Re: Ionization at 80 eV? (Yes)

[EStill@golder.com (Erik Still)]

     Bruce - It takes 13.6 eV to remove an electron from a hydrogen atom.  
     The CRC handbook includes a table of ionization potentials for all of 
     the elements.  The highest ionization potential in the table is over 
     5,000 eV.  So, an 80 eV source can cause selected ionization, but you 
     are correct in your conclusion that does not represent a health 
     concern.
     
     Erik Still
     Senior Risk Analyst
     Golder Associates Inc.
     4104 148th Ave. NE
     Redmond, WA  98052
     estill@golder.com
     voice: (206) 883-0777
     fax:   (206) 882-5498
     http://www.golder.com
     
     
______________________________ Reply Separator _________________________________
Subject: Ionization at 80 eV?
Author:  radsafe@romulus.ehs.uiuc.edu at internet 
Date:    5/16/97 2:39 PM
     
     
>Someone called our office with questions about the safety of a device they 
>are using. Apparently, this is some type of a mass spec device that is used 
>as a helium leak detector, and which has an electrical potential across a 
>cathode and anode. We were told that the "amount of radiation produced is 80 
>electron volts of ionized radiation"; we don't know if this information comes 
>from a label on the device, or the operator's manual, or somewhere else.
>
>In talking this over in our office here, we're not certain that ionization 
>would even occur at such a low potential as 80 eV (we're normally working 
>with thousands to hundreds of thousands of times this potential). However, we 
>do agree that even if ionization does occur, any resulting x-rays would be so 
>soft that they would be stopped by a small amount of air, so our conclusion, 
>based on the little we know of this device, is that there would be no 
>ionizing radiation hazard associated with its use.
>
>Now, in order to satiate our curiosity, can anyone on RADSAFE tell us what 
>the lowest electrical potential would be that would result in ionization and 
>the formation of x-rays. I presume that we would need to known the ionization 
>potential of the materials in the device's anode, but knowing almost nothing 
>of the device itself, we could only guess at what this would be made of.
>
>Bruce Pickett
>Radiation Health Protection
>The Boeing Company
>PO Box 3707 M/S 6Y-38
>Seattle, WA  98124
>(425)393-3098, FAX (425)393-3060
>bruce.d.pickett@boeing.com
>
>
>
>
>
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Subject: Ionization at 80 eV?
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