probability B(E3; 7/2(-) -> 5/2(+)) has been determined for the first time. New large-scale shell-model and beyond-mean-field calculations were performed to interpret the structure of this nucleus.

High spin states in the 96Tc nucleus were populated in the As-75(Si-28, 4p3n) fusion-evaporation reaction at E lab = 120 MeV and the de-excitations were investigated through in-beam gamma-ray spectroscopic techniques using indian national gamma array spectrometer consisting of 18 clover Ge detectors. The present level scheme of the Tc-96 nucleus has been extended substantially with the addition of about forty five new gamma transitions. The level structures in Tc-96 have been established up to excitation energy similar to 10 MeV and angular momentum similar to 25PLANCK CONSTANT OVER TWO PI. Level structures of 96Tc nucleus are discussed in the framework of triaxial projected shell model calculations.

We present a detailed investigation of photometric, spectroscopic, and polarimetric observations of the Type II SN 2023ixf. Earlier studies have provided compelling evidence for a delayed shock breakout from a confined dense circumstellar matter (CSM) enveloping the progenitor star. The temporal evolution of polarization in the SN 2023ixf phase revealed three distinct peaks in polarization evolution at 1.4 days, 6.4 days, and 79.2 days, indicating an asymmetric dense CSM, an aspherical shock front and clumpiness in the low-density extended CSM, and an aspherical inner ejecta/He-core. SN 2023ixf displayed two dominant axes, one along the CSM-outer ejecta and the other along the inner ejecta/He-core, showcasing the independent origin of asymmetry in the early and late evolution. The argument for an aspherical shock front is further strengthened by the presence of a high-velocity broad absorption feature in the blue wing of the Balmer features in addition to the P-Cygni absorption post-16 days. Hydrodynamical light-curve modeling indicated a progenitor mass of 10 M circle dot with a radius of 470 R circle dot and explosion energy of 2 x 1051 erg, along with 0.06 M circle dot of 56 Ni, though these properties are not unique due to modeling degeneracies. The modeling also indicated a two-zone CSM: a confined dense CSM extending up to 5 x 1014 cm with a mass-loss rate of 10-2 M circle dot yr-1 and an extended CSM spanning from 5 x 1014 to at least 1016 cm with a mass-loss rate of 10-4 M circle dot yr-1, both assuming a wind-velocity of 10 km s-1. The early-nebular phase observations display an axisymmetric line profile of [O i], redward attenuation of the emission of H alpha post 125 days, and flattening in the Ks-band, marking the onset of dust formation.