EGAS41 - Swansea University

41 st EGAS CP 90 Gdańsk 2009
Radiative correlated double electron capture (RDEC) in O 8+ +C
collisions at low energy
A. Simon 1,∗ , J.A. Tanis 2 , A. Warczak 1
1 Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow, Poland
2 Physics Department, Western Michigan University, 1903 W. Michigan Avenue,
Kalamazoo MI 49008
∗ Corresponding author: simon@uj.edu.pl
Radiative double electron capture (RDEC) is a one-step process where target electrons
are captured into bound states of the projectile, e.g., into an empty K-shell, and the
excess energy is released as a single photon. This process provides insight into several
very challenging problems in atomic physics, such as the electron-electron interaction in
electromagnetic fields or the search for a proper description of a two electron-continuum
wave function.
number of counts
40
35
30
25
REC
8+
O +C
2.375 MeV/u
20
15
10
5
RDEC
0
0 1 2 3 4 5 6 7
E [keV]
Figure 1: Sample X-ray spectrum registered in coincidences with double electron capture. Structure
consistent with RDEC process is visible.
The choice of the collision system used in the presented experiment was based on the
latest theoretical calculations of RDEC cross sections [1, 2, 3], which predicted enhancement
of this process in low energy systems. The experiment was conducted at Western
Michigan University using the tandem Van de Graaff accelerator. Bare oxygen ions with
energies of about 2.375 MeV/u were collided with 2 µg/cm 2 carbon target and the x-ray
spectra were registered in coincidence with single and double electron capture. Example
of a spectrum registered in coincidence with double charge change is presented in Fig. 1.
Here a peak structure near 3.5 keV consistent with RDEC is visible.
References
[1] A.I. Mikhailov et al., Phys. Lett. A 328, 350 (2004)
[2] A.I. Mikhailov et al., Phys. Rev. A 69, 032703 (2004)
[3] A. Nefiodov et al., Phys. Lett. A 346, 158 (2005)
150