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Install a regular diode connected to the Acqiris on the sample chambe chamber door and aligned align the reflected laser beam on the mirror onto that diode.Toggle Cloak
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Acqiris signal by moving the diode on the chamber door. An ND filter may be necessary to reduce the signal, as shown in the side-on view below
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Insert a nozzle rod with both a clear YAG and a frosted YAG.Toggle Cloak
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At CXI, the clear YAGs are typically thinner, around 20 um, whereas the frosted YAGs are thicker, around 50 um |
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If doing the timing with the shroud on, the bracket needs to be facing in the -Z direction when inserted into the sample chamber or it will collide with the exit cone. |
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Zoomed-in view |
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Rough timing
- If timing is desired to be done at atmospheric pressure in SC1, then the MPS interlock must be bypassed to allow the beam to come to CXI with the detector gate valve close. this requires bypassing Link Node 40, Card 3 Channel 15 to open for the duration of the timing measurement at atmosphere. This bypass can only be enabled by ACR and you must call them to request this at x2151.
- Move the fast diode into position (at this point should only need to move the SC1 sample_x stage)
- Align the diode to the x-ray beam first since the x-ray beam cannot be moved. The laser will later be steered to the diode left int he fixed locaiton of maximum x-ray signal
- The focused x-ray beam may damage the diode. If the signal on the diode is too weak for 10^-4 transmission or less, it may be that the diode is improperly biased.
- Increased x-ray signal may be achieved without damaging the diode by making the x-ray beam bigger suing the DG2 Be lenses as described later in the fine timing section.
- The focused x-ray beam may damage the diode. If the signal on the diode is too weak for 10^-4 transmission or less, it may be that the diode is improperly biased.
- Align the diode to the x-ray beam first since the x-ray beam cannot be moved. The laser will later be steered to the diode left int he fixed locaiton of maximum x-ray signal
- Measure the laser signal on the diode using the LeCroy scope to make sure there is overlap
- Turn off the laser and turn on the X-rays. Move the diode around in x and y to maximize the X-ray signal (if the steps are very large then the laser may need to be repointed)
- Save a trace of the X-rays on the scope
- Turn X-rays off and turn on laser
- Move laser delay time (LAS:R52B:EVR:31:TRIG0:TDES) to bring laser within 100 picoseconds of the X-rays using the scope
- Once the laser is timed roughly, it is time to move onto the finer timing measurement using a cross-correlation measurement
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