(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A beam of positrons (positron ≡ antielectron) travels at 0.001% the speed of light and impinges on a slit that is 1 μm wide. Use modern units to find the angle θ between the center line and 3rd minimum of the resulting diffraction pattern. How far away (in cm) would you locate a detector so that the 3rd minimum is spaced 20 cm from the center line?

2. Relevant equations

wavelength = hc/pc where hc=1240nm*ev

and i believe p=mv where mass is same as electron =9.1e-31 and so pc=mc^{2}=0.511e6

there is example in my notes where pc=mv*c=mc^{2}(v/c) was used to find wavelength if v was given in % of c. but this is where I get confused because in the notes 0.1%*c becomes 0.001 somehow (10^{-2}?)

for minima: (n-0.5)*wavelength=d*sin(θ) where asked to find θ, d=1e-6m and n=3 for this problem.

3. The attempt at a solution

so.. after various incorrect attempts it give me what the answer should be but problem is I dont know how to get it :(

θ = 46.7200 Degrees

Tries 3/3

L= 18.8339 cm

Tries 3/3

I think i should do something like find wavelength using 1240/(0.511e6*0.001) and if I do I get 2.43 nm. but i think im doing it wrong because I get wrong θ :(

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# Simple positron diffraction problem

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