TIMING By Michael Rocco Whalen and Cara Perkins
TIMING! By Michael Rocco Whalen and Cara Perkins
PUMP – PROBE EXPERIMENTS A pump-probe experiment excites an atom or molecule with a visible laser beam, then probes the object with a hard X-ray. By measuring the timing difference between the two laser pulses, one can rearrange the captured images and create a “movie” of the chemical dynamics.
SIGNAL MIXING 2 =
TESTING FREQUENCY MIXERS FOR POWER SENSITIVITY
CALCULATING SENSITIVITY
SENSITIVITY PERFORMANCE OF THE MIXERS Mini-Circuits ® Model ZX 05 -HW-S+ Mini-Circuits ® Model ZFM-4 H-S+ Average Sensitivity of the Mixers Mixer Number Sensitivity (V/ps) Mini-Circuits ® Model ZFM-150 1 0. 023 00 2 0. 018 60
CAN YOU HEAR ME NOW? White Noise Spectrum Pink Noise Spectrum
TESTING THE RF COMPONENTS FOR THEIR NOISE-TO-SENSITIVITY RATIO Mini-Circuits Splitter Model ZFSC -2 -1 W+ Anaren Splitter Model 40263
RESOLUTION BANDWIDTH (RBW) 10 Hz Resolution Bandwidth Smaller RBW’s take fewer frequency readings per unit of time. Therefore, harmonics are more apparent. Here, one can see the 60 Hz harmonics coming 10 k. Hz Resolution Bandwidth Larger RBW’s take more frequency measurements per unit of time. The averaging of these measurements eliminates most of the harmonics seen at
THE SEARCH FOR PINK NOISE This noise floor was taken at a 100 Hz RBW. The spectrum analyzer revealed a noise floor that resembled a 1/f curve, but further investigation showed that this was simply the result of averaging the incoming frequencies.
Mixer 1, Splitter 1, 100 Hz RBW 3, 00 E-06 2, 50 E-06 Average Noise of Mixer and Splitter Combinations Combinatio Noise-to. LCLS Timescale at n Sensitivity Ratio 200 k. Hz RBW (fs) (fs/√(Hz)) #1 Mixer, #1 6. 95 E-04 0. 311 Splitter #1 Mixer, #2 7. 56 E-04 0. 338 Splitter #2 Mixer, #1 9. 00 E-04 0. 402 Splitter #2 Mixer, #2 7. 47 E-04 0. 334 Splitter #3 Mixer, #1 1. 62 E-03 0. 724 Splitter #3 Mixer, #2 1. 70 E-03 0. 760 Splitter ps/ √(Hz) 2, 00 E-06 5 d. Bm LO 1, 50 E-06 10 d. Bm LO 17 d. Bm LO 1, 00 E-06 20 d. Bm LO 5, 00 E-07 0, 00 E+00 0 5 10 RF Input 15 20 NOISE-TO-SENSITIVITY RATIOS
TESTING THE COMPONENTS FOR TEMPERATURE-DEPENDENT PHASE DRIFT
TEMPERATURE AND PHASE DRIFT RESULTS Component Phase Drift (fs/⁰C) Mini-Circuits Splitter Model ZFSC-2 -1 W+ 3. 780594406 Anaren Splitter Model 40263 Mini-Circuits Mixer Model ZX 05 HW-S+ Mini-Circuits Mixer Model ZFM-4 HS+ 8. 503419973 Mini-Circuits Mixer Model ZFM-150 6. 952019732 Aeroflex Phase Shifter Model 980 24. 56293706 10' Belden Coaxial 50 Ohm 26. 79407713 1. 694897959
THANK YOU, APE (Accelerator Physics & Engineering) LAB, for all your assistance in femtosecond measuring!!
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