2.1 - particle zoo

Question 1

what are cosmic rays

Answer 1

high energy particles (phitons/small nuceli) traveling through space that come from stars

Question 2

what happens to cosmic eaves when they enter the earth’s atmosphere

Answer 2

they collide with the gasses in the atmosphere and creat new short-lived particles & antiparticles and photons

Question 3

name a common detector used to find ‘new’ particles/antiparticles

Answer 3

cloud chamber

Question 4

describe a muon relative to an e-

Answer 4

‘heavy e-‘

negatively charged particle

much larger, greater rest energy (x200) and lower stability

Question 5

give all the possible charges of pions (pi-mesons)

Answer 5

π⁺ , π^- , π⁰

Question 6

give all the possible charges of kaons (K-mesons)

Answer 6

K⁺ , K^- , K⁰

Question 7

where do mesons lie when compared to the masses of protons and e-

Answer 7

e- < π < K < P

the mesons have masses greater than e- but less than P (between the particle)

• as shown by tracks in cloud chambers

Question 8

how are mesons produced in experiments

Answer 8

in a hadron collider, colliding a proton at hight speed onto a nucleus

• by the string interaction, mesons are produced

Question 9

show the decay diagram of K & π mesons and muons

Answer 9

(π⁰ –> high enrgy photon)

K –> π –> µ –> e

(K –> µ)

[charges are conserved aross the lines

mesons decay into µ + V_µ

muons –> e- + Ve]

Question 10

What interaction are all decays caused by

Answer 10

the weak interaction