We considered 6 collimator designs at various locations. Each of the geometries for the simulations had a 50 cm thick lead shielding wall. This is neither the best wall nor a reasonable option, however given the short amount of time to generate many simulations, we went with a 50 cm thick lead wall (I had more simulations completed with a lead wall than with no wall).
The geometries considered are:
- VT 10.53: The original collimator design
- VT 10.25: Reducing theta_max to 10.25
- VT 10.25 1/2: Decreasing thickness by 1/2, leave upstream face at original location
- GW 10.25: Collimator 5.25 cm thick W + 11.2 cm thick non-defining Pb shielding, theta_max 10.25, upstream face at VT location
- GW_2 10.25: 12.5 cm upstream
- YL 10.25: 25 cm upstream
Table 1: Elastic and Inelastic Backgrounds with and without a lintel
| Elastic Photons | Elastic Photons from coll. region | Inelastic Photons | Inelastic Electrons | Lintel? | |
| VT 10.53 | 0.204375% +/- 0.004862% | 0.044000% +/- 0.001901% | 0.015188% +/- 0.000319% | 0.062165% +/- 0.001520% | no |
| 0.190644% +/- 0.005052% | 0.015059% +/- 0.001049% | 0.014251% +/- 0.000314% | 0.060140% +/- 0.001514% | yes | |
| VT 10.25 | 0.209581% +/- 0.005073% | 0.034230% +/- 0.001653% | 0.019093% +/- 0.000402% | 0.073842% +/- 0.001850% | no |
| 0.199469% +/- 0.005080% | 0.016593% +/- 0.001126% | 0.019062% +/- 0.000410% | 0.069181% +/- 0.001793% | yes | |
| VT 10.25 1/2 | 0.233799% +/- 0.005138% | 0.050179% +/- 0.001944% | 0.020137% +/- 0.000409% | 0.072730% +/- 0.001794% | no |
| 0.205258% +/- 0.004799% | 0.024085% +/- 0.001201% | 0.019522% +/- 0.000408% | 0.073087% +/- 0.001802% | yes | |
| GW 10.25 | 0.212197% +/- 0.004940% | 0.036250% +/- 0.001707% | 0.020386% +/- 0.000421% | 0.073454% +/- 0.001788% | no |
| 0.191099% +/- 0.004760% | 0.014273% +/- 0.001073% | 0.019620% +/- 0.000406% | 0.075539% +/- 0.001824% | yes | |
| GW_2 10.25 | 0.204356% +/- 0.004942% | 0.035170% +/- 0.001722% | 0.019763% +/- 0.000411% | 0.076523% +/- 0.001892% | no |
| 0.179563% +/- 0.004826% | 0.005334% +/- 0.000667% | 0.018623% +/- 0.000402% | 0.073435% +/- 0.001817% | yes | |
| YL 10.25 | 0.203853% +/- 0.004984% | 0.030238% +/- 0.001607% | 0.019698% +/- 0.000410% | 0.071440% +/- 0.001850% | no |
| 0.173794% +/- 0.004778% | 0.001828% +/- 0.000318% | 0.018821% +/- 0.000407% | 0.068924% +/- 0.001819% | yes |
The background from the collimator region makes a big comtribution when switching to having the collimator region being filled with air and the global volume filled with helium (it was the opposite before):
Table 2: Elastic photon backgrounds after GLOB=HEL
| Elastic Photons | Elastic Photons from coll. region | Lintel? | |
| VT 10.53 | 0.093145% +/- 0.002941% | 0.041068% +/- 0.001796% | no |
| 0.064209% +/- 0.002492% | 0.014987% +/- 0.001087% | yes | VT 10.25 | 0.100619% +/- 0.003196% | 0.036673% +/- 0.001721% | no |
| 0.065692% +/- 0.002421% | 0.013546% +/- 0.001012% | yes | YL 10.25 | 0.089214% +/- 0.002901% | 0.032152% +/- 0.001598% | no |
| 0.060747% +/- 0.002454% | 0.002948% +/- 0.000506% | yes |