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 2 H + z A X 1 H+ z A+1 X b-Pick Up reaction 1 H + z A X 2 H+ z A-1 X

If b<<R+r Fusion reaction or compund nucleus reaction Al+ 1 H [ Si] * 12 Mg+ He 14 Si +n 14 Si + gamma 11 Na + 3 H + n

+ +

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 56 Fe ( 1 H, 1 n) 56 Co 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/cm 2 /s, which is defined as the rate at which the neutrons cross a unite area  to the beam. Example 30 mg of 197 Au are exposed to neutron flux n/cm 2/ /s for one minute. The neutron capture cross section of gold is 99b. Find the resultant 198 Au (T 1/2 =2.7 d).

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 >> t 1/2 A(t) = R[1(1- t+….)] = R t

Examples 30 mg of 197Au are exposed to neutron flux 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 61 Cu (t 1/2 =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 59 Co. If  =0.64 b. a)What is the production rate of Cu b) what is the activity of Cu after 2 h of irradiation. copmute the Q value for the reaction 63 Cu( 2 H, n) 64 Zn If the energy of 2 H is 12 MeV, “” n is16.85 MeV find the kinetic energy of 64 Zn Calculate the threshold KE for the reaction 3 H( 1 H,2 2 H) If the proton incident on 3 H at rest If the 3 H incident on proton at rest