LOG-IN
Displaying reports 3141-3160 of 3273.Go to page Start 154 155 156 157 158 159 160 161 162 End
KAGRA AOS (General)
Print this report.
TomotadaAkutsu - 02:34, Saturday 25 July 2015 (144)Get code to link to this report
Locations of the iKAGRA beam dumps (so far around MCF and MCE)

Locations of the iKAGRA beam dumps, so far around MCF and MCE, or rather ghost beams, are described here.

http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=3900

KAGRA AOS (General)
Print this report.
SimonZeidler - 17:36, Wednesday 22 July 2015 (143)Get code to link to this report
PSD of PR and SR mirrors

Recently, Hirose-san gave me the measured surface maps of the PR3, PR2, SR3, and SR2 mirrors.
Since there were no PSD calculations yet, I did these with a scilab program that I have written for this purpose.

The results can be seen in the picture that is attached, together with the PSD of the beam splitter as comparison.
Obviously, all PSDs are not so different from each other which might be a good sign.
 

Images attached to this report
143_20150722103622_psdcomp.jpg
R&D (General)
Print this report.
SimonZeidler - 17:31, Wednesday 22 July 2015 (142)Get code to link to this report
Mirror Coating

I did some measurements with a new device in the ATC for creating surface maps together with Ezaki-san and Flaminio-san.

We measured the roughnesses of surfaces of SiO2-glass, a sapphire plate and a GaAs-wafer.
The results are still in a raw-data format and I need some calculations first to give an overview.

KAGRA MIR (Absorption)
Print this report.
ManuelMarchio - 14:52, Wednesday 22 July 2015 (141)Get code to link to this report
LMA surface sample maps

I made maps of the LMA surface sample with

High resolution 70 micron of spacing (as the dimension of the pump beam).

Calibration factor used R=13 1/W.

Scan areas are 4mm x 3mm.

 

 

LMA sample 15034

nominal absorption = 0.65ppm

pump power = 6.3W

map mean = 5ppm (including very high spiky noise or dust or scratch)

most of area value = 0.85ppm  

 

LMA sample 15032

nominal absorption = 4.5ppm

pump power = 3.36W

map mean = 17ppm (including very high spiky noise or dust or scratch)

most of area value = 5.4ppm

 

LMA sample 15033

nominal absorption = 12.8ppm

pump power = 1.18W

map mean = 20ppm (including very high spiky noise or dust or scratch)

most of area value = 14ppm

 
Non-image files attached to this report
Comments related to this report
ManuelMarchio - 10:52, Thursday 06 August 2015 (154)

I made again a map of the same area of the LMA sample 15034. In the same conditions. I didn't unmount the sample from the holder, but I noticed that after one week it was dusty. So I cleaned it again with the first contact polymer. I show the picture of before and after cleaning. I show the comparison of the same measurement in the same conditions but after a week and a cleaning.

KAGRA VIS (OSEM)
Print this report.
TomotadaAkutsu - 13:18, Wednesday 22 July 2015 (140)Get code to link to this report
Comment to Fixing coil wires to OSEM coil bodies by a vac seal (Click here to view original report: 137)

The 30 pieces of the coil bodies are "doubly" packed into clean polyethylene packs (made in a class-100 room, the provider said) in the ATC ISO-1 clean booth. Will be sent to KEK soon.

Images attached to this comment
140_20150722061859_dcim1336.jpg
KAGRA MIR (Absorption)
Print this report.
ManuelMarchio - 19:27, Tuesday 21 July 2015 (139)Get code to link to this report
Absorption simulation

I found the solution to the heat equation in this article and I calculated numerically using Matlab.

I show the solution of the heat equation for an absorbing fused silica medium.

 - oscillating pump gaussian beam size 70micron

 - oscillation frequency 430Hz

 - absorbing thickness 10micron

 - absorbed power 0.1mW

 - fused silica thermal parameters

 - scale in Kelvin

Images attached to this report
139_20150721121950_animation.gif
KAGRA MIR (Absorption)
Print this report.
ManuelMarchio - 14:22, Sunday 19 July 2015 (138)Get code to link to this report
Comment to Reference sample map (Click here to view original report: 136)

I made two resolved maps of the entire surface of the reference sample (200micron scan step) where the surface is behind the pump (flipped sample). One scanning along X axis (left in the image) and one scanning along Y axis. It shows that there are little fluctuations and they are a bit larger perpendicular to the scan axis. This happens for both maps. This means there are some long time power fluctuations. Maybe it shows more clear in the second attached image where there is only  a 2D map.

There is also a relevant difference between the center of the sample and near the edge, the maximum is near the center, and the difference depends on the map. Still to be understood.

Images attached to this comment
138_20150719070707_mapscanxmapscany.png 138_20150719071737_mapscanxmapscany2.png
KAGRA VIS (OSEM)
Print this report.
TomotadaAkutsu - 18:28, Saturday 18 July 2015 (137)Get code to link to this report
Fixing coil wires to OSEM coil bodies by a vac seal

Four 30 out of 36 washed pieces of the OSEMs, the coil wires are fixed to their bodies by a vac seal, and now being cured (for one or two days) in the ATC ISO-1 clean booth. I need more vac seals.

I use nozzles but the viscosity of the vac seal is so high that my grip now reduces forces..

Images attached to this report
137_20150718112639_dcim1333.jpg
Comments related to this report
TomotadaAkutsu - 13:18, Wednesday 22 July 2015 (140)

The 30 pieces of the coil bodies are "doubly" packed into clean polyethylene packs (made in a class-100 room, the provider said) in the ATC ISO-1 clean booth. Will be sent to KEK soon.

TomotadaAkutsu - 22:17, Saturday 10 October 2015 (182)


The Remaining 37 OSEMs are now being cured in the ISO-1 clean booth in the ATC multipurpose experimental room!



Don't touch them for a couple of days.



Previously I did this 30 OSEM coils, and today 37coils, that means there will be 67 OSEMs in total. The number is sufficient for iKAGRA, but not for bKAGRA, as at least 70 OSEMs will be required for the bKAGRA (PRM, PR2, PR3, BS, SRM, SR2, SR3).



There are some OSEM coils  washed or unwashed and used for trials of several process for the assembly, and they should be added to the number to fulfill the required numbers.




TomotadaAkutsu - 18:31, Thursday 24 September 2015 (183)

37 OSEM coil bodies are now packed into clean bags. (Akutsu, Fujii)

TomotadaAkutsu - 23:29, Wednesday 30 September 2015 (187)

Plus 5 OSEM coil bodies are washed (by ethanol), and then 67+5 = 72 OSEM coil bodies will be available in the end.

KAGRA MIR (Absorption)
Print this report.
ManuelMarchio - 15:44, Saturday 18 July 2015 (136)Get code to link to this report
Reference sample map

I measured some maps of the Surface reference sample.

I order to compare and join different areas of the  sample and in order to process datas I wrote a matlab script that read the .txt file the program uses to store measurements datas.

The map is made scanning many lines, the scan direction used here is the X axis. In the plot we can see some fluctuations that are bigger alog the Y axis. My guess is that long time fluctuations of the pump power cause this. We can also recognize the edge of the sample by the lowest signal at (x,y)=(36,30.5)

Images attached to this report
136_20150718083927_maprefsamp1.jpg
Comments related to this report
ManuelMarchio - 14:22, Sunday 19 July 2015 (138)

I made two resolved maps of the entire surface of the reference sample (200micron scan step) where the surface is behind the pump (flipped sample). One scanning along X axis (left in the image) and one scanning along Y axis. It shows that there are little fluctuations and they are a bit larger perpendicular to the scan axis. This happens for both maps. This means there are some long time power fluctuations. Maybe it shows more clear in the second attached image where there is only  a 2D map.

There is also a relevant difference between the center of the sample and near the edge, the maximum is near the center, and the difference depends on the map. Still to be understood.

KAGRA MIR (Absorption)
Print this report.
ManuelMarchio - 12:36, Saturday 18 July 2015 (135)Get code to link to this report
Comment to LMA sample 15033 (Click here to view original report: 123)

I wanted to understand the big difference between the absorption peak in the configuration where the pump is entering in the sample by the absorbing surface and the other configuration where the pump is entering the sample by the not absorbing surface (flipped sample). So I made again a calibration and also a calibration with the flipped surface reference sample and I found a calibration factor R=17 1/W (flipped) and R=13 1/W (not flipped). For the not flipped sample I made a calibration history in this post and I found a mean calibration factor R=11 1/W with fluctuatoins of 10%. I don't understand why R changes so much. 

If we calculate the LMA15033 absorption with those R factors we get 22ppm for the flipped surface and 14ppm for the not flipped surface.

R&D (FilterCavity)
Print this report.
DaisukeTatsumi - 14:04, Friday 17 July 2015 (132)Get code to link to this report
Mirror Wedge Design

I conclude that the recommended wedge angle is 20m rad.

Images attached to this report
132_20150717070524_wedgeangle.png
Non-image files attached to this report
KAGRA VIS (OSEM)
Print this report.
TomotadaAkutsu - 14:04, Friday 17 July 2015 (133)Get code to link to this report
Washing OSEM coil bodies

Akutsu and Takahashi washed 36 pieces of OSEM coil bodies with acetone in a ultrasonic bath. They are now located at the ATC ISO-1 clean booth to dry. Later, Akutsu will put vac seals to the coil to fix the wire edges, and pack into clean bags, and send to KEK for baking.

The number is just determined by the fact (1) PR2, 3, BS OSEMs are urgent, so 30 pieces are needed, (2) the ultrasonic bath can contain 12 pieces at once.

KAGRA VIS (OSEM)
Print this report.
TomotadaAkutsu - 17:08, Thursday 16 July 2015 (131)Get code to link to this report
Washing test of OSEMs
  • Five pieces of the OSEM coil bodies (wires are wounded) are washed with acetone in a ultrasonic bath (40degC, 20mins). The wires' edges are not fixed to the coil body because Takahashi-san pointed out that the vac seal could be removed by acetone.
  • A PD(S1223-01) and a LED (TSTS7100) are also washed in the same manner. I'll check if their performance would decrease (increase?) or not.

Results

Conditions:

  • The washed and non-washed PDs are different ones.
  • The same LED's intensity noises are measured before and after the wash.

The attached graph shows the washing would not affect the performance; it's only one sample, so we still lack a statistics, but we can probably say they can tolerate the ultrasonic washing.

About the PDs, noises with PDs are the same level as the 35670A at their inpur ranges. The mechanism  why the input ranges are different for the two measurements are unknown, but one thing: the Okt circuit and LEDs and PDs are connected by crocodile clips (alligator clip, whatever), and the noise level is very senstive to the arrangement of these wires!

According to the graph, it appears the washed one becomes better than unwashed one, but the measurement are the same level as the measurement noises, so we cannot say such things.

Images attached to this report
131_20150717094657_figure1.png 131_20150717094701_ledoff1.png 131_20150717094705_ledoff2.png
KAGRA MIF (General)
Print this report.
YoichiAso - 06:05, Thursday 16 July 2015 (130)Get code to link to this report
Comment to Preparing the instrument control racks for placing in the mine (Click here to view original report: 129)

I checked the temperature inside the rack after about 24 hours. It was 23.9C. The temperature raise is too small. I will look for a way to generate more heat (heater) in a controlled way (slidac ?).

KAGRA MIF (General)
Print this report.
YoichiAso - 16:20, Tuesday 14 July 2015 (129)Get code to link to this report
Preparing the instrument control racks for placing in the mine

At some point, we have to put the instrument control system racks in the humid environment of the tunnel.
I borrowed a plastic cover from DGS and put it on one of the racks. Then I turned on the system. I also put a temperature meter.
I will leave it like this until tomorrow to see if the temperature goes up high enough (above 30C).

If the temperature is high, we can expect the local humidity to drop accordingly. So we can move the rack to the field.

Right now, the wrapped rack is sitting in front of the shutter.


 

Images attached to this report
129_20150714091922_20150714132718.jpg
Comments related to this report
YoichiAso - 06:05, Thursday 16 July 2015 (130)

I checked the temperature inside the rack after about 24 hours. It was 23.9C. The temperature raise is too small. I will look for a way to generate more heat (heater) in a controlled way (slidac ?).

KAGRA VIS (OSEM)
Print this report.
TomotadaAkutsu - 20:24, Monday 13 July 2015 (128)Get code to link to this report
Comment to Hmm... (Click here to view original report: 126)

In order to see how the intensity noises of the LED (TSTS7100, not OP232) will change, I slightly modify the Okt driver. A trimmer (CT-94EW500-ohm) is attached to the driver so that the LED current can be variable. The attached graphs are the measurement results. According to the results, when the DC powers is over a certain level (in this case it is around 4Vdc... note that which is caught by the OSEM prototype setup, not the naked direct input power to the PD from the LED) , the intensity noises are not proportional to the DC intensities.

The followings can be said:

(1) because we don't want to input such a large current into vacuum, and the lowest usable DC current should be supplied to the LED (I still did not measure the trimmer's resistance). In terms of this, the DC current should be tuned to make the PD output to 1Vdc~2Vdc.

(2) If you are worrying about the other noises (scattering light of 1064nm, analog-to-digital noise, and ...) would cover the OSEM signals, the calibration factor (or sensitivity) of the OSEM should be kept high, meaning larger DC current to LED would be better. Then the maximum PD output would be  (this is only my recommendation/suggestion) around 4Vdc.

 

My recommendation:

I like to setup the PD output to 1.5Vdc, which would be sufficient.

Images attached to this comment
128_20150713132318_plot20150713pub.png 128_20150713132323_plot20150713compare1.png 128_20150713132331_plot20150713compare2.png 128_20150713132336_plot20150713compare3.png 128_20150713132342_plot20150713compare4.png 128_20150713132348_plot20150713compare5.png 128_20150713132353_plot20150713compare6.png 128_20150714025943_plot20150713compares.png
R&D (Cryogenic)
Print this report.
SimonZeidler - 14:32, Monday 13 July 2015 (127)Get code to link to this report
Cooling-down curve and warming-up

The cooling-down has been finished at Friday night. The final temperature is 4K, just as given also by the company.
The overall duration of cooling down with full vacuum is about 55 hours.

I started the warming-up today in the morning just by switching off the cryo-cooler.
The temperature curve is being recorded again.

Attached are a photograph of the temperature controller this morning and the cooling-curve as taken during the test.

 

Images attached to this report
127_20150713073143_150713103046.jpg 127_20150713073333_calibration.jpg
KAGRA VIS (OSEM)
Print this report.
TomotadaAkutsu - 20:38, Friday 10 July 2015 (126)Get code to link to this report
Hmm...

The attached graph shows noise level of two OSEM setups; with a satellite box (Sat) and with a test driver (Okt) made in NAOJ (design based on the Sat, but Akutsu chooses necessary/sufficient parts what he thought, and Okutomi made). Those two circuits supply different amount of DC current to the LED (TSTS7100). Exactly the same LED and PD combination is used for the measurements.

(0) The measurement systems's noise level (raw voltage noises) for both cases when the LEDs were turned off are in the same order of magnitude. (I don't mention the PD's noises here, and it will be mentioned in (1). I'm mentioning about the noise of measurement system with the range which is used when the PD circutis are measured. The second attached graphs are the raw voltage spectra (V/rtHz vs Freq), and showing this. S70908 (for the satellite box) measurement was done with 6.3mVpk range, while S70905 (for the Okt driver) was 7.95mVpk, and the ratio can explain the relation of both measurement noises) The difference shown are due to the difference between calibration factors (V/m) for the cases.

(1) Why are the PD noises (LED off) such different...?? For the Okt test driver, OP27G is used; for the satellite box, it seems OP2177. The transimpedances are the same (38.3k Ohm).

(2) The LED's intensity noises do not appear proportional to the DC powers. The displacement noises should be the same level if it is proportional.

(3) Additional Note: the satellite box's output of PD driver has a relatively large offset like 20mVdc even without any PDs are not connected, and which is not observed in the Okt test driver. I just add a 5.6k Ohm (by clips) parallely to the 38.3k Ohm and observed the offset decreases accordingly (38.3//5.6 = 4.88kOhm, and 38.3/4.88 = 7.84 times), and the same happens for the power spectrum of the intensity noise... so the offset would come from the opamp's current offset and current noise-like things. As was reported, some polarized capacitances are directed wrong, so some opamps would have malfunctinos now... I checked a OP2177's data sheet but cannot find descriptions on the current noise around low frequencies. The current offset is described but it is too low to explain what are happening here.

(4) Next I decied to use only the Okt test driver's PD circuit for evaluating what's going on the LED noise. With this driver, the larger (and non-proportionally large) noise of the LED driven by the satelite box is confirned again. The current to the LED would be now estimated to 88.3mA (the feedback loop makes 200//33 Ohms should be 2.5V)with the satellite box, and 8.3mA (the feedback loop makes 200+100 Ohms should be 2.5V) with the Okt test driver. This could explain, at least order, the rate why the output is 8.92Vdc for the satellite box and 740mVdc for the Okt. The intensity noise spectra are, however, not proportional to those DC voltages or current to the LEDs. Need to be more investigated; the goal would be to find the LED current setup in which the intensity noise would be slightly higher than the PD driver's noise; fortunately, I think the Okt circuit condition is very closed to this goal!

Anyway, generally speaking, I recommend to use a FET-input opamp for a transimpedance amplifier application like the PD driver circuit... as I did for the oplev QPD driver for KAGRA.

Images attached to this report
126_20150710133026_figure1.png 126_20150710165321_noises.png
Comments related to this report
TomotadaAkutsu - 20:24, Monday 13 July 2015 (128)

In order to see how the intensity noises of the LED (TSTS7100, not OP232) will change, I slightly modify the Okt driver. A trimmer (CT-94EW500-ohm) is attached to the driver so that the LED current can be variable. The attached graphs are the measurement results. According to the results, when the DC powers is over a certain level (in this case it is around 4Vdc... note that which is caught by the OSEM prototype setup, not the naked direct input power to the PD from the LED) , the intensity noises are not proportional to the DC intensities.

The followings can be said:

(1) because we don't want to input such a large current into vacuum, and the lowest usable DC current should be supplied to the LED (I still did not measure the trimmer's resistance). In terms of this, the DC current should be tuned to make the PD output to 1Vdc~2Vdc.

(2) If you are worrying about the other noises (scattering light of 1064nm, analog-to-digital noise, and ...) would cover the OSEM signals, the calibration factor (or sensitivity) of the OSEM should be kept high, meaning larger DC current to LED would be better. Then the maximum PD output would be  (this is only my recommendation/suggestion) around 4Vdc.

 

My recommendation:

I like to setup the PD output to 1.5Vdc, which would be sufficient.

R&D (Cryogenic)
Print this report.
SimonZeidler - 18:06, Wednesday 08 July 2015 (125)Get code to link to this report
First cycle of cooling

The first cycle of cooling the tank has begun today.
After having some trouble with the calibration of the temperature controller and a sudden (and still unexplained) problem with the pressure meter, we are now cooling the tank.

The rate of cooling is now approximately 0.07 K/min at an inside pressure of 2.2*10^(-4) Pa.
With this rate, the cooling down to 10 K will last at least 2,5 days (even more is expected when the temperature falls below 70 K and freeze-out of the remaining gas appears).

I think of using He gas in the future that could be injected into the tank for increasing the effectivity of the cooling process.

 

Attached is a photograph of the temperature and the pressure controller at the beginning of the cooling cycle, right after the cool-down has started.

Images attached to this report
125_20150708110752_150708132415.jpg
KAGRA MIR (Absorption)
Print this report.
ManuelMarchio - 14:55, Tuesday 07 July 2015 (124)Get code to link to this report
Power dependence of absorption

I measure the surface absorption peak of LMA sample #15033 at different powers.

The first plot shows the scans along Z axis

The second plot shows AC signal peak at the surface as a function of the pump power.

The third plot shows the proportionality as a function of the pump power

Images attached to this report
124_20150707075330_pumppower1.jpg 124_20150707075338_pumppower2.jpg 124_20150707075345_pumppower3.jpg