434 8 Nuclear Physics – II
IfEcmis the center of mass energy of the two interacting ions then the minimum
distance of approach is given by
rmin=b
√
1 −V(Ermincm)(8.48)
8.2 Problems..................................................
8.2.1 AtomicMassesandRadii ...........................
8.1 Singly-charged lithium ions, liberated from a heated anode are accelerated by a
difference of 400 V between anode and cathode. They then pass through a hole
in the cathode into a uniform magnetic field perpendicular to their direction of
motion. The magnetic flux density is 8× 10 −^2 Wb/m^2 and the radii of the paths
of the ions are 8.83 and 9.54 cm, respectively. Calculate the mass numbers of
the lithium isotopes.
[Osmania University]
8.2 A narrow beam of singly charged^10 B and^11 B ions of energy 5 keV pass through
a slit of width 1 mm into a uniform magnetic field of 1,500 gauss and after a
deviation of 180◦the ions are recorded on a photographic plate
(a) What is the spatial separation of the images.
(b) What is the mass resolution of the system?
[University of Manchester 1963]
8.3 Singly charged chlorine ions are accelerated through a fixed potential differ-
ence and then caused to travel in circular paths by means of a uniform field of
magnetic induction of 1,000 gauss. What increase in induction is necessary to
cause the mass 37 ion to follow the path previously taken by the mass 35 ion?
[University of London 1960]
8.4^2714 Si and^2713 Al are mirror nuclei. The former is a positron emitter withEmax=
3 .48 MeV. Determiner 0.
8.5 Use the uncertainty relation to estimate the kinetic energy of the nucleon, the
nuclear radius is about 5× 10 −^13 cm and the mass of a proton is about 2×
10 −^24 g.
[University of Bristol 1969]
8.6^14 O is a positron emitter decaying to an excited state of^14 N. The^14 N
γ- rays have an energy of 2.313 MeV and the maximum energy of the positron
is 1.835 MeV. The mass of^14 N is 14.003074 amu and that of electron is
0.000548 amu. Find the mass of^14 Oinamu.