# Bubble chamber experiment on a K− beam

• Aleolomorfo
In summary, the conversation discusses the spin and parity of a system composed of a Lambda particle and a pion, which is determined to be either ##\frac{1}{2}^+## or ##\frac{3}{2}^+##. The PDG data suggests that the system is most likely a ##\frac{3}{2}^+## particle, but further measurements, such as the decay ##\Sigma(1385) \to \Lambda \gamma##, may be necessary to fully determine the states of the system.
Aleolomorfo
Homework Statement
In a bubble chamber experiment on a ##K^-## beam a sample of events of the reaction ##K^- + p \rightarrow \Lambda^0 + \pi^+ + \pi^-## is selected. A resonance is detected both in the ##\Lambda^0\pi^+## and ##\Lambda^0\pi^-## mass distributions. It is called ##\Sigma(1385)##. If the study of the angular distributions establishes that the orbital angular momentum of the ##\Lambda^0\pi##system is ##L=1##, what are the possible spin parity values ##J^p##?
Relevant Equations
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Hello everybody!

Let's begin with the spin. Spin of the ##\Lambda## is ##1/2## and of the pion is ##0##:
$$\frac{1}{2} \otimes 0 = \frac{1}{2}$$

Since I know from the homework statement that ##L=1##:
$$\textbf{J} = \textbf{spin} \otimes \textbf{L} = \frac{1}{2} \otimes 1 = \frac{1}{2} \oplus \frac{3}{2}$$

Then the parity of the system:
$$P(\Lambda^0\pi) = P_{\Lambda}P_{\pi}(-1)^L= (+)(-)(-) = +1$$

So there are two possibilities: ##\frac{1}{2}^+## and ##\frac{3}{2}^+##.

But from PDG ##\Sigma(1385)## is a ##\frac{3}{2}^+## particle. I do not how to reject the other possibility of ##\frac{1}{2}^+##.
Thanks in advance!

This will probably need other measurements. ##\Sigma(1385) \to \Lambda \gamma## is another possible decay, for example.
The problem statement asks about possible states (plural) based on this individual measurements.

Aleolomorfo

## 1. What is a bubble chamber experiment on a K− beam?

A bubble chamber experiment on a K− beam is a type of particle physics experiment that uses a bubble chamber, a device filled with a superheated liquid, to detect the paths of charged particles produced by a beam of K− particles. The paths of the particles are recorded as trails of bubbles formed along their trajectories.

## 2. Why is a K− beam used in this experiment?

A K− beam, also known as a negative kaon beam, is used in this experiment because it contains particles with a negative charge, which allows them to be easily detected and their paths recorded in the bubble chamber. Additionally, K− particles have relatively low energies, making it easier to study their interactions with other particles.

## 3. What is the purpose of a bubble chamber experiment on a K− beam?

The purpose of this experiment is to study the interactions and decay processes of K− particles with other particles, such as protons and neutrons. These interactions provide valuable insight into the fundamental forces and properties of matter.

## 4. How does a bubble chamber work in this experiment?

A bubble chamber works by filling a container with a superheated liquid, such as liquid hydrogen or propane. When a charged particle passes through the liquid, it ionizes the molecules, causing them to vaporize and form bubbles along its path. These bubbles can then be photographed and analyzed to reconstruct the particle's trajectory and determine its properties.

## 5. What are some of the potential applications of this experiment?

Bubble chamber experiments on K− beams have a wide range of potential applications, including furthering our understanding of particle physics, studying the properties of matter, and potentially contributing to the development of new technologies. The data collected from these experiments can also be used to test and refine existing theories in physics, such as the Standard Model.

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