Aligarh Muslim University (AMU) 2011 B.Sc Physics Nuclear practice and Astro - Question Paper

4485

2010-2011

:    B.Sc. (HONS.) (PART - III) EXAMINATION

J    (PHYSICS)

NUCLEAR PRACTICE AND ASTROPHYSICS

(PH -316)

Maximum Marks : 40    Duration : Three Hours

Note: Answer all questions.

1.(a)    What are the important components of a mass spectrograph? Discus the working [4]

-principle of Bainbridge mass spectrograph.

(J>) Draw a typical binding energy per nucleon curve for nuclei existing in nature and [3] hence explain how the energy is released in the process of fission.

OR

l'.(a) Discuss the high energy electron scattering experiment to determine the size of the [4] nucleus.

(b) On the basis of uncertainty principle show that electrons cannot be constituent of the [3] nucleus.

2.    Answer any two of the following:    [3+3]

(a)    What are the basic differences between the energy spectrum of alpha and beta particles obtained in natural radioactive decay? Discuss the reason(s) for the typical nature of alpha particle spectrum.    ^vm

(b)    Discuss the energetics of positron decay.

(c)    Define Q-value of a nuclear reaction. Calculate the Q-value for the reaction ¹⁴N (a, p)¹⁷0, in MeV. Given, Mass of ⁴He - 4.002603 u, ¹⁴N = 14.003074u,

*H = 1.007825u and ¹⁷0 = 16.999131u.

3.(a)    Discuss the interaction processes by which 10 MeV gamma ray loses energy while [4] passing through matter.

(b) Draw the block diagram of a NaI(T/) scintillation gamma ray spectrometer. Discuss [3] briefly the function of each block. Also draw a typical gamma ray spectrum of ¹³⁷Cs gamma ray source, obtained using such spectrometer.

4.(a)    Distinguish between Fermions and Bosons.    [2]

(b) Apply conservation laws to find whether the following reactions are allowed or [3] forbidden. Give the quantum numbers which are not conserved for the forbidden reactions.

(0 ^ve +p >n + e⁺

(ii)    7t⁺ + n > a⁰ + K

(iii)    n-p + e + v_e

Name various quark flavours. Write their quantum numbers.    [2]

OR

Explain the difference between even and odd parity. Show that the pion parity is [7] odd.

What are secondary cosmic rays? Explain the development of electromagnetic [4] cascade shower.

Plot the energy spectrum of primary cosmic rays and discuss its important features.    [3]

Write notes on any two of the following:    [3+3]

(a)    Hydrostatic and Thermal equilibrium in stars.

(b)    Hertzspnmg Russel diagram

(c)    Black holes.

Attachment: aligarh-muslim-university--amu--2011-b-sc-physics-273-1.pdf

Earning:   Approval pending.