AirShower Trigger StudiesM. Bertaina, Univ. Torino

7th JEM/EUSO International meeting, UAH 21 – 25/06/2010

1st- 2nd levelPDM trigger

3rd levelCCB trigger

CONCEPT of the 1st-2nd trigger levelPersistency Track Trigger (PTT)

Hardware implementation is done by Ehwa University. The final implementation might require small changes in the algorithm to fit with hardware constraints.

FIRST + SECOND LEVEL TRIGGER CONCEPT FIRST + SECOND LEVEL TRIGGER CONCEPT

The AFTL is based on the following assumptions:•PIXELS ABOVE <BACKGROUND> . For each Elementary Cell (EC) pixels, digitalized anode pulses (pe) are counted within a GTU(2.5 µs) and compared with a pre-set digital threshold N. At every GTU the counters C1, one for each pixel, are reset. For each C1, if the counts are greater than the pre-set threshold , the successive pulses are conveyed to a second counter C2, one for each pixel, and a signal L, one for each pixel, flags the pixel as active. All the L signals are OR-ed.•ELEMENTARY CELL ACTIVITY CHECK . A counter C3 (persistency counter), only one per EC, is increased at each GTU if the output signal O of the OR-ed L signals is active else it is reset. •SPACE-TIME CORRELATION OF PIXELS ABOVE THRESHOLD . The C3 counts are compared with a pre-set digital threshold P. If the C3 counts reach the P threshold a signal is issued to the adder A that holds the C2 counters 2x2 (or 3x3) grouped. The resulting addition is then compared with the pre-set value S corresponding to the total number of pe requested in the 2x2 (or 3x3) grouped pixels. If the condition is met, an EC trigger is then generated.

Obviously read-out of data is based on “free running method”: pixels counts recorded on memories of suitable depth are reading out at the occurrence of a trigger.

EXAMPLE: TRIGGER

1 5

3 4

6

2

3 23

N≥5

0 1

0 0

2

0

0 00

PIXELS (3x3)

C1 C 2

S≥ 30

1

ADDER (A) COMPARE

C 3

P≥8

L

GTU=1O

RESET

TRIGGER=NO

RESET

C1 counters are reset every GTU

0 0

0 0

0

0

0 00

N≥5

0 1

0 0

2

0

0 00

PIXELS (3x3)

C1 C 2

S≥ 30

1

ADDER (A) COMPARE

C 3

P≥8

L

GTU=1O

RESET

TRIGGER=NO

RESET

2 5

4 6

5

4

2 32

N≥5

0 2

0 2

3

0

0 00

PIXELS (3x3)

C1 C 2

S≥ 30

2

ADDER (A) COMPARE

C 3

P≥8

L

GTU=2O

RESET

TRIGGER=NO

RESET

1 3

2 5

3

5

4 23

N≥5

0 2

0 3

3

1

0 00

PIXELS (3x3)

C1 C 2

S≥ 30

3

ADDER (A) COMPARE

C 3

P≥8

L

GTU=3O

RESET

TRIGGER=NO

RESET

2 5

4 5

4

5

2 32

N≥5

0 3

0 4

3

2

0 00

PIXELS (3x3)

C1 C 2

S≥ 30

4

ADDER (A) COMPARE

C 3

P≥8

L

GTU=4O

RESET

TRIGGER=NO

RESET

3 4

3 7

5

6

3 14

N≥5

0 3

0 7

4

4

0 00

PIXELS (3x3)

C1 C 2

S≥ 30

5

ADDER (A) COMPARE

C 3

P≥8

L

GTU=5O

RESET

TRIGGER=NO

RESET

2 3

3 6

4

5

4 21

N≥5

0 3

0 9

4

5

0 00

PIXELS (3x3)

C1 C 2

S≥ 30

6

ADDER (A) COMPARE

C 3

P≥8

L

GTU=6O

RESET

TRIGGER=NO

RESET

4 4

3 7

6

6

1 43

N≥5

0 3

0 12

6

7

0 00

PIXELS (3x3)

C1 C 2

S≥ 30

7

ADDER (A) COMPARE

C 3

P≥8

L

GTU=7O

RESET

TRIGGER=NO

RESET

4 6

3 8

6

7

1 43

N≥5

0 5

0 16

8

10

0 00

PIXELS (3x3)

C1 C 2

S≥ 30

8

ADDER (A) COMPARE

C 3

P≥8

L

GTU=8O

RESET

TRIGGER=YES

RESET

PARAMETERS:

The parameters chosen for the previous example are going to be tuned inside the simulation codes to optimize the performance and taking into account also the requirements coming from the hardware implementation, especially if M64 will be adopted as baseline

OPERATIONAL PRINCIPLE AND SCHEMATICSOPERATIONAL PRINCIPLE AND SCHEMATICS

PIXELS ABOVE <BACKGROUND>

ELEMENTARY CELL ACTIVITY

CHECK

SPACE-TIME CORRELATION OF

PIXELS ABOVE THRESHOLD 36 Parallel

inputs shouldreplaced by spacewire lines

OPERATIONAL PRINCIPLE AND SCHEMATICSOPERATIONAL PRINCIPLE AND SCHEMATICS

AFLT flow diagram

Requirements from the 1st-2nd trigger level to the 3rd trigger level

• X,Y (=pixel) position of the trigger cell at 1st level

• Pixel threshold at 1st-2nd trigger level (=yellow pixels).

Conceptual development of the 3rd trigger levelBasic concept:

1) The algorithm looks at the pixel (X0,Y0,t0) that fired trigger level 1-2 at GTU t0.

2) One of the 9 pixels around (X0,Y0,t0) is used as a starting point for tracks.

3) Tracks are 15 GTU long.4) Tracks are free to move in time (t<15GTU) around t0, therefore

the pixel (X0,Y0,t0) could be, in principle, even the first or the last pixel of the track.

5) Tracks are searched at 0 < < 360 and 5 < < 85 at 10 deg steps for both angles (~315 angles).

6) The box is still 4 pixels / GTU and only Yellow pixels inside thebox are used for integration of the signal.7) The threshold on the total photon counts inside the track is set in

order to reduce the rate of fake triggers to < 0.1 Hz/FS.

fine Linear Track Trigger (LTT)

GOOD INTEGRATION BAD INTEGRATION

ONLY 9 of 15 GTU are plotted for simplicity

Other activities:

• LAL is also investigating a new approach for the 3rd trigger level based on AdaBoost and Haar filters

(if/when the performance will be satisfactory it will be taken into consideration for its application, anyway it might be useful also for offline applications)

Trigger studies and comparisons M36 - M64

In the following slides the following nomenclature is used:

Trigger level 1-2 adopting LTT method (old baseline), accepted rate: 7Hz/PDM

Trigger level 1-2 adopting PTT method (new baseline), accepted rate: 7Hz/PDM

Trigger level 3 adopting LTT method (baseline), accepted rate: 0.1 Hz/FS

Conditions for M64:

pixel size: 2.88 mm – constantcross talk: 10% - uniform on the pixelD.E. = same as M36 (D.E.=0.26 – Q.E.~0.4 uba,C.E.~0.66)

APPLIED CONDITIONS:

RECOMMENDED CONDITIONS (Higashide-kun):

pixel size: 2.88 mm in the center, slightly bigger at the edges (2.88x3.51 mm2)cross talk: 0, because smaller than lens fluctuationsD.E. = 0.24 (C.E=0.8 constant, Q.E.=0.3)

EXPERIMENTAL MEASUREMENTS (Philippe):

cross talk: ~4% in the center of the pixelPSF radius: ~2.94 mmD.E. = 0.227-0.237

Status in May: meeting in Tuebingen

LTT

R<248km

7Hz/PDM

LTT

R<100km

7Hz/PDM

LTT

R<200km>60

7Hz/PDM

LTTTrigger efficiency and number of GTU

R<248km

7Hz/PDM

GTU = 2.0 s

Trigger efficiency and number of GTU LTT

R<200km>60

7Hz/PDM

GTU = 2.0 s

PTT

R<248km

7Hz/PDM

PTT

R<200km>60

probably can be improved by modifying some parameters in the trigger (TBC)

7Hz/PDM

R<248km

PTT

PTT

7Hz/PDM

R<200km>60

PTTPTT

7Hz/PDM

Action N.33 requested in Tuebingen

FS-20100033 The results combining L1 and L3 shall be investigated

Due date: End of May

R<248kmM64 PTT+LTT 0.1Hz/FSM36 PTT+LTT 0.1Hz/FS

R<200km>60

M64 PTT+LTT 0.1Hz/FSM36 PTT+LTT 0.1Hz/FS

More comparisons and performances of the trigger algorithms will come in the talks of the simulation session (in particular F.Fenu)

THE END