Transfer reactions are nuclear reactions in which one or more nucleons are transferred to the other nucleus. These reactions are further classified as:

• • Stripping reaction in which one or more nucleons are transferred to a target nucleus from passing particles. For example, the neutron stripping in the (d, p) reaction.
  • Pick-up reaction in which one or more nucleons are transferred from a target nucleus to a passing particle. For example, the neutron pick-up in the (p, d) reaction.
  • Break-up reaction in which a breakup of a projectile into two or more fragments occurs.
  • Knock-out reaction in which a single nucleon or a light cluster is removed from the projectile by a collision with the target.

These reactions are common in particle accelerators and astrophysics. These are useful in studying outer shell structure of nuclei. Single- and multi-nucleon transfer reactions have long been a useful tool in nuclear spectroscopy. Generally, one considers that a single nucleon (or cluster of nucleons) transfers from one nucleus to another in a direct one-step process.

Main Characteristics of Nuclear Reactions

In nuclear physics, the nuclear cross-section of a nucleus is commonly used to characterize the probability that a nuclear reaction will occur. The cross-section is typically denoted σ and measured in units of the area [m²]. The standard unit for measuring a nuclear cross-section is the barn, equal to 10⁻²⁸ m² or 10⁻²⁴ cm². It can be seen that the concept of a nuclear cross-section can be quantified physically using a “characteristic target area,” where a larger area means a larger probability of interaction.

For a given event, the cross-section σ is given by

σ = μ/n

where

• σ is the cross-section of this event [m²],
• μ is the attenuation coefficient due to the occurrence of this event [m^-1],
• n is the density of the target particles [m^-3].