Abstract:

We adjusted the ETMX height and changed the setpoint of GAS filters.
So, mirror height becomes nominal position when ETMX is ALIGNED state.

Detail:

We use two laser levelers to check the height of ETMX.
First, we set rulers near the target makers on the pillar so that the position of 500 and the center of the margker accord.
Then, we set the laser leveler at the heigher position so that light of the laser leveler can reach both inside and outside ot\f the chamber.
We measured the laser height by using the ruler, and the value is 886.5, so the height difference between laser leveler and target is 368.5.
After that, we also set ruler inside the chamber and the measure the laser height with it, and the value is 99.5.
Then, we set another laser leveler inside the chamber so that the beam hits the value of 468 of the ruler inside the chamber.
Figure 1 shows the schematic and several photos of the rulers with light from the laser levelers.

After that, Takahashi-san changes the ETMX height so that the laser leveler inside the chamber illuminate the H3 and H4 magnets.
Figure 2 and 3 show the magnet with light from the laser leveler after adjusting the height.

After the adjustment, we changed the setpoint of GAS filters, so ETMX goes to nominal height when it is ALIGNED state now.

Images attached to this report

Comments to this report:

ryutaro.takahashi - 22:55 Thursday 07 March 2024 (28785)

Before the height adjustment, we recovered the F2 GAS from the jump to the lower position of the bistable state. The suspension rod from the F3 was pulled up. The height of the F2 keystone was changed by +7mm. The setpoints were adjusted as follows. The setpoints for F1 and F3 were corrected to avoid saturation.

	Before	After	Correction
F0	491	295
F1	2800	940	740
F3	-3478	-2270	-2070
BF	1520	3900

ryutaro.takahashi - 10:14 Saturday 23 March 2024 (28949)

(Log on 22nd)

I rearranged the setpoints of the GAS filters. The height of the BF keystone had been out of the adjustment range. Though the FR for the F0 GAS had been stuck at the lower position, it was recovered by driving the stepper motor repeating HALF 100 steps.

	Before	After
F0	295	1670
F1	740	900
BF	3900	2360

ryutaro.takahashi - 15:04 Tuesday 26 March 2024 (28977)

After the rearrangement of the height of GAS filters, I checked the measured TFs. The present TFs were different from the references. I compared them with the simulation. The present TF was consistent with the TF of the BF GAS in 0.6-Hz resonance while the referred TF was consistent with the TF of the BF GAS in 0.3-Hz resonance. The height of the present BF keystone was 2360um. The height of the referred BF keystone was 1630um. I will try to measure the TF in the height of 1630um again.

Images attached to this comment

ryutaro.takahashi - 22:20 Tuesday 26 March 2024 (28982)

Though I tried to measure the TF in the BF height of 1520um, the TF did not change. It is necessary to check around the BF visually.

Images attached to this comment

ryutaro.takahashi - 16:53 Wednesday 27 March 2024 (28990)

[Takahashi, Ikeda, Hirata]

We checked the BF visually. We did not find any rubbing points around BF and inside the tube that the suspension rod goes through. We measured the TF from BF to BF by fixing the BF body. The measured TF showed simple 0.6-Hz resonance. This is consistent with the result of the simulation.

Images attached to this comment

tomotada.akutsu - 17:45 Wednesday 27 March 2024 (28994)

Maybe the following would not directly relate with this issue, but judging from the photo you attached, the tail of a PEEK-tie like one and the metal bottom plate seem about touching. If they touch with each other, such variation of resonant frequency may easily happen.