Re: Score neutron from 16O(p,xn) reaction

From: <chenyenlee_at_gmail.com>
Date: Thu, 13 Nov 2008 11:58:38 +0800

Dear Francesco:

> ii. you misinterpreted the use of the cylindrical mesh of USRBIN. Its axis
> is the z axis (since this is the standard beam axis) and, for each
> longitudinal z-bin, the transverse plane (xy) can be split into radial and
> azimuthal bins. You described correctly the azimuthal angle (going from -180
> to 180 deg, with 0 deg corresponding to the x axis), but that cannot be
> properly used as polar angle with respect to a beam direction parallel to
> the x axis!
>
I want to score the product neutron angle distribution with respect to
the beam direction, compare with ICRU63.
If I consider single longitudinal z (plane xy), then the azimuthal
angle is the angle distribution of the product neutron with respect to
the beam direction.
Sorry, I had difficulty comprehend this.

>
> It is correct. I have a couple of remarks about.
> i. you left empty WHAT(4-5) on the first line. This means that default
> values are taken and this way you score neutrons as they are produced in any
> nuclear reaction, neglecting their transport up to the detector. Note that
> if you put instead regions 2 and 3, respectively, defining the target
> surface as scoring surface (thus considering the neutron transport through
> water), the energy interval used as filter will be in fact - not apparently
> - (very) slightly changed due to matching with the group structure applying
> to neutron energies below 20 MeV.
> ii. in order to increase your statistics, you might need to bias the
> interaction probability of primary protons in water (LAM-BIAS card)

In LAM-BIAS card, I'm interested in 16O(p,n) reaction, is it correct that I set
what(4) for proton and what(5) for neutron.
I had a few runs that I need to increase the statistics,
Is there any value that I should take into consideration for biasing
the inelastic hadronic interaction length , like figure of merit(FOM)
in code MCNP or the range of 20MeV in water(1.9mm)

Please advise me.

My Best Regards.

Lee

--
Chenyen Lee
Department of Nuclear Medicine
Chang Gang Memorial Hospital
Linko,Taiwan


USRBIN.JPG
Received on Thu Nov 13 2008 - 19:35:23 CET

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