Presentation on theme: "Session II.3.2 Part II Quantities and Measurements"— Presentation transcript:
1 Session II.3.2 Part II Quantities and Measurements Module 3 Principles of Radiation Detection and MeasurementSession 2 Proportional and GM DetectorsIAEA Post Graduate Educational CourseRadiation Protection and Safe Use of Radiation Sources
2 OverviewIn this session we will discuss the principle of measuring radiation using proportional and Geiger Mueller detectors
3 Gas Filled DetectorsAs indicated in the previous lecture, ion chambers are the simplest of all gas filled detectorsAn electric field is used to collect all the ionizations (positive and negative charged particles) produced by the incident radiation in the gas volume
4 Regions of a Gas Filled Chamber RecombinationRegionThe proportional region is located where the voltage is high enough to produce secondary ionizations. The voltage causes the electrons liberated by the incident radiation to have enough energy that they are able to ionize additional atoms. Since these secondary ionizations were not produced by the incident radiation they do not carry any information relating to the incident radiation. The signal produced by these and the originally liberated electrons is “proportional” to the energy carried by the incident radiation but not equal to it.When the voltage has been increased sufficiently, the electrons liberated by the initial incident radiation have enough energy to ionize other atoms and those electrons also are able to ionize additional atoms resulting in a chain reaction of ionizations until the entire volume has essentially been ionized. The result is an electronic pulse which is independent of the amount of energy initially deposited by the incident radiation. All types of radiation and all energies will produce the same effect if they interact with the atoms inside the chamber. This is the GM region.
5 Operating Regions of a Gas Filled Detector RecombinationIonizationProportionalLimited ProportionalGeiger MuellerContinuous Discharge
6 Gas Flow Proportional Chamber In this proportional chamber, a continuous flow of gas enters the chamber. This gas is ionized by the radiation emitted from the sample placed within the chamber. The liberated electrons are collected by the wire loop anode in the center of the chamber.
7 Directional and Energy Response This GM detector responds differently depending on the direction of the incident radiation. It also responds differently depending on the energy of the incident radiation. At low energies, the radiation cannot penetrate the walls of the detector. Since this type of detector has a very thin window at the end, radiation incident from that direction more readily enters the chamber.However, the detector over-responds to the low energy photons since it was calibrated with high energy photons from 137Cs.
9 Bicron Surveyor 20000-0.2 mR/h to 0-2,000 mR/h cpm to 0-240,000 cpm Exposure accuracy within 10% (per NRC reg. guide 10.8) Meets or exceeds 10CFR35 for nuclear medicineSurveyor 2000 is compact, with doserate and countrate scales and controls for response time and audio. X-ray and gamma ray exposures are measured by an internal GM detector, and alpha, beta, X- or gamma countrates using a suitable external probe operating at 900 V. High voltage check, anti-saturation and dead time compensation are included.
10 Bicron “Radiographer” A portable survey meter with an internal energy-compensated GM detector, the Radiographer also features automatic dead time compensation, anti-saturation circuit and HV and battery checksThree linear ranges: mR/h to mR/hResponse times optimized for each rangeEnergy compensated: 40 keV to 1.2 MeVWeighs only 1 kg
11 Detector System (UWDS) Eberline UnderwaterDetector System (UWDS)Detects high gamma fields underwater. Underwater detector, 65' watertight cable and a Survey Meter which features a large, backlit digital display with analog bar graph. Data logging (up to 256 data points), adjustable alarms, and built in speaker with click rate proportional to the count rate.FEATURES - Energy compensated GM tube with a range of 10 mR/h to 10,000 R/h - Watertight detector down to 20m Detector Size 3.5 cm diameter x 23 cm longBatteries - 2 standard "AA", 250 hrs with Alkaline, 500 hrs with LithiumSimultaneous internal and external detector rate measurements OPTIONS - Stainless steel detector housing to facilitate easy decontamination - "Smart Probe" with stored calibration parameters
12 Ludlum 44-9 “pancake” GM INDICATED USE: Alpha beta gamma survey DETECTOR: Pancake type halogen quenched GMWINDOW: 1.7 plus or minus 0.3 mg/cm2 micaWINDOW AREA: Active - 15 cm2 ; Open - 12 cm2EFFICIENCY(4 geometry): Typically 5% - C14; 22% - Sr90/Y90; 19% - Tc99;32% - P32; 15% - Pu239SENSITIVITY: Typically 3300 cpm/mR/hr (Cs137 gamma )ENERGY RESPONSE: Energy dependentDEAD TIME: Typically 80 microsecondsCOMPATIBLE INSTRUMENTS: General purpose survey meters, ratemeters, and scalersOPERATING VOLTAGE: 900 voltsCONNECTOR: Series "C" (others available )CONSTRUCTION: Aluminum housing with beige polyurethane enamel paintTEMPERATURE RANGE: -20oC to 50oCSIZE: 4.6 cm H X 6.9 cm W X 27.2 cm LWEIGHT: 0.5kg
13 Eberline Monitor 4 (pocket sized meter) FEATURES Compact Easy to Use Low CostCarrying Case IncludedDETECTORGM, uncompensatedRANGES0.5, 5, 50 mR/h and 500, 5k, 50k cpmOPTIONSEnergy Compensated GM
14 Eberline HP-210 Series GM “pancake” Application/Type: Beta/Gamma surveys; GM, non energy compensatedDead Time: 50 usec nominalMica Window Size/Thickness: diameter (4.4 cm); 1.4 to 2.0 mg/cm2Background Sensitivity: ~3,600 cpm/mR/h (137Cs)Beta/Gamma Efficiency: ~22% 137Cs, ~16% 60CoBeta Efficiency (4): ~ 32% 90Sr/90Y, ~ 15% 99Tc, ~ 6% 14CAlpha Efficiency (4): ~ 25% 241AmCONFIGURATIONSModel HP-210AL: Aluminum with 1:1 window to bkg ratio (0.7 kg)Model HP-210L: Lead shielded with 4:1 window to bkg ratio (1.9 kg)Model HP-210T: Tungsten shield with 4:1 window to bkg ratio (1.9 kg)Window Area: Active - 15 cm2 Open - 12 cm2Window: 1.7 0.3 mg/cm2 micaSensitivity: ~ 3,300 cpm/mR/hr (137Cs )Beta Efficiency (4): ~ 22% 90Sr/Y; 19% 99Tc; 5% 14C; 32% 32PAlpha Efficiency (4): ~ 15% 239PuLudlum 44-40
15 Eberline HP-190A End Window GM Application: Alpha/Beta/Gamma surveysDetector Type: GM, non energy compensated, end windowOperating Voltage: 900 V +/- 50 VDead Time: 200 uSec nominalMica Window Size: 1.1 diameter (2.8 cm)Mica Window Thickness: 1.4 to 2.0 mg/cm2Gamma Sensitivity: ~ 2,500 cpm/mR/h (137Cs)Beta Efficiency (4): ~ 35% 90Sr/90Y, ~ 25% 99Tc, ~ 10% 14CAlpha Efficiency (4): ~ 6% 241AmOperating Temp: -30o to +60oCHousing: ABS plasticConnector: BNCSize: 3.9 x 12.4 cmWeight: 156 g
16 Eberline HP-271 Energy Compensated GM Application: Beta/Gamma exposure surveysDetector Type: Energy compensated GMDetector Range: 3 R/hr (with dead time correction)Energy Range: 30 keV to 6 MeVOperating Voltage: 900 V +/- 50VDead Time: 100 uSec nominalWall Material: Stainless steelWall Thickness: 30 mg/cm2 (tube only)Gamma Sensitivity: ~1,200 cpm/mR/h (137Cs)Operating Temp: -40o to +63o CHousing: ABS plastic with sliding beta shieldConnector: BNCSize: 3.5 x 15.2 cmWeight: 142 g
17 Ludlum Model 2401P “pocket meter” DETECTOR: Built-In Pancake GMSENSITIVITY: ~ 3,300 cpm/mR/hr (137Cs gamma)ENERGY RESPONSE: Energy dependentMETER DIAL: mR/hr; cpm; BAT OKMULTIPLIERS: X1, X10, X100LINEARITY: Reading within 10% of true valueAUDIO: Built in speaker (quiet position on main switch to silence audio)CALIBRATION CONTROLS: Accessible from front of instrumentRESPONSE: Typically 5 seconds from 10% to 90% of final readingPOWER: 1 ea. 9 voltBATTERY LIFE: Typically 250 hours with alkaline batteries (battery conditioncan be checked on meter )CONSTRUCTION: Aluminum housing with beige polyurethane enamel paint, and a recessed subsurface printed membrane front panelTEMPERATURE RANGE: -20 C to 50 CSIZE: 4.6 cm H X 8.4 cm W X 13.5 cm LWEIGHT: 0.4 kg including batteries
18 Ludlum Model 3-97EPExplosion Proof NaI(Tl) Gamma Scintillator & Energy-Compensated GMINDICATED USE: Gamma SurveyDETECTORS: 2.5 cm X 2.5 cm NaI(Tl) scintillatorSENSITIVITY: Typically 175 cpm/microR/hr (Cs-137 gamma)ENERGY RESPONSE: Energy dependent - Energy compensated GMENERGY RESPONSE: Within 15% of true value from 60 keV - 3 MeVWORKING ENVIRONMENT: Explosion proof housing for extreme environmentsMETER DIAL: mR/hr, BAT TESTMULTIPLIERS: X0.1, X1, X10, X100, X1kLINEARITY: Reading within 10% of true value with detector connectedCALIBRATION CONTROLS: Located in meter housingRESPONSE: 4 seconds from 10% to 90% of final readingRESET: Push-button to zero meterPOWER: 2 each "C" cell batteriesBATTERY LIFE: Typically 450 hours with alkaline batteriesCONSTRUCTION: explosion proof housingTEMPERATURE RANGE: -20o C to 50o CSIZE/WEIGHT: 16.5cm H X 20.3cm W X 17.8cm L; 6.4 kg including batteries
20 Eberline E600 Survey Meter + NRD DetectorGENERAL DESCRIPTIONThe model E600/NRD Combines E-600 Survey Meter with NRD neutron REM detector. The NRD is a 23 cm-diameter, cadmium-loaded polyethylene sphere with a BF3 tube in the center. Energy response closely follows the theoretical dose from neutrons over the energy range from eV thermal to about 10 MeV. The BF3 tube allows excellent gamma rejection.FEATURESMeasures Thermal Through Fast NeutronsGamma Rejection Up To 500 R/hDirection Independent MeasurementsBackground SubtractionData LoggingCOMBINED DETECTOR/METERSize/Weight: cm x 22.9 cm x 22.9 cm; 8.16 KgOperating Temperature: -20oC to +50oCOperating Humidity: Up to 95% non-condensing
21 Eberline E600 Survey Meter + NRD DetectorDETECTORDetector: BF3 Tube in 23 cm cadmium loaded polyethylene spherePlateau: Approximately 200 V with a slope of 5% per 100 VOperating Voltage: Dependant on sensitivity of counter and cable length;typically 1,600 to 2,000 V.Directional Response: Within 10%Energy Range: Thermal to approximately 10 MeVGamma Rejection: Up to 500 R/h. Rejection is dependant on voltage selected.Factory default is 10 mR/h.Sensitivity: Approximately 45 cpm/mrem/h (3,000 counts per mrem)SURVEY METER (E-600)Count Range: 1 to 1.3 million cpmResponse Times: Slow, Medium, Fast. Each time setting is programmable from 0 to 255 seconds.Dead Time Correction: 0 to 255 secOperating Modes: Ratemeter, Scaler, Integration, Peak Trap, BackgroundAccumulation.
22 Eberline E600 Survey Meter Eberline E600 Survey Meter + NRD DetectorEberline E600 Survey Meter+ SHP-400A(Data Logging RO-20)
23 Ludlum Model 15 (---) End Window GM Detector for Alpha Beta and GammaBF3 Proportional Detector with Moderator for Neutron4 Ranges - Total Counting Range from ,000 cpmINDICATED USE: Fast and thermal neutron, alpha, beta-gamma surveyDETECTORS: Controlled by selector switchNEUTRON: Model 42-9 BF3 proportional detector with7.6 cm diameter cadmium lined moderator for fast neutrons(remove detector from moderator for thermal neutrons)ENERGY RESPONSE: Count response is not linear throughoutenergy spectrum ( MeV)SENSITIVITY: Typically 60 cpm/mrem/hr (AmBe fast neutrons)GAMMA REJECTION: Less than 10 cpm through 10 R/hrALPHA BETA-GAMMA: Model 44-7 thin end window GM detectorWINDOW: 1.7 0.3 mg/cm2 micaWINDOW AREA: Active cm Open cm2EFFICIENCY(2 geometry): Typically 5% - 14C; 20% - 90Sr/90Y; 15% - 239PuSENSITIVITY: Typically 2100 cpm/mR/hr (137Cs gamma)
24 Ludlum Model 15 METER DIAL: 0 - 500 cpm, 0 - 2.5 kV, BAT TEST MULTIPLIERS: X1, X10, X100, X1000LINEARITY: Reading within 10% of true valueRESET: Push-button to zero meterAUDIO: Built in speaker with ON/OFF switch (greater than 60 dB at 0.6 m)CALIBRATION CONTROLS: Accessible from front of instrument (protective cover provided)RESPONSE: Toggle switch for FAST (4 seconds) or SLOW (22 seconds) from 10% to 90% of final readingPOWER: 2 each "D" cell batteries (housed in sealed compartment that isexternally accessible)BATTERY LIFE: Typically 600 hours with alkaline batteries (battery conditioncan be checked on meter)METER: 6.4cm arc, 1 mA analog typeCONSTRUCTION: aluminum with beige polyurethane enamel paintTEMPERATURE RANGE: -20oC to 50oCSIZE: 31.8cm H X 8.9cm W X 21.6cm LWEIGHT: 3.7 kg including batteries
25 “air proportional alpha” Ludlum Model 43-44“air proportional alpha”INDICATED USE: Alpha surveyWORKING ENVIRONMENT: Splashproof shields anddesiccant vented chamber for outdoor useWINDOW: 0.4 mg/cm2 aluminized mylarWINDOW AREA: Active - 76 cm2 Open - 50 cm2EFFICIENCY(4 geometry): Typically 8% 239PuCOMPATIBLE INSTRUMENTS: Models 12, 16, 18, 2000,2200, 2221, 2241, 2350OPERATING VOLTAGE: Altitude sensitiveSea level volts2000 feet volts5000 feet volts7000 feet voltsCONSTRUCTION: Anodized aluminum body with aluminum screen (65% open)TEMPERATURE RANGE: -20 C to 50 CSIZE: 10.2 cm H X 6.4 cm W X 22.9 cm LWEIGHT: 0.5kg
26 Ludlum Model 44-110 The Model 44-110 is a windowless 100 cm2 gas proportional detector for tritium detectionINDICATED USE: Tritium surface surveyWINDOW: WindowlessWINDOW AREA: Active cm2 Open cm2EFFICIENCY (4): Typically 25% - H3BACKGROUND: Typically 400 cpmOPERATING VOLTAGE: Typically 1700 voltsCOUNTER THRESHOLD SETTING: Typically 4 mVRECOMMENDED COUNTING GAS: P-10 (10% methane, 90% argon)GAS PURGE TIME: Approximately 20 secondsCONNECTOR: Series "C"CONSTRUCTION: Anodized aluminum housingTEMPERATURE RANGE: -20o C to 50o CSIZE: 12.4cm H X 11.7cm W X 22.9cm LWEIGHT: 0.9kg
27 Where to Get More Information Cember, H., Introduction to Health Physics, 3rd Edition, McGraw-Hill, New York (2000)Firestone, R.B., Baglin, C.M., Frank-Chu, S.Y., Eds., Table of Isotopes (8th Edition, 1999 update), Wiley, New York (1999)International Atomic Energy Agency, The Safe Use of Radiation Sources, Training Course Series No. 6, IAEA, Vienna (1995)