+ Black = stable (radioactive lifetime is huge), Grey = Unstable

[[./HEP/stable.jpeg]]

+ Typical \beta and \gamma decay energies are in the range of 1 MeV, and low-energy nuclear reactions take place with kinetic energies of order 10 MeV which are far smaller than nuclear rest energies. So nonrelativistic formulation is justfied for nucleons, but \beta -decay electrons must be treated relativistically.

+ Electromagnetic (\gamma) decays generally occur with lifetimes of order nanoseconds to picoseconds. \alpha and \beta decays occure with longer lifetimes, often minutes or hours. Many nuclear reactions ($^5$He or $^8$Be breaking apart) take place in the order of 10^{-20} s, which is roughly the time that the reacting nuclei are within range of each other's nuclear force.

+ Electromagnetic (\gamma) decays generally occur with lifetimes of order nanoseconds to picoseconds. \alpha and \beta decays occure with longer lifetimes, often minutes or hours. Many nuclear reactions ($^5He$ or $^8Be$ breaking apart) take place in the order of 10^{-20} s, which is roughly the time that the reacting nuclei are within range of each other's nuclear force.

*** Remember

- Z=92 for U, 26 for Fe.

- 1 u = 931.502 MeV = 1.661 $\times 10^{-27}$ Kg.

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@@ -29,7 +29,7 @@

- Like the radius of an atom, the radius of a nucleas is not precisely defined. The density of nucleons and the nuclear potential have similar spatial dependence - relatively constant over short distances beyond whic thay drop rapidly to zero.

- (Spherical) nucler shape is characterized by: *mean radius*, where the density is half its central value, and the *skin thickness* over which the density drops from near its maximum to near its minimum.

- In some experiments like high-energy electron scattering, muonic X rays, optical and X-ray isotope shifts, and energy differences of mirror nuclei where we measure Coulomb interaction of a charged particle with the nucleus we determine the /distribution of nuclear charge/ (primarily distribution of protons but also involving somewhat that of neutrons). In other experiments such as Rutherford scattering, \alpha decay, and pionic X rays, we measure the strong nuclear interaction we would determine the /distribution of nuclear matter/.

- Shape and size of an object is determined by examining the radiation scattered from it for which we need wavelength smaller than the details of the object. For nuclei with diameter 10 fm, we require \lamda <= 10 fm i.e., p >= 100 MeV/c.

- Shape and size of an object is determined by examining the radiation scattered from it for which we need wavelength smaller than the details of the object. For nuclei with diameter 10 fm, we require \lambda <= 10 fm i.e., p >= 100 MeV/c.

* Clarifications

- The moodle says 10 best out of 11 assignments. But 8 out of 11 is mentioned in class.

- Black = stable (radioactive lifetime is huge), Grey = Unstable

![](./HEP/stable.jpeg)

- Typical β and γ decay energies are in the range of 1 MeV, and low-energy nuclear reactions take place with kinetic energies of order 10 MeV which are far smaller than nuclear rest energies. So nonrelativistic formulation is justfied for nucleons, but β -decay electrons must be treated relativistically.

- Electromagnetic (γ) decays generally occur with lifetimes of order nanoseconds to picoseconds. α and β decays occure with longer lifetimes, often minutes or hours. Many nuclear reactions ($^5$He or $^8$Be breaking apart) take place in the order of 10<sup>-20</sup> s, which is roughly the time that the reacting nuclei are within range of each other's nuclear force.

- Electromagnetic (γ) decays generally occur with lifetimes of order nanoseconds to picoseconds. α and β decays occure with longer lifetimes, often minutes or hours. Many nuclear reactions (\\(^5He\\) or \\(^8Be\\) breaking apart) take place in the order of 10<sup>-20</sup> s, which is roughly the time that the reacting nuclei are within range of each other's nuclear force.

#### Remember {#remember}

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@@ -41,7 +41,7 @@ draft = false

- Like the radius of an atom, the radius of a nucleas is not precisely defined. The density of nucleons and the nuclear potential have similar spatial dependence - relatively constant over short distances beyond whic thay drop rapidly to zero.

- (Spherical) nucler shape is characterized by: **mean radius**, where the density is half its central value, and the **skin thickness** over which the density drops from near its maximum to near its minimum.

- In some experiments like high-energy electron scattering, muonic X rays, optical and X-ray isotope shifts, and energy differences of mirror nuclei where we measure Coulomb interaction of a charged particle with the nucleus we determine the _distribution of nuclear charge_ (primarily distribution of protons but also involving somewhat that of neutrons). In other experiments such as Rutherford scattering, α decay, and pionic X rays, we measure the strong nuclear interaction we would determine the _distribution of nuclear matter_.

- Shape and size of an object is determined by examining the radiation scattered from it for which we need wavelength smaller than the details of the object. For nuclei with diameter 10 fm, we require \lamda<=10fmi.e.,p>= 100 MeV/c.

- Shape and size of an object is determined by examining the radiation scattered from it for which we need wavelength smaller than the details of the object. For nuclei with diameter 10 fm, we require λ<=10fmi.e.,p>= 100 MeV/c.