Re: FLUKA: Too big material number

[Alberto Fasso' <Alberto.Fasso@cern.ch>]

Fan,

>  *** Fluka stopped in Xsread: group number disagreement between input and
> xsec file ****

There are several strange things in your input.

1)

MATERIAL, , , 1.18E-03, 12 , , , AIR1
COMPOUND 8, 1.06E+07, 7, 3.94E+07, 4, 1.32E+02 AIR1
                                   ^^^^^^^^^^^
You have defined material 4 as EARTH, but you in your air compounds
you seem to use it as it it was argon.

2) 

  SPH    1       0.0       0.0       0.0    638000000
I add a scale:
*...+....1....+....2....+....3....+....4....+....5....+....6....+....7

The last number is read as 638000, not 638000000 (I guess that is
supposed to be the Earth's radius? It turns out to be 6 km...)

3)

ASSIGNMAT 1.0 101

You are using option FREE. I am very glad (you are the first user
I know who does!) However, the use of FREE is regulated by some
strict rules. In particular, according to the manual:

   Zero values must be given explicitly or as empty places between
   two non-blank separators

If you check on output, the above line is echoed as:

 *****NEXT CONTROL CARD *****   ASSIGNMA   1.000       101.0       3.000
0.000       0.000       0.000

Note the spurious WHAT(3) = 3.0, which is interpreted by the program as:
"Assign material #1 from region 101 to region 3 (!) in step of 1"
(meaningless and with unpredictable consequences).

If I modify the above assignment to:
ASSIGNMAT 1.0, 101., , , ,

I get the correct echo:
 *****NEXT CONTROL CARD *****   ASSIGNMA   1.000       101.0       0.000
0.000       0.000       0.000 

This type of error is present in most of your input lines, and results
in a number of unexpected results. For instance:

LOW-NEUT
is read as:
 *****NEXT CONTROL CARD *****   LOW-NEUT   110.0       0.000       0.000
0.000       0.000       0.000 

(this is probably the cause of the error message you have reported).
It should be

LOW-NEUT , , , , , 
which is correctly echoed:
 *****NEXT CONTROL CARD *****   LOW-NEUT   0.000       0.000       0.000
0.000       0.000       0.000                

Apart from that, whether you use FREE input or not, I strongly advise
you to do two things:
1) Write always all the WHATs with the decimal point.  
2) Always check your input against the FLUKA main output. Many errors 
are easy to spot in the echo lines starting with 
"*****NEXT CONTROL CARD*****"

Best regards,

    Alberto



-- 
Alberto Fassò
CERN-EP/AIP, CH-1211 Geneve 23 (Switzerland)
Phone: (41 22) 767 2398    Fax: (41 22) 767 9480   Alberto.Fasso@cern.ch