Thomas Vo Scott(Apollo) Matt Evans


By offsetting the pitch and yaw test filters on the M0 stage we can see the optical lever beam move in pitch and yaw respectively.  For a sanity check, I also independently put an offset on the reaction mass test filters and this did not affect the optical lever beams so I'm sure that we are not seeing another ghost beam off the reaction mass.

BUT!!!

One thing I noticed is that there is another beam close to our currently aligned beam, approximately 3 cm away.  After looking up some specs for the test mass depth (~34cm) and the gap between the reaction mass (~5mm), Matt and I did some calculations and it looks like the beam that we are currently aligning to is the reflection off the back surface which will give you the same transfer function results as a front surface reflection.  Looking at the reflectivity/transmission data for the ETMy shows that the primary reflection off the front surface is comparable to the secondary reflection off the back surface so it is difficult to judge by eye which one is which.  These calculations will be needed in future installs for correct alignment. For optical levers with large lever arms such as ITMy (optical path ~ 60 meters), the wedge will play a significant role in determining the correct beam as well.

The solution is to go back and open up the enclosures to do yet another re-alignment to look for the correct beam off the front, that would require a soft close of the gate valve.  The reflection off the back surface will still be able to give pitch and yaw, unless the other beam encroaches on the photodetector.  

Attached are plots of dust counts > .5 microns in particles per cubic foot. I have included a plot of the mode of the dust monitor at location 15 in the LVEA (H0:PEM-LVEA_DST15_MODE) to show when the communication to it was lost.

Attached is the accumulated data of the LN2 purge on the HAM6 shipping container. At this point bumping the flow rate up to ~20 L/m has encouraged the dew point to continue to drop. After the dewar ran empty yesterday it has since been refilled, hooked back up, and data logging continues.

Greg Jim & Hugh
We tweaked the position again per IAS (Jason) and then set to attaching HEPI Actuators.  We ended up behind where we started when we found we were unable to attach the Actuator on the NW corner.  We had to jack up the Crossbeam and slide the HEPI Housing East.  This gets quite involved and we are now out of position again based on the Dial Indicators.  We'll continue with attachment and may request looks by IAS as we go.

• Work in HAM2 clean room.
• Oplev work at EY. GV 18 was closed for this work.
• Ring heater testing at ETMY. No noticable effect on vacuum pressure, plot is attached. The dip in lower signal is when the heater was turned on.
• Sno-Valley on site to work on chillers

The ring heater was turned on today to check whether running the ring heater had an effect on the vacuum pressure.   15W of power was put through each segment of the ring heater at 19:07:30 UTC until 19:37:08 UTC (by adding an offset of 25,000 counts to H2TCSETMY _EMTY_RING_HTR_SEG1_DC_I_SET and H2TCSETMY_ETMY_RING_HTR_SEG2_DC_I_SET), which is close to the maximum ouput of the ring heater.  The vacuum in BSC6 was not affected by running the ring heater, which is good.

I added in gains to the ring heater input and readout channels so that the we can input the current in amps and readout the voltage and ring current on volts and amps instead of counts (reffering to D1002529 for  the required conversion factors).

• To channels H2TCSETMY _EMTY_RING_HTR_SEG1_DC_I_SET and H2TCSETMY _EMTY_RING_HTR_SEG2_DC_I_SET I added a gain of 3.9961e4 amps/count so that you can input the curent in amps and the output of the channel is in counts (using conversion factors 0.082A/V and 20^16/20 count/V)
• To channels H2TCSETMY _EMTY_RING_HTR_SEG1_I_MON and H2TCSETMY _EMTY_RING_HTR_SEG2_I_MON I added a gain of 4.982e-5 counts/amp so that the output of the channel is in amps (conversion factors are 40/2^16 V/count and 1/12.25 A/V)
• To channels H2TCSETMY _EMTY_RING_HTR_SEG1_V_MON, H2TCSETMY _EMTY_RING_HTR_SEG1_LV_MON, H2TCSETMY _EMTY_RING_HTR_SEG2_V_MON, H2TCSETMY _EMTY_RING_HTR_SEG2_LV_MON I added a gain of 0.0024 counts/volt so that the output is in volts (conversion factors are 40/2^16 V/count, 1/0.25 V/V).

I measured the TMS ISC table angular and lateral stability when the end station VEA was quiet last night.

I found the table displacement to be around 5-10 um rms laterally and 1-3 urad rms in angle over 100s. The motion thus appears to be within the requirements: 100 um and 1 urad, respectively.

I've aligned the Hartmann plate onto the conjugate image plane of the ETM.  This was done by yawing the ETM periodically (excitation of H2:SUS-ETMY_M0_TEST_Y_EXC at 0.25Hz and 200 counts) and measuring the amount of motion of the beam spot on the CCD with the Hartmann plate removed.  Using DTT I obtained a transfer function of spot movement on the CCD over the yaw in the ETM (H2:TCS-HWS_ETMY_ITMM_CENTER_X/H2:SUS-ETMY_L1_WIT_YMON).    I moved the lens F1 along the beam path to find the position where the transfer function was zero, at which point the HWS CCD is at the image plane of the ETM.  Attached is a graph of the transfer function versus the position of F1.

The HWS was then moved back 11mm (see second attachment) so that the Hartmann plate rather than the CCD is located at the ETM image plane.  The Hartmann plate has been reattached.  The next step is to look at the quiescent prism and defocus of the beam on the HWS.  

Starting last thursday, 5th July, the backups of h2boot by the disk-to-disk backup server cdsfs1 causes a significant slowdown of all H2 front end EPICS systems. It is most noticable on MEDM screens, where the refresh rate drops to several seconds. Once the backup is completed (after about 15 minutes) the systems immediately recover. I am unable to reproduce the error on H1 or on the DTS test stand. I'll reboot h2boot at the next opportunity as part of the investigation. No significant change to the h2boot file system occured late last week (most of us were on vacation).

For now the backup of h2boot's perioicity has been reduced from every 4 hours to daily at 05:41 until the problem can be resolved.

35W beam. The ISS gain was changed from -2.1 to 7dB which seemed to quiet the noise at high frequencies.

Thomas V. Mark D.(Apollo) John W. Gerardo M.

We have finished installing the enclosures for ITMY and ETMY.  During installation, ETMY was misaligned and I mistakenly re-aligned to the reaction mass ghost beam, will fix to reflect off the ETM. ITMY is fully operational, some internal focusing of the telescope may need to take place since the beam diameter is approximately 8 mm, spec calls for 2-3 mm.  However, it is up to the commissioners of the OAT whether or not this adjustment is worth doing.

Deviations from design:

1) Due to the tightness between the ITMY transmitter pier and the viewport, we were only able to get the viewport protector in between them and couple the enclosure to the protector via sheet metal and tape.

2) It was also pretty tight between the viewport protector and the enclosure on the ETMY receiver pier, we were not able to fit a full sized bellow to couple the connection between the two.  We ended up cutting the bellow to a smaller size and using that.  Also, we adjusted the level of the receiver pier in order to not have the enclosure touch the beam tube (the corner of the enclosure was butting up against the side before).

For the evening shift, we set out to check the VCO calibration, and get some new calibrated spectra.  This work starts where entry 3400 left off...

After relocking the cavity we found that he SR560 path (which was described in 3400 as having a gain of 10 at the SR560, and another gain of 10 at the TTIF) saturated due to low frequency motion (below 1Hz).  With a gain of 1 on the SR560 it worked, and the 2 signal paths (SR560 and FMON) showed essentially perfect coherence.  This also showed that the FMON calibration is not -20dB at DC and 20dB at HF, but rather 0dB at DC and 40dB at HF (see comment to 3400).  With this direct measurement of FMON in hand, we removed the SR560 path.

Discussions with Bram brought out a missing factor of 2 in my previous calculation: since the PLL is in the 1064nm output of the laser, and we are using the 532 for locking, we get twice as much frequency change in the light seen by the cavity as the light seen by the PLL.  (The same result can be achieved by ignoring the fact that green light is used at all, such that the conversion from frequency to length becomes L_cavity / f_laser = 3995m 1064e-9m / 3e8m/s = 14.2pm/Hz.)

In summary:

• The VCO + Frequency divider gives 139kHz/V at DC, with a pole at 1.6Hz and zero at 40Hz.
• At DC, the calibration for the FMON signal is 43.4Hz/count into the PLL.
• This gives 614pm/count for FMON as seen by the cavity.
• This is not very different from the 0.8nm/count found with the OSEM calibration in entry 3363.

Attached are plots of dust counts > .5 microns in particles per cubic foot.

The H1 workstations in the control room now have a controls account.  Use caution, the controls account is the same home directory for H1 and H2, but the environment will be set up for H1 on the H1 workstations and H2 for the H2 workstations.  So, even though the controls account looks the same on H2 and H1 workstations, you cannot do H2 work on an H1 workstation, or H1 work on an H2 workstation.  Confused?  The H1 workstations are labeled as such with a tag on the upper left corner of the display.

The background of the controls account screen will no longer indicate it is "H2".

	HSTS MC1 has been moved to the testing bench and cabled to the test stand. The offsets and gains have been entered into the MEDM screens and the OSEMs have been positioned to 50% light. We will recheck and adjust the 50% light positions in the morning, if necessary. This suspension should be ready for Phase 1 testing. 
	
 M1 BOSEMs
 T1 S/N 578 OL = 25960.0 Offset = -12980 Gain = 1.156
 T2 S/N 436 OL = 29277.9 Offset = -14639 Gain = 1.025
 T3 S/N 440 OL = 27858.1 Offset = -13929 Gain = 1.077
 LF S/N 433 OL = 27758.7 Offset = -13879 Gain = 1.081
 RT S/N 424 OL = 24529.4 Offset = -12265 Gain = 1.223
 SD S/N 658 OL = 25139.5 Offset = -12570 Gain = 1.193

 M2 AOSEM
 UL S/N 453 OL = 27359.6 Offset = -13680 Gain = 1.097
 LL S/N 320 OL = 24780.7 Offset = -12390 Gain = 1.211
 UR S/N 228 OL = 25117.9 Offset = -12559 Gain = 1.194
 LR S/N 438 OL = 25521.6 Offset = -12761 Gain = 1.175

 M3 AOSEM
 UL S/N 227 OL = 28354.2 Offset = -14177 Gain = 1.058
 LL S/N 353 OL = 26509.5 Offset = -13255 Gain = 1.132
 UR S/N 276 OL = 27920.9 Offset = -13960 Gain = 1.074
 LR S/N 299 OL = 28435.2 Offset = -14218 Gain = 1.055
  

I started the evening shift with calibration of the VCO + Frequency divider used for the ALS PLL (S1200570 and S1000748).  The objective was to measure the response of the VCO output to its Tune input, which is used for locking the arm cavity and thus provides a good calibration point for the arm cavity signal.

I set up the DC calibration measurement with a signal generator (output displayed on a scope to be sure), and a frequency counter.  I took 6 samples between -1V and 1V, which resulted in an excellent linear relationship: f = 39.6MHz + 139 kHz/V * V_tune.  For example, at V_tune = 1V, I measured f = 39.739 MHz.  This is not the expected result of 50kHz/V given the nominal 100kHz/V from the VCO and the division by 2 which takes us from 80MHz to 40MHz.

From there I moved on to measure the AC response.  I did this by rigging up a frequency to voltage converter with some bubble gum and duct tape I found nearby.  The output of the converter was 725mV / V_tune.  With the help of an SR785 and a lot of patience I turned this into a response measurment between 0.5Hz and 10kHz.  I saved the curves on the SR785 floppy, which is a lot like throwing them into a black hole, so I also wrote down a few points: {-30.7dB, 178dg} at high frequency, {-27.7dB, 138dg} at 40Hz, {-16.8dB 112dg} at 8Hz, {-5.8dB, 136dg} at 1.6Hz and {-3.26dB, 136dg} at 5.62Hz.  These are well fit by the measured DC response and the expected 1.6Hz pole and 40Hz zero.

Lastly, in preparation for using this calibration for the arm cavity, I cabled up an SR560 to the IR_PWR_MON channel.  The SR560 is AC coupled with a gain of 10, and the tabletop interface gain is set to 10.  From the output of the SR560 to counts of IR_PWR_MON, I measured 32060 counts/V.  Just to be sure, I checked the gain of the SR560 and appears to be very close to the stated value of 10, so we should expect 320.6 counts/mV refered to the SR560 input, which is attached to V_tune.  Assuming the above VCO calibration is correct, this converts to 0.434Hz/count as seen at IR_PWR_MON.  The cavity should lock should convert length to frequency as L_cavity / f_laser = 3995m / 5.635e14Hz = 7.09 pm/Hz, so we will be left with 3.07pm/count as our length calibration.   (To relate this to the number found with the OSEMS in 3363, we should remove the gain of the SR560, the TTIF box, and another factor of 10 for the FMON signal filtering.  This would give 3nm/count instead of the 1nm/count found with the BOSEMS, so somewhere we're missing a factor of 3, not unlike the 139kHz/V vs. 50kHz/V discrepence... to be investigated tomorrow in the light of day.)

On a side note: I found the PLL unlocked and no beatnote evident.  On closer inspection there was no light coming from the fiber, so I went to the optics lab and found the laser in Standby.  I have no idea why it would be left in this state, since this clearly makes cavity work impossible.  That should have been enough to make me leave it as I found it, but instead I turned it back on and relocked the reference cavity.  From the trend data, it looks like it unlocked about 15 hours ago (at 16:20 UTC, see figure).