# CHARGE - CHANGING CROSS SECTIONS

# IN ION - ATOM COLLISIONS

## N.V.Novikov, Ya. A. Teplova

#### Scobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia

nvnovikov65@mail.ru | teplova@anna19.sinp.msu.ru

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### Abstract

Charge - changing phenomena have increasing interest in connection with the design of radiation detectors, with radiation damage, with studies of astrophysics, with controlled thermonuclear fusion, with the acceleration of multiply charge heavy ions, and with slowing down or energy loss of heavy ions in matter. The capture and loss of one or more electron cross sections are summarized in tables and figures as a function of the energy of the incident projectile. The experimental, theoretical and recommended data are compiled. Cross sections on gas and vapor targets are presented. We save the units of original papers and transform them to Mev/amu and 10-16 cm2/atom.

### Keywords

Charge Changing Cross Sections, Electron Capture Cross Section, Electron Loss Cross Sections.

### Introduction

The charge - changing process can be represented as
Xi+(Z) + A(Zt) → Xk+(Z) + Am+(Zt) + (k+m-i) e- (1)
where an incident projectile X with initial charge i collides with a target atom or molecule A, initially neutral and undergoes the loss (k > i) or capture (i < k) of electrons into charge state k, while the target acquires charge n. Thus (k+m-i) electrons are released in this process. The cross section for this process is denoted by σi,k 0m, where the superscripts pertain to the initial and final charge states of the target, and the subscripts pertain to those of the projectile. The cross section
σi,k = ∑m σi,k 0m (2)
is the sum over all cross sections of processes in which the ion with charge i transformed into ion with the charge k. The cross section (2) also containes the sum on all quantum states of scattered projectile Xk+ and residual target Am+(Zt). The indices i,k in (2) can range from -1 (if the negative ion exists) to nuclear charge of the projectile Z.

### Notation

Z - nuclear charge of the projectile;
Zt - nuclear charge of the target atom;
i - charge of the projectile before collision;
k - charge of the projectile after collision;
V - velocity of the projectile;
E - energy of the projectile;
E [MeV/amu] = 0.025 * (V/Vo)2; Vo=2.188e+8 cm/s
σi,k - charge - changing cross section .