Wiki source code of Trigger Howto

Version 28.1 by sndueste on 2023/04/28 10:58
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1
2
3 {{toc/}}
4
5 = Introduction (user panel)
6 =
7
8 The MTCA based triggers have a jitter in the few ps range, the delay can be shifted in 9 ns steps, One can choose between 10 Hz triggers, Triggers connected to the (fast) FEL shutters,  frequencies locked to the pulses (e.g. 1MHz) and the actual bunch patterns. A detailed description can be found at the[[ N.A.T. webpage >>url:https://nateurope.com/product/namc-pstimer/||shape="rect"]].
9
10 In short:
11
12 * the triggers are for low impedance (~~50 Ohm )
13 * signal level is:
14 ** + 3 V to + 4.5V  for high (actual trigger)  and  0V for low (baseline) at 50 Ohm
15 ** + 6 V to + 9V  for high  and  0V for low at 1 MOhm
16 ** one can also invert the signal in the expert panel ( thus the base line is + (3-5) V and the actual trigger signal is  0V)
17 * The trigger are send to the MTCA several ms before the first FEL pulse (3.1 ms for the "standard" trigger, 21.5 ms for the "early" trigger).
18 * The timer card can delay the trigger in 9 ns  steps for more than 100 ms (an option to shift the trigger in 1 ns steps is available in the expert panel)
19 * The shown delay in µs is in respect to the //first// FEL pulse. negative delay: trigger comes before FEL, positive : trigger comes after the FEL.
20 * The desired delay has to be entered in the "delay to be set" field and as second step pressing the "set delay" sends the delay value to the timer card. Then the trigger delay will be changed and the "actual delay" will be updated.
21 * The trigger can be set to only provide a trigger signal if the FEL Fast shutter is open. One has to choose which FEL shutter to use.
22 * The trigger  width can be adjusted from 9 ns to several ms in 9 ns steps
23 * The timer card can in addition to the 10 Hz triggers also provide frequencies which are linked to the FEL repetition rate and the actual burst pattern of the FEL. For details how to set these modes see below
24 * At the beamlines the triggers are provided with a  BNC patch panel
25
26 The main control can be done with a simplified user panel which can handle the timing in respect to the FEL pulses (and not in respect to some arbitrary event time)
27
28
29 \\
30
31 [[image:attach:image2020-1-23_12-10-59.png||width="700"]]
32
33 \\
34
35 \\
36
37 Choosing a FLASH1 trigger there are 2 options to be synchronized with the BL and the PG shutter :
38
39 [[image:attach:image2020-1-23_12-29-40.png||height="250"]]
40
41 A yellow background indicates that the trigger is synchronized to a fast shutter:
42
43 [[image:attach:image2020-1-23_12-31-41.png||height="250"]] or:[[image:attach:image2020-1-23_12-32-20.png||height="250"]]
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45 \\
46
47 \\
48
49 \\
50
51 = Expert panels =
52
53 \\
54
55 [[image:attach:image2020-1-23_12-28-6.png||height="250"]] [[image:attach:image2019-9-17_13-8-46.png||height="400"]]
56
57 With the **"Expert overview"** one gets the overview over all channels available on the timing card and can configure the card. This is useful to look what channels are using clock settings or burst mode settings that one wants to change ... and using the other tabs one can set parameters for clocks and bursts (see below)
58
59 \\
60
61 For each trigger channel there is in addition an **"Expert panel"** to set the properties of THIS channel
62
63 [[image:attach:image2020-1-23_12-28-46.png||height="250"]] [[image:attach:image2019-9-17_13-15-38.png||width="550"]]
64
65 \\
66
67 \\
68
69 = Set a constant frequency to a channel =
70
71 =
72 [[image:attach:image2019-9-17_13-18-9.png||height="250"]][[image:attach:image2019-9-17_13-18-37.png||height="149"]] =
73
74 \\
75
76 The timer card provides the option to generate  frequencies that are synched to the FEL reprate on the ps level. One can set 3 Clocks by deviding the reference frequency of 54.2 MHz by n.** Please check (using the Expert overview ) before changing a frequency of it is used for some other channel !!**
77
78 Since our main FEL frequency is 100.31 MHz the dividers are not straight forward:
79
80 [[image:attach:image2019-9-17_14-22-29.png||width="450" align="right"]]
81
82 \\
83
84 (% class="wrapped" %)
85 |=(((
86 Clock frequency
87 )))|=(((
88 Divider to be set
89 )))
90 |(((
91 "1 MHz" (1000.31 kHz)
92 )))|(((
93 53
94 )))
95 |(((
96 "500 kHz" (501.5 kHz)
97 )))|(((
98 107
99 )))
100 |(((
101 "250 kHz" (250.8 kHz)
102 )))|(((
103 215
104 )))
105 |(% colspan="1" %)(((
106 "200 kHz" (200.6 kHz)
107 )))|(% colspan="1" %)(((
108 269
109 )))
110 |(% colspan="1" %)(((
111 "100 kHz" (100.3 kHz)
112 )))|(% colspan="1" %)(((
113 539
114 )))
115
116 \\
117
118 == General FLASH frequencies: ==
119
120 \\
121
122 (% class="relative-table wrapped" style="width: 19.422%;" %)
123 |(% class="highlight-grey" title="Hintergrundfarbe : Grau" data-highlight-colour="grey" %)(((
124 (% style="color: rgb(0,0,0);" title="" %)**Name          
125 **
126 )))|(% class="highlight-grey" title="Hintergrundfarbe : Grau" data-highlight-colour="grey" %)(((
127 (% style="color: rgb(0,0,0);" title="" %)**Frequency                
128 **
129 )))|(% class="highlight-grey" title="Hintergrundfarbe : Grau" data-highlight-colour="grey" %)(((
130 (% style="color: rgb(0,0,0);" title="" %)**Divider**
131 )))
132 |(((
133 1.3 GHz
134 )))|(((
135 1300.000000 MHz
136 )))|(((
137 \\
138 )))
139 |(((
140 108 MHz
141 )))|(((
142 108.333333 MHz
143 )))|(((
144 12
145 )))
146 |(((
147 9 MHz
148 )))|(((
149 9.02777777 MHz
150 )))|(((
151 144
152 )))
153 |(((
154 4.5 MHz
155 )))|(((
156 4.513888 MHz
157 )))|(((
158 288
159 )))
160 |(((
161 1 MHz
162 )))|(((
163 1.003086 MHz
164 )))|(((
165 1296
166 )))
167
168 \\
169
170 Once a clock is configured with the right frequency one can choose in the "expert panel" of the according channel the "FPGA clock" in the "input source select"  chooser.
171
172 One has to set the delay to values less than the repetition rate ... (so for 1 MHz between 0 and 990 µs)  and the trigger width also less than the rep rate ...
173
174 This results in a continuous train of pulses with the set trigger width.
175
176 = Creating an (own) burst trigger =
177
178 One can use now a SECOND trigger channel which is set to a regular 10 Hz trigger  and gate the clock output to create a burst with defined start point and length,
179
180 For the example we use the FRONT.TRG2 (BL3 Trg5) as gate pulse which defines the length of the burst (set with the trigger width) and the (rough) starting point of the burst. This trigger is only used as gate and the physical trigger output is NOT used.
181
182 The  second channel (here FRONT.TRG3 (BL3 Trg6) which is set to the clock frequency defines the reprate (by the FPGA clock setting) , the exact starting point of the first trigger ( by the delay ) and the width of the  MHz/kHz triggers (width).
183
184 **To get from the clock to the burst trigger** one has to:
185
186 * set the  "2nd source select" to the gate trigger ( here FRONT.TRG2) - this defines a second source to considder for the trigger output.
187 * and the "output source select" to "AND 2nd Ch."  this finally only sends a trigger if on both inputs (clock and gate) we have a high signal.
188
189 \\
190
191 [[image:attach:image2019-9-17_14-35-5.png||height="250"]] [[image:attach:image2019-9-17_14-34-38.png||width="400"]]
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193 \\
194
195 \\
196
197 = Real bunch trigger  - get a trigger for each FEL pulse =
198
199 \\
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201 Sometimes it is convenient to get a trigger pulse for each pulse in the FEL. thus if the FEL number of bunches or reprate are changed, the trigger adapts accordingly.
202
203 For this one has to select the source of interest in the expert overview panel (tab: "Bunch pattern") ... well for us this is FLASH1 (FL1D) or FLASH2 (FL2D)
204
205 There are 6 different bunch pattern "channels" one can configure. Typically only 2 are needed ... And in each one there are 6 selectors to choose sources . We only need one - it does not matter in which one is used.
206
207 [[~[~[image:attach:image2019-9-17_14-51-28.png~|~|height="250"~]~]>>attach:image2019-9-17_14-51-28.png]][[image:attach:image2019-9-17_14-47-15.png||thumbnail="true" height="199"]]
208
209 \\
210
211 In the expert panel one can now choose the configured "Bunch Pattern" as "Input source select"
212
213 **NOTE: To shift the burst in time one can no longer use the delay of the individual channel BUT the delay in the "Bunch pattern" tab in the expert overview! This now shifts all bursts ... so you better know what you are doing. typically the burst is already shifted to the actual FEL timing ... Shifting the timing should be discussed with the beamline scientist / local contact ...**
214
215 \\
216
217 [[image:attach:image2019-9-17_15-4-47.png||height="250"]][[image:attach:image2019-9-17_14-52-40.png||height="250"]]
218
219 \\
220
221 \\
222
223 = Different trigger events (starting points) =
224
225 one can configure each channel for an individual trigger event
226
227 **FLASH1**
228
229 (% class="wrapped" %)
230 |(((
231 trigger No
232 )))|(((
233 function
234 )))
235 |(% colspan="1" %)(((
236 21
237 )))|(% colspan="1" %)(((
238 Trig16 + first bunch of FLASH1 - this trigger is shifted when FL1 starts later than "700"
239 )))
240 |(% colspan="1" %)(((
241 180
242 )))|(% colspan="1" %)(((
243 shifts with the start time of FLASH1 as event 21 but comes 23 ms  before the FEL
244 )))
245 |(((
246 16
247 )))|(((
248 the MCA trigger 3.11 ms before the Flash1 pulses (same as A6 but more stable)
249 )))
250 |(((
251 166
252 )))|(((
253 A6 event. still possible to use but less precise than 16
254 )))
255 |(((
256 162
257 )))|(((
258 A2 event as earliest ( 24 ms before the FEL)
259 )))
260 |(((
261 224
262 )))|(((
263 E0 event of the BL fast shutter ( 19 ms before the FEL) - to be switched off in 2020
264 )))
265 |(((
266 225
267 )))|(((
268 E1 event of the PG fast shutter ( 19 ms before the FEL) - to be switched off in 2020
269 )))
270
271 \\
272
273 \\
274
275 **FLASH2**
276
277 (% class="wrapped" %)
278 |(((
279 trigger No
280 )))|(((
281 function
282 )))
283 |(((
284 22
285 )))|(((
286 Trig116 + first bunch of FLASH2 - this trigger is shifted when FL2 starts at a different start time
287 )))
288 |(((
289 181
290 )))|(((
291 shifts with the start time of FLASH2 as event 22 but comes 23 ms  before the FEL
292 )))
293
294 from this trigger as starting point one can shift the timing in 9 ns steps first and finally in 0.9 ns steps for fine adjustment.
295
296 \\
297
298 \\
299
300 = Info about the Fast shutter trigger =
301
302 Since Jan 2020 the fast shutter trigger at FLASH1 is generated via local inhibit at the EXP1 and EXP2 crate and not via E0 and E1 events anymore
303
304 for details see [[doc:FLASH.Fast Shutter trigger inhibit system]]
305
306 \\
307
308 == Special trigger options for the fast shutter: ==
309
310 === Fast shutter inhibit signal ===
311
312 It is possible to have the fast shutter inhibit signal (the signal coming from the fast shutter to the inhibit boxes connected to the X2 cards) directly available for users. For this one can select the output source as 2nd channel:
313
314 [[image:attach:image2020-2-5_10-59-41.png||height="250"]]
315
316 \\
317
318 === Inverse fast shutter trigger ===
319
320 If one wants to have an inverse fast shutter trigger (10 Hz signal that comes only if the fast shutter is** CLOSED**) one can use a T and a small Lemo cable to double the input from the fast shutter  to another input at the inhibit box.
321
322 In the FL2 case input1 is the regular fast shutter channel and input2 is usually not used. for this additional input one can set the input configuration to **inverse:**
323
324 [[image:attach:image2020-2-5_14-11-55.png||height="400"]]
325
326 \\
327
328 \\
329
330 \\
331
332 \\
333
334 \\