Displaying reports 73701-73720 of 83068.Go to page Start 3682 3683 3684 3685 3686 3687 3688 3689 3690 End
Reports until 12:01, Thursday 30 January 2014
H1 SUS
betsy.weaver@LIGO.ORG - posted 12:01, Thursday 30 January 2014 - last comment - 14:07, Friday 31 January 2014(9658)
Ring Heater in line of fire during welding

We've observed some burn marks on the shielding of the ETMy ring heater cables which occured sometime during the 3 prior weld sessions (May 2012, Dec 2013, Jan 2014).  The burns are on the lowest ring heater cable that laces around the test mass and makes a connection between the test mass and the PUM.  There is a burn on the right segment and the left segment.  I dug up a picture that shows that the burn on the "right" segment (as viewed from the back of the suspension) was there just after the May 2012 weld session, so that one is not new.  However the "left" cable burn is new from the Dec or Jan welding.  We did not see when this actually occured.

Filiberto tested the ring heater cable and found that all pins are operating as per spec, although he thinks pin 1 is shorting.  We are tracking down what this means (did we test it correctly, when was it last tested, is it possible that the burn is contributing to the short, even though it does not look like it is, etc.).

Comments related to this report
betsy.weaver@LIGO.ORG - 12:03, Thursday 30 January 2014 (9659)

This is the picture of the RH "right" cable taken in May 2012.

Images attached to this comment
betsy.weaver@LIGO.ORG - 12:11, Thursday 30 January 2014 (9660)

And here is the "left" RH segment burn which happened in the Dec or Jan weld.

Images attached to this comment
filiberto.clara@LIGO.ORG - 14:07, Friday 31 January 2014 (9723)
For the ring heater cable, the following pins were tested.

Pins 2,3,4, and 5 are tied together.
Pins 14,15,16, and 17 are tied together.
The resistance between these two sets is 47.5 ohms.

Pins 8,9,10, and 11 are tied together.
Pins 20, 21, 22, and 23 are tied together.
The resistance between these two sets is 45.9 ohms.

Pin 1 is tied to shield and shorted to ground.

Filiberto Clara 
H1 CDS
patrick.thomas@LIGO.ORG - posted 10:56, Thursday 30 January 2014 (9655)
h1asc model restarted


			
			
H1 IOO
paul.fulda@LIGO.ORG - posted 10:43, Thursday 30 January 2014 - last comment - 11:24, Thursday 30 January 2014(9652)
Making REFL beam size measurements on ISCT1

I'm making a measurement of the ITMX direct reflected beam size on ISCT1. PRM is misaligned, sending the beam to the parking dump for this mesurement. Please do not align PRM as this will make the REFL beam too powerful for the beam analyzer and may fry it.

Comments related to this report
paul.fulda@LIGO.ORG - 11:24, Thursday 30 January 2014 (9657)

I'm done for now making measurements with PRM misaligned. I'll realign PRM now and measure the PRM direct reflected beam

H1 CDS
patrick.thomas@LIGO.ORG - posted 10:24, Thursday 30 January 2014 (9651)
DAQ restart for h1asc model change


			
			
H1 CDS
patrick.thomas@LIGO.ORG - posted 10:23, Thursday 30 January 2014 (9650)
h1asc model restarted (WP 4415)


			
			
LHO General
patrick.thomas@LIGO.ORG - posted 10:01, Thursday 30 January 2014 (9649)
King Soft Water taking water samples


			
			
H1 PSL (PSL)
patrick.thomas@LIGO.ORG - posted 08:44, Thursday 30 January 2014 (9648)
PSL check
Output power is 29.3 W (should be around 30 W)
FRONTEND WATCH is green
HPO WATCH is red
SysStat is good

PMC has been locked 1 day, 16 hr (should be days/weeks)
Reflected power is 10.9% of transmitted power (should be <= 10%)

FSS has been locked for 10 min (should be days/weeks)
Resonant threshold is .5V (should be .9V)

ISS diffracted power is around 8.8% (should be 10%)
Last saturation event was 16 min ago (should be days/weeks)
LHO General
patrick.thomas@LIGO.ORG - posted 08:30, Thursday 30 January 2014 (9647)
Hugh, Apollo working on HAM4


			
			
H1 ISC
kiwamu.izumi@LIGO.ORG - posted 02:06, Thursday 30 January 2014 - last comment - 02:12, Thursday 30 January 2014(9644)
Infrared laser locked to X arm for studying the green beat noise

Stefan, Kiwamu

As a part of the beat noise study, we locked the main infrared laser to the X arm cavity by feeding the reflection signal back to the MC length.

Although we succeeded in locking the IR,  the beatnote tonight was not great at all. It was roughly 500 Hz / sqrtHz in a band from 1 to 900 Hz when the infrared was locked. Plus, the mode hopping was so frequent that I was not able to integrate the spectrum lower than 1 Hz.


IR locking to the X arm:

Because the green light tonight was not stable enough for us to do the CARM hand off, we instead started locking the IR to the X arm. This is the first time for us to directly lock the infrared main laser to an arm cavity without an aid of the ALS technique. We started this from estimating the PDH optical gain of REFLAIR_RF9 by simply looking at the free swinging wave form. According to Alxea's math (alog 7054), we got ~ 1.21 counts/Hz for the optical gain. Also the MC2 M3 stage was approximated to be 18.2 / f^2  Hz / counts. Using these two information, we set the LSC gain to be 0.46 as an initial guess. Note that we cranked up the whitening gain of REFLAIR9 to its maximum. The demod phase was also adjusted to maximized the PDH signal in in-phase. We then fed it back to MC2.

A good servo gain was then empirically found to be about -0.2. Even though we didn't have a transmitted DC or reflected DC signal, we could tell if we grabbed a sideband resonance or carrier resonance by looking at the size of the Q-signal. This allowed us to detemie the right control sign.

The locking procedure is as follows:

  1. Lock IMC
  2. Remove all the notches and aggressive filters in MC2 M3 ISCINF_L.
  3. Turn on only FM3 and FM6 in MC2 M3 LOCK_L to have a large phase margin from 40  to 500 Hz.
  4. Run the beatnote tracking servo using ezcaservo (see Daniel's instruction in alog 9559).
  5. Decouple the MCL at DC by enabling FM1 of LSC_MC
  6. Make sure that the input matrix is set right so that REFLAIR_RF9_I will be used.
  7. Engage the reflection PDH servo which is currently in LSC-SRCL filter. Use  FM2 FM3 and FM4 with a gain of -0.2.
  8. Once the PDH signal becomes quitter, stop the ecaservo and also cut the LSC-MC path by enabling FM7.

One major difficulty we had during the IR lock was that a mechanical resonant mode at 41 Hz (bounce? roll? of MC2) rang up so much that we could not keep locking the IR. We often let the IMC alone to allow it to settle down for a while and this helped a lot. Also Stefan could introduce the additive offset path on top of the MC length control. He had to crank up the input gain of both common mode board and IMC board to the maximum of 31 dB. It seems that we could still go higher although we didn't quantitatively evaluate it yet. This additive offset technique should serve as a good mitigation for this 41 Hz mode issue while maintaining a high control bandwidth.

The attached is a screen shot of the IR locking configuration.

 

Noise of the green beatnote was far from good:

The noise performance of the green beatnote was not great. Something must be wrong. The smallest noise floor I could get was approximately 500 Hz/sqrtHz in a band from 1 Hz to 900 Hz.  I tried not include a mode hop during the spectrum integration. Even so, as you can see in the attached spectrum, it was suspiciously  flat. I used H1:ALS-C_COMM_PLL_CTRL for measuring the beat noise. The calibration was done by injecting a known RF frequency into the PLL and measuring the ADC counts. It was measured to be 7.916 Hz/counts. Also I added a z40/p1.6 filter to cancel the VCO response.

Images attached to this report
Comments related to this report
kiwamu.izumi@LIGO.ORG - 02:12, Thursday 30 January 2014 (9645)

Additional Note:

PRM is currently in its parking position to avoid a power-recycling fringe at the reflection port.

H1 AOS (IOO)
paul.fulda@LIGO.ORG - posted 20:41, Wednesday 29 January 2014 (9643)
IM4trans whitening gain adjusted

I noticed that IM4trans S1 and S2 channels were saturated, probably after the power increase (similar to the case for IMC WFS noted in entry 9094).

I adjusted the whitening gain down from 45dB to 36dB, which brought segments S1 and S2 down from the rails. IM4trans signal looks better now.

H1 CDS
david.barker@LIGO.ORG - posted 18:01, Wednesday 29 January 2014 (9639)
MSR doors open and fan is running
following the failure of one of the three cooling units in the MSR, as a precaution against a second failure we are keeping the hallway doors open and a fan running overnight.
H1 PSL
kiwamu.izumi@LIGO.ORG - posted 16:19, Wednesday 29 January 2014 (9637)
ISS PD offset jumped

Stefan, Kiwamu

We found that the ISS diffracted light had been high at 24%. According to the trend, it looks that both PD_A and PD_B suddenly got an offset of about 0.5-ish volt and it pushed the diffraction ratio to the high value. The jump happened at around 9:41 local in this morning. Neither Keita nor Yuta was at around the ISC/PSL rack at this specific time. At this point it is unclear what happened or what might have triggered it. The attached is the trend showing the funny jump which also decreased the carrier power everywhere.

For now, we changed the reference offset to bring it to approximately 9%. The new reference offset is:

H1:PSL-ISS_REFSIGNAL           -2.31548

A further investigation is needed.

Images attached to this report
H1 General
andres.ramirez@LIGO.ORG - posted 16:00, Wednesday 29 January 2014 - last comment - 07:52, Thursday 30 January 2014(9636)
Ops Shift Summary
8:30–9:00 Going into the LVEA to work on dust monitor – Patrick
9:01      PSL Check List done (noticed the ISS Diffracted Power was                     
          Close to 24% - It should be 5-15%)
9:00–10:30 Water Ground staff on site for water sampling – Hanford
9:27–10:03 Back in the LVEA to swap dust monitor power supply–Patrick                      
9:36-      Starting Initial Alignment of Ham 4 optical table- Hugh
9:41       PSL Check List done (noticed the ISS Diffracted Power was                       
           close to 24% - It should be 5-15%)
9:49–12:06  Working on ACB in LVEA West Bay – Mitchell/Scott
13:05-13:59 Back to work on ACB in LVEA West Bay – Mitchell/Scott
13:10-15:14 Periscope assembly on H2 PSL – Joe
13:46-14:48 Installing Tablecloth bracket on SR2 (LVEA) – Jeff B.
13:50-15:14 Joining Joe for periscope assembly on H2 PSL – Craig/Sam
15:00       Safety Meeting 
Comments related to this report
hugh.radkins@LIGO.ORG - 07:52, Thursday 30 January 2014 (9646)

Left LVEA ~1745

H1 IOO (IOO, ISC)
paul.fulda@LIGO.ORG - posted 15:02, Wednesday 29 January 2014 - last comment - 18:04, Wednesday 29 January 2014(9633)
ISCT1 beam size measurement preparation

This afternoon I went to ISCT1 to begin setting up for the beam size measurements that we hope to use to diagnose the PRC mode matching situation (see LIGO-T1400013).

I took the beam analyzer cart from the optics lab out to ISCT1 and left it set up there. I measured beam powers in two locations just after the REFL periscope: one in reflection of the pick off window directly after the lower periscope mirror, and one after. Since we aim to measure two beams in the REFL path with powers differing by a factor ~4000 it's useful to have low and high attenuation locations. The window is not AR coated so there are two beams visible in reflection. I measured the power of one to be 890uW, and the other to be 800uW, with the low-power head on the VEGA power meter. The beam in transmission of the window was measured to be 123mW. I left the table with the window reflected beam dumped, and the photon inc. beam analyzer behind the dump.The window transmitted beam is still dumped on the shutter.

Comments related to this report
paul.fulda@LIGO.ORG - 18:04, Wednesday 29 January 2014 (9640)

I just looked for the beam in the same locations with PRM misaligned (sending direct PRM reflection to the parking dump). This should be the beam transmitted through PRM, reflected off ITMX, transmitted through PRM again and sent on to ISCT1. The good news is, the beam was still nice and visible on the IR card after the pick-off window yes

I tried to measure the power at that location with the same power meter as before, expect with the filter out. Due to the X-arm work going on, the beam was finging quite a bit in the IR, so I couldn't get a very solid reading. It looked like around 50uW on average, with a peak value of ~80uW. Comparing this with the PRM aligned value it seems a little high. The PRM misaligned beam should be roughly T_PRM^2 * T_BS^2 = 2.25e-4 times the PRM aligned beam. This means I would have expected 123mW*2.25e-4 = 28uW. Maybe some of the green light was leaking in, or maybe the X-arm flashes were confusing the power meter... it will be easier to get a good measurement here with ETMX and ITMY misaligned later. I can't take beam profile measurements until then anyway.

H1 CDS
daniel.sigg@LIGO.ORG - posted 13:09, Wednesday 29 January 2014 - last comment - 18:16, Wednesday 29 January 2014(9629)
DAQ/dataviewer limitation?

We are trying to record the frequency of the ifr, but there is a 4Hz offset between the EPICS readback and the value reported by dataviewer and/or saved by the DAQ.

Images attached to this report
Comments related to this report
david.barker@LIGO.ORG - 17:45, Wednesday 29 January 2014 (9638)

Looks like a dataviewer/xmgr problem. When plotting this data using diaggui we get the correct value.

Images attached to this comment
david.barker@LIGO.ORG - 18:16, Wednesday 29 January 2014 (9641)
the eagle eyed amongst you will have noticed the root plot Y-axis doesn't look correct. The data line is 2256 but the Y-range is actually 2260 to 2270 suggesting the data is 2260 (as xmgr showed it). Jim ran command line nds client on this channel and confirmed the DAQ is recording the correct frequency of 24992256Hz. Unfortunately both xmgr and root seem to have plotting problems with static numbers of this magnitude.
H1 ISC
daniel.sigg@LIGO.ORG - posted 11:59, Wednesday 29 January 2014 - last comment - 16:06, Wednesday 29 January 2014(9626)
The way of the beast

(Alexa Daniel)

We went to EX to try to make a more precise measurement of the cavity length. For this measurement we use the fact that in reflection of a locked cavity a phase-modulated RF sideband will not convert into AM, if it is exactly on a free-spectral-range even in the presence of length locking offset. The setup is as follows:

At first glance the accuracy of this method seems to be about 5 Hz, maybe even 2 Hz. We will repeat the measurement in the afternoon to see how repeatable it is.

Comments related to this report
alexan.staley@LIGO.ORG - 12:50, Wednesday 29 January 2014 (9627)

To measure the arm cavity length we measured transfer functions while adusting the IFR frequency. The data includes the magnitude and phase at 1.3kHz for the several frequencies. The ArmCavityLength.m script computes the projection of these TFs at the various frequencies to determine the zero crossing.

The ZeroCrossing.pdf is a plot of the result. The x-axis is the frequency scaled by 24.992271MHz. Notably, the IFR frequency has an offset of 12Hz which has been adjusted for in this plot. Clearly, the zero crossing is at 24.9922709MHz, which gives an arm cavity length of L = 3994.4704m /pm .3mm assuming a zero crossing accuracy of 2Hz.

Non-image files attached to this comment
daniel.sigg@LIGO.ORG - 15:58, Wednesday 29 January 2014 (9634)

As built numbers can be found in alog 9385.
A previous measurement with less accuracy can be found in alog 9386.

alexan.staley@LIGO.ORG - 16:06, Wednesday 29 January 2014 (9635)

We repeated the measurement again this afternoon. I have attached the data, graph, and new matlab script. Again we find that the zero crossing is at 24.992271 MHz /pm 2Hz. This gives an arm cavity length of L = 3994.4704 m /pm .3mm. 

Note: the 12 Hz offset between the IFR and timing comparator was consistent.

Non-image files attached to this comment
Displaying reports 73701-73720 of 83068.Go to page Start 3682 3683 3684 3685 3686 3687 3688 3689 3690 End