Particle Physics Questions : Multiple Choice

Q11.

A CERN detector shows a signal only in the hadronic calorimeter. No signal is observed in the in the tracker, electromagnetic calorimeter or muon chambers). Therefore, this signal is most likely due to a:

A	pion
B	neutrino
C	photon
D	neutron

 

The only hadron is the neutron.

Q12.

The exchange particles carrying the strong nuclear force are the:

A	photons
B	gluons
C	gravitons
D	w-bosons

Q13.

Which was the first particle discovered which is still today believed to be elementary, i.e. not made up of further constituents?

A	electron
B	gluon
C	photon
D	proton

Q14. Which of the following is not true?

 

Q15. Which equation shows the process of annihilation?

See here for notes on annihilation.

Q16. Which of the following is not made of quarks?

A	kaon
B	muon
C	neutron
D	pion

 

The muon is a lepton, the others are hadrons.

Q17. What is the quark structure for antiprotons?

Q18. The equation represents the weak interaction between a negative pion and a proton.

π⁻ + p → K^o + X

What is the charge, baryon number and strangeness of particle X?

the charge of the proton is +1 and the pion -1 - therefore the left hand side of the equation has zero charge - the kaon has zero charge so X must have zero charge also.

the baryon number of the proton is 1 and the meson zero - giving total baryon number of one on the left hand side of the equation - kaon is zero so X must have a baryon number of 1

the pion and proton are not strange - kaon is - so X must be - with opposite strangeness number....K^o can be positive or negative.... therefore X might be +1 or -1.

See here for notes on strange particles.

Q19. Which diagram represents the process of beta-plus decay?

In positron decay a proton becomes a neutron:

p n + β⁺ +

so, quark change is: uud ddu

u d

Therefore it is either choice A or B

To balance leptons we need a lepton to be formed as well as the antilepton (positron) - so choice A is correct.