Measurements of neutron-induced reactions in inverse kinematics

Neutron capture cross sections of unstable isotopes are important for neutron induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes.

Figure 1

Schematic drawing of the proposed setup. Shown are the facility to produce and separate exotic nuclei of interest (dark gray) and the main components of an ion storage ring which include the beam lines and focusing elements (gray), dipoles (dark blue), electron cooler (green), an intersected reactor core (red), particle detection capability (black), and Schottky pickup electrodes (brown).

Figure 2

Schematic drawing of the test storage ring (TSR) [14]. The injection, electron cooler, acceleration cavity, and particle detector setups are indicated. A core of a reactor can be imagined at place for in-ring experiments (adopted from Ref. [14]).

Figure 3

Terrestrial ${\beta }^{-}$ live times for unstable isotopes on the classical $s$-process path as a function of mass number. Shown are only isotopes where the neutron capture under stellar conditions is faster than the stellar ${\beta }^{-}$ decay for a neutron density of $4\times {10}^8{\mathrm{cm}}^{-3}$ at a temperature of 30 keV, the conditions of the classical $s$ process [4]. If the $\beta$ decay is faster than the neutron capture, the $s$ process proceeds to the next higher element.