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Forum: Physics List
Re: None range cut for very thin layers (ahmet ayan)
Re: None Re: range cut for very thin layers (Vladimir IVANTCHENKO )
Re: None Re: range cut for very thin layers (Ahmet Ayan)
Re: None Re: range cut for very thin layers (michel maire)
Re: None Re: range cut for very thin layers (Ahmet Ayan)
Date: 18 Apr, 2006
From: michel maire <michel maire>

User Ahmet Ayan wrote:

>> Hi Michel, I looked at the PhotonProcesses example. I replaced the
>> medium to Tungsten and varied the thickness of it as I shot 140keV
>> gammas. For thicknesses greater than 1cm or so the calculated
>> attenuation coefficients match well with the known (NIST) values.
>> However as I go down on thicknesses, <1.*mm , I do not get the known
>> (NIST) values.
>> 
>> I,then tried to calculate it by simplying using the "Nb of incident
>> particles surviving the absorber" which given in this example code by
>> the usual I/Io = e^(-mu . t), t=thickness.
>> 
>> I still cannot reproduce mu for tungsten.
>> 
>> Am I doing/interpreting something wrong here?

  Yes. This example is not based of the evaluation of the transmitted
 particles, but on the direct calculation of the mean free path of the
 first interaction (see readme)

 Therefore, the thickness must be 'infinite'. The number of transmitted
 particles must be 0. It is printed here to indicate that something goes
 wrong, if it is not zero.

        Michel

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