 Hello everyone. So, so far we have discussed the different aspects of nuclear industry including the fundamentals of radioactivity, nuclear structure, nuclear models, different types of decays, detection of different types of radiations and also nuclear reaction mechanisms, different types of nuclear reactions including fission and fusion. And in the nuclear fission and fusion we discussed about how to tap the energy from the nuclei to produce electricity and therefore the fusion efforts are going on. So, we will now switch over to another aspect of nuclear science and technology that is their applications of the radioisotopes in different areas. So, we will not go into details of applications but how to produce the radioisotopes for applications in many, many areas. So, radioisotope applications is one area of nuclear science and technology, nuclear fission and fusion is another area. So, we will now discuss the production of radioisotopes which are useful in many, many applications. So, I have just given a nutshell what are the different ways by which we can produce the radioisotopes. So, mainly we have at our disposal the reactors or other types of neutron sources. So, we can irradiate a target material with neutrons to produce radioisotopes or can have accelerators, cyclotrons, pylotrons, bandigraha, etcetera, where in bombarded target by charged particle we can produce radioisotopes. Using neutron radiation when we radiate the stable targets we get neutron rich product which are invariably beta minus active or we can if suppose we irradiate the actinides, the fissionable materials then by nuclear fission of these heavy actinides elements we can produce fission products which are also many of them are useful different areas. In charged particle we irradiate the stable target materials and since we are bombarding with charged particles we produce neutron deficient radioisotopes which will be imitating the plus electron capture in line. So, this in nutshell gives you different ways by which we can produce radioisotopes. So, now we will first discuss the neutron based industrial production where there are different processes different ways by which we can produce radioisotopes. So, we will now discuss using neutrons what are the different ways by which we can produce radioisotopes. The first and the most common is by n gamma reaction. So, you all know that if you irradiate a target material let us say z by n gamma then we get a plus 1 x z and this invariably is with a minus active. So, we get a plus 1 y z. So, this is how we can in fact increase the atomic number of a target material by irradiating neutron and then the neutron induced reaction product is with a minus active. So, this is the most common route of radioisotope production in a reactor or it can be even other source like you can have photo neutron source or you have a ET neutron source you can have in California to fission source of neutrons. But the most common source of neutrons for radioisotope production is a nuclear reactor where you can at the same time irradiate several targets and produce large amount of duty that we discussed in the nuclear reactions. So, we have the what I have listed out in the isotopes which are very much used in some area or other. So, coval 59 n gamma gives you coval 60 having a half life of 5.274 years and which is undergoing beta minus and this coval 60 then after beta minus lands up in the exited states of nickel 60 and which gives you two beautiful gamma rays 1172 and 1332. These are the gamma ray because of this gamma ray the coval 60 finds lot of applications in irradiation of materials many applications you will find in industrial research based on gamma. The cross sections are also given here in this column cross sections are very important get higher activity we need to have higher cross sections. So, sections are given in barns one barn is 10 power minus 24 centimeter square. So, coval 60 duty in many industries like radiography or food irradiation many types of applications you will find coval 60 duty source. This is a gamma source then we have molybdenum 99 by natural molybdenum 98 n gamma reaction can also produce molybdenum by other roots which we will discuss later on. It has got a lower section 0.141 half life is 66 hours it is a parent of the 99 m magnesium which is 6 hour pipeline and then we will deal with that medicine that uses. So, again sodium 23 n gamma sodium 24 sodium 24 is a hard gamma emitter which emits high gamma in high energy gamma rays and having a half life of 15 hours it can it is used as a tracer in many many applications iridium 192 produced by 191 iridium n gamma is another isotope having 73 days half life and cross section is quite good. So, iridium actually emits different energies in hundreds of k e v and for radiography we do commonly industrial radiography of many products like non-destructive testing equipment we use. So, coval 60 and iridium are used if you want to do radiography of a heavy material heavy machine tool for high energy gamma over 60 it is a small one you want to know energy gamma resource used iridium 190. 197 gold gives you n gamma 198 gold between 2.695 days process is also quite good and 198 is used as a reducer in many applications industry bromine 81 n gamma bromine 82 you can even prepare a gaseous product to extract tracer or like halbromide so liquid is tracer. So, if you want to trace the path of a liquid or a gas you can use bromine 82 tracer. So, this 35 hours in industry bromine 82 has lot of applications when you want to trace the path of particular like a petrochemical. There is a leak of petrochemical in a long stream the underground pipeline is going on and we want to know where the leakage is there you use this bromine 82 as a tracer and you can trace where the leakage is there. So, these are the you know different ways by which n gamma way by which you can produce different isotopes and one important aspect of this is that you irradiate the target material the radioisotope also is of the same element and so bulk of the material remains the same elements therefore they are not carrier free means all the isotopes are all the atoms are not of radioisotope, but there is a bulk suppose you irradiate 1 gram of cobalt then only maybe picogram or nanogram or macrogram of cobalt will be converted into cobalt 16 bulk of it still remains the cobalt 59. So, that is what the meaning that it is not a carrier free. So, there is a carrier always associated with the carrier means the stable target element. So, this is the drawback of this n gamma root that you do not get a carrier free radioisotope and carrier free means only the radioisotopes other isotopes or a stable isotope are not available in that particular present. The other way is called the Cillard-Chalmers reaction. So, the necessity to produce carrier free radioisotope, but using n gamma reaction now led to this kind of developments in the radioisotope production. So, this can also be called as isotope enrichment by the quail chemistry. That means, you may take such a compound that after the neutron n gamma reaction the radioisotope is detached from the compound and you have a carrier free radioisotope. So, this is a little more of ideal way of speaking, but we will see that you can increase the specific activity of the radioisotope consignment by using Cillard-Chalmers. And I say specific activity means per gram of the target how many atoms are radioactive. So, what is the activity per gram of target that is for the specific activity. So, just to give you an example of Cillard-Chalmers. Cillard and Chalmers actually developed this technology of producing radioisotope. So, for example, you want to get 82 bromine in the carrier free form by bromine 81 n gamma you will get bulk of the bromine remains 81 bromine 81 and so bromine 82 will be present in a large amount of bromine 81. But if you take an organic molecule like ethyl bromide now bromine is bonded to ethyl group by a covalent bond. And when you have an n gamma reaction then the one of the bromine atom will become bromine 82. And what happens that because of the recoil when this n gamma reaction happens a gamma ray that is going out of bromine 82 bromine 82 will be excited. So, 81 bromine n gamma bromine 82 and it is excited. So, when it is emitting a gamma ray this gamma ray would give a required bromine 82 and it will be snapped from the organic moite. So, you will have bromine 82 which is not bonded to ethyl group. So, now you have bulk of the material remains ethyl bromide which has got different chemistry and the bromine 82 may become bromide iron which will have a different chemistry. So, you can separate bromine 82 from ethyl bromide and you will get ethyl bromine. Similarly, potassium chromate 50 chromate you will irradiate with neutrons to get with 51 chromate. Now, this chromate iron you know so you CrO4 2 minus that CrO bonds may get broken when the gamma ray gives a required to chromium 51 and because of the breaking of this bond you will see free chromium which may stabilize at chromium 3 plus and therefore, this has got different chemistry than the met iron which is chromium 6 and that is how the if the target and the radioact stop have different chemistry then you can do separation get a free radioact. So, what is the concept behind the required chemistry? This is because the pronged gamma that is imitated from the excited nucleus by formed by n gamma reaction then when the gamma ray gives a coil to the atom atom then the linear momentum of the gamma photon the momentum is conserved. So, we can calculate what is that required that requirement will give what energy that requirement will give get. So, the momentum is nothing but for gamma ray energy upon C energy of the gamma ray photon and the velocity speed of light and that same will be the momentum of the required. So, whatever the moment of the photon the required nucleus will get that much momentum to conserve the moment. So, if you see this is the momentum of the required then the energy will be P square upon 2 m. So, it will be P square upon 2 m C square. So, you can see here we have a 5 mv gamma ray getting limited from compound nucleus. The 5 mv gamma ray will give a coil to see what is the value. So, from bromide 82 if the required energy will be 47 electron you can see here the proper gamma ray of emitted from excited bromide H2 we give a required to this let us say ethyl bromide and then this rather than bromide 82 we will get a kick of 47 eV and that will lead to the detachment of the bromide H2 from the angle and this is per atom. So, in terms of chemical energy kilojoule per mole it corresponds to 4500 kilojoule per mole. You can see that typical bond energies are of the order of hundreds of kilojoule per mole that required energy received by the bromide will be thousands of kilojoule per mole. The net result of this require will be that since the required energy is more than the bond energy the required atoms will get detached from the bond molecule and you will have now the view as stock as a isolated atom and it will stabilize in its most stable. So, like bromide will become bromide if it is a organic solution. So, you will find that bromide bromide will have different chemistry than ethyl bromide. Similarly, the chromium will have different oxygen state than bromide. So, if you have chromium 3 plus positive ion the chromate ion 2 minus ion. So, then we can go for chemistry separate radioactive atoms from the stable target. In fact, a very interesting experiment I think we had done on such experiment was to get molybdenum 99. Molybdenum 98 n gamma gives you molybdenum 99 and bulk of the molybdenum will be molybdenum natural molybdenum with molybdenum 98 is very small abundance. And so, if you irradiate molybdenum in a come organic complex to your organic molecule like it hydroxypinolene then this n gamma reaction will give that required to the molybdenum 99 and the 99 molybdenum detached from the organic complex will be at a different oxygen state. So, you can actually do solid extraction of this molybdenum hydroxypinolene chloroform and molybdenum 99 will be left in the questions. So, that thereby you know you can detail you can have you can concentrate or you can enrich molybdenum 99 in a solution that is the bulk of the molybdenum 98 hydroxypinolene will remain in the organic phase that is how you can increase the specific activity of a n gamma. Another way of producing the carrier free radioisotopes is n gamma followed by beta minus t there which is not always possible, but there are many examples where it is possible and I will give you some examples of that. For example, tellurium 130 n gamma gives you tellurium 131 and which is also very active and undergoes beta minus decay to iodine 130. So, iodine 131 is the isotope of interest for thyroid imaging because it is emitting 364 KV gamma ray. So, if you want image the thyroid of a patient you just give him sodium iodide solution iodine is having 131 iodine activity. So, if you know this how do you get a carrier free iodine 131 you simply irradiate it from the tellurium metal target and tellurium will give you iodine which easily you can do radical separation of iodine from the tellurium because they have totally different consistency. So, this is that n gamma followed by beta minus decay then the n gamma product of tellurium is 131 tellurium just 25 minutes half life. You allow for this to decay. So, in about 4 half lives they will decay to iodine and then you can do the iodine chemistry from the tellurium target. So, tellurium 131 is actually widely used in treatment of thyroid disorders and typical specific activity of this iodine 131 you can calculate. Suppose you have all now here there are no other atoms of iodine other than 131. So, 100 percent carrier free. So, if you have one theory of 131 iodine then you can calculate the number of atoms. So, you can see it. So, activity equal to n gamma. So, n equal to a upon lambda not n lambda. So, you know the half life. So, you can substitute for the lambda in terms of the 0.693 upon t half and this t half will go up that is what I have done here. So, activity and you will get the 0.693 into t half for 8 days and then you can see every number will weigh 131 gram. So, you can calculate in terms of number and convert to grams. So, you will find that the activity specific activity of iodine 131 generated in this tellurium irradiation will be about 1.24 per 5 lakhs. So, lakhs of curing per gram very high specific activity because all atoms all radiative atoms are of 131 iodine there is no stable iodine that is 127 iodine. So, it is not present. So, these are the methods by which you can get carrier free into a stop steam by neutron reactions. Another example of this is Lutetium 177 that is produced. You can produce Lutetium 177 by 176 Lutetium n gamma, but this Lutetium will be having bulk of 176 and also you have 175 Lutetium which is the dominant element. But here you will find that if you irradiate Lutetium and Lutetium n gamma will be 177 Lutetium and which is undergoing beta minus decay to 177. So, you can though there are errors, adjacent errors, but you can still separate them by careful radiochemical separations and so, you can have carrier free Lutetium 177 6.78 which is used in treatment of neuroendocrine tumors basically for the diagnosis and therapy of the tumors in the glands. These are the examples of n gamma followed by beta minus decay of course of radioaspirates. In the case of light jet elements, lighter elements like low gel, sulfur, phosphorus, chlorine. So, up to you can say mass number 40 50 or so where the barriers for the emission of charge particles are low. So, you can have NP and alpha type of reactions. So, these reactions are possible only for the lighter targets because for heavier targets emission of proton and alpha is hindered because of the high. So, you can irradiate like sulfur irradiate sulfur compound, sulphate, sodium sulphate you will get phosphorus 32 and then phosphorus 32 the cross sections are given, alpha type of phosphorus 32 and the mode of decay is there. So, phosphorus 32 is utilized in many applications given for the skin, the skin catches for the treatment of skin cancer. Similarly, you have cobalt 58 as a from nickel 58 NP reaction. It is a small cross section and you have the 70 days alpha type of cobalt 58 and it is emitting with a plus or an electron capture tape. Over 58 use as a tracer in many applications. Then you have carbon 14 and sulfur 35 which are also used as radio tracers in organic industry you can use carbon 14 you can use in organic reactions. Sulfur 35 also sulfur 35 labeled compounds you can use in synthesis of compounds containing sulfur. So, for newton induced reactions where in the proton and alpha are imitated mostly involved in the lighter elements and certain isotopes are very useful. So, you go for these methods. Then with with the aluminum you have an alpha but that requires a fast and neutrons because they just have got threshold reaction. So, the Q value is negative. So, thermal neutrons you will not do you require a high energy neutrons energy more than a KV we will call fast neutrons. And so, you want to produce sodium 24. See normally sodium 24 you can produce by sodium 20 through N gamma reaction. But if you want carrier free sodium 24 you put this root aluminum 27 N alpha sodium 24 15 hours apply and even with thermal neutrons you can produce tritium then lithium N6 N alpha you can have to get tritium and this tritium in this in fact this root is used to produce tritium for strategic applications. And for that matter you know even for normal applications you can use your own tritium for some applications. So, you can see here if you do this method Np and alpha type of reactions. So, then by this method since then the target element and the reduced produced have different chemistry a different jet value. So, you can do chemistry and then you have these isotopes are carriers. These are the methods by which you can even use neutrons to produce carrier free radioisotopes. Then you have there are certain methods called multi stage neutron capture. Multi stage means after one neutron capture whatever isotope is formed it will continue to capture neutrons and you will get a much higher isotope same element or there can be beta. So, successive neutron capture among this happens when the flux is very high so that the radioisotope that that produce to it can further capture neutrons to next isotope. So, this in fact is happening you know if you have a nuclear reactor or reactor or such reactor to irradiate uranium. For example, if you have 238 uranium you will get N gamma 239 uranium this will further undergo beta minus into K 239 necronium it will undergo beta minus to 239 plutonium. So, in the reactor if you have bulk target is uranium natural uranium is 99.3 percent. So, you will have a continuous production of 239 plutonium and this plutonium 239 has a half life of 24000 years it will capture neutron to get 240 plutonium 240 is having half life 6000 years it will become capture another neutron 241 plutonium and which is emitting beta minus to 241 america. You can see all the isotopes have half lives in years. So, if you want to produce america 241 which is very very useful in many applications you will then you need to do. So, in the reactor you will find a lot of plutonium being produced about you know if you have a ton of fuel then about Kg of plutonium will be formed. And this just still continuously capturing neutrons to form and this. So, spend the fuel of a reactor such reactor or power reactor will always have plutonium and america. This is the way by multi plutonium capture. Similarly, in fact the same concept we do it in producing tungsten 188 tungsten 188 is a parent of rhenium 188 and 188 rhenium can also be produced by n gamma, but this is not carrier free and you require for many applications a carrier free you do as stop. So, if you regulate tungsten 186 by n gamma you get tungsten 187 having half life of 23.7 hours and you this can capture another neutron to get tungsten 188. This tungsten 188 will undergo then beta minus decay to rhenium 188. So, this is like a generator system 69 days half life of tungsten 188 going rise to rhenium. So, you can have a system column containing tungsten 188 you can milk rhenium 188. So, this is the way whatever rhenium you will get will be carrier free. But this see this successive neutron captures since the half life is short it requires a very high flux reactor otherwise you know the production rates may be much lower than the decay rate of this actually. So, typically 10 to the power 15 neutron per centimeter square per second is the flux required to produce this kind of of course, we have discussed nuclear fission in various lectures also. So, nuclear fission is a very, very rich source of beta minus radiotropes. So, you already know that radiate neutron rhenium thermal neutrons you get several pairs of fission products like one pair being 144 barium plus kilfton 90 and this is the mass distribution as a function of mass number the fission yield maximum about 8 percent minimum about 0.01 asymmetry the lower yields are also there. So, it is a asymmetric mass distribution. So, you will have a large number of fission products produced in fission and many of them are long lived and have lot of applications. So, normally the fission products have higher n by z compared to their stable isotopes and so most of them are beta minus. There is a change of isobars where in the beta decay takes place and you will have about 500 fission products that will be formed in the fission process. So, you can pick up the ones which find applications in many areas and then we can go for subsequently the radio chemical separation of visual isotopes used in different areas. Now, so this is the list of radio isotopes that are produced in fission low end fission products, ketone 85. So, you can see here you could try to draw the mass yield of A versus E typically about 8 percent 0.01 percent. Now, you can see typically this is around 95 and this is around 138. So, that gives you an idea what will be the yield of ketone 85, ketone 85 will be somewhere here and this is a gaseous radio trace. So, suppose you want to do a tracer application wherein you want to see the leakage in a gas pipeline, you can use ketone 85. If you have half pipe of 10 years you can produce you can also produce what ketone 84 n gamma, but you know irradiating a gaseous target in the reactor instead of that you can have a fission product to irradiate the uranium and you can just do distillation of the fission product as a particular very high yielded fission, ketone 85 can be produced. Stonsium 90 is another aceto which is having very long half life. So, it is present in the radiative fuel and it is parent of yttrium 90, which is 90 yttrium to 64 hours. So, it in fact goes to 90 yttrium and it is a generator system or produced in the fission products. Modulium 90 also can be produced in fission and you will have fission modelling. In fact, there are plants which are available for producing modulium by fission root 106 ruthenium is used in ocular cancer treatment 131 iodine treatment of thyroid disorders 140 barium as a tracer and then 140 huge excellent tracer for sand silt movement 144 cerium also for the tracer and Promethium 147 is a pure beta emitter and it is used in the luminescent paints. So, there are many applications of radioisotopes and most of them are available in the spent fuel. So, if you irradiate uranium you get all of them and you can then do chemistry depending upon their half-lives you can separate them and use them for different practices. So, I will stop here and I will take up the other method of charge particle radiation to radioisotopes in my next part. Thank you very much.