1. PXL vibration and stability 1/7/2014

2. Measurements of: Cooling air induced vibration of the PXL sensors as a function of air flow DC position change as a function of air flow Position change between power on, warm sector and power off cold sector

3. Radial sector motion measured with capacitive probe inserted through hole in PST North half sectors populated with operating ladders. South half populated with empty sector tubes. System operated with full cooling air

4. Probe position 1 Probe position 2 Sector 3, ladder position out3Sector 3, ladder position out2 Probe faces the carbon tube flat just west of the ladders

5. Typical screen shot at full air flow Probe signal FFT, see next page for more detail Stdev = 5  m Probe conversion = 1  m/0.04 V

6. Fourier transform of sector vibration 40 Hz 70 Hz 230 Hz Main resonance of the carbon sector tube

7. Measured sector radial vibration as a function cooling air flow for position 1 More precisely this shows measured vibration as a function of blower RPM since flow has been obtained in this case by scaling linearly with RPM. It has been shown, however, that the flow does indeed scale very closely to the blower RPM. The measured vibration with no air flowing:35 nm RMS

8. Radial displacement of the sector at position 1 as a function of vibration amplitude An arbitrary offset has been applied to give a 0 intercept since a displacement value was not recorded at zero flow for this series of measurements. The linear dependence demonstrates that the displacement like the vibration amplitude scales as the flow squared. This is not so surprising since the dynamic pressure scales as air velocity squared. Sector displacement scales as cooling air flow squared. Sector moves toward the center with increased flow.

9. Radial movement between power on and power off with full flow, i.e. Blower RPM = 5940 3 to 8  m Sector moves in toward the center when heating applied.

10. Summary Sector vibration in the radial direction scales as:flow 2 Sector vibration at full flow:5 µm RMS Sector DC displacement scales as:flow 2 Sector moves in at full flow:25 µm - 30 µm Sector moves in when ladders powered:3 µm - 8 µm Sources: OneNote logbook: work>sector vibration>Vibration test full with MSC Analysis: As>AHFT1>cHFT>m>vibration wind>vibration measured full detector.xmcd