Geiger Counter Lab Report

PROBLEM 3 - GEIGER COUNTER
Introduction:
In this problem we assume that we are at our placement at the Radiation Protection Institute of Ireland we have been assigned to the national laboratory for measurement of radioactivity levels in the environment. Our work involves the use of a Geiger counter – a device that detects radiation such as alpha particles.
Since we are going to use it regularly we are expected to have a full understanding of the principals of operation of the equipment. In order to develop the understanding principles, we are asked to draw a sketch of Geiger counter and show the main components and explain their role, explain the principle of operation of the device, show the electric field lines created in a Geiger’s counter

The ionization initiates a momentary avalanche of electrons accelerate by the high voltage potential used to power the Geiger counter tube. This avalanche, create a momentary conductive path between the wire at the center of the tube (Anode) and the wall of the tube (Cathode), resulting in a ‘click’ sound. By measuring the number of the clicks, the instrument indicates the radiation levels. (2) Radiation (dark blue) is moving randomly outside the detector tube. Some of the radiation enters the window (gray) at the end of the tube. When radiation collides with gas molecules in the tube (orange), it causes ionization, some of the gas molecules are turned into positive ions (red) and electrons (yellow). The positive ions are attracted to the outside of the tube (light blue). The electrons are attracted to a metal wire (red) running down the inside of the tube kept at a high positive voltage. Many electrons travel down the wire making a burst of current in a circuit connected to

(4)
Potential difference between two points is the work done in moving unit charge (i.e. one coulomb) from one point to the other, the formula to find potential difference is: V=W/Q (1)
Where V is the potential difference in volts, W is the work done or energy transferred in joules, J and Q is the charge in coulombs, C. (5)
The electric field of an infinite line charge with a uniform linear charge density (cylinder) can be obtained by a using Gauss' law. Considering a Gaussian surface in the form of a cylinder at radius r, the electric field has the same magnitude at every point of the cylinder and is directed outward. The formula for this is: E=1/(2πε_0 ) λ/r (2)
Where E is the electric field, ε_0 is the permittivity constant, λ is the charge per unit length and r is the radius. (6)
We need to derive a formula that shows the relationship between electric field and potential difference to do that we do the following