# I Muon lifetime measurement experiment

#### Aleolomorfo

Summary
How to treat time resolution as a systematic in a muon lifetime measurement?
Hello everybody!

I have a question regarding my physics laboratory at the university. I am performing the measure of muon lifetime. The setup is quite standard (coincidence measurement with plastic scintillators).
My question is about the time resolution. I have tried to see if the time resolution could affect as a systematic my result. To prove this, I have acquired only coinciding events and I measure the difference in time of such signals. Theoretically, it should be zero, but due to many factors this time intervals follow a gaussian distribution. My question is about the way in which I can take into consideration this systematic. Should I take the $\sigma$ of the gaussian fit or should I repeat the measure many times and take as systematic position drift of the coincidence peak?

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#### mfb

Mentor
The best approach would be to fold the exponential function with your resolution function and then use that in the fit (plus all the other stuff needed). In practice this shouldn't matter unless your time resolution is a large fraction of the muon lifetime.

#### geoelectronics

Summary: How to treat time resolution as a systematic in a muon lifetime measurement?

Hello everybody!

I have a question regarding my physics laboratory at the university. I am performing the measure of muon lifetime. The setup is quite standard (coincidence measurement with plastic scintillators).
My question is about the time resolution. I have tried to see if the time resolution could affect as a systematic my result. To prove this, I have acquired only coinciding events and I measure the difference in time of such signals. Theoretically, it should be zero, but due to many factors this time intervals follow a gaussian distribution. My question is about the way in which I can take into consideration this systematic. Should I take the $\sigma$ of the gaussian fit or should I repeat the measure many times and take as systematic position drift of the coincidence peak?
Hi Aleolomorfo.
Muon detection is of great interest to me as well. Would you please describe the scintillator paddle dimensions, spacing and thickness, and mention which coincidence detection scheme is being used? i.e. NIM or student built such as Dr H. Matis' design.

Thanks

George Dowell

#### Aleolomorfo

Hi Aleolomorfo.
Muon detection is of great interest to me as well. Would you please describe the scintillator paddle dimensions, spacing and thickness, and mention which coincidence detection scheme is being used? i.e. NIM or student built such as Dr H. Matis' design.

Thanks

George Dowell
Hello George Dowell,

I have attached the final report where you can find the information you need.

One thing to notice: last year the particle physics laboratory had too many students, so we were chosen to perform the measurement of the muon lifetime with electronic modules and scintillators found quickly around the university. Consequently, they were not the best ones and we had many problems... our job was not so strightforward. But you can extract the main idea behind the experiment.

If you have any question, ask freely!

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#### geoelectronics

Thank you, nice report, well written. The first effort I've seen to capture Cosmic "Ray" muons.

As a hardware person, the difficulties with scintillators and NIM support units is well appreciated.
I liked the part about an impromptu delay line made "of many LEMO cables".

The one I'm working on now is a single 3" X 3" BGO scintillator inside an 800 pound lead shield.

George Dowell

#### mfb

Mentor
Did you do the stability checks with MC? Doing it with the main dataset is problematic - if you change the analysis based on what looks better you can get some biases. It is interesting to see what looks like a systematic trend for muon lifetime as function of bins.

#### Aleolomorfo

Did you do the stability checks with MC? Doing it with the main dataset is problematic - if you change the analysis based on what looks better you can get some biases. It is interesting to see what looks like a systematic trend for muon lifetime as function of bins.
No, we did not. We only used the dataset but I see your point, we should have used MC.

#### geoelectronics

Hello George Dowell,

I have attached the final report where you can find the information you need.

One thing to notice: last year the particle physics laboratory had too many students, so we were chosen to perform the measurement of the muon lifetime with electronic modules and scintillators found quickly around the university. Consequently, they were not the best ones and we had many problems... our job was not so strightforward. But you can extract the main idea behind the experiment.

If you have any question, ask freely!
Again thanks for the report. I have spent considerable time reading it and several others and also consulted with a moderator to get a better understanding of the aims and the procedure.
From what I see in your paper, you are using multiple organic scintillators at the same time, correct? And recording their coincidences.
In your experiment are the original pulse and the secondary pulse detected in the same scintillator or on two or more? The reason I ask is there are two approaches to working with muons using organic scintillators and I want to understand more.

Thank you.

George Dowell

#### Aleolomorfo

Hello George!

From what I see in your paper, you are using multiple organic scintillators at the same time, correct? And recording their coincidences.
Yes, we use three scintillators at the same time, one over the other. We record a start signal from the passage of a muon in the first and the second scintillator (the events we are interested in are the ones in which the muon stops in the middle scintillator). So the start signal is a coincidence between the upper and the middle scintillator. Then we expect a signal from the decay of the muon. The muon decay mainly in electron/positron and neutrino/antineutrino. We expect a signal (the charged lepton) in the upper or the lower scintillator in a gate of 10 $\mu s$. This is the main idea.

In your experiment are the original pulse and the secondary pulse detected in the same scintillator or on two or more?
We have always used the same three scintillator

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