Determination of fission barrier height of Fr 210 and Ra 210 via neutron measurement

Fission barrier heights of short-lived nuclei away from line of β stability are not known reliably. Low-energy fission of Fr210 and Ra210, produced by (d,p) and (d,n) transfer reaction on the re-accelerated unstable beam Fr209 was investigated at HIE-ISOLDE. Four Timepix3 pixel detectors were installed on the body of the ACTAR TPC demonstrator chamber. Polyethylene converters were used for the detection of fast neutrons. Since no significant background was observed, it was possible to measure the spatial distribution of emitted neutrons reflecting the fission excitation function. Subsequent simulations employing the results of the talys code and available data on fission fragment distributions allowed to estimate directly the value of the fission barrier height for the neutron-deficient nucleus Fr210. This first direct measurement confirmed the reduction of the fission barrier compared to available theoretical calculations by 15-30%

Cryo-FALP study of collisional-radiative recombination of Ar

New flowing afterglow apparatus, Cryo-FALP, was built to study ternary Collisional-Radiative Recombination (CRR) of Ar+ ions with electrons in He/Ar afterglow plasma at temperatures 40–200 K. The obtained ternary recombination rate coefficient at 57 K is KCRR = (3 ± 1) × 10−17 cm6 s−1. It is the first time that the KCRR was measured below 77 K. The measured temperature dependence KCRR ~ T(−4.5 ± 0.4) is in a good agreement with theoretical prediction

Ternary association of H

The rate coefficient of the ternary association reaction ${\mathrm{H}}^{+}+2{\mathrm{H}}_2\to {\mathrm{H}}_3^{+}+{\mathrm{H}}_2$ has been measured at a temperature of 11 K using a 22-pole ion trap. The measurements were made over the density range of 0.5–10 × 1013 cm−3 using normal hydrogen (with 1/4 p-H2 and 3/4 o-H2). We measured an apparent binary reaction rate coefficient and from the obtained linear dependence on the hydrogen density we calculated the ternary reaction rate coefficient k3 = (3 ± 1) × 10−29 cm6 s−1. From the measured data we can deduce that there exists very slow radiative association with the rate coefficient of the order of kr ≲ 3 × 10−16 cm3 s−1 at 11 K