Mixtures and Compounds

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| Geant 3.15  |               GEANT User's Guide              | CONS110  ##
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Author(s) : R.Brun, M.Maire, J.Allison                 Submitted: 01/06/83
Origin    : R.Brun, M.Maire                              Revised: 10/12/92
                                  

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  |CALL GSMIXT (IMATE,NAMATE,A,Z,DENS,NLMAT,*WMAT*) |
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Defines mixture or compound IMATE as composed by NLMAT materials defined via the arrays A, Z and WMAT. Mixtures of compounds can also be defined.

Input parameters:

IMATE

(INTEGER) user material (mixture) number

NAMATE

(CHARACTER*20) mixture name (possibly ended by $)

A

(REAL) array of atomic weights

Z

(REAL) array of atomic numbers -3

DENS

(REAL) density in gcm

NLMAT

(INTEGER) number of elements in the mixture

NLMAT>0

WMAT is supposed to contain the proportion by weights of each material in the mixture

NLMAT<0

WMAT is supposed to contain the number of atoms of a given kind in the molecule of the compound. In this case, the content of WMAT in output is changed to contain the relative weights.

Input/Output parameters:

WMAT

(REAL) array containing the relative weights (NLMAT>0) or the number of atoms (NLMAT<0) of each component in the molecule. In output it will always contain the relative weights.

Called by: 120>

Calls: MZBOOK, MZPUSH, GMAIL, GPMATE, MZDROP, UCTOH, GHMIX

Method

For a compound (NLMAT<0) the molecular weight and charge are:

    A    =sum  N A                 Z    =sum  N Z                      (1)
     Mol    i   i i                 Mol    i   i i

th where N = WMAT(I) is the number of atoms of the i component of the i molecule. In this case the proportion by weight is:

    W  =((N  A )/(A   ))                                               (2)
     i     i  i    Mol

where W =WMAT(I) in output. From the relative weights, i GSMIXT works out the effective atomic weight and atomic number according to the following formulas:

    A    =sum  W A                 Z    =sum  W Z                      (3)
     eff    i   i i                 eff    i   i i

which are stored in the JMATE data structure [CONS199] together with the radiation length.

The radiation length is computed according to the EGS manual [bib-EGS3], formula 2 6 8 (37), for an element:

                           2                                   1/3
    ((1)/ (rhoX ))= 4alphar N  ((1)/(A))Z(Z+xi(Z))[ln((183)/ (Z   ))-F (Z)](4)
               0             Av                                       c

where

X

radiation length (in cm) 0 -3

rho

density (in gcm )

alpha

fine structure constant

r

classical electron radius (in cm)

N

Avogadro's number Av

A

atomic weight

Z

atomic number

F (Z)

Coulomb correction function c

                   2                  2                          2               4                6
    F (Z) =(alphaZ)  [((1)/(1+(alphaZ) ))+0.20206- 0.0369(alphaZ) +0.0083(alphaZ)  -0.0020(alphaZ) ](5)
     c

                          2/3                1/3
    xi(Z) =((ln((1440)/ (Z   )))/(ln((183)/(Z    ))-F (Z)))            (6)
                                                     c

for a compound or mixture:

    ((1)/ (rhoX))= sum ((W )/(rho X ))                                 (7)
                    i     i      i i

th where W is the proportion by weight of the i element. i

For more information on the organization of the data in memory see [CONS199].