Re: (n,gamma) interaction

From: George Kharashvili <georgek_at_jlab.org>
Date: Fri, 22 Jul 2011 11:30:15 -0400

Julian,
You might have PHOTONUC and LAM_BIAS activated only in lead, but nothing
in your geometry is assigned lead. Try to turn photonuclear reactions on
in all materials (vacuum to @LASTMAT).
George

On 7/22/2011 6:35 AM, Julian Rassolov wrote:
> Good day Vasilis and all fluka users.
>
> All your responses helped me a lot. And I am finaly starting to understand
> (a bit more) how powerful this tool, but i am once again quire your help.
> I am trying to count Gamma-n interactions while bombarding few bodies with
> electrons. I used the following input file :
> *
> * Created: 27.3.2011
> * At: 19:6:33
> TITLE
> MC-CAD Test
> GLOBAL 1.0 1.0
> DEFAULTS
> PRECISIO
> BEAM -.05
> ELECTRON
> BEAMPOS -0.4 20.0 20.0 1.0 0.0
> *DISCARD ELECTRON POSITRON PION+ PION-
> *PART-THR 0.02 NEUTRON 0.0
> *PART-THR -0.01 PROTON 0.0
> PHOTONUC 1. LEAD
> GEOBEGIN
> COMBNAME
> 0 0 MC-CAD
> * 1
> RPP B1 -50.0 50.0 -20. 80.0 -20.0 80.
> * 2
> RCC B2 0.0 20.00 20.00 0.04 0.00 0.0 0.06
> * 3
> RCC B3 0.04 20.00 20.0 0.10 0.00 0.0 0.06
> * 4
> RCC B4 0.14 20.00 20.0 0.10 0.00 0.00 0.06
> * 5
> RCC B5 -0.01 20.00 20.00 0.27 0.00 -0.00 0.16
> * 6
> RCC B6 -1.10 20.00 20.00 3.0 0.00 0.00 0.30
> END
> * 1; assigned material: Blackhole; mat # (1)
> R1 5 +B1-B6
> * 2; assigned material: Tantalum; mat # (18)
> R2 5 +B2
> * 3; assigned material: M100; mat # (34)
> R3 5 +B3
> * 4; assigned material: M100; mat # (34)
> R4 5 +B4
> * 5; assigned material: water; mat # (3)
> R5 5 +B5-B2-B3 -B4
> * 6; assigned material: air; mat # (8)
> R6 5 +B6-B5
> END
> GEOEND
> * 104 Air dry (near sea level)
> *
> MATERIAL .00120484 AIR
> COMPOUND -1.248E-4 CARBON -.755267 NITROGEN -.231781 OXYGENAIR
> COMPOUND -0.012827 ARGON AIR
> * 276 Water liquid H2_O
> * Chemical Formula: H -- O -- H
> MATERIAL 1.0 WATER
> COMPOUND 2.0 HYDROGEN 1.0 OXYGEN WATER
> *MATERIAL 42. 100. 10.22 MOLYBDEN
100.Mo100
> MATERIAL 42. 95.94 10.22
> MOLYBDEN
> MAT-PROP 424.0 MOLYBDEN
> MAT-PROP 75.0 WATER
> STERNHEI 3.5017 .24 2.8004 .09116 3.4773 WATER
> ASSIGNMA BLCKHOLE R1
> ASSIGNMA TANTALUM R2
> ASSIGNMA MOLYBDEN R3
> ASSIGNMA MOLYBDEN R4
> ASSIGNMA WATER R5
> ASSIGNMA AIR R6
> LAM-BIAS 0.0 0.02 LEAD PHOTON
> USERDUMP 100. 50. 0.0 dump
> RANDOMIZ 1.0
> START 10000. 0.0
> STOP
>
> and following subroutine ,kindly provided by Vasislis:
>
> SUBROUTINE MDSTCK ( IFLAG, NPSECN )
>
> INCLUDE '(DBLPRC)'
> INCLUDE '(DIMPAR)'
> INCLUDE '(IOUNIT)'
> *
> *----------------------------------------------------------------------*
> * *
> * Copyright (C) 1998-2007 by Alfredo Ferrari& Paola Sala *
> * All Rights Reserved. *
> * *
> * *
> * Created on 19 may 1998 by Alfredo Ferrari& Paola Sala *
> * Infn - Milan *
> * *
> * Last change on 18-jan-07 by Alfredo Ferrari *
> * *
> * *
> * Iflag = 1: standard Kaskad call *
> * = 2: Kaskad call after elastic (but hydrogen) *
> * = 3: Kasneu call *
> * = 4: Emfsco call *
> * *
> *----------------------------------------------------------------------*
> *
> INCLUDE '(EMFSTK)'
> INCLUDE '(FHEAVY)'
> INCLUDE '(FLKSTK)'
> INCLUDE '(GENSTK)'
> INCLUDE '(TRACKR)'
>
> LOGICAL LFIRST
> * Peak the last removed particle from the stack
> IF (ILOFLK(NPFLKA+1) .EQ. 7) THEN
> * Scan the secondary stack
> LFIRST = .TRUE.
> DO I=1,NP,1
> * Do we have a neutron there
> IF (KPART(I).EQ.8) THEN
> IF (LFIRST) THEN DO
> LFIRST = .FALSE.
> PRINT *,'Photonnuclear: E=',TKEFLK(NPFLKA+1)
> PRINT *,' Weight=',WTFLK(NPFLKA+1)
> PRINT *,'
> Pos=',XFLK(NPFLKA+1),YFLK(NPFLKA+1),ZFLK(NPFLKA+1)
> END IF
> PRINT *,' neutron E=',TKI(I), ' wgt=',WEI(I)
> END IF
> END DO
> END IF
> *
> RETURN
> *=== End of subroutine Mdstck =========================================*
> END
>
> I have simulated 5 cycles 100000 histories each but saw no Gamma-n
> interaction, and due to the calculations there are suppose to be at
> least few of them.
> Please advise, what could be the problem .
>
> Thank you in advance,
> Julian
>

-- 
George Kharashvili
Jefferson Lab Radiation Control
1-757-269-6435
Received on Sun Jul 24 2011 - 15:50:50 CEST

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