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Experiment data
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| OPERATION-2023 logbook, Contact: F.Wolff-Fabris, A.Galler, L.Samoylova, H.Sinn |
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Message ID: 5
Entry time: 21 Jan 2023, 16:38
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| Author: |
Jan Gruenert |
| Group: |
XPD |
| Subject: |
Analyze and quantify the mispositioning of the new 4mm-aperture behind the undulator |
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Goal: Analyze and quantify the mispositioning of the new 4mm-aperture behind the undulator
Positions in tunnel:
- ABSP4.2422.SA2 = ABSP4.CELL37.SA2 L_z position 2422.558m
- Last closed undulator for this test is cell16 at 2294m (at end of segment) = SR radiation source point
- IMGTR = 2576m (BT=181.1m, PD=582.0m).
- IMGSR = 2586m (BT=191.6m, PD=591.5m).
- IMGFEL = 2637m (BT=242.0m, PD=642,8m).
- Sequence: end-of-cell16 -- ABSP4 -
Measurements:
- IMGTR : dX=15.15-8.25=6.9mm. dY=17-9.8=7.2mm. Aperture shadow mean diameter = 7.1mm
- IMGSR : Aperture shadow mean diameter = ca. 8.5 mm
- IMGFEL : Aperture shadow mean diameter = 9.0 mm.
The handover cross is at dy = +1.0mm (up) and dx = -2.6mm (left) relative to the apparent center of the aperture shadow.
Comments to the screenshots:
- The handover cross on the IMGFEL cannot be seen simultaneously with the weak SR background because it has the color scaled to high intensity beam.
- The FEL beam spot is almost perfectly centered on the handover cross.
Calculations:
| IMGFEL |
Px / mm |
Position / px |
Position / mm |
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| dx |
0.715 |
3.56 |
2.5454 |
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| dy |
1.036 |
0.97 |
1.00492 |
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| Tunnel positions |
L_z |
renormalized |
aperture shadow diameter / mm |
theor. Shadow diameter |
apparent offset in x / mm |
apparent offset in y / mm |
apparent offset in x / mm |
apparent offset in y / mm |
required offset to send the FEL on the same handover cross position but through the center of the 4mm aperture |
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| Cell1 upstream end |
2197 |
-97 |
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| Cell16 downstream end |
2294 |
0 |
0 |
0.00 |
0 |
0 |
0 |
0 |
-1.99949886889298 |
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| ABSP4 |
2422.558 |
129 |
4 |
4.00 |
-0.97 |
0.37 |
-1.16 |
0.44 |
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| IMGTR |
2576 |
282 |
7.1 |
8.77 |
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| IMGSR |
2586 |
292 |
8.5 |
9.09 |
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| IMGFEL |
2637 |
343 |
9 |
10.67 |
-2.6 |
1 |
-2.6 |
1 |
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Conclusions:
The 4mm aperture is misplaced by 0.97mm (x) and 0.37mm (y).
It should be moved dx = -0.97mm and dy = 0.37mm, or the FEL has to be made on a different trajectory. |
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