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Reports until 21:07, Wednesday 03 December 2014
H1 ISC
alexan.staley@LIGO.ORG - posted 21:07, Wednesday 03 December 2014 - last comment - 05:30, Thursday 04 December 2014(15424)
CARM at 0pm, controlled by digital REFL9 I

Kiwamu, Sheila, Evan, Lisa, Daniel, Elli, Dave O., Dan, Alexa

 

On December 3rd 2014, 3:01 UTC we had the IR resonanting in all the cavities. MICH, PRCL, and SRCL were still on the 3f signals; DARM was on AS 45Q and CARM was on REFL 9 I at 0 pm. This is what we did:

 

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Comments related to this report
evan.hall@LIGO.ORG - 21:47, Wednesday 03 December 2014 (15426)

Here are the REFL and arm powers for a few values of the CARM offset (controlled via TR_REFL9, the digitized REFL9I error signal). These were taken with tdsavg and a 5 s average.

It appears that we are indeed sitting at a minimum of REFL LF and a maximum for the arm transmissions.

TR_REFL9 offset (ct) TRX QPD sum (ct) TRY QPD sum (ct) REFL LF (ct)
−1.5 78 87 53
−1.0 100 112 45
−0.5 118 134 39
0 129 146 36
+0.5 129 146 36
+1.0 119 134 39
+1.5 101 115 45
+2 80 90 51
+2.5 56 63 60
lisa.barsotti@LIGO.ORG - 21:18, Wednesday 03 December 2014 (15425)ISC
This is a trend of relevant signals during the locking sequence. 
We are running ASC loops with low bandwidth on BS, PRM and DHARD. 

The transition to REFL_9I happens at time = 600 sec. The relative increase in the power build up is only 15%.

Dan will post more precise numbers, but his first estimate is that we have a total of 280 mW at the AS port, 75% due to sideband power, 25% carrier.

POP_DC only increases by a factor of 3 when the carrier is resonant..it should be more like 10-20. 
Images attached to this comment
stefan.ballmer@LIGO.ORG - 21:44, Wednesday 03 December 2014 (15427)
Congratulations! Way to go.

Now let's chase that buildup..
albert.lazzarini@LIGO.ORG - 21:45, Wednesday 03 December 2014 (15428)
Excellent!
evan.hall@LIGO.ORG - 22:10, Wednesday 03 December 2014 (15429)

Here are the OLTFs taken at 0 pm CARM offset. The CARM loop has turned out kind of weird as it crosses unity, but it seems the phase bubble can support it. We might need to do some retuning.

Non-image files attached to this comment
alexan.staley@LIGO.ORG - 22:12, Wednesday 03 December 2014 (15430)

We rung up the BS roll mode at 25.7 Hz

daniel.hoak@LIGO.ORG - 22:26, Wednesday 03 December 2014 (15431)

And we beheld, once again, the stars.

 

Here are some power calculations for the AS port and the TMS IR QPDs:

 

==== AS_C sum output (the channel that is used for the shutter logic) ====

quantum efficiency = 0.8, QPD transimpedance = 1000 ohms, sum output gets a factor of 1/4 from R23 (see D1001974)  -->  200 volts / watt on the QPD

OM1 transmission = 5%, M6 is 50/50 splitter (see T1200410)--> AS_C gets 2.5% of the light entering HAM6

AS_C sum output is 1.4V when locked at zero CARM offset:  1.4 V * (1/200) * (1/0.025) = 0.280 W into HAM6

 

==== Transmitted power through the arms ====

Using the IR QPDs on the transmission monitor tables, H1:ASC-X_TR_A_SUM_OUTPUT and similar, and assuming the same QPD transimpedance electronics.  (I am not sure of the calibration of the other PDs, like LSC-Y_TR_A_LF.)

These four channels currently have one stage of analog whitening and 18dB of gain --> 7.9x analog gain

Quantum efficiency = 0.8, QPD transimpedance = 1000 ohms, 2x from differential output, 32768 counts per 20V --> 2621440 counts per watt

On the TMS (see T0900385), M4 is 100% reflector for IR (assumed), M12 transmission is 5%, each QPD gets half of this signal --> TR QPDs get 2.5% of light leaving arm

The QPD signals were about 6000 counts (see attached).  6000 counts * (1/2621440) * (1/0.025) * (1/7.9) = 11.5mW leaving the ETMs

From the galaxy optics page the H1 ETMs have 3.6ppm transmission, this implies about 3.2kW in the arms.

 

The first figure attached is a striptool of the second lock of the evening; the second figure has trends of the TMS QPDs.

Images attached to this comment
peter.fritschel@LIGO.ORG - 05:30, Thursday 04 December 2014 (15435)

That's great, congratulations. LLO had high arm losses (maybe not this high) at one point from poorly centered beams on the test masses; that would be something to check if you haven't already.

david.shoemaker@LIGO.ORG - 02:26, Thursday 04 December 2014 (15433)
Wonderful to see! and well-earned. Congratulations!
gabriela.gonzalez@LIGO.ORG - 04:22, Thursday 04 December 2014 (15434)
Great job, congratulations! 
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