89Y Reaction Research Articles

Decay dynamics of 9Be + 89Y reaction in view of complete and incomplete fusion mechanisms

This work is aimed to explore the reaction mechanism induced via loosely bound projectile (9Be). Various peculiar properties of such projectiles for example low binding energy per nucleon leading to low breakup threshold, larger rms radii, higher transfer probability, captivate the attention of scientists working in related field. Thus, an effort is made to analyze the complete fusion (CF) and incomplete fusion (ICF) contributions in 9Be + 89Y reaction over energy range (Ec.m. = 17.7-29.8 MeV). The projectile used in the present reaction 9Be may dissociate via 5He, 4He and 1n, which subsequently lead to ICF contribution via three different channels. Thus, the cross-sections corresponding to these ICF channels (5He + 89Y→94Nb⁎, 4He + 89Y→93Nb⁎ and 1n+89Y→90Y⁎) are duly examined. The calculations are done for quadrupole (β2-deformed) choice of fragments using optimum orientations approach of dynamical cluster decay model (DCM). The calculated cross-sections for both CF and ICF channels find nice agreement with the available experimental data. Besides this, the CF contributions are estimated for different isotopes of Tc (with ACN = 96-104) and some predictions are made for future validation.

Cross sections of proton capture reactions of Sr isotopes

Cross section measurements of the proton capture reactions of the 86Sr, 87Sr and 88Sr isotopes were carried out at energies Ep=1.4-5 MeV. At Ep <3.5 MeV an array of 4 HPGe detectors with 100% relative efficiency shielded with BGO scintillators for Compton background suppression was used, whereas at Ep >3.5 MeV, the measurements were performed by means of one HPGe detector of 80% relative efficiency. For the 87Sr(p,7)88Y and 88Sr(p,7)89Y reactions total cross sections ranging from 0.5 μο-5 mb were found. The data analysis of the 86Sr(p,7)87Y reaction is in progress. Cross sections have also been calculated by means of the statistical model code MOST. A very good agreement between the experimental data and the theoretical predictions has been found.

Low-lying states of 92,93Nb excited in the reactions induced by the weakly-bound nucleus 6Li near the Coulomb barrier * * Supported by National Natural Science Foundation of China (U1867210, 11775098, 11475013, U1832130 and 11775316)

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.

Structures in angular momentum gated proton and alpha particle spectra in low-energy 12C and 16O induced reactions

Gamma-ray multiplicity gated proton spectra have been measured in the 12C + 93Nb and 16O + 89Y reactions producing the same compound nucleus 105Ag at an excitation energy of ∼39.8 MeV, and in the 12C + 89Y reaction at E(12C) = 40 MeV. Multiplicity gated alpha particle spectra have been measured in the 12C + 93Nb reaction at E(12C) = 37.5–45 MeV. All these measurements were aimed at gaining more insight into the origin of the unexpected broad structures seen earlier in the high energy part of the proton spectra at high gamma-ray multiplicities. Two possible explanations, one of the enhanced nuclear level density within the statistical model and the other of a massive cluster transfer process, were suggested by us to understand the earlier data. The former prescription appears to be favoured by the present proton data.

Study of the 89Y(α,α)89Y reaction close to the Coulomb barrier

In order to check the reliability of global alpha-nucleus optical potential to be used in statistical model calculations, elastic alpha scattering experiments have been carried out at Ec.m. = 18.6 and 15.5 MeV on the even–odd 89Y nucleus. Moreover, the comparison of the elastic scattering cross section of the 89Y(α, α)89Y and the previously measured 92Mo(α, α)92Mo reactions will allow us to investigate the behavior of the optical potential parameters along the N = 50 isotonic chain. The experimental details of the 89Y(α, α)89Y measurement and the angular distributions are presented here.

Symmetric mass division process in the reactions 37Cl+ 68Zn and 16O+ 89Y

To investigate a feature of the symmetric mass division at high angular momentum, distributions of mass, angular and total kinetic energy have been measured with a time-of-flight telescope for the products of symmetric mass division in the 37Cl+ 68Zn and 16O+ 89Y reactions. The widths of the mass and totalkinetic energy distributions are broader than those expected from the liquid drop model.

Proton spectral functions for the hole states in 89Y using a self-consistent microscopic formalism

We have calculated the spectral functions of the proton-hole states in 89Y, using a self-consistent microscopic formalism in order to take into account the effects of particle-vibration coupling. The same effective force, a density dependent force of the Skyrme type, was used to construct the HF single-particle states, to solve the RPA equations and to set up the particle-vibration coupling vertices. The results are compared with recent high resolution measurements on the 90Zr(e, e'p) 89Y reaction. The agreement is satisfactory, even for the deep-lying hole states.

Lifetime-parameters for quasi elastic and deep inelastic collisions extracted from complete angular distributions of89Y(19F,x)y reactions

Energy spectra and angular distributions of heavy fragments produced in 19F + 89Y reaction at 140 MeV incident energy have been measured. Two different domains of reaction mechanism are observed at forward and backward angles respectively; the corresponding lifetime parameters are extracted from their angular distributions.

Spin alignment and polarisation in the (16O,15N) transfer reactions

The spin alignment of the15N 3 2/* (6.33 MeV) state was measured in the88Sr(16O,15N)89Y reaction atE L =96 MeV using theγ-recoil method. Angular distributions of excited states in15N and89Y were measured with high accuracy. The analysis in terms of DWBA shows that the spin alignment is correctly described by the usual reaction models. The polarisation of the outgoing15N1/2(GS) and15N 3 2/* (6.33 MeV) is discussed. It is shown that cross section differences for transitions to final states with different configurations are sensitive to a spin-orbit potential of15N. The strength and sign of the spin-orbit potential for15N is determined.

Single-proton transfer reactions on N = 50 nuclei

Deuterons accelerated to 30, 35.5 and 40 MeV were used to investigate 89Y(d, 3He) 88Sr reactions. A detailed study of the 88Sr ground state was made using 88Sr(d, 3He) 87Rb reactions at 35 MeV and 88Sr( 3He, d) 89Y reactions at 33.4 MeV. Angular distributions are compared with local zero-range DWBA calculations from which the transferred angular momenta and spectroscopic factors are deduced. The analysis indicates that the major proton configurations in the 88Sr ground state are 0.7 (2 p 1 2 ) −2+ 0.2 (2 p 3 2 ) −2+ 0.1 (1 f 5 2 ) −2 , in good agreement with recent theoretical calculations.

The 88Sr(p, γ) 89Y reaction near the d [formula omitted] ground-state analogue

The d 5 2 ground-state analogue of 89Sr is studied with the 88Sr(p, γ) reaction near 5.06 MeV proton energy with a Ge(Li) detector. Excitation functions for γ-ray decay to the ground state, second excited (1.49 MeV) and third excited (1.73 MeV) states of 89Y are measured. The transitions from the 5 2 + analogue state to the 3 2 - second excited state and 5 2 - third excited state are observed to resonate. The resonance cross-section ratios σ n / σ γ for the 5 2 + → 3 2 - and 5 2 + → 5 2 − γ-ray decay are, respectively, 360 and 560 with Γ γ ( 5 2 + → 3 2 -) = 7 ± 2 eV and Γ γ( 5 2 + → 5 2 -) 4 ± 3 eV .

Distorted wave predictions of observed J dependence in the (d, 3He) reaction

“ J dependence” in the l = 1 proton transfers for the 90Zr(d, 3He) 89Y reaction has been observed at 34.4 MeV. With the inclusion of a spin-orbit interaction in the deuteron channel, distorted wave calculations quantitatively predict this effect.