Atomic and Nuclear Physics Answers

1.Define a ‘detector’.

(b) List at least four important characteristics of a ‘perfect radiation detector. Give some details of each.

(c) Draw a block diagram of a typical counting set – up. Explain the function of a pre- amplifier.

2. (a) Explain briefly how the Geiger discharge is terminated.

(b) Explain the meaning of “dead time” and “recovery time” of a Geiger counter.

(c) Explain the following statement: “In a windowless proportional counter, the output pulse height from an alpha particle source will increase with increasing alpha energy, whereas for beta particles the opposite is true.

A radiation of frequency 1016Hz falls on a photocathode and ejects electrons with maximum energy of 4.2 X 10-19 J. If the frequency of radiation is changed to 5 X 1014 Hz, the maximum energy of ejected electrons becomes 0.9 X10-19J.

The planks’ constant.

(ii) The threshold frequency.

(iii) The work function.

I have twice the age you had when I had the age you have. When you will be as old as I am, the sum of our ages will be 72 years. What are our ages ??

How many number of electron shells are in the Mc-288? Given that its atomic number and neutron number are 115 and 174, respectively.

Two nuclides are represented as X(mass number= 70, proton= 32) and Y(mass number=37, proton=17) are added to a proton to form a new nuclide. Determine the ratio of a proton-neutron of the new nuclide.

Gold has a density of 19 700 kg m-3. 193 g of gold

contains 6.02 × 1023 atoms. Use this information

to estimate the volume of a gold atom, and hence

its radius. State any assumptions you make.

Determine the total number of energy states in GaAs between Ec and Ec+Tk at T=300k