Lifetime of ${}^{19}{\mathrm{Ne}}^{*}$(4.03 MeV)

The Doppler-shift attenuation method was applied to measure the lifetime of the 4.03 MeV state in ${}^{19}\mathrm{Ne}$. By utilizing a ${}^3\mathrm{He}$-implanted Au foil as a target, the state was populated using the ${}^{20}\mathrm{Ne}$(${}^3\mathrm{He}$, $\alpha$)${}^{19}\mathrm{Ne}$ reaction in inverse kinematics at a ${}^{20}\mathrm{Ne}$ beam energy of 34 MeV. De-excitation γ rays were detected in coincidence with α particles. At the 1σ level, the lifetime was determined to be ${11}_{-3}^{+4}$ fs and at the 95.45% confidence level the lifetime is ${11}_{-7}^{+8}$ fs.

Figure 1

A schematic view of the experiment. The dimensions are not drawn to scale.

Figure 2

(a) The particle identification spectrum in the silicon detectors in coincidence with either of the HPGe detectors. (b) The γ-ray spectra in the HPGe detectors in coincidence with α particles from the hatched area of part (a). The inset shows the energy range around 4 MeV in the $0^{°}$ HPGe detector.

Figure 3

γ-ray energy spectra from the $0^{°}$ HPGe detector obtained in coincidence with α particles with total energies between (a) 11 and 13 MeV and (b) 13 and 14 MeV.

Figure 4

The γ-ray energy spectrum from the ${90}^{°}$ HPGe detector measured in coincidence with α particles having total energies between 11 and 13 MeV. The Doppler-broadened peak around 4.03 MeV is consistent with the direct transition in ${}^{19}\mathrm{Ne}$ from the 4.03 MeV level to the ground state.

Figure 5

γ-ray spectra from the $0^{°}$ HPGe detector obtained in coincidence with α particles: (a) the 150 to 350 keV region; (b) the 1100 to 1300 keV region.

Figure 6

Total energy spectra of α particles observed in coincidence with the γ-ray peaks at (a) 275 and (b) 1233 keV.

Figure 7

Schematic rendering of some of the ${}^{19}\mathrm{Ne}$ energy levels and γ-ray transitions observed in the experiment. Energies are given in keV.

Figure 8

The line-shape data observed in the $0^{°}$ HPGe detector for the Doppler-shifted 4.03 MeV → ground state γ-ray transition in ${}^{19}\mathrm{Ne}$. The curves show line shapes for the best fit (solid line, $\tau =11$ fs), the 2σ lower limit (dotted line, $\tau =4$ fs), and the 2σ upper limit (dashed line, $\tau =19$ fs) lifetimes determined from a ${\chi }^2$ minimization.

Figure 9

The joint likelihood for the lifetime of the 4.03 MeV state in ${}^{19}\mathrm{Ne}$, taking into account the present measurement and that of Tan et al. [16].