Jeff K., Krishna V.

The data from Tuesday (August 12) night looks very encouraging. The tiltmeter was in vacuum (but not being pumped, so P my be ~ mtorr) and the box was closed. The first plot shows the tiltmeter data (high passed at 10 mHz) over 40k seconds starting from ~9 PM. I've divided by the transfer function to take out the resonance. Note that the vacuum vessel is still not wrapped in foam and doing so along with turning on the ion pump should improve the low frequency noise.

The next plot shows the ASD of 15k seconds of the above data during the quiet part in the middle. The third plot shows the ASD of 5k seconds of data from above, showing the quietest angle data I've ever seen :)

I'll add more about the investigation of the transfer function measurement, hopefully later tonight.

J. Kissel, J. Warner

In preparation for the planned power outage, Jim and I have brought all SUS and SEI systems to their SAFE mode -- except for ETMY -- such that there is no digital request for drive. Borja will continue to measure charge on ETMY ESD for a bit longer before moving EY to SAFE.

@DetChar -- The next few hours before the power outage is a great time to get free-swinging measurements of suspension resonances. 
All SUS (except ETMY) are in SAFE as of Aug 14 01:00 UTC.

Sheila, Kiwamu (a report from yesterday)

We switched the approach for assessing the IMC loss from the ring down measurement (alog 13319, alog 13280) to a cavity pole measurement.

The estimated cavity pole is 7745 Hz while the previous measurement was 8850 Hz which was done in February in 2013 (alog 5429).

Note that an expected value from the mirror transmissivity measurements (see the galaxy web) without taking losses into account is 9011 8625 Hz (Thanks Dan !).

(The setup)

We tried reproducing the same setup as the previous measurement (alog 5429). We used a PDA55 for monitoring the injected intensity modulation on the PSL. This is the one under the periscope i.e. H1:PSL-PERISCOPE_A_DC. Then we hooked up an SR785 to this PD and the IMC trans PD (H1:IMC-TRANS) which is an PDA100A on IOT2L. We drove the AOM with an amplitude of 200 mV and frequency band from 1 kHz to 100 kHz, swept sine. We did two kinds of measurement -- first, we measured the IMC cavity pole by driving the AOM and taking transfer function from the PSL periscope PD to the IMC-TRANS PD. Secondly, we measured the PD responses by taking the transfer function of the same PD, but without any IMC interference by misaligning MC2. Note that in order to perform the second measurement we moved the position of the PD to the IMC-REFL path such that it can observe the direct reflection from MC1. Again, these procedure are the same as the previous measurement.

(The result)

After taking the two transfer functions, we divided the IMC cavity pole transfer function by the PD response transfer function in order to reduce the effect of the PD responses. The below is the resultant transfer function and its fitting result.

I used the same fitting algorythm as Giacomo used (see alog 5541). The fitted cavity pole is at 7745 Hz. Since the data was noisy and showed a funny bump avobe 30 kHz, we excluded the data above it. Also, if we do not correct the PD response, the cavity pole is at 8380 Hz.

1600 - 1645 hrs. local -> Isolated and shut down aux. pump carts @ HAM1, HAM3, BSC3 and BSC1 -> Isolated and spun down turbos @ YBM, XBM and X-end.  Also, shut down corresponding QDP80s

I will be taking down the DMT system shortly in advance of the power outage.  It will not be back until later tomorrow. (WP 4796)

	The polarizers were retested today after #015 was redone by Alastair and the silicon had some time to cure. I remeasured the offset of all the polarizer windows, where ↑ is right side up for the label and ↓ is upside down with the label. Nominal height is 4" but it looks like there was a slight upward angle from the mirror.


	

		
015
		
↑
		
4 1/32"
		
0.3 mrad
	
	

		

		
↓
		
4 3/32"
		
0.9 mrad
	
	

		
011
		
↑
		
4 1/16"
		
0.6 mrad
	
	

		

		
↓
		
4 1/32"
		
0.3 mrad
	
	

		
009
		
↑
		
4 1/16"
		
0.6 mrad
	
	

		

		
↓
		
4 1/16"
		
0.6 mrad
	
	

		
008
		
↑
		
4 9/32"
		
2.8 mrad
	
	

		

		
↓
		
3 5/8"
		
3.1 mrad
	
	

		
001
		
↑
		
3 13/16"
		
1.3 mrad
	
	

		

		
↓
		
4 1/4"
		
2.5 mrad
	


The requirement is 7 mrad so all of the new polarizer windows look good. 

(Koji, Alexa, Dan)

We examined the beam path in HAM6 to OM1 in order to figure out the angle of the beam. We made measurements at four different points. Using an (x, y, z) coordinate system with z = up, y = East, x = South, we find at (all in mm):

Edge of table: (20.32, 0, 98)

Intermediate point 1: (0, 552.72, 95)

Intermediate point 2: (-25.4, 1219.2, 93)

OM1: (-40.64, 1574.8, 91)

The error of the measurement in height is ±1mm, and the error along the x, y axis is ±2.5mm. The attached layout shows the original (red) beam path and the new (green) beam path. From this layout, one can see the actual vs. measured angle deviation in height and along the hoirzontal plane.  Using the points above, we made a linear regression and determined the vertical angle of the beam to be 4.3 mrad. The attached plot shows the data with error bars and the linear fit. 

Robert, Christina, Dave

Robert and Christina reported some corner station PEM channels with ADC values of zero. I power cycled the h1oaf0 front end computer and its IO Chassis and these channels are now non-zero.

Sequence was:

• stop user models
• remove h1oaf0 from dolphin
• type "power off" command, but computer decided to reboot instead (sigh)
• stop user models
• remove h1oaf0 from dolphin (deja vue)
• Press the front panel power switch on the CPU
• power down the IO Chassis using its front panel switch (it worked)
• power up the IO Chassis, wait for timing slave to sync
• power up the CPU using the front panel switch

Investigation reveals that all (3) running turbos on site (YBM, XBM and X-end) shut down simultaneously at 1603 hrs. local time yesterday -> Coincidentally, this was only a few minutes prior to my opening of GV2 -> As such, my earlier theory of the XBM turbo tripping off on its safety valve pressure setpoint turned out not to be the case -> This is confirmed also by the fact that PT170A never came on scale.

Today at ~1230 hrs. local -> I spun-up to 100% rpm the troublesome XBM turbo by employing the technique of "loading" the rotor.  To do this, I maintained the turbo inlet pressure at ~ 0.2 torr by adjusting the "up-to-air" needle valve at the turbo's inlet while it spun-up -> Once at full speed, I shut off the air and eventually valved-in the turbo to the XBM volume.  


ERRORS in PRESSURE GAUGES
Also, the LHO vacuum equipment is beginning to show its age as we have been experiencing an increase in the failure rate of the site cold-cathode gauges (lifetime maturation) -> most noticeably PT180B, PT120B and PT170B are reading bogus values now for portions of their nominal range.  As of this writing, both the YBM and XBM turbo inlet CC gauges are reading 1.8 x 10-6 torr which is what I would expect for the recent history -> I would then guess the pressure at BSC2 to be 5-7 x 10-6 torr

There were 167 restarts due to storm related power glitching. Also some unexpected restarts of h1fw1. I have attached the list to spare the casual reader the gory details.

It was the best of lasing. It was the worst of lasing. It was the best of shipments (although still bad). It was the worst of shipments. It was the season of single mode. It was the season of no modes. TCS has now received back the lasers that were sent to Access for repairs. Unfortunately the first shipment containing Lasy-50 20510-208160 and RF50 208160-20510 was sent to Caltech (an oversight in shipping) and then to Hanford. It was worse for the wear and the RF driver was busted, it was blowing fuses. Using the RF50 210040 to drive the laser proved more fruitful, while RF50 208160-20510 will be sent back to Access for repairs. Here are the laser/RF driver pairs and their outputs (running at 99% duty cycle) as tested:

Attached are some of the photos from the process, including the beam on an IR card.

Replaced insulating film used to isolate the -15V regulators to the chassis metal wall for OP Lev Whitening chassis at end stations.

EY - S1101539
EX - S1101552

Filiberto Clara

The daqd process was restarted on h1nds1 to test the copied raw minute files.  WP 4790.

(Dan, Alexa)

Since the MC cavity length was adjusted, we repeated the MC cavity length measurement as described in alog 9679.

Data_refl9_short.txt is the data collected using REFL9. ArmCavityLength_v2.m is the script that determines the length given the zero crossing of the projection. The attached plot show the results with a linear regression included.

The cavity length is determined to  be L = 16.471698m ± 4um assuming 2 Hz accuracy. The 2 Hz accuracy comes from the accuracy of the IFR plus the extreme rattyness of the transfer function.

Compared to the previous measurement the delta L = L_old - L_new =  0.001914 ± 6um. This is very close to the expected 2mm reduction in length as mentioned in alog 12654.

If desired, we can repeat the measurement and include a zero crossing for REFL45 as well. However, we just wanted to make a measurement and get the result public...

(Dan, Koji, Masayuki, Alexa)

We measured the HAM6 septum angle using a laser pointer. We confirmed that there was no observable vertical component to the wedge angle, and then proceeded to measure the horizontal angle. We pointed the laser pointer such that the retro-reflected beam off the surface of the septum returned approximately directly back. Then we measured the distance from the second reflection to this point. This distance was 17mm. The distance from the laser pointer to the septum was measured to be 360mm.

This gives: wedge horizontal angle: 17/360 * 180/pi /2 /1.45 = 0.93 deg

In the equation above the factor of 2 comes from the optical lever effect. Meanwhile the factor of 1.45 comes from applying snells law with the index of refraction for glass and assuming the small angle approximation (see attached drawing).

This measurement was not extremely precise, but was close enough to the expected value of 0.75 deg.

In the attached picture, you will see the retro-reflected beam, which is almost ontop of the outgoing beam, and the second reflected beam. We used the ruler below to measure the separation.

Added the ESD Bias Path Filter Box (D1400192) to both ETMY and ETMX.
Units filter voltage noise present on the ETM bias path of the ESD HV drive.

Due to wiring differences inside the chamber, the filter units were connected as follows:
ETMY connected to pin 1 (Flange F2-3)
ETMX connected to pin 3 (Flange F2-3)

Filiberto Clara