Large pre-equilibrium contribution inα+natNiinteractions at≈8−40

Abstract

To investigate pre-equilibrium emission of light nuclear particle(s), an experiment has been performed using α beams at the Variable Energy Cyclotron Center (VECC), Kolkata, India. In the present work, excitation functions for 58 Ni(α, p) 61 Cu, 58 Ni(α, pn) 60 Cu, 60 Ni(α, p2n) 61 Cu, 60 Ni(α, n) 63 Zn, 60 Ni(α, 2n) 62 Zn, 61 Ni(α, 3n) 62 Zn, and 61 Ni(α, 2n) 63 Zn reactions have been measured by using the stacked foil activation technique followed by off-line γ -ray spectroscopy. Experimentally measured excitation functions have been compared with the prediction of the theoretical model code ALICE-91 with and/or without the inclusion of pre-equilibrium emission. Analysis of the data suggests that an admixture of both equilibrium and pre-equilibrium emission is needed to reproduce experimental data at energies ≈8-40 MeV and reveals significant contribution from pre-equilibrium emission. An attempt has also been made to estimate the pre-equilibrium contribution, which has been found to depend on projectile energy and on number of emitted particle(s). PACS number(s): 25.60.Dz, 25.70.Gh Pre-equilibrium (PE) emission in light-ion-induced (LIinduced) reactions has been a topic of considerable interest during the past decade or so from both theoretical and experimental aspects, owing to the strong competition between equilibrium and the pre-equilibrium emission of light nuclear particles [1][2][3][4]. In PE emission, energetic light nuclear particles (neutrons and protons) are emitted predominantly at the initial stages of the nuclear interactions. The emission of light nuclear particles in the PE emission process followed by nonstatistical γ rays are assumed to arise from the interaction of the projectile with the target nucleons at the early stage of reaction. However, at later stages, a fully equilibrated compound nucleus (CN) may be formed and this nucleus further decays by statistical evaporation of light nuclear particles and/or characteristic γ radiations. Recent experiments have established that, at moderate excitation energies, the equilibrium decay is influenced by the emission of light nuclear particles before the equilibration of the composite system. Some of the important experimental signatures of PE emission that have emerged from the literature are (i) the presence of a larger number of high-energy light nuclear particles in the exit channel as compared to the number emitted in equilibrium decay, (ii) a forward-peaked angular distribution of light nuclear particles, and (iii) slowly decreasing tails of the excitation functions (EFs) [5][6][7][8]. A better understanding of these aforementioned characteristics of PE emission may provide important information about the involved reaction mechanism. The measurement and analysis of the EFs can be used as an informative probe of the PE emission process. In fact, the features of the EFs at low, medium, and high energies may reveal the characteristics of the involved reaction mechanism. The low-energy portion of EFs is dominated * pushpendrapsingh@gmail...

Recommended nuclear data for medical radioisotope production: diagnostic positron emitters

“…The nine experimental datasets available in the literature are shown in Fig. 48 [36,127,[154][155][156][157][158][159][160] together with the TENDL calculations. Three datasets were rejected (Neirinckx [155] (energy shift near threshold), Singh et al [159] (discrepant values at energies below 35 MeV), and Yadav et al [160] (value too low)), and the remaining six sets were used in the statistical fitting procedure.…”

“…Fig. 48 Nine experimental datasets for the nat Ni(α,xn) 62 Zn reaction available in the literature [36,127,[154][155][156][157][158][159][160], and TENDL calculations The seven experimental datasets available in the literature are shown in Fig. 50 [36,45,66,110,[161][162][163] together with the TENDL calculations.…”

New potentialities of the Liège intranuclear cascade model for reactions induced by nucleons and light charged particles

“…The full curves correspond to the predictions of the INCL4.6+ABLA07 model and the symbols represent the experimental data. Data are from Refs [108][109][110][111][112]…”