INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 *

Outlines 1- NEMO Phase 2 Tower (N2T) 2- Montecarlo Time Windows of atmospheric muons in N2T 3- Strategies for tagging muon tracks 3- Background studies 4- Trigger Efficiencies and expected muon rates 5- Level 1 TW Trigger 7- possible L2 Triggers and their expected muon rates 8- L1 and L2 Trigger Results on Real data 9- NEMO Tower Phase 3 10- Conclusion INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

NEMO Phase 2 Tower 8 floors 8 m bars, vertical dist. = 40 m, Htot = 450 m 32 OM, 18 hydrophones oceanographic instrumentation The OM: 10” Hamamatsu R7081, Front End Module, Time Calibration, LED beacons INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Montecarlo Time Windows of atmosferic muon tracks in Nemo 2 Tower Using Mupage to generate vertical muon tracks with Zenith angle 0-3° Time Windows is the time difference between the first and the last photons of the muon track. Without background Direct photons Direct and diffuse photons INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Montecarlo Time Windows of atmosferic muons in N2T Muon tracks with Zenith angle 0-85°. Without background Most of the muon track direct photon hits are within a 1000 ns Time Windows . . INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Strategies for tagging a muon track - To reconstruct a muon track must be tagged Nhit ≥ 5 hits in different PMTs After charge calibration the hit charges > electronic pedestal After time calibration the hit times must be time ordered The hit times are in a TW < 1500 ns If from direct photons the hits are in a TW < 1000 ns - At Level 2 the trigger rate must be ~100 Hz We consider only the hit times. We choose to tag a fixed number of hits in a TW of a maximum fixed value. What is the rate ( ~ background) of the TW triggers (Level 1 )? What is the muon track TW efficiency? How to reduce the rate at Level 2 trigger maintaining the track efficiency? INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

How the TW Trigger works The selected sorted hits must have NHit from different PMT in a TW. (→ also from same PMT) 8 hits Time DN8 TW trigger (≠ PMTs) 9 hits N8 TW trigger (= PMTs) INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 *

MC Time Difference Distribution of the background Background: 47kHz for each PMT (measured mean value from data raw) to study the time difference distributions of the bk hits Time Different distribution between the 1st and 3th,…., 8th hit. Time Different distribution between the 1st and 8th hit t3-t1 8 hits in TW=1400 t4-t1 t8-t1 As the Time Difference increases the number of hits increses and the probability of having Nhit is decrasing with the hit number. INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Nhit background distribution in the TWs <DN>= 2.87 TW1200 <DN>=2.61 TW1000 <DN>=2.35 The trigger efficiency of a muon track with only few hits depends on the background rate. For an example : if a track has 5 hits in a TW1400 and the request of the trigger is “ 8 consecutive hits in the TW1400 ” at least 3 hits must be bk hits and the efficiency is~ 59% (28%+17%+8%+5%+1%....). INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 *

MC rates in kHz/ probability in % : N background hits in the TW Time Difference Distribution of the background Calculated background TW Trigger rates (kHz) MC rates in kHz/ probability in % : N background hits in the TW N1 N2 N3 N4 N5 N6 N7 N8 N ≥7 N ≥8 BK: 47.2 kHz nHit/s: 1.46 x 106 TW1000 365 / 25% 518 / 36% 350 / 24% 156 / 11% 55.5 / 3.8% 12.3 / 0.8% 2.4 / 0.16% 0.38 / 0.03% 2.8 / 0.23% 0.83/ 0.04% TW1200 277 / 19% 501 / 35% 474 / 33% 207 / 14% 82.0 / 5.6% 23.0 / 1.6% 5.4 / 0.37% 1.1 / 0.08% 6.8 / 0.47% 1.3 / 0.09% TW1400 210 / 14% 424 / 29% 409 / 28% 254 / 17% 113 / 7.8% 37.4 / 2.7% 10.9 / 0.74% 1.7 / 0.12% 13.1 / 0.90% 2.2 / 0.15% BK: 51.9 kHz nHit/s: 1.61 x 106 354 / 22% 612 / 38% 419 / 26% 190 / 12% 77.3 / 4.8% 19.3 / 1.2% 4.2 / 0.26% 0.77 / 0.05 5.0 / 0.31% 0.87 / 0.05% 258 / 16% 483 / 30% 423 / 28% 109 / 6.8% 35.0 / 2.2% 9.0 / 0.56% 1.9 / 0.12% 12 / 0.74 % 2.40 /0. 15% 193 / 12% 451 / 28% 306 / 19% 146 / 9.2% 59.0 / 3.7% 17.7 / 1.1% 4.5 / 0.28% 24 / 1.47% 5.7 / 0.35% BK: 56.4 kHz nHit/s: 1.75 x 106 333 / 19% 595 / 34% 565 / 32% 250 / 14% 94.5 / 5.4% 28.0 / 1.6 % 6.3 / 0.36% 1.19 / 0.07 8.2 / 0.47% 1.4 / 0.08 241 / 14% 490 / 28% 481 / 28% 315 / 18% 144 / 8.2% 52.5 / 3.0% 14.7 / 0.84% 3.5 / 0.2% 19.1 / 1.09% 4.37 / 0.25% 175 / 10% 429 / 25% 48ì / 28% 385 / 22% 193 / 11% 83 / 4.7% 28 / 1.6% 7.5 / 0.75% 39.2 / 2.24% 9.47 / 0.54% DN>=8T W1400 ≡ DN>=7 TW1000 (~same rates) INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Trigger Efficiency calculation A 10 µs of bk was superimposed to the hits of muon tracks with Zenith angle 0-85°. The extraction is repeteated 100 times. The trigger was applied on the 100 samples. The track is tagged if the muon hits ≥ 1 in selected N hits in TW. Few consecutive TW can tag the hits of the same muon track N8TW1400 (black) SC (aqua) FC (bright green) DN8TW1400 gives neary simlar effciency to SC with a lower background rate INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 *

Trigger Efficiency MC calculation : Muon tracks with Zenith angle 0-85°. @47kHz DN6TW1000 DN7TW1000 DN8TW1000 @60kHz Trigger efficiencies for DN6TW1000 (black), DN7TW1000 (red) and DN8TW1400 (bright green), at 47.2kHz (left) and 60 (right). We can achieve a better efficiency by requiring a small number of hits, but the corresponding rates will increase. The efficiency increases as the background rates increase. INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Trigger Efficiency N7TW1000 N8TW1400 Cut_1 (black) and Cut_4 (blue) for 47.2kHz (dash line) and 60kHz (solid line). The background increases the trigger efficiency INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

The Level 1 TW Trigger Considering - The TW trigger rates and efficiencies The time for trigger searching The probability to have more than one hit from a same PMT we propose to implement N7TW1000 as level 1 trigger: 7 consecutive hits also from the same PMT in the TW = 1000 ns MC bk rate ranging from 2.8 kHz to 8.2 kHz Mean measured rate on data: ~ 6kHz TrNhit = 5 tagging efficiency >60%: Expected muon rate With N7TW1000 1.2 Hz INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 *

Level 2 Trigger After the (L1) N7TW1000 successive L2 cuts are applied: Single Coincidence SC0 (1-2, 3-4) (same plane ΔT = 20 ns) SC1 (2-3, 1-3, 2-4) (same plane ΔT = 100 ns /80 ns) SC= SC0 + SC1 Floor Coincidence FC (Δplane =1 ΔT = 300ns / 250 ns ) 1 (L1) - N7TW1000 2 (L2) - N7TW1000 & SC 3 (L2) - N7TW1000 & FC 4 (L2) - N7TW1000 & SC & FC 5 (L2) - N7TW1000 & ( (SC & FC ) || (SC>1) || (FC>1)) 6 (L2) - N7TW1000 & (SC || FC)) 1 2 3 4 INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 *

Trigger Efficiency N7TW1000 rates @ 47 kHz and 60 kHz Trigger Efficiency for N7TW1000 @ 47 kHz (left) and @ 60 kHz (right) N7TW1000 rates @ 47 kHz and 60 kHz Cut_4 (bright blue) has the worst efficiecy in these triggers is Cut_4 = Cut_1 & SC > 0 & FC > 0 with the lowest rate. INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Distibution total number of hits of Distibution number of PMTs by Triggers Comparaisons N7TW1000 Trigger @ 47kHz and 60 kHz Hits of detected muons Hits of missed muons @ 47 kHz @ 60.0 kHz Distibution total number of hits of muon tracks Distibution number of PMTs by INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Trigger Rates raw data Estimated rates on simulated and raw data The mean PMT rates were extracted from raw data, keeping only the hits with a charge above the pedestal threshold. INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Trigger L2 The FD geometry cut We have also tested other trigger cuts: The FD geometry cut Muon tracks Bkg MC Bkg raw data Finally we merge the triggered time interval INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

(Bkg/muon tracks) @ 47kHz L2 Trigger rates (Bkg/muon tracks) @ 47kHz SC1 (100 ns), FC (300ns) N7TW1000 N7TW1000+SC N7TW1000+SC+FC N7TW1000+SC+FC+NF N7TW1000+SC+FC+NF+5PMT INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

(Bkg/muon tracks) @ 47kHz L2 Trigger rates (Bkg/muon tracks) @ 47kHz SC1 (80 ns), FC (250 ns) N7TW1000 N7TW1000+SC N7TW1000+SC+FC N7TW1000+SC+FC+NF N7TW1000+SC+FC+NF+5PMT INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Trigger Rates INFN-Pisa * INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

NEMO Tower Using N8TW700 as L1 Trigger 6 PMT / Tower SC0=20ns SC1=80ns 3 4 6 5 Using N8TW700 as L1 Trigger 2 3 4 6 5 8 floors 6 PMT / Tower SC0=20ns SC1=80ns SC2=50ns FC= 150-250ns 1 2 3 4 6 5 1 2 3 4 6 5 8 floors 2 3 4 6 5 Bkg/muon tracks rates @ 47kHz for N8TW700 using only 8 floors INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

Collaboration Meeting, Roma – 12/10/2013 Conclusion 1 – Full montecarlo for trigger test was done and tested on Raw Data. 2 - We have seen that selecting N hits in a TW as a first step reduces drastically the background trigger rates. 3- The trigger is not based on Charge threshold. 4 – The efficiency of these triggers are optimistic. 6- triggers implementation on CPU-GPUs is underway. 7- We have seen that N7TW1000 gives better efficiency with same rates as N8TW1400. 8- Waiting Trigger integration in TriDAQ. INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *

(Bkg/muon tracks) @ 47kHz L2 Trigger rates (Bkg/muon tracks) @ 47kHz N7TW1000 N7TW1000+SC+FC+NF+5PMT INFN-Pisa Collaboration Meeting, Roma – 12/10/2013 * INFN-Pisa *