Question
The Fermi Gamma-Ray telescope sometimes sees thunderstorms output gamma radiation at 511 kiloelectronvolts. Answer the following about this phenomenon, for 10 points each.
[10e] The signal is produced when a positron, a particle of this class, is created by lightning and then annihilates with an electron. Particles of this class are generally the same as ordinary particles but have opposite charges.
ANSWER: antimatter [accept antiparticle or antilepton or antielectron]
[10h] For a particle and its antiparticle to be distinct, they must be excitations of a field with this property. When quantizing a scalar field with this property, the Fourier coefficients for positive and negative frequencies become distinct creation and annihilation operators.
ANSWER: complex-valued [or complex scalar field]
[10m] The photons that Fermi detects are their own antiparticles. This neutral, massive Standard Model boson is also its own antiparticle, but, unlike the photon, it is unstable and mediates the weak force.
ANSWER: Z boson [or Z0; accept Z particle]
<RA, Physics>
Summary
| 2023 ARCADIA at Imperial | Imperial | Y | 5 | 10.00 | 80% | 20% | 0% |
Data
| Bristol | Cambridge A | 10 | 0 | 0 | 10 |
| Durham | Cambridge B | 10 | 0 | 10 | 20 |
| Birmingham | Imperial B | 10 | 0 | 0 | 10 |
| Oxford | Imperial A | 10 | 0 | 0 | 10 |
| Edinburgh | Warwick | 0 | 0 | 0 | 0 |