What Happens When Particles Travel in Non-Crystal Directions?

[aveline de grandpre]

Can someone explain this paragraph especially the bold part in simpler language:

"If it is not in a major crystal direction or plane ("random direction", Fig. 2), it is much more likely to undergo large-angle scattering and hence its final mean penetration depth is likely to be shorter." full article : https://en.wikipedia.org/wiki/Channelling_(physics)

Thank you

 

[mjc123]

Can you be more specific about what you don't understand? Do you know what a mean penetration depth is? Do you understand why it will be shorter in a random direction than along a channel? Do Figs 1 and 2 help you see this?

 

[aveline de grandpre]

Can you be more specific about what you don't understand? Do you know what a mean penetration depth is? Do you understand why it will be shorter in a random direction than along a channel? Do Figs 1 and 2 help you see this?

I don't understand why it will be shorter in a random direction

 

[mjc123]

Look again at Figure 1. Can you see that if the particle goes straight along the 110 direction of a silicon crystal, there are "channels" with no atoms down the middle, and the particle can go a relatively long way before being stopped by collision with a silicon atom. These channels only occur in certain specific directions, depending on the crystal structure. If the particle enters the crystal in any old "random" direction, there will be no such clear channels, and the particle is likely to encounter a silicon atom relatively soon along its trajectory.