introduction from a neutron flux (> 20 mev), with the leaching model (lessard) based on sbms...
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Introduction
From a neutron flux (> 20 MeV), with the Leaching model (Lessard) based on SBMS (Tables 1 and 2): https://sbms.bnl.gov/sbmsearch/subjarea/40/1r09e011.pdf , we can obtain soil activation in pCi/L (assuming soil interaction parameter of 60 cm), and vice versa.
The models in Booster that I have used here are the ones built my 2012 SULI student Allison Matus for B6 beam dump and D6 septum. The former probably has more shielding than the E7 magnet whereas the latter has less shielding than the E7 magnet.
Nevertheless, the result for the same contour are similar (probably within 50 cm or so).
2.278 x 10-104.000 x 10-11
1.297 x 10-9
7.384 x 10-9
4.204 x 10-8
Beam Dump (B6)
Beam Direction
Soil
SoilNeutron fluxes in cm-2 per incident proton
�Sky direction points out of page
Beam Dump of Booster
2.384 x 10-7
0 600 cm-600 cm
0-6
00 c
m60
0 cm
Beam Direction
Septum
0 600 cm-600 cm
0-6
00 c
m60
0 cm Soil
Soil
Concrete
�Sky direction points out of page
Neutron fluxes in cm-2 per incident proton
Extraction Septum of Booster
3.000 x 10 -111.926 x 10 -101.236 x 10 -9
7.936 x 10 -95.094 x 10 -8
2.384 x 10-7
Comparison using the soil sample in E7 Cap
Soil sample(s) placed at E7 at beam height (eg. at 90) for 4 weeks with intensity of 21011 protons every 3.9 seconds have resulted in 24.4 pCi/L (22Na) or 257 pCi/L (3H) at 90
3.1 108 neutrons/cm2 (using the afore-mentioned leaching model)
In MCNPX simulation at beam height, with the B6 model (the one with more shielding) 8 107 neutrons/cm2 near tunnel wall
below the floor 5 108 neutrons/cm2 (though inappropriate comparison)
26 times more than the above soil sample has shownIf we assume the radiochemistry done for the soil sample and our assumption of the location of the bottle are perfect, then the assumption of 100% loss of 21011
protons, the leaching model and/or MCNPX simulation are all too “conservative” (or exaggerated).
Boundaries
5 months of running with loss intensity of 41011 protons every 4 seconds
Using the limit of 1000 pCi/L (3H) (and 60 cm as soil interaction length) 1.17 108 neutrons/cm2 (using the leaching model)
{ Previously, if I used 20 pCi/L (22Na) and 40 cm as soil interaction length), it was ~1.6109 /cm2. }
With the contours underneath the floor and at beam height, I can set boundaries, after we agree on the parameters (such as loss intensity and duration ….)
1.17 x 10-8
Beam Dump (B6)
Beam Direction
Soil
SoilNeutron fluxes in cm-2 per incident proton
�Sky direction points out of page
Beam Dump of Booster
0 600 cm-600 cm
0-6
00 c
m60
0 cm Underneath
1.17 x 10-8
Beam Dump (B6)
Beam Direction
Soil
SoilNeutron fluxes in cm-2 per incident proton
�Sky direction points out of page
Beam Dump of Booster
0 600 cm-600 cm
0-6
00 c
m60
0 cm Beam
height
Backup
2.278 x 10-10
4.000 x 10-11
1.297 x 10-9
7.384 x 10-9
4.204 x 10-8
Beam Dump (B6)
Beam Direction
Soil
SoilNeutron fluxes in cm-2 per incident proton
�Sky direction points out of page
Beam Dump of Booster
2.384 x 10-7
0 600 cm-600 cm
0-6
00 c
m60
0 cm
Beam height