RE: Detectors and humidity

[John_Sukosky@DOM.COM]

Rick,



The problem is what definition of air we use, dry air or air with water

vapor.  If you look at it in a practical way,  since water vapor is part of

air, then a cubic centimeter of air containing water vapor is denser than a

cubic centimeter of dry air (since water is denser than air).  In terms of

alpha efficiency, it seems intuitive (at least to me) that alphas would

have less efficiency (and lower count rates) in air containing water vapor

than dry air.  Am I misguided on this?



Here's the definition of air from free-definition.com:

                                                                            

                                                                            

                                                                            

  Air is a name for the mixture of gases present in the Earth's atmosphere. 

                                                                            

                                                                            

  Dry air is roughly 79% nitrogen, 20% oxygen, and 1% argon. Air may        

  contain 0-7 % water vapour (the 79%, 20% and 1% become accordingly a      

  little less), and less than 1% carbon dioxide.                            

                                                                            

                                                                            





John M. Sukosky, CHP

Dominion

Surry Power Station

(757)-365-2594 (Tieline: 8-798-2594)







                                                                                                                                       

                      "Rick Orthen"                                                                                                    

                      <rorthen@cecinc.c        To:       <John_Sukosky@DOM.COM>                                                        

                      om>                      cc:                                                                                     

                                               Subject:  RE: Detectors and humidity                                                    

                      06/01/04 09:50 AM                                                                                                

                                                                                                                                       

                                                                                                                                       









Maybe I'm not seeing the forest for the trees, but I think it is

intuitively

clear why air density decreases with increasing humidity.  As humidity

increases, each cubic centimeter of air contains a larger proportion of

water molecules, effectively displacing the amount of air in that cc cube.

With less air molecules in the cube, the air density has to go down.



Rick



Richard F. Orthen, CHMM

Senior Project Manager

Civil & Environmental Consultants, Inc.

Four Triangle Lane, Suite 200

Export, PA  15632-9255

724/327-5200, ext. 231

www.cecinc.com









************************************************************************

You are currently subscribed to the Radsafe mailing list. To

unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu  Put the

text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,

with no subject line. You can view the Radsafe archives at

http://www.vanderbilt.edu/radsafe/