Proton and Two-proton Emissions from Proton-rich Nuclei with 10≦Z≦20

Key words: 
• proton emission /
• two-proton emission /
• proton-proton correlation /
• complete-kinematics measurement /
• implantation decay /
• proton-rich exotic nucleus

Abstract: Proton (p) and two-proton (2p) emissions from the proton-rich nuclei with 10≦Z≦20 have been explored by the in-fight decay and implantation decay methods, respectively, in a series of experiments at the HIRFL-RIBLL facility. The in-flight 2p emissions from the excited states of 28;29S/26;27P
and 17;18Ne were studied by complete-kinematics measurements. Mechanisms of 2p decay and related p-p correlations have been explored. Obvious 2p correlated emissions have been observed in the cases of 28;29S but not in 27;28P, indicating the 2p halo plays an important role in the diproton emission. In the 17;18Ne cases, a small 2p opening angles were deduced by the HBT analyses, implying the BCS-BEC crossover may occur in the dilute nuclear matter. Moreover, 27S/26P/25Si, 22Si/20Mg, 23Si/22Al/21Mg, 24Si/23Al, and 36;37Ca were implanted in a thin double-sided-silicon-strip detector and their -delayed p and 2p decays have been measured by a surrounding silicon detector array under the continuous-beam mode. Important information on the nuclear spectroscopy, such as energy, lifetime, branching-ratio, and so on, has been extracted, which helps us to understand the nuclear structures of proton-rich exotic nuclei close to the drip-line.