Instantaneous Lumi and Integrated Lumi

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In summary, the conversation discusses the process of converting instantaneous luminosity to integrated luminosity and the importance of taking into account the time span of data collection. It also mentions the incorrect usage of units and uses a car traveling analogy to illustrate the concept.
  • #1
ChrisVer
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I have a pretty basic question...
How can you convert the Instantaneous Luminosity [itex]L_t[/itex] to the integrated Luminosity [itex]L[/itex]?
I know that the relation is the following:
[itex]L = \int L_t dt[/itex]
but if the time is [itex]\sim 25~ns[/itex] and [itex]L_t = 1.7 \times 10^{34} ~cm^{-2} s^{-1}[/itex], then I get an integrated luminosity of:
[itex]L=42.5 \times 10^{25} ~cm^{-2} = 4.25 \times 10^{-13} fb^{-1}[/itex]
which doesn't make sense as a number... dividing with the time gives a more sensible result but right now I don't see why.
 
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  • #2
You calculated the integrated luminosity from a single LHC bunch-crossing.
If you want the integrated luminosity collected within a day, you have to take a day as time.

Dividing luminosity by time gives wrong units, how can that be more sensible?
 
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  • #3
So in general it's impossible without knowing the time-span of your data-collection to translate your integrated luminosity to the instantaneous one? (the reverse of the above)

As for the units, true... I got to use sleepnessless as an excuse.
 
  • #4
ChrisVer said:
So in general it's impossible without knowing the time-span of your data-collection to translate your integrated luminosity to the instantaneous one? (the reverse of the above)
Can you tell how fast I went in my car, traveling 30 km, if I don't tell you how long I was traveling?
 
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  • #5
mfb said:
Can you tell how fast I went in my car, traveling 30 km, if I don't tell you how long I was traveling?

Officer, I can't have been going 80 miles per hour! I've only been driving ten minutes!
 
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Related to Instantaneous Lumi and Integrated Lumi

What is instantaneous lumi?

Instantaneous lumi is a measure of the luminosity (or brightness) of a particle accelerator at a specific moment in time. It is typically expressed in units of inverse picobarns (pb^-1).

What is integrated lumi?

Integrated lumi is a measure of the total luminosity produced by a particle accelerator over a period of time. It is typically expressed in units of inverse femtobarns (fb^-1).

Why are instantaneous and integrated lumi important?

Instantaneous and integrated lumi are important because they provide information about the performance and capabilities of a particle accelerator. They are also crucial for analyzing data and making measurements in high-energy physics experiments.

How are instantaneous and integrated lumi measured?

Instantaneous and integrated lumi are measured using specialized detectors that record the number of particle collisions in a given time period. The data is then analyzed to determine the lumi values.

What is the difference between instantaneous and integrated lumi?

The main difference between instantaneous and integrated lumi is the time period over which they are measured. Instantaneous lumi is measured at a specific moment in time, while integrated lumi is measured over a longer period of time. Additionally, instantaneous lumi is typically expressed in smaller units (inverse picobarns) compared to integrated lumi (inverse femtobarns).

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