Particle-Stopping Power

Bubble point tests are used extensively in detminming the largest and mean pore, in new and recycled filters. Simultaneously, the integrity of the filter can also be estabh ed [Johnston, 1986] in detecting wear and tear of the filter bric. 

The pore radius r may also be inferred fi om permeability tests and the use of Equation (4.6)  

Experimental detemiinatians of r, rbp and Tc (pore radius by microscopic count) have established [Rushton Green, 1968] the followiag sinple relations for wov i wire of monofilament cloths  

No such relationshps are available for muhifilament cloths since the permeability is not accounted for by inspection or bubble-test. In the latter the larger inter-yam pores are measured. Calculations on the tmihifilament yams [Rnshton Griffiths, 1987] show 

The above tests are non-destractive since the filter medium is unchanged afl er conqiletion of the test. Challenge tests, involving the filtration of particles of known size are destractive since after testing, it is virtually m5 ossible to recover the original, unused characteristics of the medium. These challenge tests are considered in the next section. 

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Stopping Power—The average rate of energy loss of a charged particle per unit thickness of a material or per unit mass of material traversed. 

Straggling thus limits the depth and mass resolution for features buried within the target material. The depth resolution, Az depends on the stopping power, dE/dz, the detector resolution, AEdet and the beam energy spread, AEbeam of the incident particles ... 

Theory of Stopping Power of Fast Charged Particles... 

THEORY OF STOPPING POWER OF FAST CHARGED PARTICLES... 

FIGURE 3.1 Stopping power of water for various charged particles over a wide span of energy 1 electron, 2 (positive) muon, 3 proton, 4 carbon nucleus, and 5 fission (light) fragment. See text for details. Reproduced from Mozumder (1969), by permission of John Wiley Sons, Inc. ... 

Figure 3.1 shows the stopping power of water toward some typical charged particle radiations. For others, similar curves can be drawn using the procedure... 

ICRU, Stopping powers and ranges for protons and alpha particles, Vol. 49, ICRU Report, International Commission of Radiation Units and Measurements, Bethesda, Maryland, 1993. 

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