Determination of lifetime and ground-state energy of 8Be by α-α elastic scattering at 184 keV

Atomic effects on α-α scattering to the 8Be ground state

“…The observed multiple (satellite) structure was attributed [4,5] to atomic effects. The experiment was not performed with bare nuclides (a-particles), but with ions and atoms, which lead to possible rearrangement of the 3 electrons of the entrance channel (He + and He) into various low-lying levels of the compound atom Be + .…”

“…For a Be atom with 2 electrons (Be + +) the binding energies [6,7] are: E** = 370 eV for (1 s) 2, 249 eV for ls2s, 246 eV for ls2p, 92 eV for (2s) 2, and 85 eV for 2s 2p. The third electron in the process can be bound by at most ~-16 eV in the lowest Be + configuration and will thus simply shift or broaden the E* values by at most [4] show the split of the resonance into three apparent dips. These anomalies were attributed to atomic excitations of the first few levels of the compound atom 8Be+.…”

“…The parameters of this s-wave resonance (width ~ FR= 13.6__3.4eV, location ~ ER= 184.24__+0.10 keV, both from [4]) were determined in 1968 in a difficult experiment [4,5] at the Universit/it Z/irich by the group of H. H. Staub. The experiment introduced the crossing beams technique in nuclear physics; the collision of 4He +-particles with a supersonic 4He jet led to a total experimental energy resolution of A E = 95 eV.…”

Using Nuclear Resonance Excitation to Observe United Atoms in Symmetric Ion-Atom Collisions

“…(The difference in their centroids is unobservable, since the nuclear resonance energy K is not known absolutely.) fv(0 = fvC(e) + fR(0) (7) where…”

Efficiency calibration measurement and GEANT simulation of the DRAGON BGO gamma ray array at TRIUMF.

“…The first step would be the combination of two alpha-particles to form ®Be. ®Be is unstable against decay into two alpha-particles (Q = -92.1 keV) with a lifetime of 1 x 10"^® seconds [25].…”