Activation

From: Holbourn, MP \(Martin\) (m.p.holbourn@dl.ac.uk)
Date: Mon Apr 10 2006 - 12:57:24 CEST

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    Hi guys!
    Still working through the examples from the recent Pavia course and found something I do not understand in the scoring of activation products using the input file ex_final1.inp (from the course pickup area of the fluka site)

    The example looks at the scoring of residual nuclei using RENUCLEI and USRBIN cards in a target geometry repicated using the Lattice capability.

    **** for activation exercise
    *------------------------------------------------------------------------*
    *
    PHYSICS 3.0 EVAPORAT
    PHYSICS 1.0 1.0 1.0 COALESCE
    *
    RADDECAY 1.0 3.0 9999900000
    *
    * 7days 4days 7days
    IRRPROFI 6.048E5 1.0E5 3.456E5 0.0 6.048E5 1.0E5
    * 4days 7days
    IRRPROFI 3.456E5 0.0 6.048E5 1.0E5
    *
    * 1hour 1month
    DCYTIMES 3600. 2.592E6
    *
    DCYSCORE 1.0 act2-1h act3-1h RESNUCLE
    RESNUCLE 3.0 -61. TARGS2 act2-1h
    RESNUCLE 3.0 -61. TARGS3 act3-1h
    DCYSCORE 2.0 act2-1m act3-1m RESNUCLE
    RESNUCLE 3.0 -62. TARGS2 act2-1m
    RESNUCLE 3.0 -62. TARGS3 act3-1m
    *
    DCYSCORE 1.0 PbBq1-1h PbBq2-1h USRBIN
    USRBIN 1.0 234.0 -63.0 5.0 0.0 10.0PbBq1-1h
    USRBIN 0.0 0.0 2.0 1.0 1.0 1.0&
    USRBIN 1.0 234.0 -63.0 5.0 0.0 20.0PbBq2-1h
    USRBIN 0.0 0.0 12.0 1.0 1.0 1.0&
    *
    DCYSCORE 2.0 PbBq1-1m PbBq2-1m USRBIN
    USRBIN 1.0 234.0 -63.0 5.0 0.0 10.0PbBq1-1m
    USRBIN 0.0 0.0 2.0 1.0 1.0 1.0&
    USRBIN 1.0 234.0 -63.0 5.0 0.0 20.0PbBq2-1m
    USRBIN 0.0 0.0 12.0 1.0 1.0 1.0&
    *
    DCYSCORE 1.0 AlBq1-1h AlBq2-1h USRBIN
    USRBIN 1.0 234.0 -63.0 5.0 0.0 2.0AlBq1-1h
    USRBIN 0.0 0.0 1.0 1.0 1.0 1.0&
    USRBIN 1.0 234.0 -63.0 5.0 0.0 12.0AlBq2-1h
    USRBIN 0.0 0.0 11.0 1.0 1.0 1.0&
    *
    DCYSCORE 2.0 AlBq1-1m AlBq2-1m USRBIN
    USRBIN 1.0 234.0 -63.0 5.0 0.0 2.0AlBq1-1m
    USRBIN 0.0 0.0 1.0 1.0 1.0 1.0&
    USRBIN 1.0 234.0 -63.0 5.0 0.0 12.0AlBq2-1m
    USRBIN 0.0 0.0 11.0 1.0 1.0 1.0&

    I have run the input file for three batches 1000 protons and summarise the results below

    For the first aluminium disc in the target (TARGS2)

    RESNUCLEI (act2-1h) gives 812.201 Bq/cmq

    USRBIN (AlBq1-1h) gives 4.1494 Bq/cmq

    These should be as I understand it be different by a factor of 78.54 as the volume of the detector has not been specified using WHAT(6) of the RESNUCLEI card whereas the USRBIN estimator has uses the actual volume of the detector (pi.r^2.h) but diifer by a factor of ~200.

    However if the geometry is simplified by commenting out the LATTICE card and the ROT-DEFI card the answers I get are

    RESNUCLEI (act2-1h) gives 381.607 Bq/cmq

    USRBIN (AlBq1-1h) gives 4.8588 Bq/cmq

    These do now differ by the expected factor of 78.54!!

    What is the problem?

    Any comments gratefully recieved as usual.

    Thanks

    Martin Holbourn
    Radiation Protection Adviser
     
    Daresbury Laboratory
    Daresbury
    Warrington
    Cheshire
    WA4 4AD
     
    Tel: 01925 603266
    Fax: 01925 603381
    mailto:m.p.holbourn@dl.ac.uk

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