Question

Question 1 (a) Estimate the volume (in m3) and density (in kg m3) of a C nucleus. State your assumptions and comment on the value obtained Write down a relationship between a particle's energy, mass and momentum using relativistic (b) kinematics. The SuperKEKB b-factory will collide electrons with energy 7 GeV and positrons with energy 4 GeV in order to produce b-hadron pairs. Write down the four vectors of the electron and positron Hence work out the centre-of-mass energy of the collider Give a reason why b-factories often collide with asymmetric beams. (c) Why is ep scattering better than pp scattering in order to understand the structure of the proton? Explain how and why the proton's structure differs from the three quarks that might naively be expected. Your answer should include relevant equations

Answer 1

(a) The nuclear radii is given by,

1/3

Hence the volume is,

$V = \frac{4}{3}\pi R^3 \Rightarrow V = \frac{4}{3}\pi R_0^3 A$

The mass is A (Atomic mass number) Hence we can say that the density is,

A( 1.67 × 10-21) 3(1.67 × 10-21) 7m 0

Hence the nuclear density is independent of atomic mass number substituting the value for the constant R0, we get,

3( 1.67× 10-21) 04 x 1017 kgm2-3 4 T(1.25 × 10-15 )3-2.

Hence, from this you can see that the most of the mass of atom is concentrated at the center and not on the orbitals.