muD diffusion / files + subtle questions

[Bernhard Lauss <lauss@berkeley.edu>]

Dear Brendan & Peter and all,

I think I am ready to incorporate the correct mu_d diffusion
in the GEANT part of the Monte Carlo.
Consequently, I would like to get the latest files
(as 2 column text: radius  probability)
containting for a given times slice the radius of diffusion.
for the mu_d. Brendan, he 0.4 mus slices you have in
your April 7 presentation, Time-slice vs R histograms,
look fine, however,

please   d o  n o t   incorporate the decay time, which

I will have in my MC anyway.
I want to be able to just poll a diffusion length for a given time.
(and later incorporate capture, too)



General discussion question to all:

Fred raised the question, that the way I am intending to
incorporate the diffusion might result in a subtel bias
because of predetermination.

I am generating first a decay time,
then selecting the diffusion path length according to this
decay time and
then tracking the particle along a random direction
for the whole given decay length, polled from Brendan's diffusion
Monte Carlo.
If the particle hits material the particle vanishes and we do not
see a decay electron (he at a later time the decay time
will be modified for the capture reactio).
if after the whole diffusion length the particle is still in hydrogen
it decays at the predetermined diffusion time and emits an electron.


Fred's  caveat was that this is not a real random walk where
time and direction are chosen randomly at any given point
up to the decay.


I think as there are several random generators inwolved
- Brendan's diffusion length generator
- my decay time and direction generators
Therefore, a combination of random decay time
and random direction should have no bias.

Please communicate your considerations.


			Thanks

			Bernhard













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Bernhard Lauss                 E-Mail: lauss@socrates.berkeley.edu
Physics Department
366 LeConte Hall
University of California @ Berkeley
Berkeley, CA 94720                             Tel: (510)-642 4057
United States                                  Fax: (510)-642 9811
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