Note from Amy Regan to Will Fox: Hi Will, This comes under the heading of "Because of decisions ORNL has made that are different from what we were told when we did the initial design, a cost increase must be incurred if we are to meet spec." It all gets back to the cable phase drift due to temperature variation issue. Originally the facility temperature was going to be 75° ±2°F in the tunnel and 75° ±5°F in the klystron gallery. Given these values, we determined which of our cables needed to be heated and which did not, and established a reasonable phase error budget that allowed us to meet the ±0.5° phase change in the RF field in the cavity. Now the facility temperatures are Beam-On Beam-Off FE Building 76 F +/-2 76 F +/-2 All Tunnels 85 F +/-5 72 F +/-5 Klystron Gallery 85 F +/-5 72 F +/-5 HEBT Ser. Bld. 85 F +/-5 72 F +/-5 Ring Ser. Bld. 85 F +/-10 72 F +/-5 RTBT Ser. Bld. 85 F +/-10 72 F +/-5 This implies that the cables will see a much greater temperature variation than we expected. Which in turn implies that the vast majority of the cables we have will have to be heated and insulated. I need to do more work to determine exactly how many of the cables, and how much it will cost. I've already spent quite a few hours on it and it'll continue to take my time to address this issue (and hence money up front). My question for you, do you want me toproceed with this work? amy Amy Regan's answers to Will Fox' questions on the impact of the non-temperature-controlled reference line feeders: 1) If you don't do the work and don't change the current design what is the quantitative technical impact? e.g phase stability will be +/- ? degree? The significant problem is the cable between the cavity and our mixer that is located inside the thermal blanket that is wrapped around the reference line. This cable will be transporting an RF signal, so we need to worry about the RF phase drift seen as the cable changes length due to temperature variation in the tunnel. Given the specifications listed below, we anticipate that we will need to thermally stabilize each of these cables. They are only ~10 feet long but given the expected temperature variations, this is long enough to give us trouble. We expect that an additional uncontrolled phase change of 0.3° will occur if we do nothing. (±0.15). 0.2° of this is due to the 10' cable, the other 0.1° is due to the cable going back to the RF Controls rack from the tunnel. I didn't address this here, but it is the same problem - more temperature variation means more electrical length change. 2) What do you estimate the cost of doing the work? Anticipated M&S $1000 per field pickup loop cable x93 pickup loops = $93,000 Without spending much time on it, we also think we can alleviate the tunnel-to-rack cable problem at a cost of $30,000. You'll also need some sort of AC junction box located near the reference line for each pickup loop. M&S cost for this - I have no idea. The real kicker will be the labor, though. Let me list the things that I can think of off the top of my head that will require a person to do the work: You need to create installation drawings - 2.5 weeks All of the temperature controllers need to interface with EPICS - this requires both software support as well as possibly some special hardware - 1 mm SW, 2 mm HW You'll need a chassis in the RF Control rack to house a summing/OR-type hardware (you now have more controllers than you have IOCS, so you'll need to get that information combined somehow/somewhere). This means you have to design and build it. - 3 mm You need installation labor - no longer do you simply pull a cable and terminate the end (which in itself takes more time than you would expect, just because these terminations are a pain). In addition to that, it now needs to be insulated; have thermocouples/RTDs applied; and sensor wires, controller wire all need to be run back to the rack. - 3 hours/cable * 93 = 279 hours Then you will need some top level engineering to develop the whole thing and then oversee it all and make sure all details are covered. - 3.5 mm As far as the AC junction boxes - I have no idea how to estimate the labor required for these. None of the above time estimates include the 80% efficiency factor. 3) Do you have any flexibility in your existing work package to cover this additional cost and if not and ORNL won't fund it is there something else you would not do that is less important and what is it? I do not have any flexibility in my work package to cover this. We are extremely resource limited. This is not part of any RF Controls contingency work I had envisioned. There is nothing less important that I would not do. I have been pushed from the beginning to minimize the cost on this project to such a degree that I cut everything back to the absolute minimum. We have no fluff in our budget and scope whatsoever.