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

2. 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 *
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3. 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
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Collaboration Meeting, Roma – 12/10/2013 *
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4. 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
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Collaboration Meeting, Roma – 12/10/2013 *
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5. 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 *
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6. 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 *
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7. 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 *

8. 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 *
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9. 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 *

10. 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: 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: 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: 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)
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Collaboration Meeting, Roma – 12/10/2013 *
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11. 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 *

12. 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.
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13. 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
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Collaboration Meeting, Roma – 12/10/2013 *
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14. 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 *

15. Level 2 Trigger
After the (L1) N7TW 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
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Collaboration Meeting, Roma – 12/10/2013 *

16. Trigger Efficiency N7TW1000 rates @ 47 kHz and 60 kHz
Trigger Efficiency for 47 kHz (left) 60 kHz (right)
N7TW 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.
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Collaboration Meeting, Roma – 12/10/2013 *
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17. Distibution total number of hits of Distibution number of PMTs by
Triggers Comparaisons
N7TW kHz 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
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18. 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.
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19. 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
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Collaboration Meeting, Roma – 12/10/2013 *
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20. (Bkg/muon tracks) @ 47kHz
L2 Trigger rates
(Bkg/muon 47kHz
SC1 (100 ns), FC (300ns)
N7TW1000
N7TW1000+SC
N7TW1000+SC+FC
N7TW1000+SC+FC+NF
N7TW1000+SC+FC+NF+5PMT
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21. (Bkg/muon tracks) @ 47kHz
L2 Trigger rates
(Bkg/muon 47kHz
SC1 (80 ns), FC (250 ns)
N7TW1000
N7TW1000+SC
N7TW1000+SC+FC
N7TW1000+SC+FC+NF
N7TW1000+SC+FC+NF+5PMT
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22. Trigger Rates INFN-Pisa * INFN-Pisa
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23. NEMO Tower Using N8TW700 as L1 Trigger 6 PMT / Tower SC0=20ns SC1=80ns3 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= ns 1 2 3 4 6 5 1 2 3 4 6 5
8 floors 2 3 4 6 5
Bkg/muon tracks 47kHz for N8TW700 using only 8 floors
INFN-Pisa
Collaboration Meeting, Roma – 12/10/2013 *
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24. 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.
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Collaboration Meeting, Roma – 12/10/2013 *
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25. (Bkg/muon tracks) @ 47kHz
L2 Trigger rates
(Bkg/muon 47kHz
N7TW1000
N7TW1000+SC+FC+NF+5PMT
INFN-Pisa
Collaboration Meeting, Roma – 12/10/2013 *
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