RE: Problem trying to change the pressure of Argon

From: Joachim Vollaire <joachim.vollaire_at_cern.ch>
Date: Wed, 15 Dec 2010 09:13:23 +0000

Dear Howard,
I tried a simple case and came up with the same conclusion than you,
the deposited energy scaled with the specified density (factor 8.2).
I would not expect a factor 7 (ratio between the pressure) as your
Argon_2 has a density greater than 0.01 g/cm3 and is therefore not
considered as a gas by default.

In case it can help I draw your attention on the notes on the
MAT-PROP card in the manual:

A non-zero value of WHAT(1) must be given only for gases: it
is important when calculating the density effect parameters
of the stopping power (see Note to option STERNHEIme).
If WHAT(1) is set to a value> 0.0, the transport of hadrons will
be calculated according to a density RHO defined at the actual pressure
by the corresponding MATERIAL card, while the density effect
correction to stopping power will be calculated using a density
RHO(NTP) = RHO/WHAT(1) and then re-scaled to the actual density.
When giving a WHAT(2) non-zero value, remember that if RHO (defined
by a MATERIAL card) indicates the "transport (effective) density",
the "physical density" used to calculate the density effect on
stopping power will be RHOR*RHO.

Also note that the MAT-PROP card must be issued after the MATERIAL card
(this is one of a few cases where order of cards does matter...)
Cordially
Joachim

-----Original Message-----
From: owner-fluka-discuss_at_mi.infn.it [mailto:owner-fluka-discuss_at_mi.infn.it] On Behalf Of Howard Matis
Sent: 19 November 2010 01:59
To: fluka-discuss_at_fluka.org
Subject: Problem trying to change the pressure of Argon

We have found that we need to change the density of Argon to look at
high pressure Argon.

The following card seems to work. Note the density of argon is 7 times
higher than nominal 0.001662 .

MATERIAL 18. 39.948 0.014016
MAT-PROP 7.0 ARGON_2

pressure set to 7 and density at 0.014016 (7 *nominal)
                10.21
pressure set to 1 and density at 0.014016 (7 *nominal)
                  9.22
pressure at 7.0 and the density at 0.001662
                           2.16
pressure at 1.0 and the density at 0.001662
                          1.88

So why does the MAT-PROP card not change the ionization that is
deposited or am I doing something wrong?

Howard
Received on Wed Dec 15 2010 - 11:06:26 CET

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