Transmission Resonance Spectroscopy of the Doubly Odd $^{238}$Np in ($d$,pf) Reaction

Abstract

The fission probability of 238 Np was measured as a function of the excitation energy in the energy range of E * = 5.4-6.2 MeV in order to search for hyperdeformed rotational bands using the (d,pf) transfer reaction on a radioactive 237 Np target. The experiment was performed at the Tandem accelerator of the Maier-Leibnitz Laboratory at Garching employing the 237 Np(d,pf) reaction at a bombarding energy of E d = 12 MeV. Overlapping resonances have been observed at excitation energies around E * = 5.5 MeV. These resonances could be ordered into a hyperdeformed rotational band by the preliminary analysis of the high-resolution excitation energy spectrum. The existence of a third minimum in the fission barrier of 238 Np is also supported by nuclear reaction code (TALYS1.4) calculations which was used to describe the experimental data.

Physics at the Munich Tandem Accelerator Laboratory

“…Employing (d,p) reactions in coincidence with fission such hyperdeformed bands were found as well in 232 U [Csi09] and also in the odd-odd nuclei 232 Pa [Csi12] (see Fig. 2) and 238 Np [Csi15]. Absolutely essential for these identifications was the excellent resolution of about 6 keV for the detected protons.…”

Fission resonances observed in the $$^{237}$$Np(d,pf) reaction and the fission barrier topology of $$^{238}$$Np

“…The goodness of the fit was χ 2 /F = 1.27. In a preliminary analysis [27], we interpreted these resonances as members of a hyperdeformed rotational band, but the revised analysis with the above improved background suppression suggests that the fine structure of the observed resonances can be most convincingly described with three rotational bands with K = 4 as indicated in the figure with its picket fence structure and with a rotational parameter (h 2 /2Θ = 3.507 ± 0.250 keV) characteristic to an SD-like nuclear configuration. Here we mention that the angular data of the PSADs could not be applied to extract the spin information of the bands due to the very limited statistics and to the governing non-resonant background.…”