particle physics Flashcards
beta minus decay
n protons increase
when describing decay process (3)
- name decay
- how does nucleon n change
- how does atomic number change
(2) why alpha radiation not pose any risk in the smoke detector
(1) only small quantity needed (highly ionising and long half-life
(1) particles do not travel more than a few cm’s (penetrating ability)
what is ionisation ?
Ionisation is the removal (or addition) of electrons from (to) an atom or molecule
why leptons cannot decay further
stable (fundamental)
explain why when UV shone on positiviley charged plate no charge is lost
process involved the ejection of electrons(1)
which only make it more positive(1)
2 differences exchange particle weak + strong
gluons lighter bosons more massive (1)
gluons have longer range bosons have shorter range (1)
explain what is meant by an exchange particle (2)
moves between one object and another/carrier acting
on two particles
gives rise to the force between the particles
gluon(s) (accept pions
The deuterium nucleus is stable.
Describe how the variation of the strong nuclear force with distance contributes to the
stability of the deuterium nucleus.
[3 marks]
(Short-range) attraction up to about 3 fm (Very short-range) repulsion closer than 0.5 fm
Prevent proton and neutron moving closer or further apart
exchange particle of strong nuclear force
pion/gluon
Tritium is an isotope of hydrogen. Its nucleus contains one proton and two neutrons. Tritium undergoes radioactive decay.
Three modes of radioactive decay are
• alpha decay −
• beta minus (β ) decay • electron capture.
Deduce which of these modes could produce the nucleus of another element when
the tritium nucleus decays.
[3 marks]
Correct description of alpha decay OR Consequence of alpha decay Correct description of electron capture OR Consequence of electron capture Correct description of beta decay, with explicit conclusion that this mode is valid
whats released in annihilation
photon(s) of !electromagnetic radiation!
why mass is not always conserved
mass can be converted to energy and vice versa
In the strong interaction,
K– + p → K0 + K+ + X,
deduce the quark composition of, and state the type of, hadron represented by X.
X = sss (1) (= Ω–)
baryon (1)
A positive muon may decay to a positron and two neutrinos. Write down an equation representing the muon decay.
μ+ →
μ+ → e+ + ve + (+Q)
instead of saying escape metal say
overcome work function
what is meant by threshold frequency
- below a certain frequency no electrons emitted
- minimum frequency for electrons to overcome work function
why the photoelectric effect is not observed below a certain frequency? (3)
- energy photon depends on the frequency (1)
- below threshold frequency photon does not have enough energy to liberate electron (1)
- photon does not have enough energy to overcome work function
what’s threshold freq?
minimum energy required for electron to escape surface of metal
ionisation energy
energy to remove electron from ground state
explain process pair production (3)
photon interacts w/ orbital electron
energy photon creates particle anti particle pair
to conserve momentum photon interacts w/ intracting particle
calculate max frequency photons in annihilation 2 points
freq of one photon
mark scheme says must show explaining how it’s two
role exchange particles in exchange forces between particles (1)
forces arise when exchange particles move between other particles
a discussion of the stability of free hadrons
- what is most stable baryon
proton
a discussion of the stability of free hadrons.]
mesons
- kaon decay into pions
is X and Y same charge but X greater mass determine nuclear compositions diff
same number protons but X has more neutrons
when would weak nuclear force be responsible for something
- change in quark type
- involved leptons AND hadrons
weak nuclear force changes quarks by
By emitting an electrically charged W boson, the weak force changes the flavor of a quark, which causes a proton to change into a neutron, or vice versa.
if leptons involved
can’t be strong nuclear force
3 marker on how you can find interaction from resulting nucleus
go through equation and what is released / found
why is it important for many diff ppl to take part in advances in particle physics
peer review
expensive (e.g. particle accelerator)
-many skills + disciplines needed
for antiparticle definition
all properties opposite but mass number same
don’t say mass say
rest mass
baryon number of anti proton is
-1
photon anti particle
it’s its own anti particle
4 marker on how force works use EM and photon
- EM
- photon
- trasnfer energy/momentum
- particle receives exchange particle new particle creation occurs
Ko made out of what
down anti strange
on anti particle of electron say
positron (DO NOT ACCEPT ANTI ELECTRON)
