# How is the Neutrino Flux Measured in Accelerator Neutrino Experiments?

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• kimmm
In summary, the neutrio flux can be measured by a near detector of the accelerator neutrio experiments,such as T2K.
kimmm
How does the neutrio flux can be measured by a near detector of the accelerator neutrio experiments,such as T2K?
As I know neutrino interactions with the matter in the near detector is too low,and so how they can count the neutrino flux by counting the produced particle from the interaction?

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Have you tried to do the maths? The rate is not too low. In fact, it is typically higher than in the far detector as the near detector is much closer and the flux decreases as ##1/L^2## with the distance ##L## from the source.

Orodruin said:
Have you tried to do the maths? The rate is not too low. In fact, it is typically higher than in the far detector as the near detector is much closer and the flux decreases as ##1/L^2## with the distance ##L## from the source.

yeah as you said in the near detector the rate is higher, do you know the way of calclating the flux in the near detector?

kimmm said:
yeah in as you said in the near detector the rate is high
So why do you claim it is not?

Typically you would compute the flux by simulations of the target station. You can make a reasonable proxy by assuming an amount of produced pions and finding the corresponding flux in the forward direction - unless what you have is an off-axis beam in which case you would need an off-axis direction.

Edit: You can also look at the simulations already done by the experiments, e.g., https://arxiv.org/pdf/1211.0469.pdf

Orodruin said:
So why do you claim it is not?

Typically you would compute the flux by simulations of the target station. You can make a reasonable proxy by assuming an amount of produced pions and finding the corresponding flux in the forward direction - unless what you have is an off-axis beam in which case you would need an off-axis direction.
can I sum it up like this,although may be I am still a bit confused about that,
well as the pions produced,then they will decay to neutrinos and the neutrinos go through the detector,but still the problem is that just 1 in 10 to power 20 of the neutrios do the interaction with the target,so can we do the proportional relations to compute the neutrino flux?

Yes, why wouldn't you? The interaction rate is proportional to the flux multiplied by the cross section. Obviously you will have related statistical and systematic uncertainties, but a priori the rate is a direct proxy for the flux.

Orodruin said:
So why do you claim it is not?

Typically you would compute the flux by simulations of the target station. You can make a reasonable proxy by assuming an amount of produced pions and finding the corresponding flux in the forward direction - unless what you have is an off-axis beam in which case you would need an off-axis direction.

Edit: You can also look at the simulations already done by the experiments, e.g., https://arxiv.org/pdf/1211.0469.pdf

thanks for the paper

Orodruin said:
Yes, why wouldn't you? The interaction rate is proportional to the flux multiplied by the cross section. Obviously you will have related statistical and systematic uncertainties, but a priori the rate is a direct proxy for the flux.
thank you soooo much, it was really a huge struggle in my mind.

## 1. What is a neutrino flux measurement?

A neutrino flux measurement is a way to quantify the number of neutrinos passing through a given area over a specific period of time. This measurement is important in understanding the properties of neutrinos and their interactions with matter.

## 2. How is a neutrino flux measurement conducted?

A neutrino flux measurement is typically conducted using a neutrino detector, which is designed to detect and measure the interactions of neutrinos with matter. The detector is placed in an area where there is a high concentration of neutrinos, such as a nuclear reactor or a particle accelerator, and the data collected is then analyzed to determine the flux.

## 3. Why is it important to measure neutrino flux?

Measuring neutrino flux is important because neutrinos are a fundamental particle in the universe and play a crucial role in many astrophysical and particle physics phenomena. By understanding the properties of neutrinos through flux measurements, we can gain a better understanding of the universe and its origins.

## 4. What factors can affect neutrino flux measurements?

There are several factors that can affect neutrino flux measurements, including the energy and direction of the neutrinos, the type of neutrino being measured (electron, muon, or tau), and the density and composition of the material the neutrinos are passing through.

## 5. How are neutrino flux measurements used in research?

Neutrino flux measurements are used in a variety of research fields, including astrophysics, particle physics, and nuclear physics. They can provide insights into the behavior of neutrinos and help scientists understand the properties of matter and the universe at a fundamental level.

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