particle physics

Question 1

equation to find neutron number (N) of nucleus?

Answer 1

N = A - Z

where A = nucleon or mass number and Z = proton or atomic number

Question 2

equation for energy of particle (E rest) when v &laquo_space;c using particle’s rest mass (m0)? (m0, c)

Answer 2

E rest = m0(c^2)

Question 3

equation for energy of particle (E total) at relativistic speeds (where v ≈ c)? (γ, m0, c)

Answer 3

E total = γm0(c^2)

where γ = lorentz factor, m0 = rest mass and c = speed of light

Question 4

equation for lorentz factor (γ)? (E total, E rest)

Answer 4

γ = E total/E rest

(E total = rest E + KE)

Question 5

equation for energy of particles (E) when particles have VERY high energies? (p, c)

Answer 5

E ≈ pc

(E = pc is true for photons)

Question 6

equation for energy of particles (E)? (p, m)

Answer 6

E = (p^2)/2m

Question 7

equation for total (KE + PE) energy (E n) electron requires to be liberated from energy level n? (n, E1)

Answer 7

E n = (1/n^2)E1

where n = energy level number and E1 = energy of initial level

Question 8

equation to calculate angle (θ) of diffraction to first minima (first dark fringe) when diffracting nuclei? (λ, d)

Answer 8

sinθ = 1.22λ/d

Question 9

equation to work out radius of whole nucleus (R)? (r0, A)

Answer 9

R = r0(A^1/3)

where r0 = radius of proton (1.05 fm or 1.5 x 1E-15) and A = nucleon number

Question 10

representation of alpha decay?

Answer 10

atom -> diff atom (with 2 less protons and neutrons) + helium nucleus (2 protons, 2 neutrons)

Question 11

representation of gamma decay?

Answer 11

atom* -> same atom + γ

Question 12

representation of beta minus decay?

Answer 12

atom with neutron -> new atom where neutron changed to proton (so same nucleon number but +1 proton for proton number) + electron + antielectron neutrino

(need to release antielectron neutrino to conserve lepton number)

Question 13

representation of beta plus decay?

Answer 13

atom w proton -> new atom where proton changed to neutron (same nucleon number but -1 proton for proton number) + positron + electron neutrino

(need to release electron neutrino to conserve lepton number)

Question 14

equation for attenuation of radiation (I)? (I0, µ, x)

Answer 14

I = I0(e^-µx)

where I = intentisty, I0 = initial intensity, µ = linear absorption or attenuation coefficient and x = material thickness

Question 15

equation for half-value thickness (x 1/2)? (like half-life)

Answer 15

x 1/2 = ln2/µ

where x 1/2 = half-value thickness (for particular material, thickness need to half intensity of radiation), µ = linear absorption or attenuation coefficient

Question 16

equation for absorbed dose (D)?

Answer 16

D = E/m

where E = energy absorbed and m = mass

Question 17

equation for equivalent dose (H)?

Answer 17

H = D x Q
or
H = EQ/m

where D = absorbed dose and Q = quality factor

Question 18

what is quality factor (Q) for photons, etc?

Answer 18

• photons, all energies: Q =1

Question 19

what is quality factor (Q) for electrons + muons, etc?

Answer 19

electrons + muons, all energies: Q =1

Question 20

what is quality factor (Q) for high E neutrons?

Answer 20

high energy neutrons: Q = 10

Question 21

what is quality factor (Q) for high E protons?

Answer 21

high energy protons: Q = 10

Question 22

what is quality factor (Q) for α particles + other atomic nuclei?

Answer 22

alpha particles + other atomic nuclei: Q = 20

Question 23

equation for binding energy (ΔE)? (m, c)

Answer 23

ΔE = Δm(c^2)

where Δm = difference between sum of masses of individual nucleons + mass of nucleus

(binding energy is given as negative, bc energy is put IN)

Question 24

absorption cross section?

Answer 24

absorption cross section = πd^2

where d = diameter of particle

(acs is the distance another particle must pass within to collide with a particle)