Alpha Particle Structure of Nucleus - International PhD
Transcript of Alpha Particle Structure of Nucleus - International PhD
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Alpha Particle Structure of Nucleus
Jinesh Kallunkathariyil
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Nuclear Structure Theories
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1. Large binding energy
2. Stable isotopes
3. Abundance
4. Naturally occurring radioactive series decay to the stable
end product Pb with Z=82 in three isotopic forms having N=126 for one of them.
Experimental evidences for the existence of magic numbers
2, 8, 20, 28, 50, 82, and 126
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5. Neutron absorbing cross section is very low 7. First excited states is at higher energies 8. Electric quadrupole moment of magic numbered nuclei is near zero indicating the spherical symmetry of nucleus for closed shells. 9. High energy of alpha or beta particles emitted
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History
“Just because you see alpha particles coming out of nucleus, you should not necessarily conclude that inside they exist as such ”
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Bethe and Bacher (1936)
Ernest Rutherford (1899) Alpha particle decay
Wefelmeier (1937) Wheeler (1937) Von Weizsacker (1938)
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Hafstad and Teller (1938)
Martin Freer (2010)
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Semi-classical Microscopic Approach to the Liquid drop model
Zbigniew Sosin (http://arxiv.org/abs/1304.2846)
12C
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16O
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20Ne
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24Mg
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28Si
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40Ca
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56Ni
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Binding energy and number of bonds
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60Zn
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First Approximation
Binding energy of alpha particle (4He),
𝑏𝛼 = 28.296𝑀𝑒𝑉
𝐶12 = 3𝛼 ?
𝐵 𝐶12 = 92.163𝑀𝑒𝑉
3𝛼 = 84.888𝑀𝑒𝑉 < 𝐵 𝐶12
𝐵 = 𝑛𝛼 × 𝑏𝛼 + 𝑛𝑏 × 𝑏𝛼−𝛼
𝑏𝛼−𝛼 = 2.425𝑀𝑒𝑉
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𝐵 = 𝑛𝛼 × 𝑏𝛼 + 𝑛𝑏 × 𝑏𝛼−𝛼
From Zn, Bethe’s prediction changes
Zn
Ge
Zr
Ni
Binding energy 1 center α bond energy = 𝟑. 𝟐𝟔𝟒 𝑴𝒆𝑽
2 center α bond energy = 𝟐 × 𝟑. 𝟐𝟔𝟒 𝑴𝒆𝑽 = 𝟔. 𝟓𝟐𝟖𝑴𝒆𝑽
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Bond length and bond energy
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Z=N=odd
𝑏4𝑛+2 = 𝑏4𝑛 + 12.498𝑀𝑒𝑉
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Structure of nuclei heavier than Sn
Color lines are the experimental binding energy for all nuclei. Same color shows the isotopes of same nuclei
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Structure of nuclei heavier than Sn
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Alpha Particle structure of nuclei
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Alpha Particle structure of nuclei?
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Fission Fragment distribution
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More evidences!!
Density distribution
Giant Dipole Resonance (GDR)
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Results and Conclusion
• Structural change from Zn is the reason for the abundance of Iron peak elements in the Universe
• Alpha particle need high energy to overcome the coulomb energy of balloon like surface to enter inside
• Supernova explosion
• Nuclear fission
• Asymmetric fission
• Symmetric fission
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Thank you…
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