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Question photoneutron production in region of GDR 

Forum: Hadronic Processes
Date: 16 Oct, 2014
From: Daren Sawkey <Daren Sawkey>

Any suggestions on how to simulate photoneutron production in the region of the giant dipole resonance?

The cross section is about correct (checked with Hadr03), but 2/3 of the photonuclear interactions do not produce neutrons. All of them should. Thus there are 1/3 the expected number of neutrons produced. Example verbose output below, generated with Hadr01 and the macro below.

I've tried several physics lists (e.g. QGSP_BIC_HP, Shielding, ...) and get similar results. Geant4 version 10 patch 1 and also ref-08.

You can also use Hadr03 as described here http://bugzilla-geant4.kek.jp/show_bug.cgi?id=1680

I've seen comments that the various cascade models aren't accurate at these low energies. So: how do I get good photoneutron production? (I know I can modify the cross sections in G4PhotoNuclearCrossSection.cc).

Alternatively -- what don't I understand here?

Thanks -- Daren.

*********************************************************************************************************
* G4Track Information:   Particle = gamma,   Track ID = 1,   Parent ID = 0
*********************************************************************************************************

Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
    0        0        0     -205        15        0        0         0       World initStep
    1        0        0     -101        15        0      104       104       Check Transportation
    2        0        0     -100        15        0        1       105      Target Transportation
    3        0        0      -98        15        0        2       107      Target Transportation
    4        0        0      -96        15        0        2       109      Target Transportation
    5        0        0    -95.3         0        0    0.714       110      Target photonNuclear
    :----- List of 2ndaries - #SpawnInStep=  4(Rest= 0,Along= 0,Post= 4), #SpawnTotal=  4 ---------------
    :         0         0     -95.3        14              gamma
    :         0         0     -95.3     0.807              gamma
    :         0         0     -95.3     0.219              gamma
    :         0         0     -95.3   0.00133              Pb208
    :----------------------------------------------------------------- EndOf2ndaries Info --------------- 

  macro:
/control/verbose 2
/run/verbose 1
/tracking/verbose 2
#
/testhadr/TargetMat        G4_Pb
/testhadr/TargetRadius     10 cm
/testhadr/TargetLength     20 cm
/testhadr/NumberDivZ       100
/testhadr/PrintModulo      100
#
/testhadr/Physics          QGSP_BIC_HP
#
/run/initialize
#
/gun/particle gamma
/gun/energy 15. MeV
/run/beamOn 1000

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1 None: Re: photoneutron production in region of GDR   (Daren Sawkey - 17 Oct, 2014)
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