SOILD SCINTILLATION COUNTER PPT.pptx

IT IS A PPT ON SOLID SCINTILLATION COUNTER

1. SOLID SCINTILLATION COUNTER SUBMITTED TO : – DEPT. OF MICROBIOLOGY BY :- SNEHA AGRAWAL M.Sc. MICROBIOLOGY 2 SEMESTER SESSION 2022-2023

2. CONTENTS RADIOACTIVITY EXPERIMENT FOR RADIOACTIVITY MEASUREMENT OF RADIOACTIVITY SCINTILLATION COUNTER HISTORY TYPES DIFFERENCE BETWEEN SOLID AND LIQUID SCINTILLATION COUNTER SOLID SCINTILLATION COUNTER PRINCIPLE INSTRUMENTATION WORKING APPLICATION ADVANTAGES DISADVANTAGES REFERENCE

3. RADIOACTIVITY The phenomenon in which the nucleus of the atom of an element undergoes spontaneous and uncontrollable disintegration or decay and emit alpha, beta, or gamma rays It is the property of some unstable atoms to spontaneously emit nuclear radiation. Radioactive rays = alpha rays, beta rays, gamma rays. Radioactive elements = Uranium, Thorium etc. The phenomenon of radioactivity is discovered by HENRI BACQUEREL IN 1896.

4. EXPERIMENT FOR RADIOACTIVITY In this experiment a radioactive substance is kept between the two plates one is positively (+ ve ) charged and other is negatively (- ve ) charged. It was observed that some radiations are attracted towards negative (- ve ) plate because they will have positive (+ ve ) charge and are knows as alpha ( α ) rays. Some are attracted towards positive (+ ve ) plate because they will have negative (- ve ) charged and are knows as beta ( β ) rays. Some radiation are neither attracted towards positive (+ ve ) or negative (- ve ) plate i.e. they are neutral charge and are known as gamma ( γ ) rays

5. MEASUREMENT OF RADIOACTIVITY The amount of radioactivity is reported in Becquerel ( Bq ). The radioactivity of radioactive substance is measured or detected by instruments like :- SCINTILLATION COUNTER GAS FILLED CHAMBER

6. SCTILLATION COUNTER A scintillation counter is an instrument for detecting and measuring ionizing radiations like alpha( α ) rays, beta ( β ) rays, gamma ( γ ) rays. Scintillation is the most sensitive and versatile technique for the detection and quantification of radioactivity.

7. HISTORY The modern electronic scintillation counter was invented in 1944 by Sir Samuel Curran .

8. TYPES There are two types of scintillation counter based on the fluorescent material used they are: 1. Solid scintillation counter 2. Liquid scintillation counter

9. DIFFERENCE BETWEEN SOLID AND LIQUID SCINTILLATION COUNTER S.NO. SOLID SCINTILLATION COUNTER LIQUID SCINTILLATION COUNTER 1. IT IS A RADIATION DETECTOR WHICH INCLUDES A SCINTILLATION CRYSTAL TO DETECT RADIATION AND PRODUCES LIGHT PULSES. IT IS A INSTRUMENT FOR DETRMINING ACTIVITY OF A LIQUID SAMPLE. 2. USEFUL FOR GAMMA ( γ ) EMITTING ISOTOPES. USEFUL FOR QUANTIFYING ALPHA ( α ) AND WEAK BETA ( β ) EMITTERS. 3. MOSTLY SCINTILLATOR USED ARE INORGANIC SCINTILLATORS AND ORGANIC SCINTILLATORS. HERE, IT CAN BE EITHER LIQUID (ORGANIC SOLVENTS) OR SOLID FORM (PLASTICS)

10. SOLID SCINTILLATION COUNTER A solid scintillation counter is a radiation detector which includes a scintillation crystal to detect radiation and produce light pulses. In the solid scintillation counters, the sample is placed in a vial, just adjacent to a crystal or fluorescent material. The crystal normally used are: 1. Sodium Iodide : For gamma emitters 2. Zinc Sulphide crystal : For alpha emitters 3. A nthracene : For beta emitters

11. PRINCIPLE When high energy atomic radiations are incident on a surface coated with some fluorescent material, then flashes of light (called scintillation) are produced. The scintillation are detected with the help of a photomultiplier tube , that gives rise to an equivalent electric pulse. These output electrical pulse can then be analyses and counted electronically and gives rise to information regarding the incident radiation. The solid scintillation counter is especially useful for gamma emitting isotopes .

12. SCINTILLATORS MAY BE CHARACTERISED INTO 2 MAIN TYPES 1. ORGANIC SCINTILLATORS:- A) Pure organic scintillators :- Anthracene , etc. B)Liquid organic solutions :- pure organic scintillators are dissolved in a suitable solvent & then we obtain liquid organic scintillators . C)Plastic scintillators :- pure organic scintillators after dissolving in the solvent are subsequently polymerized. 2. INORGANIC SCINTILLATORS :- NaI ( Tl ) :- Thallium activated Sodium Iodide CsI ( Tl ) :- Thallium activated Cesium Iodide CsI (Na) :- Sodium activated Cesium Iodide

13. INSTRUMENTATION RADIATION- The high energy ionizing radiation strike the crystal. SCINTILLATOR- It consist of a scintillator which generates photons in response to incident radiation. LIGHT FLASHES- Flash or rays of light produced in a transparent material by passing a particle. PHOTOMULTIPLIER TUBE [PMT]- It converts the light to an electrical signal and electronics to process this signal. PHOTOCATHODE- A photocathode is a surface that convert light (photons) into electrons by photoelectric effect .

14. CONTII… 6. ELECTRICAL PULSE- A pulse may last from a fraction of a nanosecond upto several seconds or even minutes. 7. AMPLIFIER- It is an electronic device that measures the peak of potential pulse. 8. COUNTER- It measures the voltage of potential drop created by the electrons.

15. WORKING

16. FIG:- PHOTOMULTIPLIER TUBE

17. APPLICATION 1 . It is widely used in screening technologies, RIA alternative technologies, cancer research, scientists, physicians, engineers & technicians. 2 . Border security, nuclear plant safety, national security. 3 . This methodology is used routinely in the vast majority of diagnostic and/or research laboratories from those of biochemistry and biology to clinical departments .

18. ADVANTAGES 1 . Its counting rate is very fast and very easiest method. 2. It can detect lower levels of radiation. 3. It can measure radiations of different types of isotopes. 4. Virtually any kind of sample (liquids, solids, suspensions, emulsions, gels, chromatograms, etc.) can be accommodated in a scintillation counter and its radioactivity can be determined accurately.

19. DISADVANTAGES 1. Hygroscopicity - A disadvantage of some inorganic crystals, e.g. sodium iodide, is their hygroscopicity , a property which requires them to be housed in an airtight container to protect them from moisture. 2 . The cost per sample of scintillation counting is significantly higher. 3 . The high voltage applied to the photomultiplier tube.

20. REFERANCE BIOPHYSICAL CHEMISTRY PRINCIPLES AND TECHNIQUES BY UPADHYAYA AND UPADHYAY AND NATH. A TEXTBOOK OF MICROBIOLOGY BBY R.C. DUBEY & DR. D. K. MAHESHWARI. https://www.researchgate.net/publication/263209531_Liquid_and_solid_scintillation_principles_and_applications

21. THANKYOU…