Self-Seeding Procedure and Development

Jim Turner

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Seeding Development

Seeding procedure was developed by Jim Welch working with Zhirong Huang, Jim Turner, and Franz-Josef Decker:

• Proof of principle tests (hands on participants now gone)• Initial procedure development coupled with studies (oversight

by Zhirong) during MDs just to get repeatability among just a few physicists.

• Working with operations (meaning being on shift with them at the terminals going after every detail). May have trained up to 4 operations personnel, 2 of which have performed.

• Giving write-up to operations to test (in progress, some ups and downs)

• Operations re-writing their own (in progress)

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Short Seeded Beam Setup Procedure Using HXSSS (from Jim Welch)

• 1. Tune up SASE as 13.825 GeV BYD, 150 pC • 2. Get good reference orbit (BSA 600 shot average using BPM GUI) • 3. Go to seeded mode. (Run seeding GUI auto script)

- Turn on chicane to 20 fs. - Insert HXSSS crystal (off Large FEE display, HXS controls, move Y to so Encoder RBV

matches Encoder Ref +/- 200). • 4. Load standard seeding taper which takes out u1 and u2 and optimizes U2 taper.• 5. Adjust UND xcor,ycor15 to zero out the change to the difference orbit. (initial fit

pt xcu15, 1st BPM rfbu01, last BPM rfbu33, fit x,x', y,y' and x,y kicks. Should tune for zero kick angle)

• 6.Insert HXSSS and measure initial SASE spectrum using spectrometer GUI and profile monitor.

• 7.Do vernier scan to maximize height peak of SASE spectrum. Set energy vernier for maximum SASE peak height.

• 8. Do HXRSS crystal angle scan and find 004 (or other peak) peak. Set angle.• 9. Adjust attenuation so HXSSS doesn't saturate (4000 counts is max).

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Seeding procedure and development

• L3 energy scan vs. peak intensity of spectrometer.

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Seeding procedure and development

• Crystal angle scan. Iteration is necessary to converge.

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Seeding procedure and development

• Seeding development along with procedure development, or maybe visa versa.

• L2 Chirp scan vs peak intensity of spectrometer.

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Seeding procedure and development

• L2 Chirp scan vs peak current, goes with the previous plot. Over-compression (on the left) ran out of L2 energy, so couldn’t be pursued.

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Seeding procedure and development

• Intensity jitter of seeded beam through KMONO. 8.19keV. (from Huang-Welch et al. study)

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Seeding procedure and development

• Intensity jitter of seeded beam through KMONO vs energy BPM. 8.19keV. (from Huang-Welch et al. study)

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Seeding procedure and development

• Intensity jitter of seeded beam through KMONO where best seeded pulses are smallest on Direct Imager after KMONO. (from Huang-Welch-Turner study)

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Seeding experience Progress Summary

• Seeded Beam Setup Procedure Using HXSSS - Works well if 2 of the 4 knowledgeable physicists are present, or

if one of the two trained operations people are present- Procedure only works with operations if an operator has been

trained on one of the shifts during Jim Welch’s procedure development. (Matt Gibbs or Alison Saunders are the only ones with proven track record of getting up to 1e5 counts on spectrometer peak)

- Guiding cold operators without being in the room isn’t working. Only ½ the peak was attained with 3 hours of one shift and 8 of a second shift of operators last night.

- Operator Adam Egger is re-writing procedure after some training from Matt Gibbs.

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Seeding experienceProblem Summary

• Problems: - hitting vacuum chamber before reaching optimum delay

• Heinz-Dieter has re-aligned and will install larger bellows- HXRSS crystal hysteresis...

• needs a 20k$ encoder the first of which was destroyed.- Synchronous data with spectrometer not reliable..

• needs controls work with beam.- Absolute intensity measurements are difficult.

• Both XPP (Diling Zhu) and XCS (Aymeric Robert) have measured 200-300uJ of seeded beam through their respective monochromator systems. Zhirong, Jim and I have 100-200uJ through KMONO.

- Gas Detectors don’t yield the same numbers as other measurements.. they appear higher.• Need to study the waveform and distributions to understand that.

- Promise to potential users is 5.5keV – 10keV, but we cannot do between 5.5-7keV, also energy transition is not polished.