Hi, I have a sphere that it contains many sub-spheres. I want to define these small spheres as volumetric source. But when I run MCNP, it doesn't work. MCNP error: the sampeling effeiciency is too low(adsbygoogle = window.adsbygoogle || []).push({});

Maybe someone can help me.

100 0 10

200 1 -1 -10 fill=2

300 1 -1 -2 3 -4 5 -6 7 u=2 lat=1

fill=-8:8 -8:8 -8:8 3 4912r

400 1 -1 30 u=3

500 1 -1 -30 40 u=3

600 1 -1 -40 50 u=3

700 1 -1 -50 u=3

c *************** Surfaces**********************

10 so 5

2 px 0.31

3 px -0.31

4 py 0.31

5 py -0.31

6 pz 0.31

7 pz -0.31

30 so 0.3

40 so 0.29

50 so 0.2

c Water (rho=1)

M1 1001 0.333

8016 0.667

imp:e 0 1 1 1 1 1 1

mode e

sdef pos=0 0 0 rad=d1 cell=d2

si1 0 0.3

sp1 -21 2

si2 L (700<300<200)

sp2 1

nps 1000

Thank you

with best regards

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# MCNP lattice source

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