[fluka-discuss]: pair production in tungsten- reduced yield with higher density

From: Saurabh Mukherjee <sxm3816_at_gmail.com>
Date: Sun, 26 Jun 2016 22:31:28 +0530

  I am trying to estimate pair production induced positron flux. The target
is hollow tungsten and beam is ~3 MeV gamma. I am estimating the number of
positrons produced using USRTRACK.
 Since my target will be hollow tungsten, I have simulated the target in
FLUKA with a density of 1 gm/cc instead of the usual 19 gm/cc for tungsten
( The target is a disk of thickness 2.5 cm and dia 20 cm). To achieve this
reduced density, I defined a material called 'tung' with rho=1 and then
defined a compound card containing 100% by vol Tungsten. I initially wanted
to define two materials in the compound card- tungsten and void. But Fluka
does not allow void in the materials, it seems.

The question that I have is that I get (slightly) higher yield of positrons
when the density is low and vice versa. I was thinking that with lower
density the pair production will be less but simulations seem to suggest
different. Can someone please suggest me if I am doing something wrong? Is
this a good way to simulate a hollow tungsten?

I am attaching the yield for density= 10 and 1 gm/cc.
thank you

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(image/jpeg attachment: targetdensity1.jpg)

(image/jpeg attachment: targetdensity10.jpg)

Received on Sun Jun 26 2016 - 20:57:41 CEST

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