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Centimeters Inches Meters Feet Select Isotope (Point Source)     P-32 S-35 Sr-90 Y-90 SrY-90                              uCi Enter Activity     cm Enter Distance uR/hr Calculated Dose-Rate   Select X-Ray Dose-Rate Units uR/hr mR/hr R/hr urem/hr mrem/hr rem/hr uSv/hr mSv/hr Sv/hr   Select Activity Units   Select Distance Units   uCi mCi Ci Bq MBq Add X-Ray Shield    Beta Emitter Bremsstrahlung Calculations

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Useful for planning shielding and shipment of high energy beta sources such as P-32 or SrY-90.  Beta's interact with matter and produce Bremsstrahlung x-rays as they travel.  In general, higher atomic number (Z) element shields will produce more x-rays, so a low Z shield is a better choice for betas because a high Z shield could actually give a nearby human more dose from the Bremsstrahlung than would have been received from the original unshielded betas.  For a high activity source, common practice is to use two shields, the first low Z to stop the betas and the second high Z to stop any Bremsstrahlung produced by the first shield.  The calculator is also useful to demonstrate to students this phenomenon.  An example would be to set the calculator up to shield first with lead and then with polyethelene.  Do the calculation again with the shields reversed, polyethelene first and then lead.  The calculations will demonstrate that the second arrangement of shields is the better choice.  Click on the check box to turn on the x-ray shield. If you don't know the activity, say for a trash bag, use the beta emitter page/tab and click on "Calculate Activity" to enter your measured beta dose-rate. Use a distance of 1 cm. Copy and use the activity calculated from that page/tab and use it on the bremsstrahlung page/tab.