The Nucleus
349
Such reactions are called stripping reactions and are observed for other
projectiles, such as α particles, as well. Conversely, a fast-moving neutron (or
proton) may collect one or more nucleons and move off as a deuteron or an
α particle, e.g.
27
Al + n →
24
Na + α
(9.104)
Such processes are known as pick-up reactions.
Applications
Nuclear reactions provide a powerful tool for the investigation of nuclear
structure and properties. From the conservation of energy, the masses of the
nuclei can be deduced, while conservation of angular momentum and the angular
distribution of particles help us to determine their angular momenta. Furthermore,
the cross-sections give important information on the interaction between nuclei.
Nuclear reactions allow us to produce trans-uranic elements as well as
elementary particles. For example, plutonium (Z = 94) is produced by
bombarding uranium with 40 MeV α particles
238
U + a → 241 Pu + n
(9.105)
Similarly, other elements such as berkelium (Z = 95), californium (Z = 98),
einsteinium (Z = 99), fermium (Z = 100), nobelium (Z = 102), etc. have been
produced from nuclear reactions, the heaviest of them being hahnium
262
105 Ha.
Many elementary particles also have been produced and investigated in nuclear
reactions. Two examples are:
p + p → P + n + π
+
(9.106)
p + p → p + Σ
+
K°
(9.107)
π
+
and K° being the positively charged pi-meson and the neutral K-meson,
respectively, and Σ
+
is the positively charged sigma baryon (see Sec. 10.1).
From the point of view of practical applications, products of nuclear reactions
are of considerable utility in industry, medicine, agriculture, etc.
Their uses may be grouped in the following broad categories:
1. Radioactive isotopes, which have the same chemical properties as a given
element but decay with the emission of photons, are of general use as
tracers. These isotopes are easily detected by their characteristic radiation
and half-life. For example, the phosphorus isotope
32
P (decays via beta
decay with half-life of 14.2 days) may be used to determine the proper
application of fertilizers to plants. Radioactive tracers are also used for
analysing blood circulation, flow rates of fluids, etc.
2. Neutron activation analysis is used for detecting small amounts of
impurities. The impurities are activated by exposing them to neutron
beams. The radioactive isotope formed as a result is estimated by its
349
Such reactions are called stripping reactions and are observed for other
projectiles, such as α particles, as well. Conversely, a fast-moving neutron (or
proton) may collect one or more nucleons and move off as a deuteron or an
α particle, e.g.
27
Al + n →
24
Na + α
(9.104)
Such processes are known as pick-up reactions.
Applications
Nuclear reactions provide a powerful tool for the investigation of nuclear
structure and properties. From the conservation of energy, the masses of the
nuclei can be deduced, while conservation of angular momentum and the angular
distribution of particles help us to determine their angular momenta. Furthermore,
the cross-sections give important information on the interaction between nuclei.
Nuclear reactions allow us to produce trans-uranic elements as well as
elementary particles. For example, plutonium (Z = 94) is produced by
bombarding uranium with 40 MeV α particles
238
U + a → 241 Pu + n
(9.105)
Similarly, other elements such as berkelium (Z = 95), californium (Z = 98),
einsteinium (Z = 99), fermium (Z = 100), nobelium (Z = 102), etc. have been
produced from nuclear reactions, the heaviest of them being hahnium
262
105 Ha.
Many elementary particles also have been produced and investigated in nuclear
reactions. Two examples are:
p + p → P + n + π
+
(9.106)
p + p → p + Σ
+
K°
(9.107)
π
+
and K° being the positively charged pi-meson and the neutral K-meson,
respectively, and Σ
+
is the positively charged sigma baryon (see Sec. 10.1).
From the point of view of practical applications, products of nuclear reactions
are of considerable utility in industry, medicine, agriculture, etc.
Their uses may be grouped in the following broad categories:
1. Radioactive isotopes, which have the same chemical properties as a given
element but decay with the emission of photons, are of general use as
tracers. These isotopes are easily detected by their characteristic radiation
and half-life. For example, the phosphorus isotope
32
P (decays via beta
decay with half-life of 14.2 days) may be used to determine the proper
application of fertilizers to plants. Radioactive tracers are also used for
analysing blood circulation, flow rates of fluids, etc.
2. Neutron activation analysis is used for detecting small amounts of
impurities. The impurities are activated by exposing them to neutron
beams. The radioactive isotope formed as a result is estimated by its