From ajw@hep204.cithep.caltech.edu Fri Dec 3 14:02:53 1999 Date: Fri, 3 Dec 1999 14:01:38 -0800 From: Alan Weinstein To: wea@ligo.caltech.edu, sanders@ligo.caltech.edu, barish@ligo.caltech.edu, stan@ligo.caltech.edu, fjr@ligo.caltech.edu, nergis@ligo.caltech.edu, kells_b@ligo.caltech.edu, ugolini@caltech.edu, lazzarini_a@ligo.caltech.edu, hiro@ligo.caltech.edu, gustafso@ligo.caltech.edu, steve@ligo.caltech.edu, jim@ligo.caltech.edu, willems@ligo.caltech.edu, jay@ligo.caltech.edu, dale@ligo.caltech.edu, rolf@ligo.caltech.edu, jordan@ligo.caltech.edu, fritschel_p@ligo.mit.edu, weiss_r@ligo.mit.edu, dhs@ligo.mit.edu, kstrain@physics.gla.ac.uk CC: ajw@hep.caltech.edu Subject: 40m upgrade project status, 12/3/99 Hi 40m fans, Here's an unsolicited but long-overdue project status report. Find your name! ____________________________________________________________________ 40m upgrade project status, 12/3/99, Alan Weinstein, ajw@caltech.edu ____________________________________________________________________ - lab status: - The IFO is vented, but otherwise still intact. Oplevs are in control. Green PSL is off, but can be turned on. - We have photographed everything in sight. See the cool photos: http://www.ligo.caltech.edu/~dugolini/ - Dennis Ugolini is assembling an inventory of equipment. To lowest order, we will certainly keep: - oplevs and associated optics - newer suspensions - PSL table and all other tables - general-purpose electronics, video, etc. Items we may not need, and which Drever/Raab/Coles/Aussies/others might want: - green PSL - all green optics, including all current core optics - green sensors: WFS sensors, RFPDs, QPDs - older suspensions - all custom electronics (!) Of course, LIGO management decides these things, and all requests for equipment need to be made to them. All computers, networking, disks, etc, are owned by CDS or LDAS and will be upgraded by them as needed. - All in-vacuum equipment is poised to be removed and stored (who knows where?). I propose that the bulk of this work be handled by Steve Vass and Craig Conley, and it can start ASAP. - We can then return to high vacuum (stacks in) and do an RGA baseline. - lab building modifications: - Rumor, from Provost -> Alan Rice -> Bill Althouse -> me is that the provost has approved our $90K request for building mods: - remove doghouse - patch roof of lab and north annex - extend north annex - refurbish north annex - remove wall between current control room and IFO room - electrical wiring - Work, by Physical Plant (Ron Kibbe) can begin ASAP - coordinate EVERYTHING with Steve Vass and me - we will give Ron Kibbe the go-ahead as soon as rumor is confirmed, OKed by Gary/Barry/etc - vacuum control: - Dennis Ugolini is working on the vacuum control upgrade: - current system (PC, Sun) thinks it's 1989 - working closely with Jay Heefner - writing up the entire plan, for review - draft coming soon! - PO's have already gone out for key electronics (VME) - lots of little work required: could use an electronics tech! - Steve Vass is ordering some of the needed vacuum hardware (like ion pump gate valves); Dennis and Steve will review what other equipment is needed (Dry air scrubber & compressor?). - seismic stacks: - viton vs metal: - metal springs and flurel seats have been ordered, delivery expected any time now - have NOT YET decided on which to use! Depends on Contamination and Performance: - Contamination: - suspect flourine contamination in RGA, from existing viton - expect cleaned springs and seats to be better - therefore, worth baking out the chamber - But is viton really a problem? We might need the highly-damped viton to keep x_rms down! (See below). - If we stick with existing viton, may not be worth baking out chamber, may or may not be worth cleaning the viton and stacks. This eliminates a big and arduous job! - KEY Q: Is the viton a serious problem for the 40m upgrade?? - Performance: - metal springs have superior high-frequency isolation: T_zz seismic wall improves from ~90Hz to ~40Hz, safely away from suspension mechanical resonances at ~100 Hz. - metal springs have inferior low-frequency damping, and therefore, larger x_rms and v_rms, and therefore, poorer lock acquisition and control properties - x_rms and v_rms have been quantified for T_zz, with small but potentially significant differences between metal/viton. Less significant, for T_zx and T_xx? - would like to verify my model, by making seismic measurements - even then, I don't know how to make a decision on this based on all the information so far.... - A hybrid system turns out to solve neither problem: - Contamination: a little viton might be almost as bad as all viton - Performance: no matter where you put the viton in the stack, the low-frequency peak is dominated by the weakly-damped metal springs. - seismic measurements - would like to collect data with accelerometer on floor and on stacks, to verify T_zz modelling. - Stan, can the people who did these measurements at Hanford repeat them here? - We need to design and build a seismic stack for the output chamber, and install it and the output chamber into the IFO. - bake out: - A bake-out of the 40m is a big job; this was to be handled by Bill Althouse, but he's leaving. Is Larry Jones available? Anyone else qualified? - Is the bake-out really necessary? - Yes, if you believe that flourine contamination from existing viton will make 40m upgrade goals more difficult, and IF we plan on replacing the viton - No, otherwise... - A big job: - disassemble all seismic stacks - install the output chamber, stackless - jack up all the chambers - purchase and install heater pads under the chambers - get heater jackets for chambers and pipes, from LHO/LLO - electrical work for heaters - bake under vacuum, continuous monitoring, for months. - Other bits & pieces: - Peter King has begun assembling a new PSL, destined for 40m, and has already been spending money. Estimate: ready by summer 2000. Around $390K, including enclosure. - Janeen has estimates for LIGO-I-like suspensions, SOS scaled up for 4" core optics. Requires ~1 month of her time for re-engineering. - Jordan and Gari gave me estimates for optics. Can probably order core optics glass now. (No need to recycle the existing 40m glass, right?) - Jay Heefner prepared a detailed (but probably incomplete) list of CDS equipment for LIGO-I clone, plus some elements of Signal Mirror control. It's $800K and growing. Given the current work load and availability of the CDS crew, I expect that the timescale for re-engineering, contruction and delivery of CDS electronics will be protracted.. - Budget and Projectizing: - I have assembled a very preliminary budget, with MOST major items represented (say, 85% of the project...), which needs to be gone over thoroughly by Gary and me, with the help of all concerned. - Gary promises to "projectize" the project for/with me, including budget, timeline, person-power, etc. We should do this, soon! - Oversight committee: - A 40m upgrade oversight committee is being formed by Gary, should meet SOON! - Need to develop the 40m upgrade plan, and coordinate with MIT/LASTI and Stanford/ETF, and then present coordinated LIGO II R&D plan at next PAC meeting (when/where?). - The oversight committee will be asked to help make many key scientific decisions: - viton vs metal springs - do we bake-out? - review vacuum control system design for completeness, safety, utility - straw-man (Jim Mason) design for RSE control (input M-Z interferometer, downstream of mode cleaner, ie, in present Input chamber, to add PM sidebands and freq-shift sideband) - shall we contemplate the use of GEO multi-pendulums on one arm? Ken Strain thinks so! - heck, shall we contemplate more complex advanced seismic/suspension systems? The 40m chambers have 60cm of headroom; extendable (with, eh, a ring extender) by another 50 cm. Ricardo has volunteered to put his stuff in! - Dennis and I are preparing documents for review, which highlight these and other key questions.