Difference between revisions of "Overall trigger timing"
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| − | Below is my current understanding of the trigger timing for the BCAL test: | + | ==Timing Scheme== |
| + | |||
| + | From Elliott: Below is my current understanding (3pm 22-Sep-2006) of the trigger timing for the BCAL test: | ||
| Line 12: | Line 14: | ||
<tr> | <tr> | ||
<td>0 ns<br></td> | <td>0 ns<br></td> | ||
| − | <td> | + | <td>Electron hits tagger foil<br></td> |
<td><br></td> | <td><br></td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
| − | <td> | + | <td>115 ns<br></td> |
| − | <td> | + | <td>Photon hits BCAL<br></td> |
| − | <td>BCAL is | + | <td>125 ns to alcove, but BCAL is about 10 feet upstream on the platform<br></td> |
</tr> | </tr> | ||
| + | |||
<tr> | <tr> | ||
| − | <td> | + | <td>235 ns<br></td> |
<td>BCAL PMT signals reach discriminators<br></td> | <td>BCAL PMT signals reach discriminators<br></td> | ||
| − | <td>20 ns in PMT plus | + | <td>20 ns in PMT plus 100 ns cable<br></td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
| − | <td> | + | <td>265 ns<br></td> |
| − | <td> | + | <td>Discriminator sum outputs arrive at trigger logic<br></td> |
| − | <td>30 ns a guess | + | <td>30 ns in discriminators is a guess<br></td> |
</tr> | </tr> | ||
| − | + | <tr> | |
| − | <td> | + | <td>290 ns<br></td> |
| − | <td> | + | <td>BCAL AND and OR available<br></td> |
| − | <td><br></td> | + | <td>25 ns is a guess<br></td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
| − | <td> | + | <td>290 ns<br></td> |
| − | <td> | + | <td>Tagger MOR reaches trigger logic<br></td> |
| − | <td><br></td> | + | <td>150 ns tagger logic + 138.5 ns new cable, see [[Tagger trigger timing]]<br></td> |
| + | </tr> | ||
| + | |||
| + | <tr> | ||
| + | <td>320 ns<br></td> | ||
| + | <td>Trigger reaches trigger supervisor<br></td> | ||
| + | <td>Guess everything ready 30 ns after MOR<br></td> | ||
</tr> | </tr> | ||
<tr> | <tr> | ||
| − | <td> | + | <td>340 ns<br></td> |
| − | <td> | + | <td>L1 accept available at TS<br></td> |
| − | <td><br></td> | + | <td>20 ns internal trigger supervisor using prompt mode<br></td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
| − | <td> | + | <td>390 ns<br></td> |
| − | <td> | + | <td>earliest that ADC gate can be active</td> |
| − | <td><br></td> | + | <td>50 ns ADC gate generation, cables to ADC crate, ADC internal<br></td> |
</tr> | </tr> | ||
<tr> | <tr> | ||
| − | <td> | + | <td>435 ns<br></td> |
| − | <td> | + | <td>BCAL signals reach ADC crate<br></td> |
| − | <td><br></td> | + | <td>20 ns in PMT plus 300 ns cable plus photon flight time<br></td> |
</tr> | </tr> | ||
| + | </table> | ||
| + | <br><br> | ||
| + | If the above does not work and we have to delay the ADC signals there are a few possibilities: pulling out 37 unused 100 ns cables from the tray, cutting some of the unused 170 ns in half and installing new ends to give 85 ns delay cables, scrounging up delay boxes, etc. | ||
| + | ==Comments== | ||
| − | < | + | (Zisis' comment referred to am earlier scheme, now superceded...ejw)<br> |
| + | I agree that this will not work. I also agree on the plan of action, in the following priority: 1) Try to shorten MOR, 2) Cut unused 170ns cable (if there are enough and if this is ok with folks like Richard) and 3) Purchase new cables. -- Zisis | ||
| + | |||
| + | (my comment also referred to the older scheme, now superceded...ejw)<br> | ||
| + | 21-Jul...preliminary measurement of the RadPhi cables gives 100 and 300 ns, not 80 and 250 ns. If correct we gain an additional 50 ns delay. If we run a new MOR cable (save 150 ns) we gain a total of over 100 ns. This should be adequate to cover items missing above (patch cables, additional logic delays not accounted for yet, etc). I propose we still plan to run a new MOR cable even if the signal cables are 50 ns longer. -- Elliott | ||
| + | |||
| + | 21-Jul...everything updated based on latest understanding -- Elliott | ||
| + | |||
| + | 22-Sep...everything updated based on actual cables and measurements -- Elliott | ||
Latest revision as of 15:24, 22 September 2006
Timing Scheme
From Elliott: Below is my current understanding (3pm 22-Sep-2006) of the trigger timing for the BCAL test:
| Time |
What |
Comment |
| 0 ns |
Electron hits tagger foil |
|
| 115 ns |
Photon hits BCAL |
125 ns to alcove, but BCAL is about 10 feet upstream on the platform |
| 235 ns |
BCAL PMT signals reach discriminators |
20 ns in PMT plus 100 ns cable |
| 265 ns |
Discriminator sum outputs arrive at trigger logic |
30 ns in discriminators is a guess |
| 290 ns |
BCAL AND and OR available |
25 ns is a guess |
| 290 ns |
Tagger MOR reaches trigger logic |
150 ns tagger logic + 138.5 ns new cable, see Tagger trigger timing |
| 320 ns |
Trigger reaches trigger supervisor |
Guess everything ready 30 ns after MOR |
| 340 ns |
L1 accept available at TS |
20 ns internal trigger supervisor using prompt mode |
| 390 ns |
earliest that ADC gate can be active | 50 ns ADC gate generation, cables to ADC crate, ADC internal |
| 435 ns |
BCAL signals reach ADC crate |
20 ns in PMT plus 300 ns cable plus photon flight time |
If the above does not work and we have to delay the ADC signals there are a few possibilities: pulling out 37 unused 100 ns cables from the tray, cutting some of the unused 170 ns in half and installing new ends to give 85 ns delay cables, scrounging up delay boxes, etc.
Comments
(Zisis' comment referred to am earlier scheme, now superceded...ejw)
I agree that this will not work. I also agree on the plan of action, in the following priority: 1) Try to shorten MOR, 2) Cut unused 170ns cable (if there are enough and if this is ok with folks like Richard) and 3) Purchase new cables. -- Zisis
(my comment also referred to the older scheme, now superceded...ejw)
21-Jul...preliminary measurement of the RadPhi cables gives 100 and 300 ns, not 80 and 250 ns. If correct we gain an additional 50 ns delay. If we run a new MOR cable (save 150 ns) we gain a total of over 100 ns. This should be adequate to cover items missing above (patch cables, additional logic delays not accounted for yet, etc). I propose we still plan to run a new MOR cable even if the signal cables are 50 ns longer. -- Elliott
21-Jul...everything updated based on latest understanding -- Elliott
22-Sep...everything updated based on actual cables and measurements -- Elliott
