# Atlas Exp: Solving Calorimeter Challenges

• prochatz
In summary: Why does the full structure have barrel shape?There are a few reasons: The barrel shape provides a large cross-section for the collision events, which is important for a high-precision detector. The barrel shape reduces the distortion of the signals due to the spherical shape of the LAr ions. The barrel shape minimizes the impact of the stray field from the magnets on the signals.

#### prochatz

Considering the Atlas experiment, which are the basic theoretical decisions someone must take in order to create an effective calorimeter? In other words, which are the basic problems that someone must solve to achieve the best possible effectiveness?

For example, the high temperature problem can be solved with cryogenic methods (Liquid Argon). The geometrical orbits of particles can be fully observed if we construct our calorimeter in the shape of a barel. Are there any similar problem that physicists had to face?

I'm not sure what you mean by these "problems". What is the "high temperature problem"? Lots of people have room temperature calorimeters. If by "geometric orbits" you mean "tracks", the tracking occurs before the particle has reached the calorimeter.

Vanadium 50 said:
I'm not sure what you mean by these "problems".

In order to construct an effective calorimeter someone must, first of all, take into account all the parameters of the experiment that may lead to fail.

Vanadium 50 said:
What is the "high temperature problem"? Lots of people have room temperature calorimeters.

I'm talking about the LAr Calorimeters in Atlas experiment. Not an ordinary calorimeter.

Vanadium 50 said:
If by "geometric orbits" you mean "tracks", the tracking occurs before the particle has reached the calorimeter.

That's right, I mean tracks.

Before constructing the LAr calorimeters, in Atlas experiment, someone must know all the parameters and design these devices in order to work efficiently.

If we are talking about a "face to face" collision then we should definitely place the calorimeters in the shape of a cylinder. Otherwise, we will lose information.

If we do not use Argon (in the calorimeters) and use some other element we will fail gathering the electrons due to couplings with the element.

What other parameters had the physicists to take into account before proceding to the construction of the LAr Calorimeters?

You didn't tell me what this "high temperature problem" is. I think it would go better if you would answer my call for clarification rather than explain to me why I don't need to know it. It is absolutely not true that argon is the only possible element. Krypton works as well - and in fact, works better.

Vanadium 50 said:
You didn't tell me what this "high temperature problem" is.

As far as I know electronics cannot work efficiently in high temperatures. This is one of the reasons we must use methods to cool off our system.

Vanadium 50 said:
It is absolutely not true that argon is the only possible element. Krypton works as well - and in fact, works better.

I did not mentioned that Argon is the only possible element someone could use. However, Argon is one element that works well enough. An element that could "kill" the after collission particles should be avoided.

I'll try to ask some more specific questions in order to understand each other. Maybe is something that I do not totally understand.

i)Why are we using Argon in calorimeters?
ii)Why are we using liquid Argon instead of gaseous Argon?
iii)Why does the full structure have barrel shape?

prochatz said:
i)Why are we using Argon in calorimeters?
ii)Why are we using liquid Argon instead of gaseous Argon?
iii)Why does the full structure have barrel shape?
Have you had a chance to take a look at the technical design report ? It would help if you could find this, and point to specific questions with regards to it. I doubt your questions are not already answered there. Another possible document would be a NIM paper. From which source of information do you start ?

The electronics for the ATLAS LAr calorimeter are at room temperature.

Argon is ionized by particles, and then the ions are collected on electrodes and the signal is amplified. You can use whatever pretty much any material you want as an ionization medium, and different materials have different ion survival times, signal heights, drift speeds, etc. Liquid argon happens to be a convenient material: a big signal with a fast recovery time. But people can and do use other materials.

The beamline has cylindrical symmetry - it makes sense for the detector to match it rather than adding nonuniformities.

## 1. What is the purpose of Atlas Exp: Solving Calorimeter Challenges?

The purpose of Atlas Exp: Solving Calorimeter Challenges is to develop a better understanding of how calorimeters work and how to improve their performance. A calorimeter is an instrument used to measure the heat released or absorbed during a chemical or physical process. By solving challenges related to calorimeters, scientists can develop more accurate and efficient calorimeters for use in various fields, such as chemistry, biology, and environmental science.

## 2. What are some common challenges faced when using calorimeters?

Some common challenges faced when using calorimeters include heat loss to the surroundings, incomplete combustion of the sample, and variations in sample size and composition. These challenges can lead to inaccurate measurements and affect the reliability of the data obtained from the calorimeter.

## 3. How does Atlas Exp: Solving Calorimeter Challenges address these challenges?

Atlas Exp: Solving Calorimeter Challenges uses a variety of techniques and experiments to address the challenges faced when using calorimeters. These techniques include insulation of the calorimeter, optimization of the combustion process, and standardization of sample size and composition. By implementing these techniques, scientists can improve the accuracy and reliability of calorimeter measurements.

## 4. What are some potential applications of the findings from Atlas Exp: Solving Calorimeter Challenges?

The findings from Atlas Exp: Solving Calorimeter Challenges can have a wide range of applications in various fields. For example, in the field of chemistry, more accurate calorimeters can be used to determine the energy released or absorbed during a chemical reaction. In the field of biology, calorimeters can be used to measure the energy content of food. In environmental science, calorimeters can be used to measure the energy content of fuels and determine their impact on the environment.

## 5. How can scientists use the knowledge gained from Atlas Exp: Solving Calorimeter Challenges to improve future experiments?

The knowledge gained from Atlas Exp: Solving Calorimeter Challenges can be used to improve future experiments by providing a better understanding of the factors that affect calorimeter measurements. Scientists can use this knowledge to design more accurate and efficient experiments, as well as to identify and address potential sources of error. Additionally, the findings from Atlas Exp: Solving Calorimeter Challenges can serve as a foundation for further research and development in the field of calorimetry.