Level Density of States in ¹¹⁸Sb

A good understanding of nuclear level densities is important for estimating the rate of several types of reactions that are important in astrophysical phenomena. However, the extraction of level densities from experimental data is not straightforward, especially at higher excitation energies, where the density is high and the level spacing is smaller than the experimental resolution. In this work, the level density of states in ¹¹⁸Sb are extracted with a fluctuation analysis by using results from a high-resolution (30 keV FWHM)  ¹¹⁸Sn(³He,t) experiment at E(³He)=420 MeV, performed at the Research Center for Nuclear Physics (RCNP) in Osaka, Japan.  The level densities are determined by studying the autocorrelation function obtained from the experimental spectra.  The backgrounds in the spectra were determined and subtracted by using a discrete wavelet transformation analysis of the spectra with a normalized biorthogonal wavelet. The analysis is performed for spectra at different scattering angles to investigate the effects of contributions from states of different multipolarity, which are preferentially populated at different scattering angles. Parameters in fluctuation analysis and discrete wavelet transform are varied to understand the error present in the analysis.