RE: Question about neutron balance

From: Vasilis Vlachoudis (Vasilis.Vlachoudis@cern.ch)
Date: Tue Mar 06 2007 - 10:09:45 CET

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Hi Alfred,

the numbers mean nothing to me!
USRTRACK and USRCOLL both score particle fluence using two different
methods one with the track length estimation and the other by
collisions. Please give a look to the related tutorial on the fluka web
site http://www.fluka.org/course/WebCourse/scoring/P007.html
Check also the USRYIELD card for scoring particle yields out of an
interaction or a region

Regards
Vasilis

-----Original Message-----
From: Tang, Alfred [mailto:atang@phys.ksu.edu]
Sent: Monday, 05 March 2007 17:16
To: Vasilis Vlachoudis; fluka-discuss@fluka.org
Subject: RE: Question about neutron balance

Dear Vasilis,
Thank you for your comments. They are very informative. I have used
source.f to input muons from a realistic profile and to score the
secondary particles using USRTRACK and USRCOLL. Below is a partial list
of the numbers that I got in unit of p/cmq/pr and cm/pr (I used the
default area=1cm^2 and volume=1cm^3):

USRTRACK
muon 1184.364
particle 8 20.14018
particle 222 6418.346

USRCOLL
muon 1161.683
particle 8 20.13256
particle 222 1180.406

Do these numbers look right? What is the main difference between
USRTRACK and USRCOLL? I am primarily interested in the production rates
of secondary particles. Can I get that information from the above
numbers? Thanks again.
Regards,
Alfred

*****************************************************
Alfred Tang
Physics Department
Kansas State University
13 Cardwell Hall
Manhattan, KS 66506

(785) 532-1699

http://www.phys.ksu.edu/personal/atang

-----Original Message-----
From: owner-fluka-discuss@fisica.unimi.it on behalf of Vasilis
Vlachoudis
Sent: Sun 3/4/2007 11:56 AM
To: Tang, Alfred; fluka-discuss@fluka.org
Subject: RE: Question about neutron balance

Hi Alfred,

The neutron balance according to your definition is related to B. Is the
term that enters in the diffusion equation for a steady in time
solution.
The diffusion equation is described as:
d(Flux(r))/dt = D*\Delta2(Flux(r)) + S(r) - \Sigma_abs*Flux(r)
where S(r) term describing the sources and \Sigma_abs the absorption
cross section:
or with words the diffusion equation is (per unit volume):

dFlux(r)/dt = -[outflow rate] + [production rate] - [absorption rate]

and for a steady state solution

[outflow rate] = [production rate] - [absorption rate] = neutron balance

While the particle 8=neutron is scoring the neutron fluence. The datum
most frequently used for describing neutron fields. The fluence defined
as the number of particles that penetrate a sphere with a cross section
of pi*r^2 = 1cm2 per unit of time and/or energy. Otherwise, the
particles crossing a surface of 1cm2 that is ALWAYS perpendicular to the
direction of the particle.

Regards
Vasilis

-----Original Message-----
From: owner-fluka-discuss@fisica.unimi.it
[mailto:owner-fluka-discuss@fisica.unimi.it] On Behalf Of Tang, Alfred
Sent: Friday, March 02, 2007 17:08
To: fluka-discuss@fluka.org
Subject: Question about neutron balance

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Dear FLUKA experts,
Suppose that A=3D(number of neutrons created)+(number of neutrons
absorbed) and B=3D(number of neutrons created)-(number of neutrons
absorbed). Is it true that neutron balance (particle number 222)
neut-bala is related to A and neutron (particle number 8) is related to
B?
Regards,
Alfred
=20

**********************************************
Alfred Tang
Department of Physics
Kansas State University
13 Cardwell Hall
Manhattan, KS 66506

(785) 532-1699

http://www.phys.ksu.edu/personal/atang

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Dear FLUKA experts,

Suppose that A=3D(number of neutrons =
created)+(number of neutrons absorbed) and B=3D(number of neutrons =
created)-(number of neutrons absorbed).  Is it true that neutron =
balance (particle number 222) neut-bala is related to A and neutron =
(particle number 8) is related to B?

Regards,

Alfred

**********************************************

Alfred Tang

Department of Physics

Kansas State University

13 Cardwell Hall

Manhattan, KS 66506

(785) 532-1699

<A HREF=3D"http://www.phys.ksu.edu/personal/atang">http://www.phys.ksu.edu/personal/atang></A>

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