You work for a start-up company that is planning to use antiproton annihilation to produce radioactive isotopes for medical applications. One way to produce antiprotons is by the reaction in proton-proton collisions. You first consider a colliding-beam experiment in which the two proton beams have equal kinetic energies. To produce an antiproton via this reaction, what is the required minimum kinetic energy of the protons in each beam?
Ch 44: Particle Physics and Cosmology
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Not the one you use?Change textbook
Chapter 44, Problem 20a
Table shows that a decays into a and a photon. Calculate the energy of the photon emitted in this decay, if the is at rest.
Verified step by step guidance1
Step 1: Identify the conservation laws applicable to the problem. In this case, energy and momentum conservation are key. Since the Λ^0 is at rest after the decay, all the energy difference between the Σ^0 and Λ^0 masses will be converted into the energy of the photon.
Step 2: Write the energy conservation equation for the decay process. The total energy before the decay is the rest energy of the Σ^0 particle, given by \( E_{\Sigma^0} = m_{\Sigma^0} c^2 \). After the decay, the total energy is the sum of the rest energy of the Λ^0 particle \( E_{\Lambda^0} = m_{\Lambda^0} c^2 \) and the energy of the photon \( E_{\text{photon}} \).
Step 3: Express the energy of the photon using the conservation equation: \( E_{\text{photon}} = E_{\Sigma^0} - E_{\Lambda^0} \). Substituting the rest energy terms, \( E_{\text{photon}} = (m_{\Sigma^0} - m_{\Lambda^0}) c^2 \).
Step 4: Look up the masses of the Σ^0 and Λ^0 particles in Table 44.3 or a reliable source. Use these values to calculate the mass difference \( m_{\Sigma^0} - m_{\Lambda^0} \).
Step 5: Multiply the mass difference by \( c^2 \), where \( c \) is the speed of light (approximately \( 3 \times 10^8 \ \text{m/s} \)), to find the energy of the photon emitted during the decay.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Conservation of Energy
In any physical process, the total energy before the process must equal the total energy after the process. In particle decay, this principle dictates that the energy of the initial particle must be equal to the sum of the energies of the decay products, including any emitted photons. This concept is crucial for calculating the energy of the photon emitted during the decay of the Σ^0 particle.
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Rest Mass Energy
The rest mass energy of a particle is given by Einstein's equation E=mc², where m is the rest mass and c is the speed of light. In the context of particle decay, the rest mass energies of the Σ^0 and Λ^0 particles contribute to the total energy available for the decay process. Understanding how to calculate and apply rest mass energy is essential for determining the energy of the emitted photon.
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Photon Energy
The energy of a photon is directly related to its frequency and can be calculated using the equation E=hf, where h is Planck's constant and f is the frequency of the photon. In particle decay, the energy of the emitted photon can be determined by considering the energy balance between the initial particle and the decay products. This concept is vital for solving the problem of finding the photon's energy in the decay of the Σ^0.
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