Search for 2p decay of the first excited state of ^17Ne

Two-proton decay of the ^17Ne low-lying states populated in the ^1H(^18Ne,d)^17Ne transfer reaction was studied. The two-proton width Γ_2p of the ^17Ne first excited 3/2^- state at E^*=1.288 MeV is of importance for the two-proton radioactivity theory and nuclear-astrophysics applications. A dedicated search for the two-proton emission of this state was performed leading to the new upper limit obtained for the width ratio Γ_2p/Γ_γ < 1.6(3) × 10^-4. A novel, "combined mass" method is suggested and tested capable to improve the resolution of the experiment which is a prime significance for the study of nuclear states with extremely small particle-to-gamma width ratios Γ_part/Γ_γ. The condition Γ_part≪Γ_γ is quite common for the states of astrophysical interest which makes the proposed approach promising in this field.