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From: Alberto Fasso' (fasso@SLAC.Stanford.EDU)
Date: Wed Jan 07 2004 - 02:45:20 CET

  • Next message: Vaclav Vylet: "particle tagging"

    Hi Vashek,

    yes, there is way to tag particles in the way you want.
    In COMMON TRACKR, which is updated at each particle step,
    there are 11 integer flags (ISPUSR) and 11 double precision
    variables (SPAUSR) available to the user.
    The user can assign any arbitrary value to one or more of
    the above variables after any call of subroutine MGDRAW or to
    one of its ENTRYes:
    MGDRAW (step, with or without energy loss)
    BXDRAW (boundary crossing)
    EEDRAW (end of a history)
    ENDRAW (point energy deposition)
    SODRAW (source particle)
    USDRAW (physical interaction)

    A call to one or more of these entries is done with command
    USERDUMP. See more details on the manual, under USERDUMP and
    in Chapter 19 (user routines).
    The value of the user variables is inherited by the particle's
    progeny, as you desire.

    I guess that for your problem you could do the tagging at
    ENTRY BXDRAW. Unfortunately this entry (and EEDRAW) have been
    introduced only recently, and are not yet documented in the manual
    But the argument list should be clear enough:
          ENTRY BXDRAW ( ICODE, MREG, NEWREG, XSCO, YSCO, ZSCO )
    MREG is the region "before" the boundary, and NEWREG is the
    regione after the boundary. Yo can do the flagging by
    something like
          IF(MREG .EQ. xx) ISPUSR(1) = 1
    or even
          IF(MREG .EQ. xx) ISPUSR(1) = LTRACK (or = JTRACK)
    (that would "remember" the generation, or the type, of the particle
    which has crossed region xx)

    Ciao,

         Alberto

    > Hi,
    >
    > I would like to separate a contribution to fluence or energy deposition
    > from particles having passed through a specific region. I suppose I could
    > estimate that by having two separate runs and introducing "black hole"
    > material in appropriate places. However, this approach may be complicated
    > and error-prone for some geometries. Is there a way to "tag" particles (and
    > their progeny) that passed through a given region and score their
    > contribution separately? Perhaps one would write a collision tape and
    > post-process it with an existing utility? I would appreciate any
    > suggestions.
    > Thanks
    >
    > Vashek Vylet
    > <vashek.vylet@duke.edu>
    >
    >

    -- 
    Alberto Fassò
    SLAC-RP, P.O. Box 4349, MS 48, Stanford CA 94309
    Phone: (1 650) 926 4762   Fax: (1 650) 926 3569
    fasso@slac.stanford.edu
    

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