double slit questions

[controversialEngineer]

what are the dimensions of the double slits in comparison to the electron?

what keeps the electron from decaying outside the environment of an atom long enough to run the experiment?

how are the electrons detected before and after the slits?

[Sensei]

20 minutes ago, controversialEngineer said:

what keeps the electron from decaying outside the environment of an atom long enough to run the experiment?

Electron is stable particle in Standard Model. Decay of electron has not been observed yet.

 

Did you mean "recombination of electrons and nucleus" (i.e. deionization, capture of electron by nucleus (to form neutral atom)) instead of "decay".. ?

If so, electrons are fired in vacuum, with high enough kinetic energy given by electron gun. They must decelerate prior being captured by some nucleus (to form neutral atom).

 

20 minutes ago, controversialEngineer said:

how are the electrons detected before and after the slits?

e.g. when highly enough accelerated particle is hitting fluorescent/luminescent screen, there is emitted photon, and particle is decelerating. Photon can be observed.

You should read how CRT (Cathode Ray Tube) is designed:

https://en.wikipedia.org/wiki/Cathode_ray_tube

 

Edited August 16, 2018 by Sensei

[Strange]

1 hour ago, controversialEngineer said:

what are the dimensions of the double slits in comparison to the electron?

The distance between the interference fringes is given by [math]\Delta y = L\lambda / d[/math] (see here: https://en.wikipedia.org/wiki/Young's_interference_experiment)

The wavelength of an electron depends on its energy (how fast it is going): http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/debrog2.html

This page says that electrons in this sort of experiment are accelerated to about 120,000 km/s: http://www.hitachi.com/rd/portal/highlight/quantum/doubleslit/index.html

That should let you calculate a rough estimate for the distance between the slits to get reasonable size fringe spacing.

1 hour ago, controversialEngineer said:

what keeps the electron from decaying

Electrons don't decay. There is nothing lighter for them to decay into (unlike muons, for example).

[controversialEngineer]

not sure that answers my question. an electron is extremely small in comparison to a single hydrogen atom. how can we possibly produce a barrier small enough to appear as two slits in comparison to the electron?

aren't electrons made of quarks and energy? can we isolate an electron in a vacuum without adding energy to the electron?

[Strange]

5 minutes ago, controversialEngineer said:

not sure that answers my question. an electron is extremely small in comparison to a single hydrogen atom. how can we possibly produce a barrier small enough to appear as two slits in comparison to the electron?

As long as the distance between the slits is a several times larger than the wavelength of the electron then I'm not sure what the problem is.

7 minutes ago, controversialEngineer said:

aren't electrons made of quarks and energy?

No. Protons and neutrons are made of quarks. Electrons are elementary particles (ie not made of anything smaller).

7 minutes ago, controversialEngineer said:

can we isolate an electron in a vacuum without adding energy to the electron?

You need to add energy to the electron to free it from the electrode and then you need to accelerate it to make it fly through the dual slit apparatus. 

So, yes, you need to add energy. This will, as explained above, change the wavelength.

[controversialEngineer]

do you know the measurements involved? the size of an electron and the width of the divider between the slits? i picture shooting a pellet gun at the length of a battleship...

[Strange]

2 hours ago, controversialEngineer said:

do you know the measurements involved? the size of an electron and the width of the divider between the slits?

The wavelength of an electron depends on its energy. The link I referred to earlier will calculate it for you: http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/debrog2.html

The separation of the slits needs to be several times larger than the wave length. 

For example: 

Quote

The individual slits are 62 nm wide ... and separated by 272 nm

http://iopscience.iop.org/article/10.1088/1367-2630/15/3/033018/meta

2 hours ago, controversialEngineer said:

i picture shooting a pellet gun at the length of a battleship...

Not sure what the relevance of that picture is.