RADIOACTIVITY

Project

Physics-042
2024-2025
Submitted in partial fulfillment of the
requirement of Class XII (CBSE)

U.Muthu Dinesh
Reg:

Under the guidance of

R.Neelanda Mathava Rajan M.Sc., B.Ed

Bharath Vidya Mandir Senior Secondary
School (CBSE)

Ilanji – 627 805.

1
 BONAFIDE CERTIFICATE
This is to certify the entitled “Radioactivity”is done by
U.Muthu Dinesh of Class XII of Bharath Vidya Mandir
Senior Secondary School (CBSE), Ilanji, has completed
his project as a part of the paper of physics under my
supervision.He has taken proper care and shown
atmost sincerity in the completion of this project.
I certify that this project is upto my expectation as per the
guidelines issued by CBSE

Principal

Submitted for the viva-voce conducted on

at Bharath Vidya Mandir Senior Secondary School

(CBSE), Ilanji.

Internal Examiner External Examiner

2
DECLARATION

I hereby declare that the project titled “Radioacivity”was

submitted to Bharath Vidya Mandir Senior Secondary
School (CBSE), Ilanji for the subject Physics under the
guidance of R.Neelanda Mathva Rajan M.Sc., B.Ed.,

Date: Signature
3
ACKNOWLEDGEMENT

To begin with, I thank God almighty for this

opportunity to learn and gather hands-on knowledge
through Informatics Practices. My institution Bharath
Vidya Mandir Senior Secondary School (CBSE) is duly
acknowledged for their provision of required
infrastructure.

I also thank my honorable Principal Mr. Giftson

Kirubakaran M.Sc.,M.Ed., and the management for
their contributions. I convey my indebtedness to my
course faculty for their guidance and support throughout
the stipulated time period.

As an end point, I deliver my gratitude for the

efforts of my family and friends in effective execution of
the project.

4
TABLE OF CONTENTS

SNO CONTENTS PG.NO.

1. INTRODUCTION 6-7

2. OBJECTIVES OF THE PROJECT 8-9

3. SCOPE OF THE PROJECT 10-14

4. FEATURES OF THE PROJECT 15-18

5. SOURCE CODE 19-26

6. OUTPUT 27-41

7. BIBLIOGRAPHY 42

5
Introduction
Radioactivity:
Radioactivity is the decay or disintegration of the nucleus
of a radioactive element. The radiation emitted is the
alpha-particles, the beta-particles and the gamma rays
and a lot of heat. This phenomenon was first discovered
by a French Physicist, Henri Becquerel in 1896. Other
famous people parts of this radioactive era are; Lord
Rutherford, and the Curie couple, Marie and
Pierre.Radioactive decay is a stochastic (i.e., random)
process at the level of single atoms, in that, according
to quantum theory, it is impossible to predict when a
particular atom will decay. However, the chance that a
given atom will decay is constant over time.

A diagram showing an alpha particle (α) being ejected

from the nucleus of an atom.Protons are red and neutrons
are blue

6
 BECQUEREL’S
DISCOVERY

In March of 1896, during a time of overcast weather,

Becquerel found he couldn't use the sun as an initiating
energy source for his experiments. He put his wrapped
photographic plates away in a darkened drawer, along
with some crystals containing uranium. Much to his
Becquerel's surprise, the plates were exposed during
storage by invisible emanations from the uranium. The
emanations did not require the presence of an initiating
energy source--the crystals emitted rays on their own!
Although Becquerel did not pursue his discovery of
radioactivity, others did and, in so doing, changed the face
7
of both modern medicine and modern science. He was a
member of a scientific family extending through several
generations, the most notable being his grandfather
Antoine-César Becquerel (1788–1878), his father,
Alexandre-Edmond Becquerel (1820–91), and his son
Jean Becquerel. (1878–1953)

THE CURIE’S DISCOVERY

Working in the Becquerel lab, Marie Curie and her

husband, Pierre, began what became a life long study of
radioactivity. It took fresh and open minds, along with
much dedicated work, for these scientists to establish the
properties of radioactive matter. Marie Curie wrote, "The
subject seemed to us very attractive and all the more so
because the question was entirely new and nothing yet
had been written upon it." On February 17, 1898, the
Curies tested an ore of uranium, pitchblende, for its ability
8
to turn air into a conductor of electricity. The Curies found
that the pitchblende produced a current 300 times stronger
than that produced by pure uranium. They tested and
recalibrated their instruments, and yet they still found the
same puzzling results. The Curies reasoned that a very
active unknown substance in addition to the uranium must
exist within the pitchblende. In the title of a paper
describing this hypothesized element (which they named
polonium after Marie's native Poland), they introduced the
new term: "radio-active."
After much grueling work, the Curies were able to extract
enough polonium and another radioactive element,
radium, to establish the chemical properties of these
elements. Marie Curie, with her husband and continuing
after his death, established the first quantitative standards
by which the rate of radioactive emission of charged
particles from elements could be measured and
compared. In addition, she found that there was a
decrease in the rate of radioactive emissions over time
and that this decrease could be calculated and predicted.
But perhaps Marie Curie's greatest and most unique
achievement was her realization that radiation is an atomic
property of matter rather than a separate independent
emanation. Polish-born French physicist, famous for her
work on radioactivity and twice a winner of the Nobel
Prize. With Henri Becquerel and her husband, Pierre
Curie, she was awarded the 1903 Nobel Prize for Physics.
She was the sole winner of the 1911 Nobel Prize for
Chemistry. She was the first woman to win a Nobel Prize,

9
and she is the only woman to win the award in two
different fields.

RUTHERFORD’S
CONCLUSION

In 1911, Rutherford conducted a series of

experiments in which he bombarded a piece of
gold foil with positively charged (alpha) particles
emitted by radioactive material. Most of the
particles passed through the foil undisturbed,
suggesting that the foil was made up mostly of
10
empty space rather than of a sheet of solid atoms.
Some alpha particles, however, "bounced back,"
indicating the presence of solid matter. Atomic
particles, Rutherford's work showed, consisted
primarily of empty space surrounding a well-
defined central core called a nucleus.
In a long and distinguished career, Rutherford laid the
groundwork for the determination of atomic structure. In
addition to defining the planetary model of the atom, he
showed that radioactive elements undergo a process of
decay over time. And, in experiments which involved what
newspapers of his day called "splitting the atom,"
Rutherford was the first to artificially transmute one
element into another--unleashing the incredible power of
the atom which would eventually be harnessed for both
beneficial and destructive purposes.

Taken together, the work of Becquerel,

the Curies, Rutherford and others, made
modern medical and scientific research
more than a dream. They made it a
reality with many applications. A look at
11
the use of isotopes reveals just some of
the ways in which the pioneering work
of these scientists has been utilized.

RADIATIONS

1. Alpha-particles: This type of radiation is positively

charged. It is relatively massive. It has a low penetrating
power. It’s about 1-20th as fast as light. It is exactly like the
helium atom.
2.Beta-particles: This type of radiation is negatively
charged (but can also be +vely charged). It is relatively light.
It is about as fast as light. They are high energy electrons. It
has a medium penetrating power.
3. Gamma Rays: This radiation is neutral in charge. Has a
very high penetrating power. It is at the speed of light. It is an
electromagnetic wave with very short wavelength. It is very
light.

12
TYPES OF
RADIOACTIVITY

I. NATURAL RADIOCTIVITY
This is the type of radioactivity which consists of a
spontaneous decay of the radioactive nucleus. The
phenomenon is experienced by naturally
radioactive substances. The radiation might come
out individually or combined and, as always, with a
lot of energy.

13
 Some radioactive substances are:
Americium -241: Used in many smoke detectors for
homes and business. To measure levels of toxic lead in
dried paint samples. To ensure uniform thickness in rolling
processes like steel and paper production and to help
determine where oil wells should be drilled.
Cadmium -109: Used to analyze metal alloys for checking
stock, sorting scrap.
Calcium - 47: Important aid to biomedical researchers
studying the cell functions and bone formation of
mammals.
Californium - 252: Used to inspect airline luggage for
hidden explosives...to gauge the moisture content of soil in
the road construction and building industries...and to
measure the moisture of materials stored in silos.
Carbon - 14: Helps in research to ensure that potential
new drugs are metabolized without forming harmful by-
products.
Cesium - 137: Used to treat cancers. To measure correct
patient dosages of radioactive pharmaceuticals. To
measure and control the liquid flow in oil pipelines. To tell
researchers whether oil wells are plugged by sand. And to
ensure the right fills level for packages of food, drugs and
other products. (The products in these packages do not
become radioactive.)

14
Chromium - 51: Used in research in red blood cell
survival studies.
Cobalt - 57: Used in nuclear medicine to help physicians
interpret diagnosis scans of patients' organs, and to
diagnose pernicious anemia.
Cobalt - 60: Used to sterilize surgical instruments. To
improve the safety and reliability of industrial fuel oil
burners. And to preserve poultry fruits and spices.
Copper - 67: When injected with monoclonal antibodies
into a cancer patient, helps the antibodies bind to and
destroy the tumor.
Curium - 244: Used in mining to analyze material
excavated from pits slurries from drilling operations.
Iodine - 123: Widely used to diagnose thyroid disorders.
Iodine - 129: Used to check some radioactivity counters in
vitro diagnostic testing laboratories.
Iodine - 131: Used to diagnose and treat thyroid
disorders. (Former President George Bush and Mrs. Bush
were both successfully treated for Grave's disease, a
thyroid disease, with radioactive iodine.)
Iridium - 192: Used to test the integrity of pipeline welds,
boilers and aircraft parts.
Iron - 55: Used to analyze electroplating solutions.

15
Krypton - 85: Used in indicator lights in appliances like
clothes washer and dryers, stereos and coffee makers. To
gauge the thickness of thin plastics and sheet metal,
rubber, textiles and paper. And to measure dust and
pollutant levels.
Nickel - 63: Used to detect explosives. And as voltage
regulators and current surge protectors in electronic
devices.
Phosphorus - 32: Used in molecular biology and genetics
research.
Plutonium - 238: Has safely powered at least 20 NASA
spacecraft since 1972.
Polonium - 210: Reduces the static charge in production
of photographic film and phonograph records.
Promethium - 147: Used in electric blanket thermostats.
And to gauge the thickness of thin plastics, thin sheet
metal, rubber, textiles, and paper.
Radium - 226: Makes lightning rods more effective.
Selenium - 75: Used in protein studies in life science
research.
Sodium - 24: Used to locate leaks in industrial pipelines.
And in oil well studies.
Strontium - 85: Used to study bone formation and
metabolism.

16
Technetium - 99m: The most widely used radioactive
isotope for diagnostic studies in nuclear medicine.
Different chemical forms are used for brain, bone, liver,
spleen and kidney imaging and also for blood flow studies.
Thallium - 204: Measures the dust and pollutant levels on
filter paper...and gauges the thickness of plastics, sheet
metal, rubber, textiles and paper.
Thoriated tungsten: Used in electric are welding rods in
the construction, aircraft, petrochemical and food
processing equipment industries. It produces easier
starting, greater arc stability and less metal contamination.
Thorium - 229: Helps fluorescent lights to last longer.
Thorium - 230: Provides coloring and fluorescence in
colored glazes and glassware.
Tritium: Used for life science and drug metabolism
studies to ensure the safety of potential new drugs. For
self-luminous aircraft and commercial exit signs. For
luminous dials, gauges and wrist watches and to produce
luminous paint.
Uranium - 234: Used in dental fixtures like crowns and
dentures to provide a natural color and brightness.
Uranium - 235: Fuel for nuclear power plants and naval
nuclear propulsion systems. Also used to produce
fluorescent glassware, a variety of colored glazes and wall
tiles.

17
Xenon - 133: Used in nuclear medicine for lung ventilation
and blood flow studies.

ARTIFICIAL RADIOACTIVITY
In this radioactivity, normally unreactive elements are
made reactive by bombarding them with radiation. Curie
and Joliot showed that when lighter elements such
as boron and aluminum were bombarded with α-particles,
there was a continuous emission of radioactive radiations,
even after the α−source had been removed. They showed
that the radiation was due to the emission of a particle
carrying one unit positive charge with mass equal to that
of an electron.
Neutron activation is the main form of induced
radioactivity, which happens when free neutrons are
captured by nuclei. This new heavier isotope can be stable
or unstable (radioactive) depending on the chemical
element involved. Because free neutrons disintegrate
within minutes outside of an atomic nucleus, neutron
radiation can be obtained only from nuclear
disintegrations, nuclear reactions, and high-energy
reactions (such as in cosmic radiation showers or particle
accelerator collisions). Neutrons that have been slowed
down through a neutron moderator (thermal neutrons) are
more likely to be captured by nuclei than fast neutrons.
A less common form involves removing a neutron
via photodisintegration. In this reaction, a high energy
photon (gamma ray) strikes a nucleus with energy greater
18
than thebinding energy of the atom, releasing a neutron.
This reaction has a minimum cutoff of
2 MeV (for deuterium) and around 10 MeV for most heavy
nuclei. Many radionuclides do not produce gamma rays
with energy high enough to induce this reaction.
The isotopes used in food irradiation (cobalt-60, caesium-
137) both have energy peaks below this cutoff and thus
cannot induce radioactivity in the food.
Some induced radioactivity is produced by background
radiation, which is mostly natural. However, since natural
radiation is not very intense in most places on Earth, the
amount of induced radioactivity in a single location is
usually very small.
The conditions inside certain types of nuclear reactors with
high neutron flux can cause induced radioactivity. The
components in those reactors may become highly
radioactive from the radiation to which they are exposed.
Induced radioactivity increases the amount of nuclear
waste that must eventually be disposed, but it is not
referred to as radioactive contamination unless it is
uncontrolled.

19
Universal law of
radioactive decay

Radioactivity is one very frequent example of exponential

decay. The law describes the statistical behavior of a large
number of nuclides, rather than individual ones. In the
following formalism, the number of nuclides or nuclide
population N, is of course a discrete variable (a natural
number)—but for any physical sample N is so large
(amounts of L = 1023, Avogadro's constant) that t can be
treated as a continuous variable. Differential calculus is
needed to set up differential equations for modeling the
behavior of the nuclear decay.

One-decay process
Consider the case of a nuclide A decaying into
another B by some process A → B (emission of other
particles, like electron neutrinos ν
–
e and electrons e in beta decay, are irrelevant in what
follows). The decay of an unstable nucleus is entirely
random and it is impossible to predict when a particular
atom will decay. However, it is equally likely to decay at
any time. Therefore, given a sample of a particular
radioisotope, the number of decay events −dN expected to
occur in a small interval of time dt is proportional to the
number of atoms present N, that is

20
Particular radionuclides decay at different rates, so each
has its own decay constant λ. The expected
decay −dN/N is proportional to an increment of time, dt:

The negative sign indicates that N decreases as time

increases, as each decay event follows one after
another. The solution to this first-order differential
equation is the function:

Where N0 is the value of N at time t = 0.

We have for all time t:

Where Ntotal is the constant number of particles

throughout the decay process, clearly equal to
the initial number of A nuclides since this is the
initial substance.
If the number of non-decayed A nuclei is:

Then the number of nuclei of B, i.e. number of

decayed A nuclei, is

21
 HALF-LIFE
Given a sample of a particular radionuclide, the half-life is
the time taken for half the radionuclide's atoms to decay.
For the case of one-decay nuclear reactions:

The half-life is related to the decay constant as follows:

set N = N0/2 and t = T1/2 to obtain

This relationship between the half-life and the decay

constant shows that highly radioactive substances are
quickly spent, while those that radiate weakly endure
longer. Half-lives of known radionuclides vary widely, from
more than 10 years, such as for the very nearly stable
nuclide 209Bi, to 10−23 seconds for highly unstable ones.
The factor of ln (2) in the above relations results from the
fact that concept of "half-life" is merely a way of selecting a
different base other than the natural base e for the lifetime
22
expression. The time constant τ is the e -1 -life, the time
until only 1/e remains, about 36.8%, rather than the 50%
in the half-life of a radionuclide. Thus, τ is longer than t1/2.
The following equation can be shown to be valid:

Since radioactive decay is exponential with a constant

probability, each process could as easily be described with
a different constant time period that (for example) gave its
"(1/3)-life" (how long until only 1/3 is left) or "(1/10)-life" (a
time period until only 10% is left), and so on. Thus, the
choice of τ and t1/2 for marker-times, are only for
convenience, and from convention. They reflect a
fundamental principle only in so much as they show that
the same proportion of a given radioactive substance will
decay, during any time-period that one chooses.
Mathematically, the nth life for the above situation would be
found in the same way as above—by setting N =
N0/n, {{{1}}} and substituting into the decay solution to
obtain

23
OCCURRENCE IN NATURE

According to the Big Bang theory, stable isotopes of the

lightest five elements (H, He, and traces of Li, Be, and B)
were produced very shortly after the emergence of the
universe, in a process called Big Bang nucleosynthesis.
These lightest stable nuclides (including deuterium)
survive to today, but any radioactive isotopes of the light
elements produced in the Big Bang (such as tritium) have
long since decayed. Isotopes of elements heavier than
boron were not produced at all in the Big Bang, and these
first five elements do not have any long-lived
radioisotopes. Thus, all radioactive nuclei are, therefore,
relatively young with respect to the birth of the universe,
having formed later in various other types
ofnucleosynthesis in stars (in particular, supernovae), and
also during ongoing interactions between stable isotopes
and energetic particles. For example, carbon-14, a

24
radioactive nuclide with a half-life of only 5730 years, is
constantly produced in Earth's upper atmosphere due to
interactions between cosmic rays and nitrogen.
Nuclides that are produced by radioactive decay are
called radiogenic nuclides, whether they themselves
are stable or not. There exist stable radiogenic nuclides
that were formed from short-lived extinct radionuclides in
the early solar system. The extra presence of these stable
radiogenic nuclides (such as Xe-129 from primordial I-129)
against the background of primordial stable nuclides can
be inferred by various means.Radioactive primordial
nuclides found in the Earth are residues from
ancient supernova explosions which occurred before the
formation of the solar system. They are the long-lived
fraction of radionuclides surviving in the primordial
solar nebula through planet accretion until the present.
The naturally occurring short-
lived radiogenic radionuclides found in rocks are the
daughters of these radioactive primordial nuclides.
Another minor source of naturally occurring radioactive
nuclides are cosmogenic nuclides, formed by cosmic ray
bombardment of material in the
Earth's atmosphere or crust. The radioactive decay of
these radionuclides in rocks within
Earth's mantle and crust contribute significantly to Earth's
internal heat budget.

25
DETECTION OF
RADIATIONS
1. USING A DOSIMETER OR A FILM BADGE: A
dosimeter is a device worn by radioactive workers. It is
basically a film
which
darkens on

incidence of radiation. It is used

to know the level of
radiation the worker has been explosed to.

2. A GEIGER COUNTER: This consists of a Geiger-

Muller tube (which consists of a wire), a scale/rate
meter, and often a loudspeaker. The walls of the
container acts as the cathode while the central wire acts
as the anode. The radiation enters through a thin
window. Each particle or ray ionizes several gas atoms.
Ions attracted to the cathode, electrons to the anode.
Other atoms are hit on the way creating an avalanche of
more ions and electrons. The loudspeaker amplifies a

26
 click sound for each pulse showing the randomness of
the decay.
3. Pulse (Wulf Electroscope)
4. Cloud Chamber
5. Bubble Chamber
6. Scintillation Counter (for detecting gamma rays)

USES OF RADIOACTIVITY

1. Radiology: This is used for research and study in

the medical field.

2. Radiotherapy: This is used in the treatment of

diseases, especially cancer. Due to the penetrating
power of gamma rays, they are used to collectively and
controllably destroy malignant cells.

27
3. Irradiation: This is the exposure of controlled gamma
rays to fruits or vegetables to delay ripening and
improve freshness length of the irradiated foodstuffs.

4. Gamma-Radiography: This is the production of a

special type of photograph, a radiograph. It is used for
quality control in industries. The making of a
radiograph requires some type of recording
mechanism. The most common device is film. A
radiograph is actually a photographic recording
produced by the passage of radiation through a subject
onto a film, producing what is called a latent image of
the subject.

28
5. Radiocarbon or carbon dating: All living matter
contains carbon-14 absorbed from the atmosphere.
This radioactive element has a half-life of about 5300
years. The element continues decaying even after
death of the living organism. This phenomenon is used
to estimate the amount of years the organisms have
been in existence. This is very useful to archaeologists
and researchers.

6. Tracers are a common application of radioisotopes. A

tracer is a radioactive element whose pathway through
which a chemical reaction can be followed. Tracers are
commonly used in the medical field and in the study of
plants and animals. Radioactive Iodine-131 can be
used to study the function of the thyroid gland assisting
in detecting disease.

7. Other uses of radioactivity:Sterilization of medical

instruments and food is another common application of
radiation. By subjecting the instruments and food to
concentrated beams of radiation, we can kill
microorganisms that cause contamination and disease.
Because this is done with high energy radiation
sources using electromagnetic energy, there is no fear
29
of residual radiation. Also, the instruments and food
may be handled without fear of radiation poisoning.
Radiation sources are extremely important to the
manufacturing industries throughout the world. They
are commonly employed by nondestructive testing
personnel to monitor materials and processes in the
making of the products we see and use every day.
Trained technicians use radiography to image
materials and products much like a dentist uses
radiation to x-ray your teeth for cavities. There are
many industrial applications that rely on radioactivity to
assist in determining if the material or product is
internally sound and fit for its application.

30
HAZARDS OF
RADIOACTIVE
SUBSTANCES

The dangers of radioactivity and radiation were not

immediately recognized. The discovery of X-rays in 1895
led to wide spread experimentation by scientists,
physicians, and inventors. Many people began recounting
stories of burns, hair loss and worse in technical journals
as early as 1896. In February of that year, Professor
Daniel and Dr. Dudley of Vanderbilt University performed
an experiment involving x-raying Dudley's head that
resulted in him losing hair under where the tube was
placed (reported in the The X-rays Science news
supplement). A report by Dr. H.D. Hawks, a graduate of
31
Columbia College, of his suffering severe hand and chest
burns in an x-ray demonstration, was the first of many
other reports in Electrical Review. Many experimenters
including Elihu Thomson at Thomas Edison's lab, William
J. Morton, and Nikola Tesla also reported burns. Elihu
Thomson deliberately exposed a finger to an x-ray tube
over a period of time and suffered pain, swelling, and
blistering. Other effects were sometime blamed for the
damage including ultraviolet rays and (according to Tesla)
ozone. Many physicians claimed there were no effects
form x-ray exposure at all.
The genetic effects of radiation, including the effect of
cancer risk, were recognized much later. In
1927, Hermann Joseph Muller published research
showing genetic effects, and in 1946 was awarded
the Nobel Prize for his findings.
Before the biological effects of radiation were known,
many physicians and corporations began marketing
radioactive substances as patent medicinein the form of
glow-in-the-dark pigments. Examples were
radium enema treatments, and radium-containing waters
to be drunk as tonics. Marie Curieprotested this sort of
treatment, warning that the effects of radiation on the
human body were not well understood. Curie later died
from aplastic anemia, likely caused by exposure to
ionizing radiation. By the 1930s, after a number of cases
of bone necrosis and death of enthusiasts, radium-
containing medicinal products had been largely removed
from the market (radioactive quackery).

32
BIBLIOGRAPHY

1. NCERT Physics Textbook for class XII

2. www.wikipedia.org
3. www.google.com
4. en.wikibooks.org

33