PYQ Bank

Describe briefly how parity violation in \beta-decay was experimentally observed? What do you understand by the statement, 'neutrinos are left-handed'?

Distinguish between charge independence and charge symmetry of nuclear force. Give one example of each of these.

Estimate the order of nuclear radius of lead (Z = 82) using the large angle (back) scattering of alpha particles of energy 10\,\mathrm{MeV} incident on a target (lead). [Given: (4\pi\epsilon_0)^{-1} = 9 \times 10^{9}\,\mathrm{N\,m^2\,C^{-2}}]

What is meant by quark confinement ? Why are the masses of hadrons larger than the sum of the masses of their constituent quarks ?

State the three characteristic properties of strong, weak and electromagnetic forces distinguishing one from the other.

Explain briefly SU(3) flavor symmetry and SU(2) isospin symmetry in particle physics.

Point out the interactions in which the following conservation laws are obeyed or violated

(i) Isotopic spin

(ii) Hyper charge

(iii) Lepton number

(iv) Charge conjugation

Write down the quark constituents of each of the following:

(i) \pi^+

(ii) K^+

(iii) \Delta^{++}

(iv) \Sigma^0

(v) \Omega^-

Obtain the Q-values for the following four nuclear reactions :

(i) ^{14}_{7}\text{N} + ^{4}_{2}\text{He} \rightarrow ^{17}_{8}\text{O} + ^{1}_{1}\text{H}

(ii) ^{7}_{3}\text{Li} + ^{4}_{2}\text{He} \rightarrow ^{10}_{5}\text{B} + ^{1}_{0}\text{n}

(iii) ^{6}_{3}\text{Li} + ^{1}_{1}\text{H} \rightarrow ^{3}_{2}\text{He} + ^{4}_{2}\text{He}

(iv) ^{23}_{11}\text{Na} + ^{1}_{1}\text{H} \rightarrow ^{20}_{10}\text{Ne} + ^{4}_{2}\text{He}

What are the quantum numbers of u, d and s quarks and of the corresponding antiquarks (\bar{u}, \bar{d}, \bar{s})? Obtain the quark contents of proton (p), neutron (n), positively charged pion (\pi^+) and negatively charged omega minus (\Omega^-) particle.

What is parity transformation? Discuss the experiment that confirms the violation of parity in beta decay.

Show that in the nuclear shell model, the level spacing between major oscillator shells is approximately \hbar\omega = 41\,A^{-1/3}\,\mathrm{MeV}.

State the basic assumption of single particle shell model. How do the centrifugal and spin-orbit terms remove the degeneracy of a three-dimensional spherical harmonic oscillator?

Explain why the deuteron has no excited state.

Explain unification of electromagnetic and weak interactions. What is Z^0-boson? What is its relevance in electroweak unification?

What are elementary particles and how are they classified? Describe in brief the different types of interactions that can occur between the elementary particles.

Give an outline of meson theory of nuclear forces. Describe the physical basis of short-range nuclear repulsion between like nucleons : proton-proton (p\text{-}p) or neutron-neutron (n\text{-}n). Consider the following two three-nucleon systems : (p\text{-}p\text{-}p) and (n\text{-}n\text{-}n). Which one is more likely to form a bound state?

In a nuclear fusion process, four hydrogen nuclei combine to form a helium nucleus. Obtain the energy released in such a process. If the same process is responsible for energy of a star of mass 2 \times 10^{30}\text{ kg}, each kilogram having 6 \times 10^{26} protons, what could be the magnitude of energy released in it?

Describe the properties of field quanta of electro-weak and strong interactions of particles.

Predict the spin and parity of ground states of the following nuclei on the basis of shell model:

(i) {}_{8}\mathrm{O}^{15}

(ii) {}_{8}\mathrm{O}^{16}

(iii) {}_{17}\mathrm{Cl}^{38}