1. Trigger report from Run2009
D. Nicolò
Pisa

2. Outlook New features Performance Run summary Todo’s for Run 2010
hardware
firmware
Performance
event reconstruction
observable resolution
efficiency
a novel trigger: a-calibration with beam on
Run summary
Todo’s for Run 2010
automatic gain adjustment
dead time reduction
Trigger report ...
1/30/2018

3. Hardware Optimization of FADC dynamic range
needed to be improved from Run 2008
further increase of XEC light yield towards nominal value
construction of newly designed FE cards with (0÷2V) swing
(used to be (0÷1V) beforehand)
400 brand-new cards mounted on XEC Type1 channels
(inner PMT 1:1 + side&outer PMT 4:1 inputs)
board reworking
transmission of FADC selection bit
operated from the beginning of CEX run (15/10/09)
with all XEC channels in the extended range
Resetting of active splitters
CM voltage changed to fit FADC range
 linearity from a few up to 130 MeV
Trigger report ...
1/30/2018

4. New FE scheme Low-pass filters (BW = 22 MHz) VOCM = VREF/2
Test and installation completed in October
Trigger report ...
1/30/2018

5. Board modification User-programmable bit to select AD9218 gain
0 = [0:1V]
Z = [0:2V]
completed in September
Trigger report ...
1/30/2018

6. Tuning of active splitters
used to be optimized to DRS2 range
depending on the offset value the CM output might exceed the voltage swing of amplifiers
only part of the current is integrated
 the gain is ~ 0.5 at low pulse height
 induced non linearity on the 4:1 output
Trigger report ...
1/30/2018

7. Splitter tuning Completed thanks to Y.Yudin before offset correction
after offset correction
Trigger report ...
1/30/2018

8. online vs offline, CEX Run 2008
Eγ, linearity in Run 2008…
online vs offline, CEX Run 2008
~4 MeV offset
Trigger report ...
1/30/2018

9. Eγ-linearity in Run 2009 - p  0 n  γ γ - p  γ n 11B(p,γ)12C
offset < 150 keV
int. non-linearity < 1%
7Li(p,γ)8Be
Trigger report ...
1/30/2018

10. Online Eγ resolution
7.5% FWHM
Trigger report ...
1/30/2018

11. Eg efficiency Gaussian smearing at threshold
Correlation with offline TRG energy
6% FWHM: compatible with 0 sR
trgenetotalsum.energy (MeV)
Trigger report ...
1/30/2018

12. Effect of saturation 2.5 MeV shift
ISAT = 0
ISAT = 1
2.5 MeV shift
23% of events with at least one saturated channel 55 MeV)
threshold reduced by 3.5 MeV in the case of saturation
Trigger report ...
1/30/2018

13. Todo use QEs for PMT calibration
XEC stable, but need to compensate for gain variation
forced to reduce the threshold during Run 2009
Trigger report ...
1/30/2018

14. Δteγ |ΔT (LXe-TC)| expected to be flat (due to accidental background)
σ(ΔT) = (3.1±0.1) ns (used to be 3.8 in run 2008)
Online offset changed during the run
Both edges are > 2.8 σ out of the signal
(as determined by the RMD peak)  εΔT > 99.5%
start
end
Δt (ns)
Δt (ns)
Trigger report ...
1/30/2018

15. zTC calibration z-positron obtained by using TC bars
based on λ log(Qu/Qd)
need to
equalize PMT
use LUTs (one a bar) to implement the log function
the absorption length was computed for each bar by using cosmic muons
may differ significantly one each other (ranging from 0.5 to 1m)
 different LUTs for each bar been implemented since Dec 14
used to be the same beforehand
 same λ for all bars
z-resolution improved from 7.1 to 5.5 cm
(might be 2.5 cm by using TC APDs)
Trigger report ...
1/30/2018

16. Cosmic muons common LUT individual LUTs s = 7.1 cm s = 5.4 cm DZ (cm)
Trigger report ...
1/30/2018

17. MEG events common LUT individual LUTs s = 7.1 cm s = 5.6 cm DZ (cm)
Trigger report ...
1/30/2018

18. TC inefficiency
Wrong LVDS transmission
TC Type1 board  Type2 board
6 bits missing  only te+ info got screwed
TC acceptance loss 7/30 = 23.3 %
in the data collected from 5th to 27th November
Transmission check implemented
data bus are recorded in memory buffers on both source and destination boards
memory comparison operated on-line by the Event Builder
check active on pedestal trigger (0.1 s-1) from then on
48 bits serialized by DS90CR481 on 8+1 LVDS connections
4.8 GBits/s
Trigger report ...
1/30/2018

19. e+-γ direction based on a LUT to associate XEC PMT  (φTC, zTC)
LUT generated by assuming σ(zTC) = 7.3 cm
efficiency computation based on a sample of Michel’s
a) search for “good quality” track candidates
(χ2, matched extrapolation to TC)
b) track a backward hypothetical γ from the decay vertex;
c) γ hit position  XEC PMT index;
d) XEC PMT index  search for hits on the TC in the LUT
turns out to be (88 ± 1)%
don’t expect significant variation with improved tracking
improved resolution (σ(zTC) =2.5 cm) in Run 2010 should result
in a significant efficiency improvement
Trigger report ...
1/30/2018

20. Performances: 2008 vs 2009 Observable Run 2008 Run 2009 Run2010 (goal)
ΔEγ/Eγ (%)
8.9 ± 0.1
7.5 ± 0.1 7
%saturation 50 23
Eγ threshold (MeV)
40 ± 1
44 ± 1
eγ (%)
> 99.5
δTeγ (ns)
3.8 ± 0.1
3.1 ± 0.1
ε(Teγ ) (%)
δzTC (cm)
7.1 ± 0.1
5.5 ± 0.1
2.5
ε(Θeγ ) (%)
66 ± 2
88 ± 1 95
Trigger report ...
1/30/2018

21. -trigger /γ separation based on different scintillation decay time
= 22 ns, γ= 45 ns
couldn’t be operated last year due to ionization quenching  γ
Trigger report ...
1/30/2018

22. On-line -rings -selection efficiency  90% with the beam on!
residual contamination from beam-related background < 20%
 suppression by 3-orders of magnitude
Trigger report ...
1/30/2018

23. After off-line cut
Trigger report ...
1/30/2018

24. Physics Run Start Run 50180 2009-10-29 11:27:59
End Run :25:33
Total ‘wall clock time’ (WCT) s
~ 54 d ID
DAQ #
DAQ rate (s-1)
Total
435761
6.36
MEG
387982
5.66
MEG lowQ 1
5613
0.08
MEG wide angle 2
2558
0.04
MEG wide time 3
1490
0.02
Radiative narrow 4
2445
XEC alone High Thr 9
3983
0.06
Alpha 12
4528
0.07
LED 14
5713
DC track 18
7294
0.11
TC alone 22
7288
XEC Cosmic 27
4150
Pedestal 31
2724
Trigger report ...
1/30/2018

25. DATA runs Physics run Period (#50180 - #64482)
Time fraction dedicated to different run types
#run
L.T.
T.T. DT
DT cor
% of DT cor
Total
13855
MEG
11111
84.7
LED
1279
122120
245900
247941
256692
6.5 CW
297
53211
93628
94047
96079
2.4
Xec cosmic 99
5303
24322
25101
25778
0.7
XEC alpha
243
7922
45443
46392
48055
1.2
XEC AmBe 71
1283
13887
13972
14458
0.4
XEC single
126
1063
9496
27509
28371
Michel 26
2143
3933
3968
4146
0.1
TC alone
150
826
11339
11451
12477
0.3
TC cosmic
233
7724
39578
40855
42449
1.1
NaI &BGO
149
32222
46684
46959
47978
Test 51
10445
18054
18307
18656
0.5
XEC calib
10.3%
DC calib
0.1%
TC calib
3.0%
Trigger report ...
1/30/2018

26. DAQ summary Total ‘wall clock time’ (WCT) 4 669 056 s
Total ‘beam ON time’ (BOT) s (88% of WCT)
Total of Stop-Start time (DT) s
Total of Stop-Start time (MEGT) s
Fractions:
DT / WCT 84.8 % (running DAQ)
MEGT / BOT 81.6 % (running MEG when beam on)
other / BOT % (beam related calibrations)
LT / BWCT % (DAQ livetime fraction)
Leading to
LT/BOT = 66 %
LT/WCT = 59 %
slightly increased w.r.t. Run 2008
LT/WCT = 49 % (55% if we exclude RMD runs)
Trigger report ...
1/30/2018

27. How to improve? DAQ Digitizer read-out
reduce inter-run gap (6.8 s, 2.1% deadtime)
and/or wake-up time (2.1 s, 0.6% deadtime)
(alternatively) have longer runs  larger filesize
Digitizer read-out
reduce read-out time
new memory arrangement with multi-event buffering
Deadtime 26 ms  15 ms
 17%  10%  demands for a major firmware upgrade
Trigger report ...
1/30/2018

28. Outlook Hardware Firmware Further improvements
extended and programmable FADC range
Firmware
reconstruction improved w.r.t. Run 2008
Stronger background rejection
Higher efficiency
-trigger implemented
efficiency > 80% (even higher in the case of side PMTs)
3-order of magnitude suppression of beam-related background
don’t need dedicated runs any longer
Further improvements
zTC reco by TC-APDs
periodical XEC PMT gain calibration
reduce deadtime
Trigger report ...
1/30/2018

29. Backup slides

30. TC equalization PMT equalization with cosmic muons, 2 factors
Assume ETC = sqrt(A0 * A1) and ZTC = ln(A0 / A1 )
Use of cosmic muons
Equalize the landau distr.
Center at 0 the Z distr.
1/30/2018
Offline TRG ETC (a.u.)
Trigger report ...
Offline TRG ZTC (a.u.)

31. Beam duty Beam ON Start 2009-10-29 11:27:57 End 2009-12-22 11:27:32
Total ‘proton time’ (PT) s
Total ‘beam ON time’ (BOT) s
(p-current>1500 mA)
Fraction of ‘beam ON time’ (BOT/WCT) %
Trigger report ...
1/30/2018

32. MEG run benchmark 216 contiguous MEG runs in December
Start run :58:20
End run :33:13
Benchmark ‘wall clock time’ (BWCT) of s
Live Time (LT) s
Total Time (TT) s
Sum of Stop-Start time (DT) s
Fractions:
LT / TT % (event read out, coherent with DAQ rate)
LT / BWCT % (event read out + DAQ)
DAQ contribution to Dead Time
DAQ wake up time (DT-TT)/ s
DAQ inter run gap (BWCT-DT)/ s
Trigger report ...
1/30/2018

33. Cyclic buffers Diff. driver Cyc. buff LVDS Tx Type1 FPGA Cyc. buff
FADC
Cyc.
buff
Proces.
Algor.
LVDS Tx
Type1
FPGA
Type1 layer
Analog inputs
Cyc.
buff
Proces.
Algor.
LVDS Tx
Type2
FPGA
LVDS Rx
Type2 layer
Cyc.
buff
Proces.
Algor.
LVDS Tx
Type2
FPGA
LVDS Rx
Final Type2
Trigger output
Trigger report ...
1/30/2018

34. TC inefficiency TC trigger problem Direction match LUT OK Time match
New degrader
Red TRG 22
Black TRG 0
Direction match LUT OK
On Type2-0
MC generated
Symmetric US/DS
Time match
On Type1-3 OK
Transmitted through LVDS Error
Type 1-3 Board replaced on Nov. 27th
Efficiency loss 7/30 = 23.3 %
Trigger report ...
1/30/2018