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Indirect acceleration
Second order Fermi acceleration In this model Fermi proposed that CRs are accelerated through encounters with moving magnetic clouds. When a particle enters a cloud it changes its energy: it can gain energy in head-on ( velocity v of magnetic clouds towards the incoming particle) collisions and loses energy in overtaking (v away from the incoming particle) collisions. The probability of head-on collisions is higher than that overtaking, so the particle gains more energy then loses energy.
Dosimetry
After the discovery of X rays in 1895 by Roentgen and radioactivity in 1896 by Becquerel, it has been known that exposure to ionizing radiation can be harmful to humans. In any use of ionizing radiation, one must prevent or minimize the risks of the use of radiation while allowing its beneficial applications [18]. For this purpose, two international commissions, the International Commission on Radiation Units and measurements (ICRU) and the International Commission on Radiological Protection (ICRP) were established. ICRU is charged to define units concerning radioactivity and their effects and ICRP is charged to define protection criteria against ionizing radiation. The field of work of these tow commissions has widened from protection in medical radiology to all aspects of protection against ionizing radiation. In this chapter we describe the principal concepts upon which radiation dosimetry is based, biological effects that can ionizing radiation produce in the human body, and the ways in which ionizing radiation can be detected and measured.
Ionizing radiation
According to the ability to ionize matter, radiation can be classified into two main categories, non-ionizing radiation which has enough energy to move or vibrate atoms in a molecule, but not enough to change them chemically, and ionizing radiation which has enough energy to actually break the chemical bonds. The ionizing radiation falls into two categories: direct ionizing radiation (charged particles such as protons, electrons, α-particles, and heavy ions) and indirect ionizing radiation (uncharged particles such as high energy photons and neutrons). When a charged particle passes in a medium it loses a fraction of its energy through direct coulomb interactions between the charged particle and the orbital electrons of atoms or molecules. The transferred energy causes the affected electrons to move into higher orbital energy levels (excitation) or to escape the orbital atomic structure completely (ionization).
The loss of energy continues until the remaining energy of charged particles is not sufficient to produce additional excitation or ionization. In addition, a charged particle may lose energy by emission of electromagnetic radiation during deceleration (bremsstrahlung radiation).
Introduction
Chapter 1: Cosmic Rays
1.1. History
1.2. The main properties of cosmic rays
1.2.1. Composition
1.2.2. Energy spectrum
1.2.3. Isotropy
1.3. Origin and acceleration mechanisms
1.3.1. Acceleration mechanisms
1.3.2. Cosmic ray sources
1.4. Air shower
1.4.1. Electromagnetic shower
1.4.2. Hadronic shower
1.5. Detection of cosmic rays
1.5.1. Direct detection
1.5.2. Indirect detection
Chapter 2: Dosimetry
2.1. Introduction
2.2. Ionizing radiation
2.3. Biological effects of ionizing radiation
2.3.1. Stochastic effects
2.3.2. Deterministic effects
2.4. Dosimetric quantities and units
2.4.1. Physical quantities
2.4.2. Protection quantities
2.4.3. Operational quantities
2.5. Dosimetric methods
2.5.1. Ionizing method
2.5.2.Thermoluminescence method
2.5.3. Chemical method
2.5.4. Calorimetric method
Chapter 3: Cosmic ray dosimetry
3.1. Cosmic ray spectra in the atmosphere
3.1.1. Neutron spectra
3.1.2. Proton and helium ion spectra
3.1.3. Electron, positron and photon spectra
3.1.4. Secondary muon spectra
3.2. Cosmic ray dosimetry in the atmosphere
3.2.1. Fluence to dose conversion coefficients
3.2.2. Cosmic ray dosimetry at ground level
3.2.3. Cosmic ray dosimetry at high altitude
3.2.4. Comparison between the experimental and calculated data
Conclusion
Bibliography
