Mb. Shah et al., NEW LOW-ENERGY MEASUREMENTS AND CALCULATION OF IONIZATION IN H-H COLLISIONS(), Journal of physics. B, Atomic molecular and optical physics (Print), 31(19), 1998, pp. 757-762
In response to the strong current theoretical interest in models of lo
w-energy ionization in H+-H collisions, a crossed-beam coincidence cou
nting technique previously used in this laboratory to obtain cross sec
tions in the range 9-1500 keV amu(-1) has been successfully adapted to
extend the measurements downwards in energy from 9 to 1.25 keV amu(-1
). In addition, we have extended the triple-centre calculations of McL
aughlin B M, Winter T G and McCann J F 1997 J. Phys. B: At. Mol. Opt.
Phys. 30 1043, down to 0.5 keV amu(-1) where agreement with experiment
is found to be satisfactory. Our new measurements and calculation are
at variance with relative cross sections measured by Pieksma M, Ovchi
nnikov S Y, van Eck J, Westerveld W B and Niehaus A 1994 Phys. Rev. Le
tt. 73 46 in the range 1-6 keV amu(-1), but are in good accord with th
eir calculations based on the hidden-crossings model including only S
and T promotion. However, our measurements and calculation do not supp
ort the more recent calculations by Pieksma M, Ovchinnikov 8 Y and Mac
ek J H 1998 J. Phys. B: At Mol. Opt. Phys. 31 1267 in which a contribu
tion from a radial decoupling mechanism is also included in the model.