ATOMIC NUCLEUS and RADIOACTIVITY

ATOMICNUCLEUSandRADIOACTIVITY

ATOMIC NUCLEUS and RADIOACTIVITY + + + + + + + + + + + + + + + + + + + + + α

Thiscourseisbased on the followingprinciples: • Learning by inquiry • Learning by experiment • Stimulation of studentsactivity • Promote the activity of girlstudents • Indicate the applications in variousdomains of humanactivity • Applied convention and the main „actors”: • teacher -Marie Curiestine • students: • Daniel Robinson • Tom Disbeliever • Alice Wonderlander • Ways of knowledgeverification:

The followingstatements from STEM4you(th) proposalaretaken as key-remarks, to develop the concepts and structure of thisleson/action 1. „…to show that science is part of human history and culture, and that it is a corner stone in our present, modern world view (…) as well as a basic element of many jobs and occupations.” 2. It is known that traditional ways of teaching discourage the process of inquiry. 3. Inquiry based learning is not just asking questions, but it is a way of converting data and information into useful knowledge. Takingitintoaccount, the followingstructureisproposed. • Complete lessons/activitiesusingwelldefinedteaching/learning method. • Thismethodcontains a scenario of inquirybaseddiscussionincorporating the RRI ideas. It isNOT a traditionallectureby the teacher with the questionsafterit. It isshownthatquestionsdispersed in the context of lessons, and questions/answersamongstudentscan much strongerstimulatetheirinquirybasedactivity. • The role of teacheris to stimulatediscussion, to correctmistakes and to show the ways for the application of acquiredknowledge. • Lessonincludesanexample of hands-onexercise, real experiment via internetconnection and the movies with the interview of experts. • Thismaterialcanserve as anexample of a real lesson/action. It isalso a base to be used (and modified) by the teacher in dependence on needs.

. Let’s start our lesson. Tell me please – What are your associations, when you hear about the atomic nucleus and/or radioactivity ? . • INTERESTING ! • Mysterious • Invisible • Smallest • Interacting • Controversial • Omnipresent . . FASCINATING ! • Strongest • Giving energy • Radiating • Penetrating • Decontaminating • Fighting cancer TERRIBLE ! • Dangerous • Atomic bomb • Hirishima • Czernobyl • Polution • Cancer . OK, so try to justify your opinion.

First of all, I have never seen an atom, nor anatomicnucleus. Everything in the world (includingyou) consists of atoms. Atomic nuclei make up more than 99.9 of your mass and of everything in the world. Atomsarevery small and you cannot see them by your eyes, though the entire worldiscomposed of them. Therefore, learning aboutatoms and aboutthe smallest components of matter is so interesting.

When I was just a little girl, I asked my mother, What is the smallestin the world? My motheranswered: Lookaround; yousee the landscape of manykolometers: the hills, forests, sky, rainbowetc… kilometers meters Ifyoulookcloser; youseesmallersizes but candistinguishmoredetails: the grass, flowers etc. centimeters The smallersizesyousee, the moredetailsyoucan distinguish: leaves, flower petals, bee milimeters But to seevery small sizes, youmust be equipped with the special devices. And what we willsee zooming more, more and more?

To answer this question, we can ratherask differently: Are there such particles that do not consist of smaller elements? We will call them elementary particles. Ancient philosopher - Democritus from Abdera believed that everything in the world is composed of atoms, which are eternal and indivisible. Atoms come together to form the molecule. Molecules combine to form the cells of living organisms. Plants, animals and people consist of cells.

. Remember forever, when you admire the blue sky and colorfull rainbow, the green fields and beautifil flowers - you see only the last element of beauty that is hidden in the structure of matter. So, whatis the structure of matter?

Letussee the structure of matter. 1 m Everything consists of atoms 10-10 m characteristic sizes 10-14 m Atom consistsof atomicnucleus with a positive electric charge and electrons charged negatively 10-15 m Verycomplicated! 10-18 m Atomic nucleus is composed of protons... Verysimple! and neutrons Veryinteresting! Protons and neutrons are composed of quarks. According to our current knowledge, quarks have no internal structure.

Whatdoesitmean10 -10 ? I cannotimagine the size of atom. 10 -10 = 0.000 000 000 1 10 -10 is a numer with digit 1 on the 10 positionafter the decimal point. It is a very, very small numer. „Very small” - itsaysnothing. Youarealso small with respect to anelephant. Do not argue. I willgiveyouanexcellentexample.

The size of the grain of poppyisabout1mm = 10-3m Letusenlargeit1010times. 10-3 m * 1010 = 107 m = 104 km. The size (diametr) of the Earth isabout12 700km= 1.27*104km. Enlarge1010timesislike to enlarge the grain of poppy to the size of the Earth. 1mm = 10-3 m 1010times BRAVO Alice ! And now a task to Tom. Whatwill be the size of atom ifyouenlargeit1010times?. 12 700km= 1.27*104km=1.27*107m It isverysimple to count: 10-10m * 1010=1m. Atom will be a bit smallerthan me oryou. BRAVO Tom!

OK, now a newtask to all of you. Imaginethatyouenlarge the size of atom (10-10m) to the size of the football field. (100m=102m) Whatwill be then the size of atomicnucleus? It isquitesimple: 10-10 m *1012 = 102m, (The coefficient of enlargementis 1012 ) The size of enlarged atomicnucleusis: 10-14m*1012= 10-2m= 1cm, The atomicnucleuswill be of the order of the ping-pong ball. But notealsothat 99.9 % of the mass of atom is in atomicnucleus – so small and somassive. If you enlarge the atom to the size of football field „boisko”, the nucleus will be like the ball „pilka” of Ping-Pong.

Ifatomsareso small, how to provetheirinternalstructure? Youcan do ityourselfmakingverysimpleexperiment. Letusseparatesomeelectrons from atom provingthat atom consists of atomicnucleus and electrons. Ha, ha – try to takeelectrons by hands. OK, let’s do it by hands. 1. Take a pen and scraps of paper napkins. 3. Now the pen is positively charged and attracts scraps of paper. 2. Removesome electrons from the atoms in pen, by rubbing it with a handkerchief. 4.One can neutralize the charge of pen by touching it by hand. 5. Now the pen no longer attracts the scraps of paper. We haveprovedthat atom consistsof atomicnucleus and electrons, whichcan be separated. Such atom in which numer of electronsis not equal to the numer of protons in the nucleus, iscalled ION – rememberit. Click the photo. See the video animation of our experiment. Repeatthisexperimentathome. Show it and explain to yourcolleagues and parrents.

But when the nucleiareradioactive? Nucleus is radioactive when it spontaneously decay, emitting a particle: alpha, beta orgamma. α Type of decay α α Emission of particle composed of two protons and two neutrons (alpha) decay Emission of particle (electron) (beta) decay γ γ Emission of quanta (photon) γ (gamma) transformation Interesting - but howithappensthat the nucleussuddenlydecayemitting a particle?

N – numer of neutrons To answerthisquestion, let me clarifysomeimportantinformation. α decay Z→ Z-2 Path of stability N→ N-2 Radioactivenuclei • Remember from the lessons of physics: • Nucleusiscomposed of protons and neutrons. • Proton has a positiveelectricchargeequal to the negativecharge of electron. Neutron has no electriccharge. • Nucleus, together with souroundingelectronsformsan atom. • The mass of electronisalmost 2000 times less than the mass of proton or neutron • Nuclei with the same numer of protonsarecalledisotopes. Differentisotopeshavedifferent numer of neutrons. • Isotopescan be stableorradioactive. • Radioactiveisotopesdecayemittingalphaor beta particles. • Veryfrequentlyafter the decay, anexcittednucleusemitsphotons (gamma radiation). • The stableisotopes form anareacalled the path of stability. See the figure • The decay of nucleusoccursspontaneously. • The frequency of decaysaredifferent for differentisotopes. Stablenuclei N=Z β¯ decay Z→ Z+1 N→ N-1 β+ decay N→ N+1 Z→ Z-1 Z – numer of protons

It iscompetelyincomprehensible. Whatdoesitmean „spontaneously”. It meansthatitoccurswithoutanyintervention from exterior. It issimplyaninternalproperty of a givenisotope, but nobodyknowwhen the decay of a givennucleusoccurs. TERRIBLE ! . FASCINATING ! . VERY INTERESTING ! . Notehoweverthat we candetermine the timewhenappriximately a half of nuclei in the radioactivesamplewilldecay. Thistimeiscalled a „half-time”. At lastitisclear. It meansthataftertwo half-times, all the nuclai in the sampledecay. Absolutely NO! After the second half-time, a half from a half of nucleiwilldecay. A half of a half itis one quarter.

OK, Daniel isright. And after the third half time the numer of decayingnucleiwill be: ¼* ½ = 1/8 of the initial numer of nuclei in the sample. Bravo Alice! One cancontinueyourcalculations and after N half-times the numer of nucleiwill be: 1/2Nnuclei. Notealsothataccording to thisformula, all the nucleiwillneverdecay. Even for a verylargevalue of N, the value of 1/2Nwill not be zero. It is a veryimportantproperty of radioactivedecay and iscalled „a radioactivedecy law”. But itis not all. We have „discovered” together one of the importantlaws of Nature. It is a law governingall the „ processes of relaxation” – i.e. the processesleading to the state of equlibrium. In ourcaseitis the statewhen the nucleiare not radioactive. The commonproperty of the processes of relaxationisthat the changeN of the quantityNdescribing the deviation from the equilibriumisproportional to the currentvalue of thisquantity. It can be expressed in the form N=-k*N, wherekis the coefficient of proportionality and remainconstant in a givenprocess. The minus signdenotes the dimnishing of N in the proces of relxation. In ourcase in meansthat the numer of decayingnucleiisproportional to the currentnumber of nuclei in the sample. It is a plenty of similarprocesses in the nature.

I have a proposition of a simple modelling of radioactive decay. Let’s take bottle-caps as atomic nuclei (see the figurebelow). When dropping down many caps we have two possibilities for each of them. Afterfalling down the bottom of the cap can be up or down (fig. a). Let a cap fallingbottom down corresponds to the decayednucleus, and this cap will be elliminated from the next step of modelling. Let’s drop again, but only the capsfalledbottom up. We canrepeatitmanytimes. The ratio N/N, where N is the number of droppedcaps and N is the numer of capsfallingbottom-down, will be the same for eachdropping, but the numer of capswill be systematicallydecreasing. The same is in radioactivedecay. Thisexperimentisdescribed in details on the web-site : http://ilf.fizyka.pw.edu.pl/podrecznik/1/3/5 Any of uscanalso do itathome. Consideralsoananotherexample. Temperature of hot water left in the glass gradually decreases approaching the ambient temperature. The greater the difference between water temperature and ambient temperature, the faster watercools. This can be observed by measuring the water temperature in regular intervals.Details of such experience are alsodescribed on thewebsitementioned by Daniel:

Theypentrate the matter, interacting with atoms and atomicnuclei. It isextremallyinteresting, see the figurebelow. OK, nucleusdecayemittingparticles. And how these particles behave in the matter? CONCRETE LEAD Penetration of nuclear radiation through matter depends on the type and energy of radiation and on the material properties. ALUMINIUM Interaction with matter of different types of nuclear radiation • Alpha particles are stopped by the epidermis of hand • Beta particles are stopped by a few millimeters thickaluminum plate • Gamma radiation is effectively attenuated by the plate of lead. • Neutrons effectively are slow down by a layer of concrete or water

And these effects are certainly dangerous. Can be dangerous and can be useful. Theseunusualpossibilitiescan be usedifferently. It depends on you. Radioactive sources, streams of neutrons from nuclear reactors, beams of charged particles from accelerators, X-ray beam and gamma radiation – all of itare unique tools which can penetratethe unavailable spaces and which can be used in many areas of human activity. It symbolizes the signpost below, showing some of directions, where the methods and nuclear installations find practical applications. INDUSTRY- radiometric equipment: measurement of density, concentration, chemical composition, weight, thickness, leaks etc.search of oil, gas and other mineral resources, profiling, drilling, flaw detection, search for hidden defects in engineering materials MEDICINE- radiology and radiotherapy:tomography, scintigraphy, NMR, PET, etc. AGRICULTURE - decontamination of foodstuffs • Protection of environment • air dust measurement, • fire detectors, • radiotracers test for propagation of pollutants, • treatment of flue gases from power and heating plants GEOLOGY - dating of fossils and organic debris, study of the structure and composition of the rock layer. ENERGY - nuclear power plants and in future - thermonuclearpower plants …and many, many otherapplications.

Now we willmake a real experiment with the gamma radiationemitted by radioactivesource. I do not agree to work with radioactivesource. It isdangerous and gamma radiationisespeciallydangerous. Do not be afraid. The radioactivesourcewill not be here but at the Faculty of Physics , Warsaw University of Technology in Poland, and all the safetyconditionsarestrictlypreserved. We will do ourexperimentusing Internet connection. Detailed application instructions of this experiment can be found at: http://ilf.fizyka.pw.edu.pl/silf/. In the experiment we will examine the attenuation of the beam of gamma rays as they pass through different materials. We will observe and measure the reduction of the beam intensity with increasing materialthickness and for three materials: aluminum, copper and lead. Importantsteps of experimentarefollowing: Login at the CLF website: http://ilf.fizyka.pw.edu.pl/silf/. Select the experiment to be performed. (In ourcase „Osłabienie promieniowania gamma” - in Polish) Reserve the timenecessary for measurements. Switch on the experiment (click „podłącz”) Start with the backgroundmeasurement, Select the material to be measured. Start the materialmeasurement. Observe the prograss of the measurement. Remark: As the measurements for differentthickness of the material will be changedautomatically, we cancontinueourdiscussion. The device for our experimed is controlled from distance via Internet.

It is impossible to describe in detail all the applications of nuclear methods. Let’sseesome examples. Industrial radiometry - How to measure the level of liquid in the tank without the access to its interior? Put the radioactive source on the top of the container and the detector on the other side at the bottom. Liquid causes the absorption of radiation. The higher level of liquid, the stronger absorption. Just calibrate once this dependence and the meter is ready for use. Defectoscopy- how to examine the leaks in the pipeline at the terrain, The probe contains a radioactive source and a detector and measures the intensity of the radiation scattered by the test material. When the material has homogeneous structure, the signal remains at the same level. Any heterogeneity are recorded by the radiation detector. Activation analysis - How to examine the chemical composition of unknown materials without a complicated chemical analysis? The test material is irradiated by a beam of charged particles or neutrons. The material is activated, and each component has a different specificspectrum of radiation. We analyze the results, and determine the composition of the testedmaterial.

Seemoreexplanations by dr. Rafalski from the Institute of NuclearChemistry and Technology (Poland) And somemoreexamples. Click the photo. Radiation sterilization of medical materials, ordestruction of all microorganisms in the materials with an electron beam accelerated in the accelerator. This method enables this operation without removing the packaging material. In some cases, it is very important from the point of view of utility. The dose can be changed by choosing the intensity of the beam and the speed of moving boxes of materials under the head of the control beam, as illustrated by the photo. Fot. Sterilization of medical materials in the Institute of Nuclear Chemistry and Technology in Warsaw.Vertical red arrow indicates the initial direction of movement of the electron beam, horizontal arrow shows the range of "sweep" in the horizontal. direction. The green arrow shows the movement of boxes of medical materials. Measurement of atmospheric dust is an important element of environmental protection. The principle of the measurement consists in determining the weight of the dust deposited on the air passed through the filter. The volume of air determines the time of pumping air through the filter. The mass of deposited dust is determined by measuring the attenuation of beta rays originating from a radioactive source, the carbon isotope 14C. D 14C Fig. Isotopic meter of pollinated air AMIZ produced at the Institute of Nuclear Chemistry and Technology. Red arrow shows the inlet of air. Green arrow shows samples of dust collected on the filter. Symbol 14C indicates the place where the radioactive isotope is installed and the symbol D, where is the detector. The filter strip moves automatically enabling maintenance-free operation.

Seemoreexplanations by prof. P. Kukolowicz from the Institute of Oncology (Poland) Let’sseesomemedical applications Click the photo. X-ray imaging - historically, the oldest method of radiodiagnosis. The dependence of X-rays penetration in the tissue allows for imaging the distribution of organs in the interior of the body. Currently, there are many methods of medical imaging, that use a lot of physical phenomena of radiation interaction with matter. Let’s list some of them: ComputerTomography, CT - allows to obtain cross-sectional images of the interiors of object (the body) as a result of computer reconstruction of many X-ray pictures taken from different directions. Positron emission tomography PET - differs from Computer Tomography as the radiation source is located inside the body, in the pathologically changed internal organs. It is very clever applicationof the annihilation of positrons emitted in β + dacay. Scintigraphy - is based on the introduction to the organism ofsuch radio-pharmaceutics that will be accumulated in the organ under consideration.Emitted radiation is registered by a set of detectors.The system provide information regarding the location and structure of the test organs. Nuclear magnetic resonance imaging NMR– this method uses the phenomenon of nuclear magnetic resonance, where the test sample is exposed to strong magnetic fields and electromagnetic waves that cause the phenomenon of resonance. This process depends on the type of tissue and allows the location of organs in the interior of the body.

Medicalphysicist – professionindispensable in allonkologicalhospitals Radiotherapy is using ionizing radiation and radioisotopes for medical purposes - mainly to fight against cancer. The main task of medical physicists is to plan the process of radiation therapy in order to destroy the tumor, but not damage healthy organs. This is illustrated in figure. Tumor tissue is under development and is more susceptible to radiation. The dose (doza” -in the picture) be chosen in this way that the probability of destroying the tumor (in the picture – „guz”), is the greatest, and damage of healthy tissue „tkanka zdrowa ”- as small as possible. As can be seen from the figure, this is not an easy task. Dose selection must be precise, CT is usedto accurately locate the tumor and then a series of exposures (fractions) is made from different directions in such a way that every time the tumor is exposed but a normal tissue is exposed only once. Thus, healthy tissue receives a dose that does not destroy it, but the tumor receives a dose destructive.

Fissionreaction absolutelyfascinating, source of giantenergy Whereis thisenergy? n note three reaction steps Kr n 2 3 1 1. Neutron hits uranium nucleus 235U 236U* n n Ba 3. … and decaysinto twoothernuclei and someneutrons… 2. Uranium nucleus becomesexcited,… An example of fission reaction 3+ … emitting a huge amount of energy, first of all as a kineticenergy of the fission products. This energy is about 50 million times larger than the energy in the combustion of the carbon atom !!!!!!!!!!!!!!

Seemoreexplanations by dr H. Tietze-Jeans from the NuclearInstitute of Julich (Germany) Click the photo. Nuclear Power Plant One truck of 30tonnes per year Unbelievable! Sotell me how much fuel per yearconsumes nuclear power plant and how much consumescoal powerstation? 30T OK, let’scompare: With a high concentration of energy, 1 gram of uranium can be equivalent of 1.5 tonnes of coal. A nuclear power plant with a power of 1000 MW requires approx. 30 tonnes of nuclear fuel a year. Coal powerstationof the same power burns during the year up to 4 million tons of fuel. It isillustrated in the figures. Coal power station 50 000 wagons of 80 tonnes per year, 137 wagons per day 80T

Nuclearpower plant isworkingdays and nights, respecting simultaneously the natural environment. See the photo I havemade during my flight to Geneva. Nuclearpower plant in the landscape of Switzerland.

As yousee, the atomicnucleushas the properiesunknown in ourmacroscopicworld. Also a giantamount of energyishidden in the atomicnucleus. Radioactivenucleiemit the radiationwhichcan be useful, if we knowhow to aplyit for ourneeds. Thereis a lot of possibleapplication of nuclearradiation. Yes you are right. I have changed my mind about the atomic nucleus and nuclear radiation. Tell me pleasewherecan I find a job in order to work with the application of nuclearmethods.

Let’sseenuclearinstitutions in Warsaw National Atomic Energy Agency: http://www.paa.gov.pl/ Central Laboratory for Radiological Protection http://www.clor.waw.pl/ Institute of Nuclear Chemistry and Technology http://www.ichtj.waw.pl/drupal/ National Centre of Nuclear Research https://www.ncbj.gov.pl/ Heavy Ion Laboratory of Warsaw University: http://www.slcj.uw.edu.pl/en/home-page/ Institute of Plasma Physics and Laser Microfusion: http://www.ipplm.pl/pl/ Onkological Centre – Maria Sklodowska-Curie Institut: http://www.coi.waw.pl/

Ourcommonconclusions: Nucleusisfascinating and powerful. Nuclearmethods and technologieshaveplentyapplications in all the domains of humanactivity. Do not be afraid of radiation, butyoumust know when it is useful and when it is dangerous.

Thankyou for yourattention Alice, Daniel and Tom - Warsaw, February 2017

Backup data: Isotoppe method for leakages control and localization Electron beam flue gas treatment to reduce of gas pollution from fossil luel combustion and gas purification Membrane distillation for liquid waste tratment Food irradiations to elliminate biological contamination. Industria radiography for the identification of defects in materials, corrosion detection in pipelinesetc. Measurements and monitoring of dust concentration Measurements of the thin layers covering the ceramic material Determination of natural radioactivity of granite and river water in the locations of enlarged natural activity Biological dosimetry to estimate the dose of raiatinfollowing an accidential exposure. Boron beutron capture therapy Brachyteraphy – cancer tratment based on the radioactive sources insertion in the rumor. Irradiation of materials to improve their quality (heat resistance, tensile strength, cold flow, chemical resistance, durability). Measurements of radon concentration in public and private buildings. Measurements of radionuclides in soil and water.

ATOMIC NUCLEUS and RADIOACTIVITY