INSTRUMENTATION AND CONTROL Module 6 …

1 Department of EnergyFundamentals HandbookINSTRUMENTATION AND CONTROLM odule 6 radiation DetectorsRadiation DetectorsTABLE OF CONTENTSTABLE OF CONTENTSLIST OF ivLIST OF detection 1 Electron-Ion 1 Specific 1 Stopping 3 radiation 4 Alpha 4 Beta 5 Gamma 10 GAS-FILLED 13 DETECTOR 14 Applied 18 PROPORTIONAL 22 Rev. 0 Page iIC-06 TABLE OF CONTENTSR adiation DetectorsTABLE OF CONTENTS (Cont.)PROPORTIONAL COUNTER 27 IONIZATION 34 COMPENSATED ION 39 ELECTROSCOPE IONIZATION 41 GEIGER-M LLER 44 SCINTILLATION 48 GAMMA 50 MISCELLANEOUS 51 Self-Powered Neutron 51 Wide Range Fission 52 Activation Foils and Flux 53 Photographic 54IC-06 Page iiRev.

2 0 radiation DetectorsTABLE OF CONTENTSTABLE OF CONTENTS (Cont.)CIRCUITRY AND CIRCUIT 62 SOURCE RANGE NUCLEAR 65 INTERMEDIATE RANGE NUCLEAR 68 POWER RANGE NUCLEAR 71 Rev. 0 Page iiiIC-06 LIST OF FIGURESR adiation DetectorsLIST OF FIGURESF igure 1 Alpha Particle Specific Ionization -vs- Distance Traveled in 5 Figure 2 Photoelectric 6 Figure 3 Compton 6 Figure 4 Pair 7 Figure 5 Schematic Diagram of a Gas-Filled 11 Figure 6 Ion Pairs Collected -vs- Applied 15 Figure 7 Proportional 19 Figure 8 Gas Ionization 20 Figure 9 Proportional Counter 23 Figure 10 Single Channel Analyzer 24 Figure 11 Single Channel Analyzer 25 Figure 26 Figure 13BF3 Proportional Counter 26 Figure 14 Simple Ionization 29 Figure 15 Recombination and Ionization 30 Figure 16 Ionization 31 Figure 17 Minimizing Gamma Influence by Size and 32 Figure 18 Minimizing Gamma

3 Influence with Boron Coating 33 Figure 19 Compensated Ion 35IC-06 Page ivRev. 0 radiation DetectorsLIST OF FIGURESLIST OF FIGURES (Cont.)Figure 20 Compensated Ion Chamber with Concentric 36 Figure 21 Typical Compensation 38 Figure 22 Quartz Fiber 40 Figure 23 Gas Ionization 42 Figure 24 Electronic Energy Band of an Ionic 45 Figure 25 Scintillation 46 Figure 26 Photomultiplier Tube Schematic 47 Figure 27 Gamma Spectrometer Block 49 Figure 28 Multichannel Analyzer 50 Figure 29 Self-Powered Neutron 51 Figure 30 Analog and Digital 56 Figure 31 Single and Two-Stage Amplifier 58 Figure 32 Biased Diode 59 Figure 33 Log Count Rate 60 Figure 34 Period Meter 61 Figure 35 Source Range 64 Figure 36 Intermediate Range 67 Figure 37 Power Range 70 Rev.

4 0 Page vIC-06 LIST OF TABLESR adiation DetectorsLIST OF TABLESNONEIC-06 Page viRev. 0 radiation DetectorsREFERENCESREFERENCESKirk, Franklin W. and Rimboi, Nicholas R., INSTRUMENTATION , Third Edition, AmericanTechnical Publishers, ISBN , , Basic radiation Protection Technology, Pacific radiation Press, TempleCity, , H., Introduction to Health Physics, Pergamon Press Inc., Library of CongressCard #68-8528, Program for Nuclear Power Plant Personnel, Volume IV, General PhysicsCorporation, Library of Congress Card #A 397747, April , , Nuclear Energy Technology, McGraw-Hill Book , James M., Radioactivity and Nuclear Physics, Third Edition, D. Van NostrandCompany, , B., INSTRUMENTATION and CONTROL of Nuclear Reactors, ILIFFE Books Ltd.

5 , , , INSTRUMENTATION in Process CONTROL , CRC Press, Cleveland, , and Carroll, , Industrial Instruments for measurement and CONTROL ,Second Edition, McGraw-Hill Book measurement Fundamentals, Volume I, General Physics Corporation, ISBN 0-87683-001-7, Fozard, INSTRUMENTATION and CONTROL of Nuclear Reactors, ILIFFE Books Ltd., , Glenn F., radiation detection and measurement , John Wiley and Sons, ISBN 0-471-49545-X, 0 Page viiIC-06 OBJECTIVESR adiation DetectorsTERMINAL protection principles to include definition of terms, types ofradiation, and the basic operation of a gas-filled following radiation detection relationship between stopping power and specific following types of radiation to include the definition and interactionswith ( ) ( ) ( ) (n)

6 Principles of operation of a gas-filled detector to the electric field affects ion gas amplification a diagram of an ion pairs collected -vs- detector voltage curve,DESCRIBE theregions of the curve to name of the taking place within the gas of the between the alpha and beta curves, where applicableIC-06 Page viiiRev. 0 radiation DetectorsOBJECTIVESTERMINAL principles of operation of various types of radiation operation of a proportional counter to a block diagram of a proportional counter circuit,STATEthe purpose of thefollowing major channel operation of an ionization chamber to sensitivity a compensated ion chamber compensates for gamma operation of an electroscope ionization operation of a Geiger-M ller (G-M) detector to ion operation of a scintillation counter to classes of tube operationRev.

7 0 Page ixIC-06 OBJECTIVESR adiation DetectorsENABLING OBJECTIVES (Cont.) operation of a gamma spectrometer to of detector analyzer the following detect neutron range fission a photographic film is used to measure the radiation doseIC-06 Page xRev. 0 radiation DetectorsOBJECTIVESTERMINAL operation of typical source, intermediate, and power range following per minute (DPM) type of detector used in each of the following nuclear a block diagram of a typical source range instrument,STATEthe purpose of count rate a block diagram of a typical intermediate range instrument,STATEthe purposeof major n protection reason gamma compensation is NOT required in the power a block diagram of a typical power range instrument,STATEthe purpose of protection interfaceRev.

8 0 Page xiIC-06 radiation DetectorsIntentionally Left BlankIC-06 Page xiiRev. 0 radiation DetectorsRADIATION detection TERMINOLOGYRADIATION detection TERMINOLOGYU nderstanding how radiation detection occurs requires a working knowledge ofbasic the following radiation detection powerEO the relationship between stopping power andspecific PairIonization is the process of removing one or more electrons from a neutral atom. This resultsin the loss of units of negative charge by the affected atom. The atom becomes electricallypositive (a positive ion). The products of a single ionizing event are called an electron-ion IonizationSpecific ionization is that number of ion pairs produced per centimeter of travel through 6-1 expresses this relationship.

9 (6-1)Specific Ionizationion pairs producedpath lengthSpecific ionization is dependent on the mass, charge, energy of the particle, and the electrondensity of matter. The greater the mass of a particle, the more interactions it produces in a givendistance. A larger number of interactions results in the production of more ion pairs and ahigher specific particle s charge has the greatest effect on specific ionization. A higher charge increases thenumber of interactions which occur in a given distance. Increasing the number of interactionsproduces more ion pairs, therefore increasing the specific the energy of a particle decreases, it produces more ion pairs for the same amount of distancetraveled.

10 Think of the particle as a magnet. As a magnet is passed over a pile of paper clips,the magnet attracts the clips. Maintain the same distance from the pile and vary the speed of themagnet. Notice that the slower the magnet is passed over the pile of paper clips, the moreRev. 0 Page 1IC-06 radiation detection TERMINOLOGYR adiation Detectorsclips become attached to the magnet. The same is true of a particle passing by a group of atomsat a given distance. The slower a particle travels, the more atoms it PowerStopping power or linear energy transfer (LET) is the energy lost per unit path length. Equation6-2 expresses this relationship.(6-2)SLET E XwhereS= stopping powerLET = linear energy transfer E= energy lost X= path length of travelSpecific ionization times the energy per ion pair yields the stopping power (LET), as shown inEquation 6-3.