The Second Revised Edition of Thermal Physics and Statistical Mechanics
Published by Ananda Book Depot6/13, Poes 4th Street Teynampet, Chennai18

FAILURE? OR STEPS TO REACH SUCCESS

Failure is a vital and necessary part for the success. The following is a record of a man that shows “quitters do not win and winners do not quit”

This man failed in his business in 1831

He was defeated in his bid for the legislature in 1832

He failed in business again in 1834

In 1835, his sweet heart dies

In 1836, he had nervous break down

He lost his bid for speaker of the house in 1838,

He lost congressional campaigns in 1843 and 1945

In 1955, he was defeated at the senate

He lost the nomination for vice president in 1856

He was defeated again for the senate in 1858

But in 1860, he was elected the president of the United State of America

The man underwent all the above failures--  Abraham Lincoln.

STEPS TO PREPARE FOR EXAMS….

DAILY ROUTINE

Daily do self-hypnosis in front of a mirror. Follow it getting blessings from the parents.

Do not keep your head to north side while studying or sleeping

Study in the morning rather than in the late night.

In the night, soon after studying, go to bed straightaway without spending time in front of TV or gossip magazines. The matter goes into your mind forgetting what all you have studied before.

Have a nap in the afternoon during study holidays.

When back from school/college in the evening, have a brief nap, play, bathe, take refreshments and go to study room.

Do palming and blinking very often before study.

To be a ranker, always go head of the teacher’s coverage.

To have a bright career, always be ahead of the syllabus.

Create positive anchors for concentration

Slightly over read all the subjects.

STUDY ATMOSPHERE

Study room should be airy, dust free, bright, mosquito free, noise free, away from TV and radio.

Use comfortable chair. Book shelf should be in order. Have pen, pencil, eraser, scribbling pad etc at your reachable distance. English dictionary, subject books should be at your arm’s length.

Do not study in dull light or very bright light. Always use fluorescent lamp and it should have been fitted on to your left hand side.

Do not keep changing your study place.

Do not go for group study but group review is useful

Give ten minutes break for every one hour study

Give one hour break to every four hour study.

Take rest in the break by listening melodious music but not cricket or cinema music.

BEFORE STUDYING

Observe your breath for two minutes before studying

Never straightaway begin to study without visualizing your goal

Before studying glance the lessons at once.

Do body yawning very often.

WHILE STUDYING

Prepare your own notes well ahead. Read only notes during preparative holidays. Prepare fast forward notes. Read only fast forward notes on the day of examination.

Make figure charts wherever possible.

Study with clarity and understanding. Do not mug up study materials

Always use unrulled paper for all notes to minimize the hidden imprints

While studying, scribble in a scribbling pad

Do not eat or chew while studying

Keep sipping water while studying

Avoid listening to any music while studying except while writing records and routine home work. Even then, do not listen to drums, beats and noisy music.

Do cyclic method for peak concentration

Do not stand or walk or lie down while studying except when concentration is lost.

Do not read aloud except when concentration is lost.

Read three years question papers and learn the answers

Write model exams

AFTER STUDYING

Use fast forward technique after studying and before going to bed. It gets permanently impregnated into the mind.

In the morning, review first what you studied in the night and then only study fresh subject.

Never discuss or read anything one hour before the examinations

Avoid eating anything one hour before the examinations

Activate the left brain just before writing the examinations

DURING EXAMINATION

Always write the roll number, name of the paper, subject code, date of examination and the other details first before writing anything.

Write the question numbers properly and legibly. Write the page number as soon as you take the additional sheet and arrange them properly.

During the examination, always have a spare pen which should be the same in every respect with the main pen.

Never overwrite or over scratch in the examination paper.

Always plan for at least ten seconds before attending the question.

Always choose to write from long answer, paragraph answer and finally short answer questions.

Stop writing the exam five minutes before the time and check whether the question numbers and page numbers are written properly.

Your presence is a gift to the world

You are unique and one of a kind

Your life can be what you want it to be

Take it one day at a time

Count your blessings not your troubles

And you will make it through what comes along

Within you are so many answers

Understand, have courage, be strong

Do not put limits on yourself

Your dreams are waiting to be realized

Do not leave your important decisions to chance

Reach for your peak, your goal and your prize.

ராஜலட்சுமி சிவலிங்கம்

அமெரிக்க எழுத்தாளர்

பிரபல அமெரிக்க எழுத்தாளரும், நேர்மறை சிந்தனை வாயிலான மருத்துவ முறையை வழங்கியவருமான லூயிஸ் லின் ஹே (Louise Lynn Hay) பிறந்தநாள் இன்று (அக்டோபர் 8). அவரைப் பற்றிய அரிய முத்துக்கள் பத்து:

*அமெரிக்காவின் லாஸ் ஏஞ்சல்ஸ் நகரில் ஏழ்மையான குடும்பத்தில் (1926) பிறந்தவர். இவருக்கு ஒன்றரை வயதாகும்போது பெற் றோர் பிரிந்தனர். அம்மா 2-வது திருமணம் செய்துகொண்டார். புதிதாக வந்தவரால், தாயும் மகளும் பல கொடுமைகளுக்கு ஆளாகினர்.

*பள்ளிக் கல்வியைக்கூட முடிக்க இயலவில்லை. தீய பழக்கங் களுக்கு ஆளானார். 16-வது வயதில் ஒரு குழந்தைக்குத் தாயாகி, அதை யாருக்கோ தத்து கொடுத்துவிட்டார். வேலை தேடி சிகாகோ வந்தவர், குறைந்த சம்பளத்தில் பல வேலைகளைப் பார்த்தார்.

*நியூயார்க் சென்று ஃபேஷன் மாடலானார். 1954-ல் திருமணம் செய்துகொண்டார். 14 ஆண்டுகள் இந்த பந்தம் நீடித்தது. தேவாலயத்தில் தங்கி, பல்வேறு பணிகளை மேற்கொண்டார். சிந்தனையின் ஆற்றலையும், அது நம்மை மறுவடிவம் பெறவைக்கும் நுட்பத்தையும் அங்கு கற்றுக்கொண்டார்.

*மன ஆற்றல் குறித்து ஏராளமான நூல்களைப் படித்தார். நேர்மறை சிந்தனை நமது மனத்தை மட்டுமல்லாமல் பொருளியல் சூழலையும் மாற்றவல்லது. அதன்மூலம் நோய்களையும் குணப்படுத்திக்கொள்ள முடியும் என்பதை அறிந்தார்.

*தேவாலயத்தில் மனநல ஆலோசகராகப் பணியாற்றினார். 1970-களில் மத அறிவியல் பயிற்சியாளராக மாறினார். ‘நம் வாழ்க்கையை நாமே சிறந்த முறையில் மாற்றிக்கொள்ளலாம். அதற்கு என் வாழ்க்கையே சிறந்த உதாரணம்’ என்பார். ஏராளமான பயிலரங்குகள் நடத்தி பிரபலமானார்.

*மகரிஷி மகேஷ் யோகியிடம் தியானம் கற்றுக்கொண்டார். 1977-ல் இவருக்கு கருப்பை வாய் புற்றுநோய் வந்தபோது, குணப்படுத்த முடியாது என்று டாக்டர்கள் கைவிரித்தனர். அதன் பிறகு, தன்னைத் தானே குணப்படுத்திக்கொள்ளும் முறை மூலம் அதை குணப்படுத்திக்கொண்டதாகக் கூறியுள்ளார்.

*‘ஹீல் யுவர் பாடி’ என்ற கையேட்டை 1976-ல் வெளியிட்டார். இதை மேலும் விரிவாக்கி 1984-ல் ‘யு கேன் ஹீல் யுவர் லைஃப்’ என்ற நூலாக வெளியிட்டார். இது பரபரப்பாக விற்பனையானது. ‘நியூயார்க் டைம்ஸ்’ பத்திரிகையின் ‘அதிகம் விற்பனையாகும் நூல்கள்’ பட்டியலில் இது பல ஆண்டுகாலம் இடம்பெற்றது. இந்நூல் 35-க்கு மேற்பட்ட நாடுகளில் தமிழ் உட்பட 30 மொழிகளில் மொழிபெயர்க்கப்பட்டுள்ளது.

*உடல், மனப் பிரச்சினைகளுக்கு ஆலோசனை நாடி ஏராளமானோர் இவரிடம் குவிந்தனர். சிறப்பு அழைப்பின்பேரில் பல இடங்களில் உரையாற்றினார். 20-க்கும் மேற்பட்ட நூல்களை எழுதியுள்ளார். ஏராளமான ஒலி நாடாக்களை வெளியிட்டுள்ளார். எய்ட்ஸால் பாதித்த வர்கள் நிவாரணம் பெற ஆலோசனைகள், பயிற்சிகளை வழங்கி னார். ‘ஹே ஹவுஸ் பப்ளிஷிங்’ என்ற பதிப்பகம் தொடங்கினார்.

*‘ஹே ஃபவுண்டேஷன்’ அறக்கட்டளையை 1985-ல் ஆரம்பித்தார். 70 வயதுக்குப் பிறகு தோட்டக்கலையில் ஆர்வம் பிறந்தது. வீட்டிலேயே தோட்டம் போட்டார். நடனம் கற்கவேண்டும் என்ற குழந்தைப் பருவ ஆசையை 76-வது வயதில் நிறைவேற்றிக் கொண்டார். முறையாக ஓவியக்கலை பயின்று, பல ஓவியங்களை வரைந்தார்.

*ஆதரவின்றி தெருவில் கிடக்கும் விலங்குகளை பராமரித்தார். சுய உதவி இயக்கம் மூலம் உலகம் முழுவதும் பல்லாயிரக்கணக்கான மக்களுக்கு வழிகாட்டியாக உள்ளார். பல்வேறு அறப்பணிகளை தொடர்ந்து செய்துவரும் லூயிஸ் லின் ஹே இன்று 91-வது வயதில் அடியெடுத்து வைக்கிறார்.

Second revised edition of thermal physics is going to released soon.

The second edition of Solid State Physics from MJP Publishers, Chennai

I am very happy to say, the second edition of the book Solid State Physics is released on 17th October 2013. Now the book has been published from MJP Publishers, Muthu Kalathy Street, Triplicane, Chennai. You can now onwards contact MJP Publishers to buy Solid State Physics,

MY DAYS IN NATIONAL ENGINEERING COLLEGE

Dr. K. ILANGOVAN

Professor of Physics

RKM Vivekananda College

Mylapore, Chennai-04

I joined National Engineering College on 10^th September 1984 and worked up to 14^th December 1998 which means that I have served for 14 long years in a self financing Engineering College. I now feel that it is possible only because of the chairmanship of Thiru K. Ramasamy and Prof. S.Kannanppan who served National Engineering College as Special Officer, Principal and Director.

The college was started in a Ginning factory near Nalattinputhur railway station. I still remember, when I got down in Nalttinputhur from the bus in search of the college, I could see only the name board of the college and vacant place behind the board. I was little bit shocked and asked a person about the college. He said you have to walk for another 2 miles and could see a ginning factory in which the college is functioning.

The college which has been started in a 5 acre land of ginning factory now expanded to 150 acre land with many buildings and infrastructure. The staff room alone would have been shifted to 10 different places in 5 years. The college got into a permanent shape and size only during 1995. There are many persons associated with the expansion of the college starting from the mesons constructed the building to lecturers, professors and non teaching staff. The persons to whom I have been associated from the inception of the college and still working are  Mr. S.Rammoorthy, Mr. M.A.Perumal, Ms.Shenbagavalli and Ms.Manimegalai (teaching), Mr. G.Karpagasundaram and Mr.Jeevanandam (non teaching)

Personally speaking, I joined this institution only with my M.Sc degree in Physics. I was allowed to do my part time M.Phil Physics from St.Joseph’s College, Trichy. Then, I was given leave on loss of pay to continue my Ph.D studies from Howard University, Washington DC, USA. Due to my personal problems I could not complete my Ph.D studies from Howard University. But still I could manage to finish my Ph.D in Nuclear Physics from Manonmaniam Sundaranar University, Tirunelveli. Every year I was allowed to participate in a DAE Nuclear Physics conference with leave on other duty for nearly ten days. In South India, first time I had written a book on Engineering Physics. Throughout my tenure in National Engineering College, this book was prescribed for the students of this college. I was serving National Service Scheme unit of this college for 2 years and was editor of National Engineering College magazine for two years. I do not say all these as my achievements but I could proudly say that this college has given me chances to grow as a multidimensional person. 

                                                                                                    

Prof.S. Kannanppan who served in Thiagarajar College of Engineering, Madurai for 30 years and after retirement joined in National Engineering College as special officer. When you see him first time you may underestimate his strength in running the college and you may not accept him as an administrator. Many occasions, we may feel that the proverb, “appearance is deceptive” is exactly correct. I should accept here that only after working under his guidance for 14 years, I understood him as an excellent administrator and wonderful financial advisor.

One fine morning I was in the cabin of Prof.S Kannappan to discuss about National Service Scheme camp. During that time three persons came from a reputed computer company to finalize a Mini-Magnum computer with 30 parallel terminals. The company had quoted the computer for 12 lakhs rupees. Prof.S.Kannappan had said coolly, “See gentlemen! Do not get offended by my quote for this computer. I prefer to buy this computer only for 2 lakhs”. You may not believe that the company finally sold the same computer to the college for just 4 lakhs rupees.

Now, National Engineering College stands like a banyan tree spreading its branches proudly after completing 30 years. But it has been designed step by step, stone by stone and inch by inch. Prof.S.Kannappan as a Special Officer is not in a hurry to build the National Engineering College on a single day. He is there to fix the fees regulations of the college, food in the hostel, staff welfare, design the college emblem, buying college bus, buying equipments for laboratories, designing various buildings and laboratories. There were lots and lots of quotations, enquiries, representatives, sales personnel, visitors, parents and reporters. Prof.S.Kannappan was not all excited but kept cool all the time. He is the sculpture who made this college into an excellent statue by imposing rules and regulations based on university and government norms. 

The greatest success this college has attained only on the following reasons. The college fees have been regulated in such a way that not a single rupee has been collected extra from the fees fixed by the government. There are no extra fees collected for transport or the breakfast and lunch. The teaching staff members have been paid with a good salary based on the AICTE norms and the salary has been credited in Indian Overseas Bank extension branch. The leave facilities (casual leave and annual leave or semester leave and latter years, earned leave and maternity leave have been included) for the staff members have been fixed according to the university rules and regulations. There were scarcity for the M.E graduates during those days and hence the staff members were sent to higher studies with study leave and half salary.

Finally, I should have to conclude this article by saying few words about the first batch students of this college. As I have told in the beginning that I could be able to complete 14 long years in National Engineering College only because of Thiru.K.Ramasamy and Prof.S.Kannappan, I should have to add one more reason that it is because of my first batch students also. They gave greatest enthusiasm in learning and giving respect to the teachers. I wish this silver jubilee reunion a grand success and wish them to celebrate golden jubilee reunion also.

STEPS TO ORDERLY LIVING……

Enjoy the joy of being orderly and systematic life using the following yardsticks:

EARLY RISE

It is the beginning of orderly living. Go to bed by 10.30 P.M to rise at 5.00 A.M

EXERCISES/YOGA AND MEDITATION

Whether you are sixteen or sixty, do not skip to perform exercises/yoga for at least 15 minutes in the morning. It keeps your body fit. Your tummy is inversely proportional to your orderliness and self-discipline. Meditation gives you mental strength through calmness whereas exercise removes internal disorders.

EATING HABBITS

Eat more nature foods such as fruits, vegetable salads, sprouts and drink more water and liquids. Avoid overeating particularly fast foods. Most importantly maintain timely eating.

DRESS

Never wear clothes with wrinkles. Avoid not well fit clothes. Dress has got tremendous impact on your bioplasmic energy. It not only anchors you to be positive, tidy, alert and fresh, it influences others as well.

PUNCUTALITY

Defy the Indian Stretchable Time (IST) for good. An orderly person can never be late.

WORK DIARY

It is worth million rupees to maintain a work diary. Always remember the proverb, “A stitch in time saves nine”.

MAINTAIN HOME/OFFICE

Maintain the living place, home or office more orderly. This has a strong impact on the mind and anchors to be more systematic. Not only that others at home and office slowly imitate the same and imbibe orderliness.

ZEN WAY OF LIFE

Zen way of life is to be “present in the present”. Lack of Zen is the mother of all disorders including absent mindedness. So be a Zen master and practice Zen meticulously.

ROTE MEMORY TECHNIEQUE

Recall the entire day’s activities in chronological order for about five minutes at bed time. It not only increases the natural memory but also imparts time consciousness.

SPEND TIME WITH FAMILY

Try to spend time with your family at least half an hour daily and three hours weekly. This keeps you and your family in good stead.

WHAT TO CARRY WITH YOU?

You tell your friends, I will tell about you, is the well known saying. Now it is to be said, you show your ker-chief, I will tell how orderly you are? Hence, keep the ker-chief neatly folded each time after you use it.

WISH AND WILL

Above all, the very wish and will, will instill orderliness. Orderliness takes you to excellence. It is said that excellence at work is a kind of yoga you are practicing.

enjoy the joy of orderly living

NUCLEAR PHYSICS

Nucleus:

Nucleus is the central core of an atom. Entire mass of an atom is concentrated in the nucleus. The atomic nucleus was discovered in 1911 by Rutherford. Nucleus consists of protons and neutrons and in general protons and neutrons are called nucleons. Hydrogen nucleus does not contain neutron and has only one proton.

Proton:

The rest mass of proton is 1.007277 amu and charge of proton is +1.6 x 10^–19 coulomb. The rest mass of proton is 1836 times the rest mass of electron.

Neutron:

The rest mass of neutron is 1.008665 amu and charge of neutron is zero. Neutrons are slightly heavier than proton.

Atomic mass unit:

1 atomic mass unit (amu) is 1.66 x 10^-27 kg. The mass of a nucleon is 1.67 x 10^–27 kg.

Atomic mass unit is defined as mass of 1/12^th of carbon-12 atom and the energy equivalent of 1 amu is 931 MeV.

Representation of a nucleus:

The symbolic representation of a nucleus is _zX^A.  Z is the atomic number and the atomic number can be the number of protons or number of electrons. A is the mass number, which consist of the number of protons and neutrons.

Nuclear radius:

The nuclear radius is of the order of 10^–14 m to 10^–15 m. The equation for the atomic radius is given by R = r_o A^1/3, where r_o is a constant and has a value of 1.3 x 10^–15 m.

Nuclear mass:

The nuclear mass is the total mass of protons and neutrons and is also equal to the total mass of the nucleons. Nuclear mass = Zm_p + Nm_n = Am_N where Z is the number of protons and m_p is mass of one protons, N is the number of neutrons and m_n  is mass of one neutron, A is mass number and m_N is mass of one nucleon.

  

Nuclear density:

Nuclear density = nuclear mass / nuclear volume. Nuclear density is independent of mass number A. Nuclear density has value of 1.816 x10¹⁷ kg/m³. Nuclear density is extraordinarily very high and it very large compared to density of lead (1.134 x 10⁴ kg/m³), which is considered to be the highest dense material available.

Isotopes:

Elements having the same atomic number Z and different mass number A are called isotopes. Examples are isotopes of hydrogen, ₁ H ¹, ₁ H ², ₁ H ³ and ₉₂ U ²³⁵, ₉₂ U ²³⁸. Since the number of charge is responsible for the characteristic property of an atom, all isotopes

of an element have the same chemical properties but different physical properties

Isobars:

Elements having the same mass number A and different atomic number Z is called isobars. The nuclei ₈ O ¹⁶, ₇ N ¹⁶ are example of isobars. The isobars are atoms of different elements and have different physical and chemical properties

Isotones:

Elements having the same number of neutrons are called isotones. Examples are isotopes of hydrogen, ₆ C ¹⁴, ₇ N ¹⁵, ₈ O ¹⁶, N = 8 in each case.

Isomers:

Elements having the same atomic number Z and same mass number A but differ from one anther is their nuclear energy states and exhibit differences in their internal structure are called isomers. The elements are distinguished from their different half life time.

Mass defect:

Mass defect is defined as the mass difference between the sum of the masses of the constituents of an atom and its actual mass M. Mass defect Dm = [(Zm_p + Nm_n)– M]

Binding energy:

Binding energy B.E is the energy needed to bind the nucleons in the nucleus and is also the conversion of mass defect into energy to bind the nucleons in the nucleus. Binding energy = Dm C² = [(Zm_p + Nm_n)– M]C²

Nuclear force

Nuclear force is the strongest force that binds the protons and neutrons inside the nucleus. There are three types of nuclear forces namely (p-p) force, (p-n) force and (n-n) force.

  

Ø  Nuclear forces are short-range forces and they are effective only at short range.

Ø  Nuclear forces are charge independent.

Ø  Nuclear forces are the strongest known forces in nature.

Ø  Nuclear forces have saturation property which means nuclear forces are limited in a particular range. As a result each nucleon interacts only with a limited number of nucleons nearest to it.

The liquid drop model:

The liquid drop model was proposed by Neils Bohr. Neils Bohr has observed that there are certain marked similarities between an atomic nucleus and a liquid drop.

Ø  The nucleus is spherical in shape in the stable state just as a liquid is spherical due to symmetrical surface tension forces.

Ø  The force of surface tension sets on the surface of the liquid drop and similarly there is a potential barrier at the surface of the nucleus.

Ø  The density of the liquid drop is independent of its volume and similarly the density of the nucleus is also independent of its volume.

Ø  The intermolecular forces in a liquid are short-range forces. The molecules in a liquid drop interact only with their immediate neighbors. Similarly the nuclear forces are short-range forces. The nucleons interact only with their neighbors and this leads to the saturation in the nuclear forces and constant binding energy per nucleon.

Ø  The molecules evaporate from a liquid drop on raising its temperature. Similarly when energy is given to a nucleus by bombarding it with a nuclear projectile a compound nucleus is formed which emits nuclear radiation.

Ø  When a small drop of liquid is allowed to oscillate it breaks up into two smaller drops of equal size. Similarly when sufficient energy is given to a nucleus by bombarding with a nuclear projectile it breaks into two smaller nuclei.

Shell model:

Shell model is some times referred to as independent particle model. According to this model the protons and neutrons are grouped in shells in the nucleus similar to extra nuclear electrons are grouped in shells in the nucleus. The number of nucleons in each shell is limited by Paula exclusion principle.

Neutron:

Neutron is emitted when Beryllium is bombarded by alpha particles.Bothe and Becker identified them as highly penetrating radiations. Joliot and Curie detected that they can knock out protons from hydrogenous substances. Chadwick discovered that their mass is nearly equal to that of protons and he is the one who named it as neutron.

   

Ø  Neutrons are changeless particles.

Ø  They are fundamental constituents of all nuclei except hydrogen ₁H¹.

Ø  It has greatest stability and has high penetrating power.

Ø  It cannot be deflected by electric and magnetic field

Ø  The free neutron is unstable, its half-life is 13 minutes and it decays into a proton, electron and antineutrino.

Ø  Slow neutrons have energy range between 0 to 1000 eV and fast neutrons have energy range between 0.5 MeV to 10 MeV.

Ø  Fast neutrons are slowed down by moderators. Since the slow neutrons are in thermal equilibrium with the medium through which they pass, they are also called as thermal neutrons. Paraffin, heavy water and graphite are used as moderators. Slow neutrons are capable of producing fission reaction when sent to uranium nucleus.

Nuclear fission:

Nuclear fission is the process of breaking a heavy nucleus into two smaller nuclei with the release of large amount of energy. For example when Uranium is bombarded with neutron it splits into Barium, Krypton, neutron and energy. ₉₂U²³⁵ and ₉₄Pu²³⁹ are fissionable materials, which are used as fuels in nuclear reactors. by neutrons of all energies. The material ₉₂U²³⁸ is fissionable only with fast neutrons.

Chain reaction:

Chain reaction is a self-propagating process in which number of neutrons goes on multiplying rapidly almost in geometrical progression during fission till whole of fission material is disintegrated.

Chain reaction consists of two types namely controlled chain reaction, which lead to nuclear reactor, and uncontrolled chain reaction, which lead to an atom bomb.

Multiplication factor:

The multiplication factor k is defined as the ratio of number of neutrons in any one generation to the number of neutrons in the preceding generation. The fission reaction is critical or steady when k = 1, is building up or super critical when k >1 and it is dying down or sub critical when k < 1.

Critical size:

Critical size of a system containing fissile material is defined as the minimum size for which the number of neutrons produced in the fission process just balance those lost by leakage and non fission capture.

Atom bomb:

The principle of fission is made use in the construction of the atom bomb. An atom bomb consists essentially of two pieces of uranium each smaller than the critical size and a source of neutron. A cylindrical third mass of uranium is propelled so that it will fuse together with the other tow pieces.

Parts of nuclear reactor:

                                      

Ø  Fuel or fissionable materials are mostly uranium and rarely plutonium, which are sealed in aluminium cylinders.

Ø  Neutron source gives thermal neutrons to induce fission reactions.

Ø  Moderators, which are heavy water, graphite and paraffin, used to slow down the fast neutrons.

Ø  Control rods, which are cadmium or boron, can absorb neutrons so that the fission reaction can be controlled.

Ø  Neutron reflector, which reflects the escaping neutrons back to the reactor.

Ø  Coolant, which is heavy water or liquid sodium, can absorb the heat generated.

Ø  Shielding can be done by thick lead lining surrounded by concrete wall to prevent harmful radioactive radiation.

Nuclear fusion:

Nuclear fusion is the process of fusing two or more light nuclei combine together to form a single heavy nucleus with the release of large amount of energy.For example when four hydrogen nuclei are fused together, a helium nucleus is formed. The mass of the single helium nucleus formed is less than the sum of the masses of four hydrogen nuclei. The difference is mass is converted into energy according to Einstein’s mass energy equation.

In the sun hydrogen and helium are in plasma state i.e. highly in ionized state. Proton-Proton cycle takes place in sun.  Carbon-Nitrogen cycle takes place in stars whose temperature is greater than that of the sun. In this cycle carbon is used as a catalyst.

Thermonuclear reactions:

The main difficulty is the fusion of nuclei is the electric force of repulsion between the positively charged nuclei. Fusion is possible when the kinetic energy of each of the nucleus is large enough to overcome the repulsion. Fusion reaction can take place only at very high temperatures of the order of 10⁷ to 10⁹ K.

Hydrogen bomb:

Hydrogen bomb is a device, which makes use of the principle of nuclear fusion. The very high temperature required for an uncontrolled thermonuclear reaction is obtained by the detonation of an atom bomb. The atom bomb by fission process produces a very high temperature at which thermonuclear reactions start resulting in the fusion of hydrogen to form helium and release of very high energy.

Elementary particles

Baryons or heavy particles:

Proton and particles heavier than proton form this group. Protons and neutrons are called stable baryons and particles having masses greater than nucleons are called unstable baryons. Every baryon has an antiparticle.

Hyperons:

Hyperons are special cases of baryons called unstable baryons characterized by time decay of the order of 10^-10 second. Hyperons have mass value greater than the mass of nucleons or the mass value intermediate between those of neutron and deuteron. There are four types of hyperons namely Lambda, sigma, Xi and omega.

Leptons:

This group contains particles of mass less than the mass of p mesons or pions. electrons, positrons, neutrino, antineutrino, positive and negative muons are leptons.

Mesons:

The rest mass of these particles varies between 250m_e and 1000m_e. The mesons are agents of interaction between particles inside the nucleus. Baryons and mesons are jointly called hadrons and are the particles of strong interaction.

Radioactivity:

Natural radioactivity was discovered by Henry Becquerel in 1896. The rays emitted from uranium were called Becquerel rays.Madame curie and here husband Pierre Curie discovered the highly radioactive element radium

Natural radioactivity is the spontaneous emission of alpha, beta and gamma rays by elements whose atomic number are greater than 82. That is, all elements having atomic number greater than lead are natural radioactive elements.

Radioacivity was not affected by strongest physical and chemical treatment and excessive heating or cooling or powerful reagent.

The electrons orbiting the nucleus are not responsible for radioactivity. The source of radioactivity is the nucleus of an atom. Radioactivity is the result of the disintegration of an unstable nucleus.

The half-life period of a radioactive material is the time taken by the element for half the number of its atoms to disintegrate. The half-life period of a radioactive element is inversely proportional to the decay constant of the element. T = 0.6931/l.

The mean life of a radioactive material is the average or mean lifetime of all the atoms of a radioactive element present. The mean life t = total life time of all the atoms/total number of atoms = 1/l.

The unit of radiation is roentgen. The quantity of radiation that produces 1.6 x 10¹² ion pairs in 1 gm of air is defined as roentgen.

Alpha decay

The emission of alpha particle by a nucleus leads to a decrease of atomic number decreases by 2 and a decrease of mass number by 4.

Beta decay

The emission of beta particle by a nucleus leads to an increase in atomic number by 1 and mass number remains the same.

Gamma decay

The emission of gamma rays by a nucleus leaves the atomic number mass number remain unaltered.

Geiger Nuttal law:

The range of R of an alpha particle and the disintegration constant l of the radioactive element that emits it are related as logl  = A+B log R. According to this relation when the disintegration constant is high the range is also high. Since the range depends on the energy we conclude that the radioactive substances of large decay constant emit higher nervy alpha particles.

The neutrino theory of beta decay:

In 1934 Fermi developed a theory to explain the continuous beta ray emission. According to this theory, during beta decay a neutron disintegrates into a proton, electron and a neutrino. The proton remains inside the nucleus and the electron and antineutrino are released from the nucleus.

Artificial radioactivity:

Artificial radioactivity discovered in 1934 by Curie and Joliot. The disintegration of light elements leads to artificial radioactivity. Artificial radioactive substances emit electron, neutron and positron or gamma ray and they do not emit alpha rays.

The transmutation of one element into another by artificial means is called artificial transmutation or artificial radioactivity.

Radioisotopes can be produced by bombarding the element with accelerated particle from a cyclotron. An element can be converted into a radioisotope by continuous bombardment of neutron inside the reactor.

Applications of radioisotopes

Radio-hosphorous-30 is used to determine the rate of absorption of an element in a fertilizer.

Radio-cobalt-60 is used to treat malignant tumour-cancer.

Radio-iodine 131 is used to locate brain tumour, to find the extent of enlargement of thyroid gland.

Radio-sodium-24 is used to check the blood circulation in heart and other parts

Radio-carbon-14 is used to determine the age of fossils and relics.

Uranium 235 and Lead 206 are used to determine the age of rocks.

Radio carbon dating:

Living being takes carbon-14 with food and air. When death occurs the intake of carbon-14 stops. Thencarbon-14 deacy and get converted into nitrogen-14. By determining the percentatge of carbon-14 in dead matter the age of specimen can be estimated. This method is used to find the age of mummies and relics. Thus carbon-14 provides radioactive clock for anthropologists.

Uranium dating:

The age of earth has been determined by the amount of uranium-235 and Lead-206 present in the specimen

Geiger Muller counter:

Geiger Muller counter is a device used to detect the radiation. The neon gas is used for ionization. The principle of this counter is based on the property of alpha particles have the highest ionizing power, beta particles have lower ionizing power and gamma rays have lowest ionizing power. The Geiger Muller counter has a cylinder containing a gas and if the radioactive rays sent to the gas it gets ionized based on the type of radioactive ray. The emf developed due to ionization is amplified to activate an electronic counter.

Nuclear interaction and particle accelerators:

The rearrangement of nucleons leading to the formation of new nuclei when two or more nuclei are close together is called nuclear interaction. Nuclear reactions are produced by bombardment with energetic projectiles like protons, deuterons, alpha particles, neutrons and electrons.

Cyclotron:

The cyclotron is one of the particle accelerators, which accelerates particles to very high kinetic energy. The cyclotron is a spiral type accelerator and was developed by Lawrence in 1930. It has a hollow cylinder divided into tow sections known as Dees. The Dees are connected to high frequency oscillator. A magnetic field perpendicular to the place of the Dees is applied.

By the action of high frequency oscillator and magnetic field the ion inside the Dees describes a circular path of angular velocity w = v/r = Bq/m is a constant. The frequency of rotation in a cyclotron is equal to Bq/2pm and the time period of rotation is equal to 2pm/Bq.

The advantages of cyclotron:

Ø  Cyclotron can accelerate protons, deuterons and alpha particles.

Ø  It requires comparatively low voltages and occupies a comparatively low space.

The limitations of cyclotron:

Ø  It is difficult to arrange an intense magnetic field over a large area and the deflector plates consume a large voltage.

Ø  At very high voltages the frequency Bq/2pm is not a constant and thus lead to phase instability. The frequency of the ion can be kept constant by increasing the magnetic field. In another form of apparatus the frequency of the applied ac is varied so that it is always equal to the frequency of rotation of the ion.

Ø  Electrons cannot be accelerated by cyclotrons due to their relativistic mass variation eve at low energy level of 20 keV.

Synchrocyclotron:

Synchrocyclotron is a modified form of the Lawrance cyclotron. This consists of only one Dee placed in a vacuum chamber between the poles of an electromagnet. Instead of second Dee opposite the opening of the Dee there is a metal sheet connected to the earth. The alternate potential difference applied to the Dee is made to ruse and fall periodically instead of remaining constant.

The frequency is changed at such a rate that as the ion lags a little due to the increase in mass caused by increase in velocity the electric field frequency also automatically lags in variation. Hence the particle always enters the Dee at the correct moment when it can experience maximum acceleration.

The Betatron:

Betatron is a device used to accelerate electrons (beta particles) to very high energies. D.W.Kerst constructed it in 1941. It consists of a doughnut shaped vacuum chamber placed between the pole pieces of an electromagnet. The electromagnet is energized by an alternating current. The magnet produces a strong magnetic field in the doughnut. The electrons are produced by an electron gun and are allowed to move in a circular orbit to constant radius in the vacuum chamber. The magnetic field varies very slowly compared with the frequency of the electrons in the equilibrium orbit.

The linear accelerator:

The linear accelerator consists of a series of coaxial hollow metal cylinders or drift tubes 1,2,3,4,5, etc. They are arranged linearly in a glass vacuum chamber. The alternate cylinders are connected together, the odd numbered cylinders being joined to one terminal and the even numbered ones the second terminal of the high frequency oscillator. After half a cycle the polarities are revered ie 1 and 3 will be negative and 2 and 4 positive.

The positive ions enter along the axis of the accelerator during the half cycle, when the drift tube 1 is negative so that the positive ions pass through the first tube with a velocity. The length of the tube 1 is so adjusted that as the positive ions come out of it, the tube has a positive potential and the next tube 2 has a negative potential and thus the positive ions are accelerated with high kinetic energy.

The limitations of linear accelerator:

Ø  The length of the accelerator becomes inconveniently large and it is difficult to maintain vacuum in a large chamber.

Ø  The ion current available is in the form of short interval impulses because the ions are injected at an appropriated moment.