In anticipation of 16O2+ delivery mid-week, we checked 16O2+ production from the Supernanogan source. No problem. We did have to use the tightest slit settings to achieve a low enough current for the user. Here are emittance scans, normal and with our test booster amplifier inline respectively. Subsequently we set up the line to match into the RFQ. Bias is at 16.32KV. Then we returned the mass selection to 16O7+ for the night. A final emittance scan of 16O7+ for today is shown. It clearly needs a stronger signal. With some slight tweaks, there are some 1nA of 16O7+ on FC6 now.

Today is the last day of this set of Supernanogan Development. The source ran at 16KV overnight, in anticipation of 16O2+ delivery later today. I expected more bias sparking, but it appears that it sparked off only once. So I will condition at a higher bias later today. Meanwhile, the operators reported touching up the tune with the magnet and the RF. Perhaps we are seeing some temperature effect on the source, so I will be looking at effects of RF on 16O7+ for the next while.

 Below is a stripchart of the beam (in blue; turquise is RF power) for the last three hours, of which the last 150 minutes are at the present settings. Pretty good, I'd say. I double-checked the range on the RF, and it's exactly the same as the start. Excellent. To round things out, here is a last emittance scan of 16O7+ before we move to 16O2+.

We now have about 80nA of 16O2+, using the same source parameters as before. Keep a watch for a while, then tune the source to match user's needs, somewhere in the 10nA range.

Here is a stripchart of the 16O2+ beam for the last half-hour or so., and also the stripchart of it juxtaposed with 16O7+ earlier. Also a first 16O2+ emittance scan for this run. I will do source tuning with it momentarily.

After a first round of source and line tuning for good current with minimum RF power, we have about 8nA of 16O2+ on FC6. Here is an emittance scan of that. Present RF settings are 15.438GHz and -1.0dB with less than 1W of RF power. Bias is 16.32KV. Let's do some bias conditioning for a bit.

Supernanogan bias for this run is 16.32KV. After we were finished with source tuning, etc., we conditioned up to 20KV. Then beam was returned and 16O2+ tuned saved as 090623_1730.snapmcisfc6. Next step: Prepare MWS for dual operation. Source open now for source gas installation. Then Keerthi will develop a daul-mode tune, where the B1A bender only need be switched on or off to run either the MCIS or MWS source.

See ISAC elog entry today.  Keerthi developed a dual-mode tune last night, so that we can run the MWS at will if so desired. Save file: 090624_0930.snapmcisfc6. Emittance scans done. Overnight FC6 also attached. Sophia took the beam at 10:00.

Note: This is an updated emittance plot. The bias voltage was incorrect in the original datafile, therefore so were the emittance calculations. The plot itself is identical.

We handed over a 16O2+ beam on Wednesday morning to Sophia for TACTIC setup. On our side, everything went well. TACTIC switched to RIB on Saturday night. See ISAC elog entry. We remain on standby for pilot beam. Schedule switched to development tomorrow morning. Attached is a stripchart of our beam for the last several hours. As good as it gets! Save file: 090629_1730.snapmcisfc6.

Supernanogan development starts today. The TACTIC run, which ended around 08:30 today, appears to have been a success. TACTIC used our beam for setup and pilot, then took 8Li from downstairs. Marco is doing some EOB checks now. We will begin at 10:00. First part of our run plan will be to compare the present 16O2+ beam with how it looked when we started, and identify what might have changed.

Proposed Run Plan for Today &ff

1. Compare present 16O2+ beam with start of TACTIC run and identify change factors.
2. RF frequency scans versus each charge state of 16O.
3. Identify frequency with largest bandwidth for each state.
4. Emittance scan for best beam of each state.
5. Compare with earlier emittance scans.
6. Select one clean beam and test whether or not RF amplitude changes best frequency.
7. Comprehensive mass scan.
 

Setup teething pains... The Start button on the emittance panel worked this time. But ICR called, requesting a few minutes more for Marco. No problem. When I went to restart the scan, the button no longer worked. Restarting X11 made no difference. However, there is a significant update available for X11, so I am installing it now. I perceive that it works, yes, significantly faster than its predecessor. Good, all good.

The first emittance scan sort of got interrupted; it auto-restarted just before the previous scan had finished. I thought the resulting plot was somewhat interesting. The emittance isn't half-bad either. A better scan follows. TACTIC took beam again for a while this afternoon to shake down a timing discrepancy. We got it back around 4pm. One more emittance scan for good measure.

First, with upstream slits opened, then with both open. Original slit setting was 1mm. Finally, restore slits to 1mm and see if it reproduces. It does.

There seemed to be some small change to the beam over the week of TACTIC running. I would like to poke around a bit. The emittance plots suggest some vertical movement at least. The two plots are the before (emittance) and after (emittance). The two tune saves are 090624_0930.snapmcisfc6 and 090629_1730.snapmcisfc6 (present tune) respectively. Here is how they look juxtaposed. I restored the downstream elements. Let's see what that looks like in an emittance scan. They compare well! All changes in beam position can be completely attributed to tuning changes. End of story. I have restored the tune and centred up the emittance plots. Done.

Happy Canada Day!

I noticed a long-term trend in beam intensity. I have every reason to believe that the source itself is rock-solid. I think it is temperature variation affecting the Philtek power suply on the separator magnet. What bothers me is that the stability program appears to not be compensating for this. I am looking into this now. Here is a plot of beam current, mag field and temperature (at AHU-1, the best I could do). There appears to be a delayed response to temperature. I have turned off our Hall probe for an hour or so to watch the response on a stripchart.

Well, there were results, but not what I expected. The beam became nearly out of control while the stability program was disabled. What's more is that the correct field came back immediately upon turning on our Hall probe again. Here are a couple of stripcharts, one snapped right after turning on the probe, and again a while later The stability program was disabled during the middle couple of hours or so. Note that the beam is oddly more stable in the short term now also.

Let's take a look at varying frequency versus beam current for 16O2+. Starting RF values shown below. FC6 = 1.09enA.

What I did: Pan RF frequency between about 12.5GHz and 14GHz. Plasma seemed to extinguish at a frequency under 13GHz.

What I found: Two peaks on the low side, right around 13GHz.

How I proceeded: I panned across those two peaks for stability. I found that the stronger peak in fact was noisier, and also at risk of losing plasma.

Screengrabs:

1. Starting RF settings

2. Lower window of "good" RF frequency.

3. Higher window of "good" RF frequency.

4. Original beam plot.

5. Beam plot at middle of "good" frequency range.

6. Beam after frequency restored to starting value.

7. Frequency survey correlation plot.

As it turns out and as you can see, the original frequency not only provides the same intensity of beam, the beam is also visibly more stable. (Keerthi found this one.)

Lesson learned: Discovery of the ideal frequency is an iterative process. At least three passes, each successively finer, are required.

Here are some pics and data from total MCIS beam on FC3 overnight. A bit inconclusive, but there may be a temperature correlation.

16O2+ beam on FC6 = 10nA as before. Move to 16O3+ A/q = 5.33...

A frequency scan between 13 & 14GHz. I panned closer around two peaks at 13.11 and 13.12GHz. Best frequency so far is 13.1321GHz, which provides a reasonably stable 150pA of 16O3+.

Later... more scans, etc. One of several possible solutions for 16O3+: ~450pA at 13.6348GHz. Let it cook for a while.

We had 16O3+ on FC6 on Friday. An IOSIOC reboot occurred mid-afternoon Friday unfortunately. Operators restored beam at about 06:00 on Saturday. Beam came back fine. I requested FC3 in at 18:00 Saturday to get some temperature correlation with total beam. Maybe there is a correlation, but a longer stretch is needed. Something stopped at 18:00 on Sunday. Keerthi told me this morning that he found steerers off, and switching them on restored beam instantly. Good. Plot attached. Red is FC6 beam. Brown is FC3 beam.

This morning Keerthi began studies on 18O background. Optics are now set for 18O2+ delivery. We will pursue that today. Tentatively the run plan for this week will include:

1. 18O background studies.

2. Repeat emittance scans of the charge states of 16O with slits open.

3. Prepare emittance versus charge and frequency versus charge for 16O, 17O, 18O, 20Ne, 21Ne and 22Ne.

Well... my browser blew away just before I submitted version one of this entry. Let's try again.

Keerthi changed the tune this morning to 10kV on the MCIS bias in order to allow the full throw of the Enzel lens power supply. (Remember, for the moment the panel displays twice what the physical power supply is actually delivering, because it is a 10kV supply, whereas the control system expects a 20kV supply. Such will be the reality in the fullness of time.) He looked at 18O in background gas. It's there all right. We have an up-coming TIGRESS run that calls for 18O delivery. The schedule shows 21Ne for that run, which goes from July 15 - 20.But in fact 21Ne was just a placeholder and 18O is really required. That put us in a spot, because we had not ordered a backup bottle of 18O source gas, and our present bottle would only give us a very few days of operation from the MWS. However, the same bottle would run for months in the MCIS.Pick an option. We floated this situation at the Beam Delivery meeting today. The user really wants 18O, not just an A/q=18 or 9 pilot beam. Good. We can delivery plenty of 18O4+ from the MCIS. Gordon confirmed that 18O from the MCIS is a done deal, and the general attendance concurred.

Run plan for the short term:

1. Complete 18O background studies today.

2. Shut down OLIS for transformer work in the morning.

3. Spin down turbos for source gas change.

4. Install 18O source gas tomorrow morning.

5. Restart vacuum system and source mid-morning.

6  Condition as required.

7. Check intensity and emittance of 18O4+.

Note that 18O4+ is the only charge state that fits within the acceptance range of the DTL. However, it is on the lower end of the Pre-Buncher. Historically a low-level pre-amp was required on the Pre-Buncher in order for it to operate properly. That's between Marco and Ken Fong et al.

Well... Firefox crashed again. What's up with that?

I am having an argument with the OLIS emittance rig. It is returning zero data on 18O scans. Try with 12C, where there is oodles of beam. Aha! A spot! A couple more passes, and we have a "perfect" 12C1+ emittance scan. Here it is. Note: Slits are at 5mm setting.

Now I am trying a scan of 18O2+ with some 1.5nA on FC6. Here we go... Faint, but it's there. Slightly different vertical offset. Done.

Prepare for orderly shutdown of source.

Keerthi and I were front and centre doing ISIS emittance rig testing this morning. He ran it, and I tried to find ways to run the data in Matlab afterwards. Main limitation up there at the ISIS Console is lack of any ssh-enabled terminals. Keerthi's wireless laptop is okay, but this stuff pushes the poor little thing to the edge. Plus, there were some X display issues on it. He has Matlab installed locally, but it takes a bit of a rocket scientist to run it, and once you do get it going, Matlab complains that the data file format is incorrect. We believe it's a matter of line endings: Windows versus the rest of the unix/Linux/Mac/VMS world. So it goes. All in all, a successful morning. There is enough data to think about how it all works, and we have a couple of hours of R&D again tomorrow morning before production beam. I'll put in a few emittance panels here in a while. Keep in mind that these are with beams on the order of mA, not nA!

DataFile    Pulser     Arc       90%     86%     63%    cut%    #71    #72    111    112    113    30    nor. Emit.
 95152        5%        6A      4.01    3.51    1.91     1%                    0      4k     4k             0.101
102032       10%        6A      1.59    4.02    2.1      1%                    0      4k     4k             0.116
102904       20%        6A      4.89    4.29    2.21     1%                    0      4k     4k             0.122
103602       30%        6A      5.18    5.11    2.7      1%                    0      4k     4k             0.131
105650       40%        6A                               1%                    0      4k     4k        
             60%        6A                               1%                    0      4k     4k        
115852       70%        6A      6.21    5.56    3.07     1%                    0      4k     4k             0.157
120728       70%        6A      6.07    5.41    3        1%    2159            0      4k     4k             0.154
122216       70%        6A      5.96    5.32    2.94     1%           2247     0      4k     4k             0.151
123149       70%        7A       (no tuning)             1%           2247     0      4k     4k             0.147
124609       60%        7A       (bit of tuning)         1%     all tuned           all tuned                    

Meanwhile, OLIS and the Supernanogan were off overnight in preparation for transformer tap selection for the sake of the CSB. See WP#2009-07-07-7 for more details.Turbos were turned off in preparation for attaching 17O and 18O source gases. Both are attached now, and valved off presently. I restarted the Supernanogan with about a nA of 18O2+ at FC6. Let it cook for a bit.

As noted earlier, we have 17O and 18O source gas attached to the Supernanogan source chamber. Both are valved off presently. The source has been running for a while. I set it to 18O4+ on background, which gives about 125epA on FC6. Now let's stop the source, open the bottle and try the same again.

I opened the 18O valve just around 18:00. Beam is on now, around 150pA. That's a good sign. It's growing too. Even better. The MCIS tank pressure moved from ~6.5e-8 Torr to ~6.6 as I opened the valve, which is located upstream of a calibrated leak. Note that both source gas bottles have 10-5 calibrated leaks in series, so it will take a while to reach equilibrium. I attempted a couple of emittance scans, but it's too early yet.