Preface

Isotopes are atoms of the same element having different atomic mass because they have a different number of neutrons in their nuclei with the identical number of protons. Some isotopes are unstable due to a specific combination of neutrons and protons which occurs naturally or can be artificially produced by bombarding the target atoms with neutrons in a nuclear reactor or with charged particles in an accelerator. These unstable nuclei attain their stability by emitting nuclear radiations such as neutrons, alpha particles, beta (positron/electron) or gamma rays and are termed as radioisotopes, while the term radioactivity is used to describe these spontaneous, energy emitting, atomic transitions that involve changes in the state of the nucleus of an atom. Radioactivity was discovered by A. H. Becquerel in l896 when he was investigating the fluorescence of a double sulphate of uranium and potassium, using a photographic plate. Marie Curie coined the word radioactivitè, investigated this property in a number of minerals containing uranium, which she found to be more active and subsequently polonium was discovered. Readers are referred to read more in NCRP Report No.58, A Handbook of Radioactivity Measurements and Procedures.

Radiation from radioisotopes plays a very important role in all fields, useful in our life such as soil and earth science, radioactive dating, environment, archeology, agriculture, biochemical analysis, radiotherapy and cancer treatment, medical diagnosis, nuclear medicine, biological sciences, sterilization of medical products, non‐destructive elemental analysis and testing of materials, oceanography, pharmaceutical, radioisotope power systems for space applications and many more.

The basic aim of this book is to present a very comprehensive review. Applications of radioisotopes have been reviewed and compiled in chapters contributed by world known authors in their respective specialized fields of research. The book contains three sections; Radioisotopes and some physical aspects, Radioisotopes in environment and Radioisotopes in power system for space applications.

In Tech Open Access Publisher has put in a lot of effort to complete the task of publishing this book for the immense benefit of the scientific and technical

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community, to discharge their social obligation and serve mankind all over the world. With this background I acknowledge the contributions put in these volumes by my expert colleagues and I endorse my special thanks to In Tech Open Access Publisher to assign me the job as an editor and for giving me an opportunity to review the all chapters published in the book.

#### **Nirmal Singh**

Emeritus Professor, Department of Physics, Panjab University, Chandigarh, India
