Explain the change of quark character associated with the beta-plus decay and deduce the equation.

First, we can deduce the equation for beta-plus decay in terms of the nucleons. We know a positron, ß+ (antilepton), is produced, so to conserve lepton number an electron neutrino, ve (lepton), must also be produced. As we know this is a nuclear reaction (occurring in the nucleus) it must involve either proton or neutron decay. We can then work out that, to conserve charge, it must be a proton decaying into a neutron as the positron on the right-hand side is positively charged:

p → n + ß+ +ve

Now we consider the quark composition of the proton and neutron. As baryons both must contain 3 quarks. As the up quark has charge +2/3 and the down has charge -1/3 we can use our knowledge of the charge of the proton and neutron to figure out their compositions; uud and udd respectively. Finally, we can see the actual change occurring is an up quark decaying into a down quark:

u → d + ß+ +ve

Answered by Thomas F. Physics tutor

4753 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

Describe the process of nuclear fission is induced


Using Newton's law of gravitation, derive a suitable formula for the escape velocity of an object at Earth's surface.


What is the De Broglie wavelength of an electron given it has a kinetic energy of 1 eV? You are given the mass of an electron is 9.11x10^-31 kg and Planck's constant is 6.63x10^-34


Explain how a stationary wave is produced when a string fixed at both ends is plucked


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences