Lecture 12 Irradiation Principles

Question 1

ionizing radiation includes what kinds of radiations?

Answer 1

gamma, x-ray, ultraviolet

Question 2

non-ionizing radiation includes what kinds of radiations?

Answer 2

infrared, microwaves, radio, extremely low frequency

Question 3

the high energy of x-ray and gamma rays enables what?

Answer 3

knocking off of an electron from an atom or molecule to cause ionization

Question 4

frequency is _____ related to wavelength

Answer 4

inversely

Question 5

energy level is given by what equation?

Answer 5

Planck’s; involves Planck’s constant
E=hv

h = Planck’s constant

Question 6

rays moving toward anode are the

Answer 6

alpha rays

Question 7

rays moving toward cathode are the

Answer 7

beta rays

Question 8

what are gamma rays?

Answer 8

true EM waves.

Question 9

penetration power is very ____ for alpha rays

Answer 9

low; they can be stopped by a sheet of paper

Question 10

penetration power is ____ for beta rays

Answer 10

medium: they can be stopped by a sheet of aluminum

Question 11

the gamma rays are _____ and ______ in energy

Answer 11

neutral, high energy; they can penetrate a thick lead block

Question 12

what happened from 1920-1940?

Answer 12

x-ray tube discovered, use in medical applications, therapeutic treatment of cancer

Question 13

what happened from 1940-50?

Answer 13

radiology equipment, medical research, diagnostic & treatment

Question 14

what happened from 1950-1960?

Answer 14

cobalt 60, cesium 137, electron beam, medical & dental applications, sterilization of non-food items, surgical equipment, cosmetics

Question 15

what happened from 1960-70?

Answer 15

major food research applications, industrial irradiators, wider applications (polymer crosslinking - textile, leather, tires)

Question 16

what happened form 1970-current?

Answer 16

widespread applications, small and industrial scale equipment, clearance for food processing

Question 17

what is the main source of ionizing radiation?

Answer 17

cobalt 60 derived from cobalt cobalt 59 (by addition of a neutron)

Question 18

what is the second main source of ionizing radiation?

Answer 18

Cs-137

Question 19

what is the third main source of ionizing radiation?

Answer 19

beta-rays which are a stream of high velocity electrons

Question 20

beta rays need to be _____ to acquire sufficient kinetic energy

Answer 20

accelerated

Question 21

why do you need to slow down when travelling across bridges?

Answer 21

when you’re travelling faster, your mass in motion is actually a greater load on the bridge

actually this is negligible because we’re looking at this in relation to the speed of light. cars don’t need to worry about this. we do this mostly because we don’t want to cause traffic accidents lol

Question 22

what does the variable C represent?

Answer 22

light’s velocity

3x10^8 m/s

Question 23

what does CANDU stand for?

Answer 23

CAN = canada
D = deuterium
U = uranium

Question 24

what happens inside a CANDU reactor?

Answer 24

constant fission and fusion reactions (very high energy processes); if it’s not contained the energy will expand at ungodly rates and create Bad Explosions

but hey, lots of energy

Question 25

the processes within a CANDU reactor are held under _____. why?

Answer 25

heavy water; to contain the reactions heavy water absorbs energy and brings it to regular water that turns into high pressure steam, which generates turbines, generating electricity. this is also an effective way to make hot water.

Question 26

true or false: Ni-60 s radioactive

Answer 26

false

Question 27

what food product uses Co-60 and Cs 337C?

Answer 27

frruit juices

Question 28

carrier irradiator's are only efficient if:

Answer 28

it's constantly running. you can't stop.

Question 29

what are the units for ionizing radiation?

Answer 29

2 units: 1) radiation intensity: Curie (1 Curie = 3.7 x 10^10 disintegrations/s) Curies are abbreviated as Ci 2) radiation dose: Rad or Gray one Gy = 100 Rad one Gy = absorption of 1 J/kg

Question 30

what is half life?

Answer 30

videogame made by valve; also the time it takes for intensity to be reduced by 50%

Question 31

current intensity is determined by _____ intensity, ______, and the _____ __ _____ since inception

Answer 31

initial intensity, half-life, length of time

Question 32

what are the 3 classes of doses?

Answer 32

- low (up to 1kGy) - medium (1-10 kGy) - high (10-50 kGy)

Question 33

what is the dose for sterilization and how much does the temp change?

Answer 33

required 20 kGy - 20 kJ/kg. Q = 4.8C. only changes by basically 5 degrees. this is called cold sterilization.

Question 34

list 3 properties of radiation intensity. regards time, distance, and penetration

Answer 34

1) radioactive intensity decreases with time (half-life) 2) radioactive intensity decreases with distance (absorption coefficient) 3) radioactive intensity decreases with penetration into a body (penetration depth)