Nonelastic Breakup

What is Nonelastic Breakup?

Nonelastic breakup is a nuclear reaction process in which a projectile nucleus breaks apart when interacting with a target nucleus, and some of the fragments interact with the target through nuclear forces rather than simply scattering elastically.

Approach

A loosely bound projectile (deuteron, ⁶Li, ⁷Li, ⁹Be, or halo nuclei) approaches the target

Dissociation

The projectile dissociates into its constituent clusters under Coulomb and nuclear forces

Fragment Reaction

At least one fragment undergoes nuclear reaction with target: absorption, fusion, or transfer

Key Characteristics

Partial Absorption - Not all fragments react with the target
Incomplete Fusion - Distinct from complete fusion of intact projectile
Complex Products - Multiple reaction products are generated

Elastic vs Nonelastic Breakup

Elastic Breakup

Coulomb Dissociation

Also known as diffractive breakup

All fragments scatter elastically
No nuclear reaction occurs
Fragments retain original properties
Both fragments escape the target

Fragment Absorption

Fragment interacts via nuclear forces

At least one fragment is absorbed
Fusion or transfer may occur
Produces incomplete fusion products
One fragment escapes as spectator

Typical Projectile Nuclei

Deuteron (d)

p + n

The simplest composite nucleus, consisting of one proton and one neutron loosely bound together. With a binding energy of only 2.22 MeV, it easily breaks up near a target nucleus.

Typical reactions:
d + A → p + (n + A) or d + A → n + (p + A)

Lithium-6 (⁶Li)

α + d

Can be viewed as an alpha particle + deuteron cluster structure. Breakup threshold energy is approximately 1.47 MeV.

Typical reaction:
⁶Li → α + d, with one fragment absorbed by target

Lithium-7 (⁷Li)

α + t

Alpha particle + triton cluster structure. Breakup threshold energy is approximately 2.47 MeV.

Typical reaction:
⁷Li → α + t, fragments may trigger secondary reactions

¹¹Be - One-Neutron Halo Nucleus

¹⁰Be + n

A classic one-neutron halo nucleus with an extremely low neutron separation energy of only 0.50 MeV. The valence neutron extends far beyond the ¹⁰Be core, forming an extended halo structure.

Typical reaction:
¹¹Be → ¹⁰Be + n, with the halo neutron easily stripped

¹¹Li - Two-Neutron Halo Nucleus

⁹Li + n + n

A Borromean two-neutron halo nucleus. The two-neutron separation energy is only 0.37 MeV, while neither ¹⁰Li nor the dineutron is bound. All three components are needed for binding.

Typical reaction:
¹¹Li → ⁹Li + 2n, exhibiting anomalously large reaction cross-section

Research Significance

🔬

Fusion Studies

Understanding fusion mechanisms near the Coulomb barrier, distinguishing complete fusion from incomplete fusion

☢

Radioactive Ion Beams

Production and study of exotic nuclei far from the stability line

⭐

Nuclear Astrophysics

Understanding reaction pathways in stellar nucleosynthesis processes

📊

Nuclear Structure

Probing cluster structures in weakly bound nuclei and halo nucleus properties

Key Physical Quantities

σ_total = σ_CF + σ_EB + σ_NEB

Total reaction cross-section components:
CF = Complete Fusion, EB = Elastic Breakup,
NEB = Nonelastic Breakup (includes Incomplete Fusion)

E_th = S_n or S_p

Breakup threshold energy equals the separation energy