1. Simulations of SST options (an update)‏
R D Parsons

2. Secondary optics in sim_telarray
Simulation of secondary optics is possible within sim_telarray
Curved focal planes are implemented by staggering of the pixels
Mirror shapes must be included in the form of a polynomial
Cross checks show it reliably recreates the results of other ray tracing programs

3. Telescope PSF
Version 17 telescope (JS) found to have best performance of those tested
Telescope has 4m primary and 2m secondary
PSF does not degrade too significantly across the field of view
Plate scale is however too large for our pixel size
Telescope size must be scaled down (3.4m)‏

4. Camera Layout 1472 pixel camera Consists of 23, 64 channel MaPMTs
Angular size of 0.2 deg
Using super bi-alkali photo- cathodes
Each pixel is 6.2mm
Camera Effective size of deg

5. 4 Large (23m)‏
23 Medium (12m)‏
120 Small (3.4m sec optics)‏

6. Results (Oxford)‏
Improvements seen in effective area over E at high energies (> 3 TeV)‏
At 1 TeV effective area lost where DC SSTs would be triggering
SecOpt (2 tels)‏
Array E (2 tels)‏
Loss in angular resolution over array E is minimal, especially if harder cuts are used
SecOpt (3 tels)‏

7. Array Layout Previous array found to have poor layout of telescopes
Cost model was also probably a little optimistic
A new simulation configuration has been suggested by Jim Hinton
Containing 3 array layouts, all sharing the same LST and MST arrangement

8. Array Layout 4 23m LSTs and 25 12m MSTs at the array centre
DC array , centre surrounded by 36 6m DC optics SSTs (green)‏
SO_1, centre surrounded by m SC optics SSTs (red)‏
SO_2, centre surrounded by m SC optics SSTs (magenta)‏

9. Array Layout
SO_1 aims to have a similar effective are a as DC array (~5 km2), but should have an improved angular resolution due to the smaller spacing of telescopes
SO_2 attempts to maximise effective area (~10 km2) while keeping the telescope spacing similar to that of the DC option
The comparison between these two SO arrays and the DC array, should help us understand angular resolution vs. effective area tradeoffs

10. Improvements to electronics
Previous SC telescope simulations have included unrealistic (and pessimistic) simulations of the camera electronics and image analysis
Improvements and investigations need to be made before SC optics can be included in prod 2 simulations
What needs improvement?
FADC Readout window
FADC sample rate
Trigger threshold
Tail cut level
Something else?

11. Investigations into SO SSTs
Simulations have been performed to find the optimum trigger threshold to the telescope
FADC sampling rate reduced to 500MHz
Two FADC window sizes will be investigated, 50 ns and 100 ns
The effect of using pulse finding algorithms on these large window sizes will also be investigated
Simulations adding these improvements and using the new array layout are underway

12. New Array Response
SO_2
Some low stats simulations have been performed with the new layout
Using a 50 ns gate length and no pulse finding DC
SO_1
Plots made are pre-background rejection cuts
30 p.e. amplitude cuts and 2 telescope multiplicity cuts

13. Other SST options
It has also been suggested that G-APDs may be used as a light sensor on a DC optic telescope (similar to FACT)‏
It should be possible to simulate such an arrangement within sim_telarray
Detailed input required:
QE of photosensor
Angular response of sensor + cone
Cost of sensor + cone, etc

14. Other SST options
It is also possible to use G-APDs as the sensor in the secondary optics solution
This would require a curved solid Winston cone surface
Some simulations have been performed by Isabel Braun
Again requires more detailed input for simulation in sim_telarray

15. Summary
sim_telarray is able to simulate all the proposed designs for the SST
Some early studies using SC optics have been performed, showing an increase in effective area above 3 TeV, with little effect on angular resolution
Work on a more realistic study is underway, improving the array layout and simulating the electronics chain more accurately
This work should produce results soon
Before G-APD designs can be simulated within sim_telarray more input is required