Pound-Rebka Experiment: Understanding Gamma Ray Detection & Doppler Effect

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In summary, the Pound-Rebka test involved moving a gamma ray detector and using the relativistic Doppler effect to cancel out the gravitational blueshift. This was achieved by measuring the elevator speed and using it as an easy to measure effect. The Zee man effect could potentially be used to measure the shift, using an atom with a specific wavelength that could be absorbed at the emitter but not at the detector due to the redshift. By placing the atoms in a magnetic field at the detector and tuning the strength of the field, the shifted photon could potentially be accepted.
  • #1
cragar
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Im trying to understand the pound- rebka test , so was the gamma ray detector moving
, when the photon gets shot from the top of the 4th floor of the science building at harvard
to the bottom it will be blue shifted , so would they want to move the detector away at a certain speed so the doppler effect will cancel out the blueshift , and the speed that the detector is moving then using the doppler effect equation we could calculate the shift.
Any input will be much appreciated.
 
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  • #2
Yes, I think you're on the right track although it's hard to follow what you've written. This Wiki entry might explain ( if you have not seen it already ). The experimenters certainly moved the receiver to offset the gravitational frequency shift with a Doppler shift.

http://en.wikipedia.org/wiki/Pound–Rebka_experiment
 
  • #3
cragar said:
Im trying to understand the pound- rebka test , so was the gamma ray detector moving
, when the photon gets shot from the top of the 4th floor of the science building at harvard
to the bottom it will be blue shifted , so would they want to move the detector away at a certain speed so the doppler effect will cancel out the blueshift , and the speed that the detector is moving then using the doppler effect equation we could calculate the shift.
Any input will be much appreciated.

The reason is that once you move the detector at the right speed, the experimenters managed to cancel out the gravitational blueshift through the relativistic Doppler redshift. The idea was that the Doppler redshift was used as an easy to measure effect (through measuring the elevator speed "v").
 
  • #4
ok so the detector was moving towards the Earth in an elevator with a speed V .
And i am just wondering could we use the zee man effect to measure the shift ,
could we use an atom that had a specific wavelength of a photon between the ground state and some other state , that could be absorbed from the emitter but could not be absorbed at the detector because of the red shift , but if we placed the atom's in a magnetic field at the detector and had the strength of the B field tuned precisely to accept the shifted photon , would this work.
 
  • #5
cragar said:
ok so the detector was moving towards the Earth in an elevator with a speed V .
And i am just wondering could we use the zee man effect to measure the shift ,
could we use an atom that had a specific wavelength of a photon between the ground state and some other state , that could be absorbed from the emitter but could not be absorbed at the detector because of the red shift , but if we placed the atom's in a magnetic field at the detector and had the strength of the B field tuned precisely to accept the shifted photon , would this work.

yes, should work
 
  • #6
sweet thanks for your response .
 

1. What is the Pound-Rebka Experiment?

The Pound-Rebka Experiment was a scientific experiment conducted in 1959 by Robert Pound and Glen Rebka at Harvard University. The experiment aimed to test the gravitational redshift predicted by Einstein's theory of general relativity.

2. How does the Pound-Rebka Experiment work?

The experiment involved measuring the frequency of gamma rays emitted by a radioactive source at different heights in a tower. According to general relativity, the frequency of light should decrease as it moves away from a source of gravity. By measuring the change in frequency, the scientists were able to confirm the existence of the gravitational redshift.

3. What is the significance of the Pound-Rebka Experiment?

The Pound-Rebka Experiment provided strong evidence for the validity of Einstein's theory of general relativity. It also demonstrated the link between gravity and time dilation, which is a key concept in understanding the fabric of spacetime.

4. How does the Doppler Effect play a role in the Pound-Rebka Experiment?

The Doppler Effect is the change in frequency of a wave due to the relative motion between the source of the wave and the observer. In the Pound-Rebka Experiment, the Doppler Effect is used to measure the change in frequency of gamma rays as they move away from the source of gravity.

5. What are some applications of the Pound-Rebka Experiment?

The Pound-Rebka Experiment has been instrumental in furthering our understanding of the effects of gravity on light and time. It has also been used to study other phenomena, such as gravitational lensing and the behavior of black holes. Additionally, the experiment has practical applications in areas such as astrophysics and satellite navigation systems.

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