Shembhu Pair-Production.ptx.pptx

ppt for pair production

1. PAIR PRODUCTION Submitted By:- shembhu ram JAI NARAIN VYAS UNIVERSITY (JODHPUR) DEPARTMENT OF PHYSICS NUCLEAR PHYSICS – 1 SUBMITTED TO :- Dr. G. C. SIR

2. PAIR PRODUCTION Introduction:- Pair production is a process in which the energy of a photon is converted into rest mass. In this process, the photon disappears as an electron (negatron) and positron pair is created .

3. PAIR - PRODUCTION DIAGRAM

4. HISTORY OF PAIR PRODUCTION The pair production phenomena was first predicted by a British physicist P.A.M. Dirac in 1925. His work suggested the existence of a sea of particles below physical matter which remains unobservable. Dirac’s concept which predicted the positron, the anti electron, was rather than two separate particles being produced, an electron is released from an infinite sea of particles below empty space. In removing a particle from sea, the remaining particle would act as the antiparticle.

5. CONT..… For photon with the energy exceeding 2mc 2 or 1.02 MeV, it is possible to create an electron-positron pair through the interaction of such a quanta with the field of nucleus. High energy photon interaction with the nucleus or near the nucleus causes ionization of the atom to produce a pair of charged particles (negatron and positron). The resulting kinetic energy of the produced charged particles is equal to E = E’-2mc 2

6. CONT….. In the Born approximation (which is not very accurate for low energy or high Z) one finds

7. CONT….. TOC Photon with sufficient energy passes near nucleus Energy of photon turns into matter Pair of matter/anti matter is created Nucleus must carry off momentum Electron m = 9.11 x 10 -31 kg Charge = -e Positron m = 9.11 x 10 -31 kg Charge = +e Help me! I’m going to be annihilated presently!

8. Solving pair production E = hf = hc/  E = mc 2 E - Energy m - mass c = 3.00 x 10 8 m/s 1 eV = 1.602 x 10 -19 J

9. Applications of Pair Production BRACHYTHERAPY PROTON THERAPY CONFORMAL RADIATION THERAPY

10. Thanks for Your Attention !!!