Heavy Particles Charge Exchange and Nuclear Stopping

1 Heavy Particles Charge Exchange and Nuclear Stopping 

Positive ions start to capture electrons from the medium when their velocity is comparable to that of an electron in an ls-orbital around itself. On further slowing, at first the captured electron is soon lost, and then another electron is captured. Thus cycles of capture and loss continue until it is energetically impossible to lose the captured electron. If the incident particle is multiply charged, another charge exchange cycle will soon be set up, and so on until the particle is reduced to a neutral atom. 

Charge exchange cross sections depend on a high inverse power of velocity (Bohr, 1948) thus, at high speeds, they are insignificant. At low speeds, however, 

Chapter 2 Interaction of Radiation with Matter Energy Transfer 

---