Phys 309 Assignment 1 Answer
PHYS 309 (2013) Nuclear Physics: Assignment N1
(Due 5pm Friday 26 July 2013; Assignment answers will be posted on Blackboard after the deadline) Note that the relevant nuclear mass information for these questions is available on Blackboard in the two files 309nuclides*.pdf
1. Determine the ratio of the electron binding energy in the deuteron to the rest energy of the deuteron and the binding energy of the deuteron. Is it therefore reasonable to ignore electronic binding energies when doing nuclear calculations?
2. A neutron star (which is predicted to be formed in a supernova explosion) consists only of neutrons held together by the gravitational force. Using reasonable assumptions and stating what they are, calculate the mass of 10 cm 3 of neutron star material and compare this with the mass of the same volume of water.
3. Determine the binding energies per nucleon for the nuclides 4 He and 8 Be and hence show that 8 Be is unstable to decay into two α particles.
4. Compute the total binding energies and binding energy per nucleon for the nuclides:
2
H, 3 He, 4 He, 7 Li,
12
C,
14
N,
16
O,
20
Ne,
40
Ca,
56
Fe,
133
Cs,
197
Au,
208
Pb,
238
U,
and construct a graph of binding energy per nucleon versus mass number. It will be convenient and efficient to use a spreadsheet such as Excel (or the Openoffice equivalent) to perform the calculations.
5. The Earth is about 4.5 billion years old. If 235 U is 0.72% abundant today, how abundant
92
was it when the Earth formed?.
Note: Uranium isotope half lives and present day abundances:
234 2.455×105 y
235 7.038×108 y
238 4.468×109 y
0.006%
0.72%
99.27%
1
(Due 5pm Friday 26 July 2013; Assignment answers will be posted on Blackboard after the deadline) Note that the relevant nuclear mass information for these questions is available on Blackboard in the two files 309nuclides*.pdf
1. Determine the ratio of the electron binding energy in the deuteron to the rest energy of the deuteron and the binding energy of the deuteron. Is it therefore reasonable to ignore electronic binding energies when doing nuclear calculations?
2. A neutron star (which is predicted to be formed in a supernova explosion) consists only of neutrons held together by the gravitational force. Using reasonable assumptions and stating what they are, calculate the mass of 10 cm 3 of neutron star material and compare this with the mass of the same volume of water.
3. Determine the binding energies per nucleon for the nuclides 4 He and 8 Be and hence show that 8 Be is unstable to decay into two α particles.
4. Compute the total binding energies and binding energy per nucleon for the nuclides:
2
H, 3 He, 4 He, 7 Li,
12
C,
14
N,
16
O,
20
Ne,
40
Ca,
56
Fe,
133
Cs,
197
Au,
208
Pb,
238
U,
and construct a graph of binding energy per nucleon versus mass number. It will be convenient and efficient to use a spreadsheet such as Excel (or the Openoffice equivalent) to perform the calculations.
5. The Earth is about 4.5 billion years old. If 235 U is 0.72% abundant today, how abundant
92
was it when the Earth formed?.
Note: Uranium isotope half lives and present day abundances:
234 2.455×105 y
235 7.038×108 y
238 4.468×109 y
0.006%
0.72%
99.27%
1