If the Coordinates system is. R r b (impact parameter.
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Transcript of If the Coordinates system is. R r b (impact parameter.
Type of Nuclear traction Depends on the impact parameter
1- for b > r+R
Scattering reaction
The scattering reaction could be
1- elastic sacattering or
2- inilastic scattering
2- if b<r+R
Transfer reaction
a- Stripping reaction
2H + zAX 1H+ z
A+1X
b-Pick Up reaction
1H + zAX 2H+ z
A-1X
If b<<R+r
Fusion reaction or compund nucleus reaction
1327Al+ 1H [14
28Si]*
12Mg+ He
14Si +n
14Si + gamma
11Na + 3 H + n
S
NIR ob
Suppose a beam of particles is incident on a thin target of area S, which contain a total number of N nuclei. The effective area of each nucleus is and total effective area will be N. the fraction of the target area which this represents is N/S
Example
in the following reaction 56Fe (1H , 1n)56Co has a cross section of 0.6 b. if a target in the form of a 1 cm square, 1, micrometer thick had been bombarded with a beam of protons equivalent to 3 microAmper . At what rate are the neutrons produced
In a reactor the intensity of neutrons is expressed neutron flux n/cm2/s, which is defined as the rate at which the neutrons cross a unite area to the beam.
Example
30 mg of 197Au are exposed to neutron flux 3 1012 n/cm2//s for one minute . The neutron capture cross section of gold is 99b. Find the resultant 198Au (T1/2=2.7 d).
M
mσ10 6.02R 23
Radioisotope production in nuclear reactions
In a time interval dt the number of Y nuclei produced = R dt .
Since Y is radioactive, the number of Y that decay in time dt =Ndt
The net change
dN = Rdt- Ndt
dN/dt= R - N
The solution of this differentia equation is
N(t)= (R/ ) (1-e -t)
The activity is
A(t)= N= R(1-e -t)
At t= 0 A=0
t >> t1/2 A(t) = R[1(1- t+….)]
= R t
Examples30 mg of 197Au are exposed to neutron flux 3 1012 n/cm2//s for one
minute . The neutron capture cross section of gold is 99b. Find the resultant 198Au (T1/2=2.7 d).
The radioactive 61Cu (t1/2=3.41 h) is produced by a 12 A beam of particles on 1.5 cm x 1.5 cm x 2.5 m target of 59Co. If =0.64 b.
a) What is the production rate of Cub) what is the activity of Cu after 2 h of irradiation.
copmute the Q value for the reaction 63Cu(2H, n)64Zn If the energy of 2H is 12 MeV, “” n is16.85 MeV find the kinetic energy of 64Zn
Calculate the threshold KE for the reaction 3H(1H,2 2H) If the proton incident on 3H at restIf the 3H incident on proton at rest