Resolution Characterizations of JetRIS in Mainz Using 164Dy

Abstract

Laser spectroscopic studies of elements in the heavy actinide and transactinide region help understand the nuclear ground state properties of these heavy systems. Pioneering experiments at GSI, Darmstadt identified the first atomic transitions in the element nobelium. For the purpose of determining nuclear properties in nobelium isotopes with higher precision, a new apparatus for high-resolution laser spectroscopy in a gas-jet called JetRIS is under development. To determine the spectral resolution and the homogeneity of the gas-jet, the laser-induced fluorescence of 164Dy atoms seeded in the jet was studied. Different hypersonic nozzles were investigated for their performance in spectral resolution and efficiency. Under optimal conditions, a spectral linewidth of about 200–250 MHz full width at half maximum and a Mach number of about 7 was achieved, which was evaluated in context of the density profile of the atoms in the gas-jet.

Proposal of a New Double-Nozzle Technique for In-Gas-Jet Laser Resonance Ionization Spectroscopy

“…Schematic views of the JetRIS setup are presented in the both [32] and [33] articles (see Figure 1 there).…”

“…Three different nozzles, which cross sectional profiles shown in the Figure 3 in [33], were used at JetRIS setup in offline test measurements of neutral 164 Dy atoms fluorescence induced by one-step laser excitation. All these nozzles have the same throat diameter of 1 mm, but different length and contour of diverging supersonic part.…”

“…All these nozzles have the same throat diameter of 1 mm, but different length and contour of diverging supersonic part. The authors of [33] note, that these three nozzles were designed for different stagnation pressure in the gas cell (Pcell) and background pressure (Pbg) in the vacuum chamber of the gas jet expansion, we will refer to as a gas-jet chamber. The sophisticated contours of the left and right nozzles (see Figure 3 in Ref.…”

“…The sophisticated contours of the left and right nozzles (see Figure 3 in Ref. [33]) were designed (Ref. [35]) and produced in KU Leuven, but due to the lack of exact information available to us about these nozzle's profiles, we could not use these two nozzles in our gas dynamic simulations.…”

“…Contrary, the third nozzle, shown in the middle of Figure 3 (Ref. [33]) and referred to as "mid-range nozzle", has a simple conical diverging part with the length of 20 mm.…”