RE: buildup factors

[Gerald.P.Lahti@ucm.com]

The best buildup factor data may be found in the ANS standard 6.4.3.  The
draft standard (with all of the data) was published as ORNL/RSIC-49, Sept
1988.  ORNL/RSIC-49 is entitled "New Gamma-Ray Buildup Factor Data for Point
Kernel Calculations:  ANS-6.4.3 Standard Reference Data".  This is the fine
work of David Trubey, now retired from ORNL's Radiation Shielding
Information Center.  Here you will find in Table 5.1, for example, fitting
parameters for water buildup factors for photon energies from 0.015 MeV to
15 MeV.  The data is good to 40 mfp.

* * * * * * * * * * * * * * * * * *
Jerry Lahti
Radiological Safety Specialist
ComEd - Downers Grove
(630) 663-6659
gerald.p.lahti@ucm.com
* * * * * * * * * * * * * * * * * * 

> -----Original Message-----
> From:	Karam, Andrew [SMTP:Andrew_Karam@URMC.Rochester.edu]
> Sent:	Tuesday, April 11, 2000 1:24 PM
> To:	Multiple recipients of list
> Subject:	buildup factors
> 
> Dear Colleagues:
> 
> I am working a problem that calls for calculating attenuation of
> low-energy
> radiation (about 20 KeV photons) by thin to moderate layers of water (0.1
> to
> 10 cm).  The tables I have found in the Rad Health Handbook for buildup do
> not consider photons less than 100 KeV.  I would greatly appreciate any
> suggested references for buildup factors of 20 KeV photons in water.
> 
> In a related problem, I am trying to find similar factors for 200 KeV
> photons in air, but over very long distances (up to 150 relaxation
> lengths).
> This information is posing similar problems as the RHH goes up to 40
> lengths.
> 
> If you reply to me directly, I can post a summary to Radsafe.  Thanks in
> advance for your help.
> 
> Sincerely,
> 
> Andy
> 
> Andrew Karam, CHP              (716) 275-1473 (voice)
> Radiation Safety Officer          (716) 275-3781 (office)
> University of Rochester           (716) 256-0365 (fax)
> 601 Elmwood Ave. Box HPH   Rochester, NY  14642
> 
> Andrew_Karam@URMC.Rochester.edu
> http://Intranet.urmc.rochester.edu/RadiationSafety
> 
> Mathematics may be compared to a mill of exquisite workmanship which
> grinds
> you stuff of any degree of fineness; but, nevertheless, what you get out
> depends on what you put in; and as the grandest mill in the world will not
> extract wheat-flour from peascods, so pages of formulae will not get a
> definite result out of loose data.  (T.H. Huxley, 1869)
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