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1 BFEM Trigger Diagnostics Mar 12, 2002 Tsunefumi Mizuno Note: For reference, this document includes some works already reported (pages 2-5 and 7). The.

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Presentation on theme: "1 BFEM Trigger Diagnostics Mar 12, 2002 Tsunefumi Mizuno Note: For reference, this document includes some works already reported (pages 2-5 and 7). The."— Presentation transcript:

1 1 BFEM Trigger Diagnostics Mar 12, 2002 Tsunefumi Mizuno Note: For reference, this document includes some works already reported (pages 2-5 and 7). The study is done with help of many colleagues, especially Tony Waite and Masaharu Hirayama.

2 2 Trigger Efficiency of each Layer (1) Hit in the data Fast-Or capture As already reported, three layers do not participate to trigger and an apparent “inefficiency” is seen in all other layers. A Blue histogram (counts in data) and a Red one (counts in Fast-Or capture) disagree with each other.

3 3 Trigger Efficiency of each Layer (2) Hit in the data Fast-Or capture Here we select charged events with following criteria one or more ACD tiles show PHA above 0.2MIP Single track (number of tracks reconstructed is 2 -- x and y) The track is straight (reconstructed value of chi^2 is below 0.1) All 26 layers are hit. Then, an apparent trigger inefficiency becomes typically 20 % and reaches up to ~50 % (layer23). Does BFEM really miss the trigger with such high probability?

4 4 Trigger Capture efficiency Study was made if we see any events where no 3-in-row is found in trigger capture, and we found that all events registered >=3 in-row. We can conclude that trigger capture worked for the layers that caused L1T.

5 5 Possible Explanations 1.Trigger Mask and Hit Mask was different. When hits occurred in such strips, the layer showed hits but could not cause trigger. 2.Some layers are noisier than others and “data” may include accidental hits. 3.Some layers are noisier than others and accidental hits prior to the event caused dead time to the Fast-Or signal that participated in the trigger. 4.First 3-xy-pairs cause immediate (~100ns) capture of all Fast- Or 1-shots. This is too short compared to the rise-time of the signal of the SSD and the propagation time through the readout chips in a layer (a possibility proposed by Dave Lauben).

6 6 Trigger and Hit Mask (possibility #1) mask FE --plane=0 --strip=1141 --type=data mask FE --plane=3 --strip=530 --type=data mask FE --plane=3 --strip=531 --type=data mask FE --plane=4 --strip=1365 --type=data mask FE --plane=4 --strip=1366 --type=data mask FE --plane=4 --strip=1367 --type=data mask FE --plane=6 --strip=1544 --type=data mask FE --plane=6 --strip=1545 --type=data mask FE --plane=6 --strip=1546 --type=data mask FE --plane=7 --strip=82 --type=data mask FE --plane=7 --strip=85 --type=data mask FE --plane=7 --strip=86 --type=data mask FE --plane=7 --strip=506 --type=data mask FE --plane=7 --strip=1190 --type=data mask FE --plane=7 --strip=1191 --type=data mask FE --plane=7 --strip=1192 --type=data mask FE --plane=9 --strip=88 --type=data mask FE --plane=9 --strip=89 --type=data mask FE --plane=9 --strip=90 --type=data mask FE --plane=9 --strip=1409 --type=data mask FE --plane=9 --strip=1410 --type=data mask FE --plane=9 --strip=1411 --type=data mask FE --plane=10 --strip=1545 --type=data mask FE --plane=10 --strip=1546 --type=data mask FE --plane=14 --strip=285 --type=data mask FE --plane=14 --strip=288 --type=data mask FE --plane=15 --strip=1385 --type=data mask FE --plane=15 --strip=1514 --type=data mask FE --plane=15 --strip=1516 --type=data mask FE --plane=16 --strip=382 --type=data mask FE --plane=16 --strip=383 --type=data mask FE --plane=17 --strip=305 --type=data mask FE --plane=17 --strip=1176 --type=data mask FE --plane=17 --strip=1178 --type=data mask FE --plane=17 --strip=1181 --type=data mask FE --plane=17 --strip=1182 --type=data mask FE --plane=17 --strip=1279 --type=data mask FE --plane=21 --strip=613 --type=data mask FE --plane=21 --strip=758 --type=data mask FE --plane=21 --strip=761 --type=data mask FE --plane=23 --strip=16 --type=data mask FE --plane=23 --strip=18 --type=data mask FE --plane=23 --strip=55 --type=data mask FE --plane=23 --strip=666 --type=data mask FE --plane=23 --strip=667 --type=data mask FE --plane=24 --strip=39 --type=data mask FE --plane=24 --strip=40 --type=data mask FE --plane=24 --strip=583 --type=data mask FE --plane=25 --strip=80 --type=data mask FE --plane=25 --strip=81 --type=data mask FE --plane=25 --strip=84 --type=data mask FE --plane=25 --strip=85 --type=data mask FE --plane=0 --strip=1141 --type=trigger mask FE --plane=3 --strip=530 --type=trigger mask FE --plane=3 --strip=531 --type=trigger mask FE --plane=4 --strip=1365 --type=trigger mask FE --plane=4 --strip=1366 --type=trigger mask FE --plane=4 --strip=1367 --type=trigger mask FE --plane=6 --strip=1544 --type=trigger mask FE --plane=6 --strip=1545 --type=trigger mask FE --plane=6 --strip=1546 --type=trigger mask FE --plane=7 --strip=82 --type=trigger mask FE --plane=7 --strip=85 --type=trigger mask FE --plane=7 --strip=86 --type=trigger mask FE --plane=7 --strip=506 --type=trigger mask FE --plane=7 --strip=1190 --type=trigger mask FE --plane=7 --strip=1191 --type=trigger mask FE --plane=7 --strip=1192 --type=trigger mask FE --plane=9 --strip=88 --type=trigger mask FE --plane=9 --strip=89 --type=trigger mask FE --plane=9 --strip=90 --type=trigger mask FE --plane=9 --strip=1409 --type=trigger mask FE --plane=9 --strip=1410 --type=trigger mask FE --plane=9 --strip=1411 --type=trigger mask FE --plane=10 --strip=1545 --type=trigger mask FE --plane=10 --strip=1546 --type=trigger mask FE --plane=14 --strip=285 --type=trigger mask FE --plane=14 --strip=288 --type=trigger mask FE --plane=15 --strip=1385 --type=trigger mask FE --plane=15 --strip=1514 --type=trigger mask FE --plane=15 --strip=1516 --type=trigger mask FE --plane=16 --strip=382 --type=trigger mask FE --plane=16 --strip=383 --type=trigger mask FE --plane=17 --strip=305 --type=trigger mask FE --plane=17 --strip=1176 --type=trigger mask FE --plane=17 --strip=1178 --type=trigger mask FE --plane=17 --strip=1181 --type=trigger mask FE --plane=17 --strip=1182 --type=trigger mask FE --plane=17 --strip=1279 --type=trigger mask FE --plane=21 --strip=613 --type=trigger mask FE --plane=21 --strip=758 --type=trigger mask FE --plane=21 --strip=761 --type=trigger mask FE --plane=23 --strip=16 --type=trigger mask FE --plane=23 --strip=18 --type=trigger mask FE --plane=23 --strip=55 --type=trigger mask FE --plane=23 --strip=666 --type=trigger mask FE --plane=23 --strip=667 --type=trigger mask FE --plane=24 --strip=39 --type=trigger mask FE --plane=24 --strip=40 --type=trigger mask FE --plane=24 --strip=583 --type=trigger mask FE --plane=25 --strip=80 --type=trigger mask FE --plane=25 --strip=81 --type=trigger mask FE --plane=25 --strip=84 --type=trigger mask FE --plane=25 --strip=85 --type=trigger Trigger mask (right) and Hit mask pattern (left) are the same with each other. (Information from Tony Waite)

7 7 Noise occupancy (possibilities #2 and #3) The average channel occupancy is of the order of 10^-6 (H. Ohyama, W. Kroeger and H. Sadrozinski; LAT-TD-00364) Oh the other hand, noise occupancy of the order of 10^-4 is required to explain the apparent inefficiency of ~20%(Gary Godfrey; Mathcad- Snrate7.pdf) Eye-scan of charged events in BFEM real data also showed that the occupancy of extra-hits (hits that do not belong to straight line) is up to ~10^-5 (T. Kamae and T. Mizuno; BFEMTriggerAnormaly.ppt).

8 8 TOT Distribution and the propagation delay (possibility #4) A strip of smaller energy deposition requires longer time to hit the comparator, whereas BFEM immediately (~100ns) scan the Fast-Or when any three x-y pairs in-a-raw cause trigger. Then, BFEM may fail to capture the Fast-Or. When energy deposition is small in a layer, the value of TOT is also small. Is there any relation between the TOT and the (apparent) trigger inefficiency? BFEM may also fail to capture the Fast-Or when the propagation delay is not negligible. Following two methods give the value of TOT. getToT(0); gives TOT of left controller. getToT(1); gives TOT of right controller. The nomenclature of left/right controller and R0(adjacent to Strip 0)/R1 controller is swapped in somewhere. Here I assume that getToT(0) gives TOT of R0 for layers 0, 2, 4, …, 24 and R1 for layers 1, 3, 5, …, 25. The read-out configuration is given in page 9 and TOT distributions are given in pages 10-12. Hit strip distribution is also shown in page 13.

9 9 Read-out configuration The configuration shown below is given by Tony Waite. For most layers, R0 read 12 chips and R1 read 13 chips. In some layers, all information is read out by one controller (R0 or R1).

10 10 TOT Distribution (R0) of all layers #25 #18 #19 #12 #11 #0 #4 #5 Blue: all events where the layer has hits read-out by R1. Red: events where the BFEM failed to capture the Fast-Or of the corresponding layer.

11 11 TOT Distribution (R1) of all layers #25 #18 #19 #12 #11 #0 #4 #5 BFEM tends to fail to capture the Fast-Or when the TOT (energy deposition) is small (red histogram is narrower than the blue one). Blue: all events where the layer has hits read-out by R1. Red: events where the BFEM failed to capture the Fast-Or of the corresponding layer.

12 12 TOT Distribution of Layer23 All events Events where BFEM did not capture the Fast-Or of Layer23 (the value of TOT=5 means 1us) BFEM tends to fail to capture the Fast-Or when the TOT (energy deposition) is small. Sometimes BFEM failed to capture the Fast-Or even when TOT is high.

13 13 Hit Strip Distribution of Layer23 All events Events where BFEM did not capture the Fast-Or of Layer23 BFEM tends to fail to capture the Fast-Or when the hit is far from the read-out controller (propagation delay?). R0(not used for this layer) R1

14 14 Conclusion Trigger/Hit mask are the same with each other and cannot explain the apparent trigger inefficiency (page 6). Noise occupancy is too small (by a factor of 10-100) to explain the trigger inefficiency seen in the data (page 7). BFEM tends to fail to capture the Fast-Or when the energy deposition (the value of TOT) is small or the propagation delay is large (hits are far from the read-out chip). They could be the main reason of the apparent trigger inefficiency (pages 8-13). Do the width of Fast-Or 1-shot is larger than the (“rise- time of the signal” + ”maximum of the propagation delay”)? If not, BFEM may have missed some events (and the GLAST satellite will do).


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