Changing a velocity distributions

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A Gaussian velocity distribution can change when a portion of particles is bunched into a lower velocity class. This change raises the question of whether it constitutes cooling as well as slowing of the atoms. One viewpoint argues that cooling is a collective property affecting all atoms, while another perspective from the laser-cooling field acknowledges that cooling can apply to a subset of particles. The relationship between randomized kinetic energy and temperature is also discussed, emphasizing the complexity of defining cooling in this context. Ultimately, the conversation highlights differing interpretations of cooling in relation to velocity distribution changes.
Niles
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Hi

Say I have a Gaussian velocity distribution for a collection of particles. Then I make a change to the setup in a way that the velocity distribution changes. This change is such that a part (not all) of the distribution gets bunched into one particular velocity class lower than the mean of the Gaussian.

Does this constitute cooling of the atoms as well as slowing? I would say no myself, as "cooling" is a collective parameter of all the atoms, not just some of them.


Niles.
 
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The velocities are still random?
What is the relationship between randomized kinetic energy (and, therefore, speed) and temperature?
 
Niles said:
Hi

Say I have a Gaussian velocity distribution for a collection of particles. Then I make a change to the setup in a way that the velocity distribution changes. This change is such that a part (not all) of the distribution gets bunched into one particular velocity class lower than the mean of the Gaussian.

Does this constitute cooling of the atoms as well as slowing? I would say no myself, as "cooling" is a collective parameter of all the atoms, not just some of them.


Niles.
It is considered cooling in the laser-cooling field, with the understanding that it is a subset of the entire collection of atoms that has been cooled.
 
For simple comparison, I think the same thought process can be followed as a block slides down a hill, - for block down hill, simple starting PE of mgh to final max KE 0.5mv^2 - comparing PE1 to max KE2 would result in finding the work friction did through the process. efficiency is just 100*KE2/PE1. If a mousetrap car travels along a flat surface, a starting PE of 0.5 k th^2 can be measured and maximum velocity of the car can also be measured. If energy efficiency is defined by...

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