D.J. Vieira

Development of the helium-jet fed on-line mass separator RAMA, I

Abstract Development of general experimental systems capable of mass analysis of radioactive species with half-lives as short as 50 ms and with simple application to a vast majority of the chemical elements is clearly of great interest in the study of nuclei far from stability. Such an on-line system has been developed which employs a helium-jet to transport activity from the target area to a mass separator. The initial development and early experiment use of this recoil atom mass analysis system (RAMA) are described. RAMA as a typical total efficiency of 0.01%, which should apply to ∼75 elements of melting point M ΔM ∼ 200 .

Masses of the unbound nucleiNe16,F15, andO12

The (/sup 4/He,/sup 8/He) and (/sup 3/He,/sup 8/Li) reactions have been employed at detection angles near 8/sup 0/ on gas targets of /sup 20/Ne and /sup 16/O to produce and measure the masses of the nuclei /sup 16/Ne, /sup 15/F, and /sup 12/O. The (/sup 4/He, /sup 8/He) reactions were performed at an incident energy of 117 MeV, and the (/sup 3/He, /sup 8/Li) reaction was done at 88 and 75 MeV. The mass excesses of /sup 16/Ne, /sup 15/F, and /sup 12/O were determined to be 23.92 +- 0.08, 16.67 +- 0.18, and 32.10 +- 0.12 MeV, respectively. Estimated ground state decay widths were GAMMA/sub c.m./ = 0.2 +- 0.1, 0.8 +- 0.3, and 0.40 +- 0.25 MeV, for /sup 16/Ne, /sup 15/F, and /sup 12/O, respectively. A d coefficient of 8 +- 5 keV is indicated for the isobaric multiplet mass equation description of the mass-16 multiplet. Consideration of the possible decay mechanisms of /sup 16/Ne and /sup 12/O indicates that both nuclei probably have an appreciable diproton decay width.

Masses of the unbound nuclei /sup 16/Ne, /sup 15/F, and /sup 12/O

The (/sup 4/He,/sup 8/He) and (/sup 3/He,/sup 8/Li) reactions have been employed at detection angles near 8/sup 0/ on gas targets of /sup 20/Ne and /sup 16/O to produce and measure the masses of the nuclei /sup 16/Ne, /sup 15/F, and /sup 12/O. The (/sup 4/He, /sup 8/He) reactions were performed at an incident energy of 117 MeV, and the (/sup 3/He, /sup 8/Li) reaction was done at 88 and 75 MeV. The mass excesses of /sup 16/Ne, /sup 15/F, and /sup 12/O were determined to be 23.92 +- 0.08, 16.67 +- 0.18, and 32.10 +- 0.12 MeV, respectively. Estimated ground state decay widths were GAMMA/sub c.m./ = 0.2 +- 0.1, 0.8 +- 0.3, and 0.40 +- 0.25 MeV, for /sup 16/Ne, /sup 15/F, and /sup 12/O, respectively. A d coefficient of 8 +- 5 keV is indicated for the isobaric multiplet mass equation description of the mass-16 multiplet. Consideration of the possible decay mechanisms of /sup 16/Ne and /sup 12/O indicates that both nuclei probably have an appreciable diproton decay width.

Masses of the unbound nuclei Ne-16, F-15, and O-12

The (/sup 4/He,/sup 8/He) and (/sup 3/He,/sup 8/Li) reactions have been employed at detection angles near 8/sup 0/ on gas targets of /sup 20/Ne and /sup 16/O to produce and measure the masses of the nuclei /sup 16/Ne, /sup 15/F, and /sup 12/O. The (/sup 4/He, /sup 8/He) reactions were performed at an incident energy of 117 MeV, and the (/sup 3/He, /sup 8/Li) reaction was done at 88 and 75 MeV. The mass excesses of /sup 16/Ne, /sup 15/F, and /sup 12/O were determined to be 23.92 +- 0.08, 16.67 +- 0.18, and 32.10 +- 0.12 MeV, respectively. Estimated ground state decay widths were GAMMA/sub c.m./ = 0.2 +- 0.1, 0.8 +- 0.3, and 0.40 +- 0.25 MeV, for /sup 16/Ne, /sup 15/F, and /sup 12/O, respectively. A d coefficient of 8 +- 5 keV is indicated for the isobaric multiplet mass equation description of the mass-16 multiplet. Consideration of the possible decay mechanisms of /sup 16/Ne and /sup 12/O indicates that both nuclei probably have an appreciable diproton decay width.