Nuclear Properties and Models - Nuclear and Particle Physics - Physics Previous Year Questions

1

2007 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2007

In the deuterium + tritium (\( d + t \)) fusion more energy is released as compared to deuterium + deuterium (\( d + d \)) fusion because

A

tritium is radioactive.

B

more nucleons participate in fusion.

C

the Coulomb barrier is lower for the \(d + t \) system than \(d + d \) system.

D

the reaction product \(^4 \)He is more tightly bound.

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2

2007 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2007

According to the shell model the ground state spin of the \( ^{17} \)O nucleus is

A

\(\frac{3}{2}^+ \)

B

\(\frac{5}{2}^+ \)

C

\(\frac{3}{2}^- \)

D

\(\frac{5}{2}^- \)

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3

2007 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2007

In the deuterium + tritium (\(d + t\)) fusion more energy is released as compared to deuterium + deuterium (\(d + d\)) fusion because

A

tritium is radioactive.

B

more nucleons participate in fusion.

C

the Coulomb barrier is lower for the \(d + t\) system than \(d + d\) system.

D

the reaction product \(^4\)He is more tightly bound.

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4

2007 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2007

According to the shell model the ground state spin of the \(^{17}\)O nucleus is

A

\(\frac{3}{2}^+\)

B

\(\frac{5}{2}^+\)

C

\(\frac{3}{2}^-\)

D

\(\frac{5}{2}^-\)

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5

2007 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2007

A neutron scatters elastically from a heavy nucleus. The initial and final states of the neutron have the

A

same energy.

B

same energy and linear momentum.

C

same energy and angular momentum.

D

same linear and angular momenta.

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6

2007 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2007

The neutrons are observed at the rate of \(1.806 \times 10^8 s^{-1}\). If the density of rhodium is approximated as \(10^4 kg m^{-3}\) the cross-section for the reaction (in barns) is

A

0.1

B

0.2

C

0.4

D

0.8

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7

2007 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2007

The neutrons are observed at the rate of \(1.806 \times 10^8\) s\(^{-1}\). If the density of rhodium is approximated as \(10^4\) kg m\(^{-3}\), the cross-section for the reaction (in barns) is

A

0.1

B

0.2

C

0.4

D

0.8

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8

2008 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2008

An O¹⁶ nucleus is spherical and has a charge radius \(R\) and a volume \(V = \frac{4}{3}\pi R^3\). According to the empirical observations of the charge radii, the volume of the \(_{54}Xe^{128}\) nucleus, assumed to be spherical, is

A

\(8V\)

B

\(2V\)

C

\(6.75V\)

D

\(1.89V\)

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9

2008 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2008

The following gives a list of pairs containing (i) a nucleus (ii) one of its properties. Find the pair which is INAPPROPRIATE.

A

(i) \(_{10}Ne^{20}\) nucleus; (ii) stable nucleus

B

(i) A spheroidal nucleus; (ii) an electric quadrupole moment

C

(i) \(_{8}O^{16}\) nucleus; (ii) nuclear spin J=1/2

D

(i) \(_{92}U^{238}\) nucleus; (ii) Binding energy = 1785 MeV (approximately)

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10

2008 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2008

The four possible configurations of neutrons in the ground state of \(_{4}Be^{9}\) nucleus, according to the shell model, and the associated nuclear spin are listed below. Choose the correct one:

A

\((1s_{1/2})^2(1p_{3/2})^3\), J=3/2

B

\((1s_{1/2})^2(1p_{3/2})^2(1p_{1/2})^1\), J=3/2

C

\((1s_{1/2})^2(1p_{3/2})^4\), J=1/2

D

\((1s_{1/2})^2(1p_{3/2})^3(1p_{1/2})^1\), J=1/2

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11

2008 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2008

The mass difference between the pair of mirror nuclei \(_{6}C^{11}\) and \(_{5}B^{11}\) is given to be \(\Delta\)MeV/c². According to the semi-empirical mass formula, the mass difference between the pair of mirror nuclei \(_{7}F^{17}\) and \(_{8}O^{17}\) will approximately be (rest mass of proton \(m_p\) = 938.27 MeV/c² and rest mass of neutron \(m_n\) = 939.57 MeV/c²)

A

1.39Δ MeV/c²

B

(1.39Δ + 0.5) MeV/c²

C

0.86Δ MeV/c²

D

(1.6Δ + 0.78) MeV/c²

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12

2008 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2008

A heavy nucleus is found to contain more neutrons than protons. This fact is related to which one of the following statements.

A

The nuclear force between neutrons is stronger than that between protons.

B

The nuclear force between protons is of a shorter range than those between neutrons, so that a smaller number of protons are held together by the nuclear force.

C

Protons are unstable, so their number in a nucleus diminishes.

D

It costs more energy to add a proton to a (heavy) nucleus than a neutron because of the Coulomb repulsion between protons.

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13

2009 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2009

Pick the WRONG statement.

A

The nuclear force is independent of electric charge

B

The Yukawa potential is proportional to \(r^{-1} \exp \left( -\frac{mc}{\hbar} r \right) \), where \(r \) is the separation between two nucleons

C

The range of nuclear force is of the order of \(10^{-15} m - 10^{-14} m \)

D

The nucleons interact among each other by the exchange of mesons

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14

2009 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2009

Consider a nucleus with \( N \) neutrons and \( Z \) protons. If \( m_p \), \( m_n \) and \( BE \) represent the mass of the proton, the mass of the neutron and the binding energy of the nucleus respectively and \( c \) is the velocity of light in free space, the mass of the nucleus is given by

A

\(Nm_n + Zm_p \)

B

\(Nm_p + Zm_n \)

C

\(Nm_n + Zm_p + \frac{BE}{c^2} \)

D

\(Nm_p + Zm_n + \frac{BE}{c^2} \)

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15

2009 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2009

Consider the following expression for the mass of a nucleus with \(Z\) protons and \(A\) nucleons: \(M(A,Z)=\frac{1}{c^2}(f(A)+yZ+zZ^2)\). Here \(f(A)\) is a function of \(A\), \(y=-4a_a\), \(z=a_cA^{-1/3}+4a_aA^{-1}\), \(a_a\) and \(a_c\) are constants of suitable dimensions. For a fixed \(A\), the expression of \(Z\) for the most stable nucleus is

A

\(Z = \frac{A/2}{1+\left(\frac{a_c}{a_a}\right)A^{2/3}}\)

B

\(Z = \frac{A/2}{1+\left(\frac{a_c}{4a_a}\right)A^{2/3}}\)

C

\(Z = \frac{A}{1+\left(\frac{a_c}{4a_a}\right)A^{2/3}}\)

D

\(Z = \frac{A}{1+A^{2/3}}\)

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16

2009 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2009

Let \(|n⟩\) and \(|p⟩\) denote the isospin states with I = 1/2, I₃ = 1/2 and I = 1/2, I₃ = -1/2 of a nucleon respectively. Which one of the following two-nucleon states has I = 0, I₃ = 0?

A

\(\frac{1}{\sqrt{2}}(|nn⟩-|pp⟩)\)

B

\(\frac{1}{\sqrt{2}}(|nn⟩+|pp⟩)\)

C

\(\frac{1}{\sqrt{2}}(|np⟩-|pn⟩)\)

D

\(\frac{1}{\sqrt{2}}(|np⟩+|pn⟩)\)

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17

2010 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2010

In the nuclear shell model the spin parity of \(^{13}N\) is given by

A

\(\frac{1}{2}^-\)

B

\(\frac{1}{2}^+\)

C

\(\frac{3}{2}^-\)

D

\(\frac{3}{2}^+\)

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18

2010 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2010

The ground state wavefunction of deuteron is in a superposition of \( s \) and \( d \) states. Which of the following is NOT true as a consequence?

A

It has a non-zero quadrupole moment

B

The neutron-proton potential is non-central

C

The orbital wavefunction is not spherically symmetric

D

The Hamiltonian does not conserve the total angular momentum

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19

2010 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2010

The first three energy levels of \( ^{228}Th_{90} \) are shown below

4+	187 keV
2+	57.5 keV
0+	0 keV

The expected spin-parity and energy of the next level are given by

A

\((6^+, 400 \text{ keV}) \)

B

\((6^+, 300 \text{ keV}) \)

C

\((2^+, 400 \text{ keV}) \)

D

\((4^+, 300 \text{ keV}) \)

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20

2011 · Physics · Nuclear and Particle Physics · Nuclear Properties and Models

Physics (PH) 2011

The semi-empirical mass formula for the binding energy of nucleus contains a surface correction term. This term depends on the mass number A of the nucleus as

A

A^-1/3

B

A^1/3

C

A^2/3

D

A

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