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Usage

First you must initialize the event generators, i.e., create a table of the functions tex2html_wrap_inline11026 and tex2html_wrap_inline11028. They are three-argument functions. In the program, tex2html_wrap_inline7924, tex2html_wrap_inline7928, and tex2html_wrap_inline11084 (tex2html_wrap_inline11086) are used as the independent variables. To initialize the generators, you must specify the range and number of mesh points for these variables.

The present version allows to enhance the probability of a part of spectrum. See below.

1ex

C ALL NLCPST(MY,MPH,MXI,MLM,XIMAX,LMMAX,LENHCP,ENHCPF,IRTN)

    MY
    Number of y's. (i-th y point is tex2html_wrap_inline11094, tex2html_wrap_inline11096)
    MPH
    Maximum number of laser photons. (tex2html_wrap_inline11098)
    MXI
    Number of tex2html_wrap_inline7924's. (tex2html_wrap_inline11102, tex2html_wrap_inline11104)
    MLM
    Number of tex2html_wrap_inline7928's. (tex2html_wrap_inline11108, tex2html_wrap_inline11110)
    XIMAX
    Maximum tex2html_wrap_inline7924.
    LMMAX
    Maximum tex2html_wrap_inline7928.
    LENHCP
    Flag to apply a rate enhancement function.
    ENHCPF
    Enhancement function name declared external. Used when LENHCPtex2html_wrap_inline72481. 
    IRTN
    Return code.
A second call of NLCPST will replace the parameters and the arrays created in the first call.

The enhancement function, if needed, has to be defined as

            FUNCTION ENHCPF(Y)
            REAL*8 ENHCPF,Y
            ENHCPF=......
            RETURN
            END
The enhancement function has to be a function of tex2html_wrap_inline11084 (tex2html_wrap_inline11086) only and it must be tex2html_wrap_inline7900 for all y. The probability functions tex2html_wrap_inline10242 are multiplied by ENHCPF(y). Note that y close to 1 represents events with high energy photons and, hence, low energy recoil electrons. See NLCPGN for how the enhancement should be treated in the simulation.

Possible errors 1ex

    IRTN=1000
    Memory insufficient. You have to reduce MYtex2html_wrap_inline9166MPHtex2html_wrap_inline9166MXItex2html_wrap_inline9166MLM or increase the parameter MW in the FORTRAN source.
    IRTN=1001 to 1004
    Either one of MY,MPH,MXI,MLM is too large.
    IRTN=1100
    The enhancement function less than 1 at some y.

After initialization, an event can be generated by 1ex

   CALL NLCPGN(PE1,WL,NL,HE1,HL,PD,DT,PMAX,IRR,NPH,PE2,HE2,PG,HG,
               PROB,WGT,IRTN)

Input variables

    PE1
    Array of dimension (0:3). Initial electron 4-momentum (eV/c).
    WL
    Laser photon energy (eV).
    NL
    Array of dimension 3. Unit vector along the laser direction.
    HE1
    Initial electron helicity. (tex2html_wrap_inline11140HE1 tex2html_wrap_inline7954).
    HL
    Laser helicity. (+1 or -1).
    PD
    Laser power density (Watt/mtex2html_wrap_inline7792).
    DT
    Time interval times velocity of light. (meter).
    PMAX
    Maximum radiation probability in the given time interval. If the probability exceeds PMAX, return with IRTN=100 without event generation. You need to reduce the time interval DT.
    If you set, for example, PMAX=0.1, then you are ignoring the probability (=PMAXtex2html_wrap_inline7792=0.01) of two (and more) events within DT. A smaller PMAX is safer but more time consuming.
    IRR
    Random number seed.

Output variables

    NPH
    If tex2html_wrap_inline11152, one event is created with NPH laser-photon absorption. If =0, no radiation (following variables are meaningless.)
    PE2
    Array of dimension (0:3). Final electron 4-momentum (eV/c).
    HE2
    Final electron helicity. (tex2html_wrap_inline11140HE2 tex2html_wrap_inline7954).
    PG
    Array of dimension (0:3). Final photon 4-momentum (eV/c).
    HG
    Final photon helicity. (tex2html_wrap_inline11140HG tex2html_wrap_inline7954).
    PROB
    Calculated event probability. When an error occurs with IRTN=100, you have to multiply DT at least by a factor PROB/PMAX.
    WGT
    Weight factor of the event. It is always 1 if LENH=0 at the initialization. If not equal to 1, then you should asign a weight tex2html_wrap_inline11164WGT for the final photon end electron and let the initial electron survive with the weight tex2html_wrap_inline11166, where tex2html_wrap_inline11168 is the weight of the initial electron before the event. If WGT=1, you should eliminate the initial electron and asign the weight tex2html_wrap_inline11168 for the final photon and electron.
    IRTN
    Return code.

Possible errors

IRTN=1000
Initialization not yet done.
IRTN=1001
tex2html_wrap_inline7924 is larger than XIMAX.
IRTN=1002
tex2html_wrap_inline7928 is larger than LMMAX.
IRTN=100
The total rate exceeds PMAX.


next up previous contents index
Next: Algorithm Up: Compton Process Previous: Formulas

Toshiaki Tauchi
Thu Dec 3 17:27:26 JST 1998