MCNPX dose result is too small

  • Thread starter Kim Jae ryang
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    Mcnpx
In summary, there could be several reasons why your MCNPX dose result is showing as too small, including errors in your input file, improper selection of materials or geometry, or incorrect boundary conditions. To fix this issue, you should carefully review and correct any mistakes in your input file, make adjustments to accurately represent the system, and adjust your boundary conditions if necessary. While limitations of the program could potentially contribute to small dose results, it is more likely that the issue lies within the input file or simulation setup. To avoid small dose results, it is important to carefully review and validate your input file, consult with experienced users, and refer to the program's documentation for best practices. If you do encounter a small dose result, it is possible
  • #1
Kim Jae ryang
1
0
I want to calculate absorbed dose by MCNP and phantom.
describe x-ray tube and set radiation filed is 30cm x 30cm
I use SRS-78, describe sorce card. 100kev 20mAs 14degree target is tungsten and film is Al 3mm.

I use *f6 tally
so I convert jerk/g ->Mev/g use 1Mev = 1.60E-22jerk
and then Mev/g->Gy use 1gy=6.24E+07mev/g
finallt comply photon number, electron's number (0.02A/1.602*10-19c) * electron->phton convert percentage (0.002072)

then ESD is 1.08E-30 -> 0.027882mGy
and real esd is 2.41mGy... my result is too small... ;(
What can I do...? sombody please help me...
:oldeek: :bow:
Code:
cell card
666 0   11 -12 13 -14 16 -17  fill=1000  imp:p,e=1 $ phantom box
        *trcl=(0 0 0  180 90 90  90 0 90 90 90 180
999 0   99                               imp:p,e=0                               $ exterior - zero importance
101 101 -11.34 -110 120 310              imp:p,e=1                               $ out
201 201 -1e-20 -120 #310                 imp:p,e=1                               $ in
310 201 -1e-20 -310                      imp:p,e=1                               $ hole
401 401 -1.19 -401                       imp:p,e=1                               $ table
255 301 -4.0866e-05 -255 imp:p,e=1
888 301 -4.0866e-05  -99 #101 #310 #201 401 255 #666  imp:p,e=1                            $ remainder

C ******************************************************************************
C                               Surface cards
C ******************************************************************************
7   rpp 0 0.40702 0 0.40702 0 0.41494
11  px -26.4563 $ phantom box
12  px  26.4563
13  py -10.98954
14  py  10.98954
16  pz -85.47764
17  pz  85.47764
99  so  200  $ exterior boundary
401 rpp -30 30 10.99 15.99 -90 120                                                     $ table
c 310 arb -0.75 -95 26.5   -0.75 -95 23.5    0.75 -95 26.5    0.75 -95 23.5 &
c          -1.05 -93 26.8   -1.05 -93 23.2   1.05 -93 26.8   1.05 -93 23.2 &
c          1234 5678 1256 2367 3478 1458
310 arb -1.05 -93 26.8  -1.05 -93 23.2  1.05 -93 26.8  1.05 -93 23.2
         0 -100 25 0 0 0 0 0 0 0 0 0 1234 1250 1350 2450 3450 0
110 rpp -10 10 -105 -93  0 60                                                   $ out
120 rpp -7 7 -103 -95 3 57                                                      $ in
255 rpp -10 10  -11.15 -10.99 5 45                                             $ dosimeter

C ******************************************************************************
C                                Data cards
C ******************************************************************************
mode p
c ***************************external source definition ************************
sdef erg=d1 par=p vec=0 1 0 x=d2 y=-100 z=d3
# si1     sp1                                                                    $ 100kev/photon per
      H       D   
0.0055  0
0.0060 2.53787E-36
0.0065 4.53838E-28
0.0070 7.90870E-22
0.0075 4.60489E-17
0.0080 2.27444E-13
0.0085 2.32820E-09
0.0090 3.80753E-08
0.0095 2.48905E-05
0.0100 6.76525E-04
0.0105 6.50982E-04
0.0110 7.32045E-03
0.0115 1.29870E-01
0.0120 2.14734E-01
0.0125 7.89059E-01
0.0130 2.81979E+00
0.0135 8.54959E+00
0.0140 2.12839E+01
0.0145 4.84736E+01
0.0150 9.98039E+01
0.0155 1.89155E+02
0.0160 3.34992E+02
0.0165 5.51036E+02
0.0170 8.70073E+02
0.0175 1.29511E+03
0.0180 1.86130E+03
0.0185 2.58252E+03
0.0190 3.45899E+03
0.0195 4.51790E+03
0.0200 5.74212E+03
0.0205 7.10781E+03
0.0210 8.70630E+03
0.0215 1.03834E+04
0.0220 1.22547E+04
0.0225 1.41938E+04
0.0230 1.62758E+04
0.0235 1.83238E+04
0.0240 2.05871E+04
0.0245 2.27133E+04
0.0250 2.48106E+04
0.0255 2.70535E+04
0.0260 2.92121E+04
0.0265 3.12390E+04
0.0270 3.33473E+04
0.0275 3.52724E+04
0.0280 3.72598E+04
0.0285 3.89947E+04
0.0290 4.07637E+04
0.0295 4.22247E+04
0.0300 4.36956E+04
0.0305 4.51762E+04
0.0310 4.62913E+04
0.0315 4.75532E+04
0.0320 4.85658E+04
0.0325 4.95373E+04
0.0330 5.03755E+04
0.0335 5.11067E+04
0.0340 5.17434E+04
0.0345 5.23314E+04
0.0350 5.27595E+04
0.0355 5.31692E+04
0.0360 5.34815E+04
0.0365 5.36802E+04
0.0370 5.38625E+04
0.0375 5.39485E+04
0.0380 5.40203E+04
0.0385 5.39978E+04
0.0390 5.39147E+04
0.0395 5.38207E+04
0.0400 5.36686E+04
0.0405 5.34596E+04
0.0410 5.32113E+04
0.0415 5.29090E+04
0.0420 5.26018E+04
0.0425 5.22902E+04
0.0430 5.18971E+04
0.0435 5.15484E+04
0.0440 5.11055E+04
0.0445 5.06928E+04
0.0450 5.02196E+04
0.0455 4.97774E+04
0.0460 4.92918E+04
0.0465 4.87643E+04
0.0470 4.82981E+04
0.0475 4.77767E+04
0.0480 4.72306E+04
0.0485 4.67309E+04
0.0490 4.61933E+04
0.0495 4.56191E+04
0.0500 4.50884E+04
0.0505 4.45276E+04
0.0510 4.39724E+04
0.0515 4.34214E+04
0.0520 4.28426E+04
0.0525 4.23043E+04
0.0530 4.17376E+04
0.0535 4.11770E+04
0.0540 4.06226E+04
0.0545 4.00416E+04
0.0550 3.94994E+04
0.0555 3.89313E+04
0.0560 3.83698E+04
0.0565 3.78146E+04
0.0570 3.72656E+04
0.0575 3.67225E+04
0.0580 1.23163E+05
0.0585 3.56251E+04
0.0590 3.50996E+04
0.0595 1.88026E+05
0.0600 3.40095E+04
0.0605 3.34735E+04
0.0610 3.29431E+04
0.0615 3.24184E+04
0.0620 3.18991E+04
0.0625 3.13850E+04
0.0630 3.08510E+04
0.0635 3.03473E+04
0.0640 2.98484E+04
0.0645 2.93304E+04
0.0650 2.88176E+04
0.0655 2.83319E+04
0.0660 2.78289E+04
0.0665 2.73305E+04
0.0670 7.95528E+04
0.0675 2.63477E+04
0.0680 2.58629E+04
0.0685 2.53824E+04
0.0690 3.88928E+04
0.0695 2.39214E+04
0.0700 2.09638E+04
0.0705 2.06428E+04
0.0710 2.03035E+04
0.0715 1.99791E+04
0.0720 1.96530E+04
0.0725 1.93095E+04
0.0730 1.89802E+04
0.0735 1.86343E+04
0.0740 1.83022E+04
0.0745 1.79541E+04
0.0750 1.76193E+04
0.0755 1.72691E+04
0.0760 1.69182E+04
0.0765 1.65799E+04
0.0770 1.62271E+04
0.0775 1.58738E+04
0.0780 1.55325E+04
0.0785 1.51777E+04
0.0790 1.48223E+04
0.0795 1.44665E+04
0.0800 1.41103E+04
0.0805 1.37538E+04
0.0810 1.33969E+04
0.0815 1.30397E+04
0.0820 1.26925E+04
0.0825 1.23345E+04
0.0830 1.19764E+04
0.0835 1.16182E+04
0.0840 1.12507E+04
0.0845 1.08927E+04
0.0850 1.05345E+04
0.0855 1.01766E+04
0.0860 9.81862E+03
0.0865 9.46077E+03
0.0870 9.10319E+03
0.0875 8.74571E+03
0.0880 8.38856E+03
0.0885 8.02516E+03
0.0890 7.66889E+03
0.0895 7.31300E+03
0.0900 6.95752E+03
0.0905 6.59716E+03
0.0910 6.24292E+03
0.0915 5.88924E+03
0.0920 5.53613E+03
0.0925 5.17944E+03
0.0930 4.82790E+03
0.0935 4.47707E+03
0.0940 4.12365E+03
0.0945 3.77464E+03
0.0950 3.42647E+03
0.0955 3.07668E+03
0.0960 2.73057E+03
0.0965 2.38544E+03
0.0970 2.03966E+03
0.0975 1.69685E+03
0.0980 1.35403E+03
0.0985 1.01373E+03
0.0990 6.74065E+02
0.0995 3.36438E+02
0.1000 2.80147E+01
si2 h -2.5 2.5
sp2 0 1
si3 h 22.5 27.5
sp3 0 1
c ******************************************************************************
c
c ***************************internal source definition ************************
c read file=OrganID_10.txt noecho
c ******************************************************************************
nps 10e7
c ------------------------------------------------------------------------------
*f106:p (10<555)  $ rbm
*f126:p (12<555)  $ colon
*f146:p (14<555)  $ lung
*f166:p (16<555)  $ stomach
*f186:p ((18 19)<555)  $ breast (adipose tissue)
*f206:p (20<555)  $ ovary
*f226:p (22<555)  $ bladder
*f246:p (24<555)  $ oesphagus
*f266:p (26<555)  $ liver
*f286:p (28<555)  $ thyroid
*f306:p (30<555)  $ bone
*f326:p (32<555)  $ brain
*f346:p (34<555)  $ salivary glands
*f366:p (36<555)  $ skin
*f386:p (38<555)  $ Adrenals
*f406:p (40<555)  $ ET region
*f426:p (42<555)  $ Gall bladder
*f446:p (44<555)  $ Heart
*f466:p (46<555)  $ Kidneys
*f486:p (48<555)  $ Blood (Lymphatic nodes)
*f506:p (50<555)  $ Muscle
*f526:p (52<555)  $ Oral mucosa
*f546:p (54<555)  $ Pancreas
*f566:p (56<555)  $ Uterus
*f586:p (58<555)  $ Small intestine
*f606:p (60<555)  $ Spleen
*f626:p (62<555)  $ Thymus
*f646:p (64<555)  $ Eyes
*f666:p (66<555)  $ Lens
*f686:p (68<555)  $ Spinal cords
*f706:p (70<555)  $ Teeth
*f726:p (72<555)  $ Tongue
*f746:p (74<555)  $ Tonsils
*f766:p (76<555)  $ Trachea
*f786:p (78<555)  $ Bronchi
*f806:p (80<555)  $ Ureter
*f826:p (82<555)  $ Pallopian tubes
*f846:p (84<555)  $ Vagina
*f906:p (90<555)  $ Residual tissue
*f996:p 401
*f986:p255
-------------------------------------------------------------------------------
read file=HDRK-Woman_mat noecho
m101  82000 1.0                                                                  $lead
m401  6000  1.0                                                                  $C
m201 8000 0.2 7000 0.8                                                           $vacuum
m301   6000 -0.000124                                                            $C
       7014  -0.755636                                                           $N
       8016 -0.231475                                                            $O
       18000 -0.012889                                                           $Ar
 
Last edited by a moderator:

Related to MCNPX dose result is too small

1. Why is my MCNPX dose result showing as too small?

There could be several reasons why your MCNPX dose result is showing as too small. It could be due to errors in your input file, improper selection of materials or geometry, or incorrect boundary conditions. It is important to carefully review your input file and make sure all parameters are correct before running the simulation.

2. How can I fix the issue of MCNPX dose result being too small?

If the cause of the small dose result is due to errors in your input file, you should go back and carefully review and correct any mistakes. If the issue is related to the selection of materials or geometry, you may need to make adjustments to accurately represent the system you are simulating. Additionally, you may need to adjust your boundary conditions to better reflect the real-world scenario.

3. Can the small MCNPX dose result be due to limitations of the program?

While it is possible that the small dose result could be due to limitations of the MCNPX program, it is more likely that the issue lies within the input file or setup of the simulation. MCNPX is a widely used and reliable simulation program, so it is important to carefully review your inputs and ensure they accurately represent your system.

4. Are there any best practices for avoiding small MCNPX dose results?

To avoid small dose results in MCNPX, it is important to carefully review and validate your input file before running the simulation. This includes checking for errors, selecting appropriate materials and geometry, and accurately representing boundary conditions. It may also be helpful to consult with experienced MCNPX users or refer to the program's documentation for best practices.

5. Is it possible to troubleshoot and improve a small MCNPX dose result?

Yes, it is possible to troubleshoot and improve a small MCNPX dose result. As mentioned before, carefully reviewing and correcting your input file is the first step. You may also want to consider adjusting your simulation parameters, such as increasing the number of particles or refining your mesh. Additionally, seeking assistance from experienced MCNPX users or consulting the program's documentation may provide helpful insights and solutions.

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