High-energy photons propagating through space can convert into electron-positron pairs by scattering with cosmic microwave background (CMB) photons. Taking the average CMB temperature of 2.8 K, a typical CMB photon will have an energy of roughly 7 x 10-4 eV. Calculate the minimum energy required for the high-energy photon to produce an electron-positron pair (me = 511 keV) if a. the CMB photon momentum is perpendicular to that of the high-energy photon ¹: I chose the light-by-light scattering because the kinematics are algebraically simpler for zero masses. But hopefully you also find the subject of interest. Light-by-light scattering has been studied in the lab for many years using high-intensity laser light scattering off (virtual) photons in the electric field of electrons. However, the first observation of the scattering of two real, high-energy photons was done by my experiment (ATLAS) at the LHC for the first time in 2019. The fact that the measurement uses nuclear collisions with the initial-state photons being associated with the electric field of the nucleus connects to physics that we will discuss this semester.
High-energy photons propagating through space can convert into electron-positron pairs by scattering with cosmic microwave background (CMB) photons. Taking the average CMB temperature of 2.8 K, a typical CMB photon will have an energy of roughly 7 x 10-4 eV. Calculate the minimum energy required for the high-energy photon to produce an electron-positron pair (me = 511 keV) if a. the CMB photon momentum is perpendicular to that of the high-energy photon ¹: I chose the light-by-light scattering because the kinematics are algebraically simpler for zero masses. But hopefully you also find the subject of interest. Light-by-light scattering has been studied in the lab for many years using high-intensity laser light scattering off (virtual) photons in the electric field of electrons. However, the first observation of the scattering of two real, high-energy photons was done by my experiment (ATLAS) at the LHC for the first time in 2019. The fact that the measurement uses nuclear collisions with the initial-state photons being associated with the electric field of the nucleus connects to physics that we will discuss this semester.
Related questions
Question
please see image below.
Transcribed Image Text:High-energy photons propagating through space can convert into electron-positron pairs by scattering with
cosmic microwave background (CMB) photons. Taking the average CMB temperature of 2.8 K, a typical
CMB photon will have an energy of roughly 7 × 10-4 eV. Calculate the minimum energy required for the
high-energy photon to produce an electron-positron pair (me = 511 keV) if
a. the CMB photon momentum is perpendicular to that of the high-energy photon
1: I chose the light-by-light scattering because the kinematics are algebraically simpler for zero masses. But hopefully you
also find the subject of interest. Light-by-light scattering has been studied in the lab for many years using high-intensity
laser light scattering off (virtual) photons in the electric field of electrons. However, the first observation of the scattering of
two real, high-energy pho
the measurement uses nuclear collisions with the initial-state photons being associated with the electric field of the nucleus
connects to physics that we will discuss this semester.
was done
my
periment (ATLAS) at the LHC for the first time in 2019. The fact that
b. the CMB photon propagates in the direction opposite the high-energy photon.
c. Suppose the CMB photon propagates in the same direction as the high-energy photon. Is it ever
possible for the two photons to collide and produce an electron-positron pair?
Expert Solution
This question has been solved!
Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.
This is a popular solution!
Trending now
This is a popular solution!
Step by step
Solved in 2 steps
