development of a gamma-ray beam profile monitor for the high-intensity gamma-ray source thomas...
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Development of a Development of a Gamma-Ray Beam Gamma-Ray Beam
Profile Monitor for the Profile Monitor for the High-Intensity Gamma-High-Intensity Gamma-
Ray SourceRay Source
Thomas Regier,Thomas Regier,Department of Physics and Department of Physics and
Engineering PhysicsEngineering PhysicsUniversity of Saskatchewan University of Saskatchewan
Beam Profile MonitorBeam Profile Monitor
Component of Beam Component of Beam Diagnostic SystemDiagnostic System
Provides Gamma-Ray Provides Gamma-Ray Position and Flux Position and Flux InformationInformation
Assists users and Assists users and operators in operators in experiment and beam experiment and beam configurationconfiguration
The High Intensity Gamma-Ray The High Intensity Gamma-Ray SourceSource
270 MeV Linear Accelerator
Electron Source
Electron Storage Ring
OK-5 Free Electron Laser
RF Booster
Experimental Area
Design RequirementsDesign Requirements
Sub-millimeter resolutionSub-millimeter resolution
Easy to useEasy to use
Non-destructiveNon-destructive
Handle beam energies between 2 and 225 Handle beam energies between 2 and 225 MeVMeV
Handle beam fluxes between 10Handle beam fluxes between 105 5 and 10and 101010 gammas per secondgammas per second
Detecting Gamma-RaysDetecting Gamma-Rays
Design ConceptDesign Concept
Gamma-Rays interact with the scintillator, generating flourescent illumination.
The illuminated scintillator is imaged onto a Charge Coupled Device by a lens system.
The CCD records the illumination pattern by converting the incident photons into electrons
System ModelSystem Model
NC
Relates the number of counts registered by the CCD camera to the power absorbed by the scintillator and the length of the exposure through the
responsivity of the system.
RSYS Pabsorbed tINT= int[ ]
CCD NoiseCCD Noise
DesignDesign
Light Tight Box
CCD Camera
Lens System
Scintillator
Inrun / Outrun Windows
CCD CameraCCD Camera
Starlight Express MX-5Starlight Express MX-5 Sony ICX055BL CCD ChipSony ICX055BL CCD Chip Single Stage Thermoelectric Single Stage Thermoelectric
Cooler (Room Temp – 30Cooler (Room Temp – 30ooC)C) External USB ControllerExternal USB Controller Capable of ‘binning’Capable of ‘binning’
Linux Based Data AcquisitionLinux Based Data Acquisition 33rdrd Party USB drivers Party USB drivers Custom camera control Custom camera control
softwaresoftware
OpticsOptics
- Had to balance…Had to balance…- Overall lengthOverall length- Number of lensesNumber of lenses- ApertureAperture- MagnificationMagnification
Source TestingSource Testing- Used 23 mCi 137Cs source to test system response
- Testing resulted in a series of improvements to apparatus
137137Cs Emission SpectrumCs Emission Spectrum
Data Analysis/ProcessingData Analysis/Processing
Original Image of 137Cs Source Radiation
Background Subtracted Image
Image processed to remove bad pixels
CalibrationCalibration
-Performed to find the system responsivity, RSYS
-Combines…
- Source profile measurement data
- Source flux measurement data
- Geant simulation results
-Provides a link between the image intensity and the gamma-ray flux
Source Profile Data
Geant Simulation
Source FluxMeasurement
-Determined by the number of counts in a particular region of the image, divided by the amount of energy deposited in the corresponding region on the scintillator
RSYS = NC / (Pabsorbed tINT) = 126 Counts per GeV
Source Flux Measurement with NaI
Detector
and
Geant Simulation Results
Predicted Exposure TimesPredicted Exposure Times
-Dictated by the signal to noise ratio
-Calculated by examining an individual camera “bin”
Portion of the signal generated by something other than the incident
illumination
Portion of the output signal generated due to exposure to illumination
nfull
rsysPabsorbedtINTnT = + idarktINT + nfloor
Predicted Exposure TimesPredicted Exposure Times
nT = rsysPabsorbedtINT + idarktINT + nfloor
nB = idarktINT + nfloor
nS = nT – nD = rsysPabsorbedtINT
δnS2 = δnT
2 + δnB2
Background Subtraction is performed to find signal
Predicted Exposure TimesPredicted Exposure Times-Select a fraction of error, ε, that gives
εnS(tINT) = δnS(tINT)
-Find a solution for tINT that satisfies this relationship
A Plot of the Time Required to Obtain a Fraction of Error, ε, for Pabsorbed Values of 20, 60 and 100 GeV/s
ε
The Time Required to Achieve 5% Error Per Pixel Versus Beam Energy For Various Scintillator-Converter Configurations
ConclusionsConclusions
- The combination of a scintillator, lens system, and CCD camera can be used to measure the profile of a gamma-ray source
- Submillimeter resolutions are achievable
- The method is non-destructive
- Predicted exposure times for a nominal beam flux are less than a minute
In-Beam TestingIn-Beam Testing
In-Beam TestingIn-Beam Testing
In-Beam TestingIn-Beam Testing
In-Beam TestingIn-Beam Testing
In-Beam TestingIn-Beam Testing
In-Beam TestingIn-Beam Testing
In-Beam TestingIn-Beam Testing
In-Beam TestingIn-Beam Testing
In-Beam TestingIn-Beam Testing
In-Beam TestingIn-Beam Testing