RADIOACTIVE EXPLORATION METHOD.ppt

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RADIOACTIVE EXPLORATION METHOD

BY: SARMAD HASSAN SHARIF

ELECTRICAL & RADIOACTIVITY EXPLORATION METHODS



RADIOACTIVITY

Discovered by Becquerel in 1896

He found that minerals containing Uranium and salts of uraniumemit radiations which can pass through material opaque to

ordinary light and can affect the photographic emulsions in amanner similar to X-Rays.

Madame Curie investigating minerals of Uranium extracted twonew elements: Polonium and Radium, which were more active than

uranium.

Schmidt discovered that Thorium was radioactive.

Diabierne found the new radioactive element Actinium.



RADIOACTIVITY

At least twenty naturally occurring elements are now known to beradioactive, among which only Uranium, Thorium and an isotope ofPotassium are of importance in exploration.

Rubidium is useful in determining ages of rock.

Radioactive method is based on natural emission of radioactiveelements. They emit spontaneous radiations.

Other elements are either rare or weakly radioactive (or both) andare not usually used in applied geophysics.

U & Th are now important as a source of fuel for generation of heatand power in nuclear reactions.



RADIOACTIVE MINERAL EXPLORATION

Recording, classification, evaluation of outcrops of radioactive

minerals and study of their relation to the geological setting.




Delineation of areas with favorable conditions for the occurrence ofradioactive ore deposits.




Location of uranium deposits with modern methods and miningworks.




Feasibility studies for investigating the possibility of developmentof radioactive ore bodies.



GAMMA RAY LOGGING

Gamma Ray Logging is used in borehole well logging as well aswell designing.



RADIOACTIVITY IN MINERALS

Radioactivity in minerals are caused by the inclusion of naturally-occurring radioactive

elements in the mineral's composition.

The degree of radioactivity is dependent on the concentration and isotope present in the mineral.

For the most part, minerals that contain potassium (K), uranium (U), and thorium (Th) are

radioactive.



RADIOACTIVITY IN MINERALS

ElementIsotope

Symbol

Natural

AbundanceHalf-life (Years)

Primary Decay

ModeTellurium 130Te 33.97% 2,400,000,000,000,000,000,000.00

Vanadium 50V 0.25% 390,000,000,000,000,000.00 EC

Zirconium 96Zr 2.80% 360,000,000,000,000,000.00

Samarium 149Sm 13.80% 10,000,000,000,000,000.00 alpha

Samarium 148Sm 11.30% 7,000,000,000,000,000.00 alpha

Osmium 186Os 1.58% 2,000,000,000,000,000.00 alpha

Neodymium 145Nd 8.30% 1,100,000,000,000,000.00 alpha

Platinum 192Pt 0.79% 1,000,000,000,000,000.00 alpha

Indium 115In 95.70% 600,000,000,000,000.00 beta -

Gadolinium 152Gd 0.20% 110,000,000,000,000.00 alpha

Tellurium 123Te 0.89% 13,000,000,000,000.00 EC

Platinum 190Pt 0.01% 690,000,000,000.00 alpha

Samarium 147Sm 15.00% 108,000,000,000.00 alpha

Rubidium 87Rb 27.83% 49,000,000,000.00 beta -

Rhenium 187Re 62.60% 45,000,000,000.00 beta -

Lutetium 176Lu 2.59% 22,000,000,000.00 beta -

Thorium 232Th 100.00% 14,000,000,000.00 alpha

Uranium 238U 99.28% 4,460,000,000.00 alpha

Potassium 40

K 0.01% 1,250,000,000.00 beta -Uranium 235U 0.72% 704,000,000.00 alpha

http://webmineral.com/chem/Chem-Te.shtml

http://webmineral.com/chem/Chem-V.shtml

http://webmineral.com/chem/Chem-Zr.shtml

http://webmineral.com/chem/Chem-Sm.shtml


http://webmineral.com/chem/Chem-Os.shtml

http://webmineral.com/chem/Chem-Nd.shtml

http://webmineral.com/chem/Chem-Pt.shtml

http://webmineral.com/chem/Chem-In.shtml

http://webmineral.com/chem/Chem-Gd.shtml




http://webmineral.com/chem/Chem-Rb.shtml

http://webmineral.com/chem/Chem-Re.shtml

http://webmineral.com/chem/Chem-Lu.shtml

http://webmineral.com/chem/Chem-Th.shtml

http://webmineral.com/chem/Chem-U.shtml

http://webmineral.com/chem/Chem-K.shtml



http://webmineral.com/chem/Chem-K.shtml


http://webmineral.com/chem/Chem-Th.shtml

http://webmineral.com/chem/Chem-Lu.shtml

http://webmineral.com/chem/Chem-Re.shtml

http://webmineral.com/chem/Chem-Rb.shtml




http://webmineral.com/chem/Chem-Gd.shtml

http://webmineral.com/chem/Chem-In.shtml


http://webmineral.com/chem/Chem-Nd.shtml

http://webmineral.com/chem/Chem-Os.shtml



http://webmineral.com/chem/Chem-Zr.shtml

http://webmineral.com/chem/Chem-V.shtml




MINERAL RADIOACTIVITY

Mineral radioactivity is due to alpha, beta, and gammaradiation from the unstable isotopes in the composition.

Isotopes are variants of atoms of a particular chemicalelement, which have differing numbers of neutrons.Atoms of a particular element by definition must containthe same number of protons but may have a distinctnumber of neutrons which differs from atom to atom,

without changing the designation of the atom as aparticular element. The number of nucleons (protonsand neutrons) in the nucleus, known as the massnumber, is not the same for two isotopes of any

element.



MINERAL RADIOACTIVITY

Of the three main types ofradioactive decay, gammaradiation causes the mostdamage because it has a greatereffect on biological materials andis neutralized only by heavy

shielding.

The next most damaging type ofradiation is beta particles whichis absorbed by a few feet of air.

The least damaging is alphaparticles which has a range of 6inches or less in air.



MAJOR PROPERTIES

1. They affect photographic film

2. They ionize gas making it electrically conductive

3. They produce phosphorescence in certain minerals andcompounds

α+β-

γ



ALPHA PARTICLES

Alpha rays are the nuclei of helium atoms, two protons and twoneutrons bound together. Alpha rays have a net positive charge.

Alpha particles have only a weak ability to penetrate. A couple ofinches of air or a few sheets of paper can effectively block them.

Alpha particles (named after and denoted by the first letter in theGreek alphabet α) consist of two protons and two neutrons boundtogether into a particle identical to a helium nucleus, which isproduced in the process of alpha decay. The alpha particle can bewritten as He2+, 4

2He2+

or 4 2He.

When an atom emits an alpha particle, the atom's mass numberdecreases by four due to the loss of the four nucleons in the alphaparticle. The atomic number of the atom goes down by exactly two,

as a result of the loss of two protons – the atom becomes a newelement. Examples of this are when uranium becomes thorium, or



ALPHA DECAY

Alpha decay is due to theejection of a helium nucleus (2protons and 2 neutrons) from theparent isotope. This alphaparticle is accompanied by

gamma radiation and a daughterisotope which is two protons andtwo neutrons lighter than theparent isotope.



SOURCES

Alpha particles are commonly emitted by all of the largerradioactive nuclei such as uranium, thorium, actinium and radium.Unlike other types of decay, alpha decay as a process must have aminimum-size atomic nucleus that can support it. The smallestnuclei that have to date been found to be capable of alpha

emission are the lightest nuclides of tellurium(element 52), withmass numbers between 106 and 110.

The process of emitting an alpha sometimes leaves the nucleus inan excited state, with the emission of a gamma ray removing the

excess energy.

As noted, helium nuclei may participate in nuclear reactions instars, and occasionally and historically these have been referred toas alpha reactions.



APPLICATIONS

Most smoke detectors contain a small amount of the alpha emitteramericium-241. The alpha particles ionize air between a small gap.A small current is passed through that ionized air. Smoke particlesfrom fire that enter the air gap reduce the current flow, soundingthe alarm. The isotope is extremely dangerous if inhaled or

ingested, but the danger is minimal if the source is kept sealed.Many municipalities have established programs to collect anddispose of old smoke detectors, to keep them out of the generalwaste stream.

Alpha decay can provide a safe power source for radioisotopethermoelectric generators used for space probes and artificialheart pacemakers. Alpha decay is much more easily shieldedagainst than other forms of radioactive decay. Plutonium-238, asource of alpha particles, requires only 2.5 mm of lead shielding to

protect against unwanted radiation.



APPLICATIONS

Researchers are currently trying to use the damaging nature ofalpha emitting radionuclides inside the body by directing smallamounts towards a tumor. The alphas damage the tumor and stopits growth while their small penetration depth prevents radiationdamage of the surrounding healthy tissue. This type of cancer

therapy is called unsealed source radiotherapy.



BETA PARTICLES

Beta rays are identical to the electrons found in atoms. Beta rayshave a net negative charge. Beta rays have a greater penetratingpower than Alpha rays and can penetrate 3 mm of aluminum.

Beta particles are high-energy, high-speed electrons or positronsemitted by certain types of radioactive nuclei such as potassium-

40. The beta particles emitted are a form of ionizing radiation alsoknown as beta rays. The production of beta particles is termed betadecay. They are designated by the Greek letter beta (β). There aretwo forms of beta decay, β− and β+, which respectively give rise to

the electron and the positron.



BETA DECAY

Beta decay is due to the ejection of an electron from a neutron inthe parent nucleus. This particle is accompanied by gammaradiation and a daughter isotope which is one proton heavier andone neutron lighter than the parent isotope.



APPLICATIONS

Beta particles can be used to treat health conditions such as eyeand bone cancer, and are also used as tracers. Strontium-90 is thematerial most commonly used to produce beta particles. Betaparticles are also used in quality control to test the thickness of anitem, such as paper, coming through a system of rollers. Some of

the beta radiation is absorbed while passing through the product. Ifthe product is made too thick or thin, a correspondingly differentamount of radiation will be absorbed. A computer programmonitoring the quality of the manufactured paper will then movethe rollers to change the thickness of the final product. The well-

known 'betalight' contains tritium and a phosphor.

Beta plus(or positron) decay of a radioactive traces isotope is thesource of the positrons used in positron emission tomography(PET scan).



GAMMA RAYS

Gamma rays are high-energy photons. This type of ray has thegreatest penetrating power. It is able to pass through severalcentimeters of lead and still be detected on the other side. Thicklead is needed to protect against gamma radiation.

Gamma radiation, also known as gamma rays (denoted as γ), is

electromagnetic radiation of high frequency (very shortwavelength). They are produced by sub-atomic particle interactionssuch as electron-positron annihilation, neutral pion decay, fusion,fission.

Because gamma rays are a form of ionizing radiation, they pose ahealth hazard.



GAMMA RAY PRODUCTION

Gamma rays from radioactive gamma decay are producedalongside other forms of radiation such as alpha or beta, and areproduced after the other types of decay occur. The mechanism isthat when a nucleus emits an α or β particle, the daughter nucleusis usually left in an excited state. It can then move to a lower

energy state by emitting a gamma ray, in much the same way thatan atomic electron can jump to a lower energy state by emittinginfrared, visible, or ultraviolet light.

Emission of a gamma ray from an excited nuclear state typically

requires only 10−12 seconds, and is thus nearly instantaneous,following types of radioactive decay that produce other radioactiveparticles. Gamma decay from excited states may also happenrapidly following nuclear reactions such as nuclear fission ornuclear fusion.



APPLICATIONS

Gamma rays travel to Earth across vast distances of the universe,only to be absorbed by Earth's atmosphere. Different wavelengthsof light penetrate Earth's atmosphere to different depths.Instruments aboard high-altitude balloons and such satellites asthe Compton Observatory provide our only view of the gamma-spectrum sky.

Gamma-induced molecular changes can also be used to alter theproperties of semi precious stones, and is often used to changewhite topaz into blue topaz.

Gamma radiation is often used to kill living organisms, in a processcalled irradiation removing decay-causing bacteria from manyfoods or preventing fruit and vegetables from sprouting to maintainfreshness and flavor.

Despite their cancer-causing properties, gamma rays are also used



HEALTH EFFECTS

All ionizing radiation causes similar damage at a cellular level, but

because rays of alpha particles and beta particles are relativelynon-penetrating, external exposure to them causes only localizeddamage, e.g. radiation burns to the skin.

Gamma rays and neutrons are more penetrating, causing diffusedamage throughout the body (e.g. radiation sickness), increasing

incidence of cancer rather than burns.

External radiation exposure should also be distinguished frominternal exposure, due to ingested or inhaled radioactivesubstances, which, depending on the substance's chemical nature,can produce both diffuse and localized internal damage.

The most biological damaging forms of gamma radiation occur in

the gamma ray window, with higher energy gamma rays being lessharmful because the body is relatively transparent to them.



ELECTRON CAPTURE

Electron Capture (EC) decay is very rare and is theresult of the nucleus capturing one of the atom's orbitalelectrons. This decay is accompanied by gammaradiation and a daughter isotope which is one neutron

heavier and one proton lighter than the parent isotope.





AIRBORNE RADIOMETRIC SURVEY



GEIGER MULLER COUNTER

A Geiger counter, also called a Geiger-Müller counter, is a type ofparticle detector that measures ionizing radiation. They detect theemission of nuclear radiation: alpha particles, beta particles, orgamma rays. A Geiger counter detects radiation by ionizationproduced in a low-pressure gas in a Geiger-Muller Tube Each

particle detected produces a pulse of current, but the Geigercounter cannot distinguish the energy of the source particles.Geiger counters are popular instruments used for measurements inhealth physics, industry, geology and other fields, because theycan be made with simple electronic circuits.



DESCRIPTION

Geiger counters are used to detect ionizing radiation, usually betaparticles and gamma rays, but certain models can detect alphaparticles. An inert gas-filled tube (usually helium, neon, or argonwith halogens added) briefly conducts electricity when a particle orphoton of radiation makes the gas conductive. The tube amplifies

this conduction by a cascade effect and outputs a current pulse,which is then often displayed by a needle or lamp and/or audibleclicks.

Modern instruments can report radioactivity over several orders of

magnitude. Some Geiger counters can be used to detect gammaradiation, though sensitivity can be lower for high energy gammaradiation than with certain other types of detectors. The density ofgas in the device is usually low, allowing most high energy gammaphotons to pass through undetected. Lower energy photons are

easier to detect, and are better absorbed by the detector. Examplesof this are the X-Ra Pancake Gei er Tube.



DESCRIPTION

Good alpha and beta scintillation counters also exist, but Geigerdetectors are still favored as general purpose alpha/beta/gammaportable contamination and dose rate instruments, due to their lowcost and robustness. A variation of the Geiger tube is used tomeasure neutrons, where the gas used is boron trifluoride and a

plastic moderator is used to slow the neutrons. This creates analpha particles inside the detector and thus neutrons can becounted.



DESCRIPTION

8848



TYPES AND APPLICATIONS

A GM instrument is one of many different types of radiationdetectors. The Geiger-Muller tube is one form of a class of radiationdetectors called gaseous detectors or simply gas detectors.Although useful, cheap and robust, a counter using a GM tube canonly detect the presence and intensity of radiation (particle

frequency, as opposed to energy). The Geiger-Müller counter hasapplications in the fields of nuclear physics, geophysics (mining),and medical therapy with isotopes and x-rays. Some of theproportional counters have many electrodes and are called multi-wire proportional counters or simply MWPCs.



SCINTILATION COUNTER

A scintillation counter measures ionizing radiation. The sensor,called a scintillate, consists of a transparent crystal, usuallyphosphor, plastic (usually containing anthracene), or organic liquidthat fluoresces when struck by ionizing radiation. A sensitivephotomultiplier tube (PMT) measures the light from the crystal. ThePMT is attached to an electronic amplifier and other electronic

equipment to count and possibly quantify the amplitude of thesignals produced by the photomultiplier.

The scintillation counter was invented in 1944 by Sir SamuelCurran whilst he was working on the Manhattan Project at the

University of California at Berkley, and it is based on the earlierwork of Antoine Henri Becquerel, who is generally credited withdiscovering radioactivity, whilst working on the phosphorescenceof certain uranium salts (in 1896).



SCINTILATION COUNTERS

Scintillation counters are widely used because they can be made

inexpensively yet with good quantum efficiency. The quantumefficiency of a gamma-ray detector (per unit volume) depends uponthe density of electrons in the detector, and certain scintillatingmaterials, such as sodium iodide and bismuth germinate, achievehigh electron densities as a result of the high atomic numbers of

some of the elements of which they are composed.

However, detectors based on semiconductors, notably hyper puregermanium, have better intrinsic energy resolution thanscintillators, and are preferred where feasible for gamma-ray

spectrometry.

In the case of neutron detectors, high efficiency is gained throughthe use of scintillating materials rich in hydrogen that scatterneutrons efficiently.



APPLICATIONS

Scintillation counters can be used to measure radiation in a varietyof applications.

Medical imaging

National and homeland security

Border security Nuclear plant safety

Several products have been introduced in the market utilizingscintillation counters for detection of potentially dangerousgamma-emitting materials during transport. These include

scintillation counters designed for freight terminals, bordersecurity, ports, weigh bridge applications, scrap metal yards andcontamination monitoring of nuclear waste. There are variants ofscintillation counters mounted on pick-up trucks and helicoptersfor rapid response in case of a security situation due to dirtybombs or radioactive waste. Hand-held units are also commonlyused.



LAST ASSIGNMENT

Q#1. Explain Thorium, Uranium and Potassium with respect to their radioactive

properties.

Q#2. Define the following terms:

A. Stable and Unstable Isotopes

B. Nuclear Fission

C. Nuclear Fusion

Assignment should be handed over on 19th May 2011.

50% of assignment will be marked according to the predefined format and50% will be marked on the Quiz for this assignment on that day.

Anyone failing to submit the assignment will be marked zero and will not beeligible to take the quiz.

Anyone who arrives 10 minutes after the class starts may consider his/hermarks as zero in both quiz and assignment.

This assignment and quiz will be included for those students who will be

marked by their best of three assignments and quizes For the rest missing

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RADIOACTIVE EXPLORATION METHOD.ppt