Minimising the impact of arrow mass and stiffness variations on an archer’s score

A Monte Carlo technique was used to study the arrow mass and stiffness tolerances necessary to minimise the degradation of an archer’s likely score at normal competition distances. The archer’s arrow groups on the target were modelled using a half-normal distribution, where the standard deviation of the arrow’s distance from the centre depends upon the archer’s skill level and target distance. Equipment tolerances were modelled by varying the arrow positions on the target in either or both the vertical and lateral axes. This study showed that score loss due to arrow tolerance can be reduced well below score losses resulting from other sources by matching arrow mass to ±0.5 grains and arrow stiffness to ±1%.

Accessing tens-to-hundreds femtoseconds nuclear state lifetimes with low-energy binary heavy-ion reactions

A novel Monte Carlo technique has been developed to determine lifetimes of excited states in the tens-to-hundreds femtoseconds range in products of low-energy heavy-ion binary reactions, with complex velocity distributions. The method is based on a detailed study of Doppler-broadened $$\gamma $$ γ -ray lineshapes. Its relevance is demonstrated in connection with the $$^{18}\text {O}(7.0\, \text {MeV/u})+\,^{181}\text {Ta}$$ 18 O ( 7.0 MeV/u ) + 181 Ta experiment, performed at GANIL with the AGATA+VAMOS+PARIS setup, to study neutron-rich O, C, N, ... nuclei. Excited states in $$^{17}\text {O}$$ 17 O and $$^{19}\text {O}$$ 19 O , with known lifetimes, are used to validate the method over the $$\sim 20{-}400\,\text {fs}$$ ∼ 20 - 400 fs lifetime-sensitivity range. Emphasis is given to the unprecedented position resolution provided by $$\gamma $$ γ -tracking arrays, which turns out to be essential for reaching the required accuracy in Doppler-shift correction. The technique is anticipated to be an important tool for lifetime investigations in exotic neutron-rich nuclei, produced with intense ISOL-type beams.