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In a material medium, when a position me...

In a material medium, when a position meets an electron both the particles annihilate leading to the mission of two gamma ray photon. This process forms the basis of an important diagnostic procedure called

A

MRI

B

PET

C

CAT

D

SPECT

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The correct Answer is:
D
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A moving positron and electron both with kinetic energy 1 Me V annihilate with each other and emits two gamma photons. If the rest mass energy of an electron is 0.51 MeV, the wavelength of each photon is ?

Following reactions are known as inverse beta decay p+vecvrarrn+e^(+) n+vrarrp+e^(-) These reactions have extremely low probabilities. Because of this, neutrinos and antineutrinos are able to pass through vast amount of matter without any interaction. In an experiment to detect neutrinos, large number of neutrinos coming out from beta decays of a radioactive material were made to pass through a tank of water, containing a cadmium compound in solution, which provided the protons to interact with antineutrinos, which provided the protons to interact with antineutrinos. Immediately after a proton absorbed a neutrino to yield a positron and a neutron, the positron encountered an electron and both got annihilated. the gamma ray detectors surrounding the tanks responded to the resulting photons. This confirmed that the above reaction has taken place. (a) How many gamma ray photons are produced when a electron annihilates with a positron? What is energy of each photon? Take the mass of an electron to be 0.00055 u. (b) The neutron produced in the above reaction was captured by .^(112)Cd to form .^(113)Cd . The atomic masses of these two isotopes of cadmium are are 111.9028u and 112.9044u respectively. mass of a neutron is 1.0087u. find the Q value of this reaction. Assume half of this energy is excitation energ of .^(113)Cd . if the nucleus de-excites by emitting a gamma ray photon find its wavelenght.

The positron is a fundamental particle with the same mass as that of the electron and with a charge equal to that of an electron but of opposite sign. When a positron and an electron collide, they may annihilate each other. The energy corresponding to their mass appears in two photons of equal energy. Find the wavelength of the radiation emitted. [Take : mass of electron = (0.5//c^(2))MeV and hc = 1.2 xx 10^(-12) MeV-m , where h is the Planck's constant and c is the velocity of light in air.

Two very small particles are executing SHM along very near parallel lines about the same mean position, same amplitude and the same frequency. At t = 0 both the particle are moving with speed of 1m//sec but on the opposite side of the mean position and having same direction of velocity at a distance of 5cm from the mean position. At t = 4sec they are at the same position moving with speed of 1m//sec but in opposite direction. Assuming that this is the minimum time form t = 0 where they are meeting for the 1st time. If the maximum speed of either particle is (xpi)/(4sqrt(2))cm//sec Find x

It is possible for a photon to materialize into an electron and a position. The process is called pair production. (a) Using conservation of energy and momentum prove that pair production cannot occur in empty space. (b) Argue qualitatively that such pair production is possible near a nucleus.

photoelectrons are emited when 40 nm radiation is incident on a surface of work function 1.9 eV These photoelectron pass tjhrough a ragain cotaining a - particle A maximum energy electron conbines with an a - particle to from a He^(+) ion emitting a single photon in this process He^(+) ions thus formed are in their fourth excited state find the energies in eV of the photons typing is the 2 to 4 eV rage, that are likrly to be emitted during and after the combiution [Take h = 4014 xx 10^(-15) eV s]

Photoelectrons are emitted when 400 nm radiation is incident on a surface of work - function 1.9 eV. These photoelectrons pass through a region containing a-particles. A maximum energy electron combines with an a -particle to from a He^+ ion, emitting a single photon in this process. He^+ ions thus formed are in their fourth excited state. Find the energies in eV of the photons lying in the 2 to 4 eV range, that are likely to be emitted during and after the combination. [Take, h = 4.14xx10^(-15) eV -s]

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