Summary of (our knowledge about) 2nd loop array units are available on DCC: https://dcc.ligo.org/LIGO-D1101059
We opened the container of S1202966 in the optics lab for inspection. This is a unit removed from LHAM2 in 2016.
We found no damage (1st picture), all photodiodes and the QPD look OK, no chipping of the optics, but many components are missing.
- Missing upgrade components to lift QPD higher to make it closer to the optical plane of the array photodiodes. We'll search for spares.
- Missing upgrade components to tilt QPD. We have spare parts.
- D1400146 Beveled C-bore Washer to tilt the QPD assy by 1.41deg to avoid direct reflection back. We have spares we can use.
- D1300963-V2 updated QPD clamp plate to accomodate 1.41deg tilt. V1 doesn't work. We have spares we can use.
- Missing extended ISS array cover/lid assembly parts (ECR https://dcc.ligo.org/LIGO-E1300662). We will search for spares.
- D1300717 Array Cover (Extended). Unlike the name would make you believe, this is not the cover assembly, but is a kit comprising one each of 5 different panels i.e. D1300717-101, D1300717-102, D1300717-103, D1300717-104 and D1300717-105.
- At least 5 kits have been made according to ICS. We know of four kits used for existing arrays, i.e. two in the existing IFOs (one each at LHO and LLO), one in the optics lab for S1202965, and the last one for S1202967 that was bent and contaminated. Assuming that the 3IFO unit (S1202968) has the cover, we might not have a spare.
- But the same ICS record also shows 5 pieces of mysterious (to me) D1300717-00, four of which are supposed to be at LHO. If D1300717-00 means the entire kit comprising 5 panels, we might have spares.
- D1300890 Array Cover Corner Support. This is a kit of 3 different corner braces, i.e. 1 piece of D1300890-1, 2 pieces of -2 and 1 piece of -1.
- According to ICS we seem to have produced 9 kits. Like D1300717, we know four kits used for existing assemblies (H1, L1, S1202965, S1202967), and I assume that the 3IFO unit (S1202968) has one. So we should have four spares somewhere.
- D1300717 Array Cover (Extended). Unlike the name would make you believe, this is not the cover assembly, but is a kit comprising one each of 5 different panels i.e. D1300717-101, D1300717-102, D1300717-103, D1300717-104 and D1300717-105.
I decided to disassemble the damaged/contaminated S1202967 partially to send some of the parts to C&B and keep them as the last-resort spares. Jennie sent the following parts to C&B. There are deep scuffs which should be the result of repeated metal-to-metal contact/scratching, but they should be OK for use once they go through C&B.
- D1300718. A kit comprising two 4.501" poles with cutout, one 6.511" pole and two thinner 3" poles.
- D1300719. Top platform to mount the QPD as well as the ISS array cover assembly.
- Related hardware.
ISS array cover might be salvageable but the place where the poles are attached is bent so badly, bending it back might break it. See the 2nd picture, the surface is supposed to be flat.
Brief update about the following two items. No spare was found at LHO as of Jun/18/2025, so in the worst case we will use the parts salvaged from the damaged S1202967 assembly (they were already sent to C/B).
- D1300718. This is a kit comprising two 4.501" poles with cutout (Type 1), one 6.511" pole (Type 2) and two thinner 3" poles (Type 3).
- Total of 10 Type 1, 8 Type 2 and 10 Type 3 have been manufactured (ICS record) enough to manufacture 5 kits.
- One kit is in WHAM2, one in LHAM2, one in the damaged S1202967, there might be another one for India unit S1202968, that's 4 kits in total maximum. There should be at least one spare kit somewhere.
- D1300719. This is called QPD MT PLATE, it's a top platform to mount the QPD as well as the ISS array cover assembly.
- Total of 8 has been manufactured (ICS record).
- Like D1300718, 3 or 4 pieces were used (WHAM2, LHAM2, damaged S1202967, maybe one in India unit S1202968). There should be at least 4 spare pieces somewhere.