Thu - May 4, 2006

Update


Just an outline of things going on.

In the past month, a number of things have gone on. I got final L1B0a thresholds and updated LET matrices for FM1 and FM2, and I've been trying to keep them in people's minds for the next firmware update.

I went to the ACE SWT meeting at APL earlier in April, after the previous blog update.

Branislav (mostly) and Mark pushed the project to allow L3 detectors to be replaced in FM1 and FM2, which is a huge risk to the schedule. However, they managed to convince many people to do it, including those who opposed the effort, saying we could get enough science out of the crippled instruments. Recently, Branislav and Sandy have been working to remove screws holding the instruments together, and breaking a few screws in the process.

I did a cursory examination of some Canberra 2022 shaping amplifiers to use with Macsys. We need more. I don't know when or if we'll ever bring the ultra-thin silicon detector work to an accelerator.

Yesterday, I finally managed to get started (or restarted) on the charge states paper. I want it off my desk ASAP.

Posted at 12:00 PM    

Mon - April 3, 2006

LET matrices



Showed some CPT data plots in the STEREO LET data meeting this morning, and I got jumped all over by Dick, Mark, and Rick L. for not having centered the STIM boxes by now. Personally, the STIM boxes work fine where they are, and I was waiting for the completion of the thermal vac runs before changing them anyway. Furthermore, I've been showing these plots with the STIM events on the STIM boxes for weeks, and nobody jumped on me before.

Anyway, I spoke with Rick C., and there may be an opportunity to change the matrices in the next couple of weeks or so.

Posted at 12:55 PM    

Fri - March 24, 2006

L3B leakage currents



With the L3B leakage currents growing in FM1 and FM2, it's pretty obvious that they'll fail in flight. I had done calculations earlier (months ago) which showed that we could still do science with the loss of the L3B's by accepting smaller energy ranges. I gave those calculations to Dick, who used them in discussions with the project management. The failing L3B's both have dual oxide layers; the good L3A's have single oxide layers, so the problem seems associated with dual oxide layers.

Last week, we had a number of meetings through Friday in which we tossed about the possibility of replacing the flight L3B's with some spare L3's we have here which should be single-oxide. Tycho, Mark, Sandy, and Branislav favored replacing the detectors if schedule permits, with Branislav being most forceful in support of replacing the detectors. Ed, Dick, Alan, and Rick C. opposed replacing the detectors, citing the fact that we can still get science without the L3B's and the risks in missing the schedule (and being left off the spacecraft), the ~160 screws (epoxied onto the LET instruments), the flexi-cables, etc. Branislav replied that we had the skill on hand (notably himself and Sandy) to keep the physical risks to the detectors minimal. Those opposing the replacement would have to be the ones writing up a proposed replacement schedule, and they didn't feel they could write it up convincingly. By late Thursday, the majority vote (Hiromasa and I didn't speak up; lack of seniority) seemed to favor just accepting the crippled instrument, but by Friday, Lil (our rep with the project) e-mailed us and opened the possibility of our proposing a repair. Branislav jumped all over the opportunity presented, and we had another round of meetings this week.

Yesterday, I managed to attend the second half of the STEREO engineering meeting (Rick C., Dick, Mark, Hiromasa, Branislav, and Alan already in attendance), and when I arrived, they started coming up with a possible timeline for doing the replacements. They figured a 3 week minimum time to replace one L3 on one flight unit, barring accidents, scheduling conflicts (e.g. in getting the thermal vac chamber available for some CPTs afterward), and so on -- about 5 and a half weeks if we include contingency for snafus. Later yesterday, Alan sent an e-mail to Lil detailing our discussions. I was worried (and I noted this in the meeting) that, while the minimum time is probably solid, detailing the contingency time would open us up to further criticism.

Anyway, it looks like the LETs can come off the spacecraft around 4/29 or maybe a bit earlier, but they'd have to be back on by around 5/12. That's not enough time for us. So, for now, we stick with the crippled instruments and hope that some other delay on the project opens us up some more time.

In the meanwhile, Dick asked me to do some more simulations concerning energy ranges with the lost L3Bs. I'm still working on reading the macsys binary output files -- Macsys itself seems to be reading histograms in various inputs as read by jam; my problem is just in the binary data files. Plus, I still have to contribute to the LET instrument paper, and I have to finish my charge states paper, which my career currently depends on. (I've been embarrassed that Luke got his own charge states paper out in draft form recently, while mine has languished for years.)

Posted at 02:36 PM    

Mon - March 13, 2006

Macsys, LET data, Rick's eye


Has it been over a month since my last update?


On 2/22/06, I got Rick C. downstairs with me to work on Macsys, and he spent quite a bit of time using the Mac Classic as a terminal to poke into Macsys and determine that it appeared to be working just fine. Then he noticed that I was missing an "optical box" between jam (Sparcstation) and Macsys. I had used a direct cable connection between the DRV-11 card in jam and Macsys, but apparently I needed a separate box full of opto-isolators and other electronics to go between them. (I'll have to write up my notes on Macsys later, for future user reference.) After a day or so, Matvey found the optical box for me, and I put it in and managed (finally!) to get histograms in a couple of channels. I also had to round up a NIM bin along with a pulser and TC-213 amplifier for shaping.

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Since mid-February (or possibly earlier -- I'll have to check my e-mail archive), Hiromasa and I have been looking at thermal balance and thermal vacuum CPT and normal run data for tests going on at APL for STEREO (LET in our case). I found some STIM event glitches during ADC-mode to Normal-mode transitions and reported them out to the collaboration, and Rick C. figured that those glitches weren't a problem and could be explained by us apparently not allowing the DACs to settle before proceeding after such transitions.

Hiromasa has noticed no problems with leakage currents until this past weekend, when he noticed that the L3Bo (and L3Bi, to a lesser extent) leakage current started to rise to 10 microamps. He reported on this at the data meeting this morning.

On a related note, Dick has started assembling the LET instrument paper, and assignments have gone out to various people to write sections. I've got some of the data formatting sections, which I plan to condense from the LET Science Data Format document I've already written.

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Last week, Rick L. finally went to see his eye doctors after noticing deteriorating vision in his left eye -- the eye that had the detached retina during the trip to the India ICRC. I drove him to his doctors, including his eye surgeon, and the surgeon found that a keloid had formed after his earlier surgery, making the retina detach again. The fix was surgery again, this time draining the eye, probably removing the keloid tissue, and reattaching the retina with a laser. I drove Rick to the hospital for his surgery last Thursday, and Mark W. handled his transportation thereafter (as I was busy later in the week).

Posted at 01:12 PM    

Tue - January 24, 2006

Macsys



A couple of months or so ago, Mark asked me if I was willing to contribute to the ultra-thin silicon detector work being done here, especially given that part of my salary was being paid out of that grant. (I didn't know that part!) I agreed, eager to get back into the lab anyway. Last month, my assignment was to get Macsys up and running. Macsys is an ancient multichannel analyzer about the size of a small laundry machine; it has about 24 channels (or is it 32?). It was ancient when I was a grad student. It is controlled by a Mac (running as a terminal via RS232 to the FORTH system onboard Macsys), and data is read by a Sparcstation. I got Minerva to revive the old Sparcstation that was the data-acquisition computer, and I got the old Mac up and connected. Everything has been moved to room 5. By yesterday, I confirmed that the Mac was uploading the FORTH software correctly to Macsys, and I was able to diddle a little with the Sparcstation, but I lacked some privileges.

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Not much else going on on STEREO for me. Every once in a while, a CPT or other test is performed on FM1 and/or FM2 at APL, and I look at the data and report at our data meetings. I've been working on a "run summary" plot package.

Still need to get out my Q-states paper.

Posted at 01:18 PM    

AGU Meeting

L1B0a thresholds

ACE CRIS/SIS and SWT Meetings

CPTs

Working working working.

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