1. Reconstruction of the SC with rime
Dmitry Chirkin, LBNL

2. SC event sample cuts
distance from COG: poorly reconstructed cascades (e.g., muon events) are pushed far away
log likelihood difference of cascade and track reconstructions
energy part or llh (Phit-Pnohit)

3. Cuts and reconstructed energy
100% laser intensity run
cascade peak is well selected as seen from both energy and Nch distributions
reconstructed energy is log(8.76)/81 cm^2/ = 0.52 PeV

4. Why Nch distribution is so wide

5. Positional resolution

6. Positional reconstruction accuracy

7. All runs: summary % En GeV Rms x y z 100 8.76 519 0.29 15.29 6.11 3.00
8.91
732
0.23
19.81
7.51
2.62 50
8.80
452
0.19
12.80
4.46 25
8.57
335
15.11
6.49
2.59 5
8.10
113
0.16
7.83
3.58
2.46
0.5
7.30 18
0.08
13.53
6.47
3.14

8. Linearity at high Q

9. Systematic errors, or charge reweighting
Too much emphasis is given the saturated DOMs
Remove DOMs above saturation charge from energy llh
assign them systematic errors instead of sqrt(N) Poisson
still correct charge below and close to saturation
Apply the systematic error “belt” to the probability function
for 1 d(ln f) error distribution and small systematic errors analytic approximation is possible
for 1 df distribution solution is terms of a difference of incomplete gamma functions (still computationally difficult)
may need to compute integrals numerically
a hybrid approach is possible with systematic errors larger in the intermediate distance region or for charges close to saturation

10. Laser prepulsing
a signal component correlated with the main pulse, some 300 ns before
this is larger than the PMT transient time – due to fast decay states or circuit LED light leaking out?
While the prepulse is cleaned away by the FeatureExtractor (it’s under 5% of the main pulse), the charge estimate is incorrect

11. Corrected energy estimate
100%, 50%, 76%, 50%, 25%, 5%, 0.5%
50%, 5%, 0.5%

12. Laser energy linearity

13. Laser energy estimate Cascade: 1.37 105 photons/GeV 
PMT efficiency / glass transparency at 337 nm at 40% of max
at 0.5%: 10^7.3 m^2 / (81 cm^2 * 40%) = ^9 photons
corresponds to energy of N/ = 45 TeV
scaling up 200 times: at 100% N = ^12; E=9 PeV
while N agrees with expectation, E is somewhat smaller
 different conversion factor?

14. Summary
Charge is underestimated due to a large emphasis on saturated PMT signal  somewhat correctable by removing oversaturated DOMs from energy llh, still needs better Ellh
deficiency in the flux function is somewhat repaired by adding systematic error consideration to the calculation
At 5 DOMs away from the laser the charge is proportional to the power percentage setting
At 0.5% the laser output is equivalent to a 45 TeV cascade
Therefore, at 100% the laser output is equivalent to a cascade of energy 9 PeV, still much less than 100 PeV
this is still much better than direct estimate: 1.5 PeV