Beam ran well overnight. Last evening Vacuum Group diagnosed and repaired a catastrophic leak in the ILT cross region. You can see in the attached plot how venting that section caused elevated pressures in IOS, most likely due to the direction in which IOS:IV7 is installed. Most often it is the IOS section that is vented, and the neighbouring sections remain at high vacuum. So this gate valve would be installed looking downstream so that venting on the upstream side would tend to close the valve even harder. Yesterday was one of those rare times when the pressures were reversed, leaving only the spring tension of the valve maintaining vacuum in IOS. Pretty good, actually.

We are delivering a beam intensity exceeding the agreed rate. Intensity dropped off a little overnight, and it is pretty evident that it correlates with a higher vacuum in MCIS, suggesting that the 17O2 source gas flow has also dropped off. There is ample headroom presently, but the users may request a tweak after the energy change (in progress circa 09:00) and checks are complete.

Later... ICR requested a source tweak, which we did. A little increase.

Beam and energy changes continued over the weekend. The ICR reports that things are going swimmingly, and that the users are happy. Scaler counts are up some 30% or so from Tuesday. All good. A source and line touch-up Wednesday (Remembrance Day) morning and a tuning effort following an energy change during the day on Wednesday produced strong and stable beam running.

Attached is a stripchart of the last day or so of running. The thick blue trace is the DRAGON scaler. The fine green trace is a source collimator, representative of total beam from the source and its stability. The spikes are periodic Faraday cup readings.

Beam delivery continued through the weekend. As noted on Saturday, current dropped precipitously due to source gas pressure. We have 2.3e-6eµA this morning.

A comment about RF power came up at the presentation this morning. Intense X-rays can be produced not only at the peak efficiency and output of the RF amplifier but also as a function of other parameters including source gas pressure, isotope(s), whatever you can think of. I set the RF at a mid-level power, with power setpoint at 0dB and adjusted the RF for optimal current on FC6. This occurred at 13.0306GHz with 35W power. About 6nA of beam. Take a quick emittance scan.

090916_1242ILTEMIT.txt  17O+5 has two peaks.

090916_1355ILTEMIT.txt  Repeat same measurement an hour later. (IOS bias was off in-between due to IOC/PLC reboots.)

090916_1215ILTEMIT.txt    EL increased, ~4.5uA, emittance increases, 50x100   17O+3

090916_1222ILTEMIT.txt  Changed the MCIS steering to center the beam in the EL. 17O+3 ~5uA, 50x100

090916_1156ILTEMIT.txt      17O+3  good settings 50x100 ,   333nA Scale, ~4uA

090916_1206ILTEMIT.txt      17O+3  good settings 100x200 ,   333nA Scale, ~4uA

17O+3 at FC6 became 550nA.

17O hand valve found to be closed. Probable cause may be the cold weather.

After opening the valve beam came back. 2.6uA of 17+3 at FC6.

Notes by DMG 8-Nov-2009:

This valve is barely cracked. Temperature will affect it at such close settings.

Starting pressure Saturday when beam fell off: 4e-8 Torr.

Pressure today with strong beam: 6e-8 Torr.

Pressure during Saturday setup where beam began to quench: 8e-8 Torr.

Conclusion: Correct operating pressure range for Supernanogan source is tight. We removed the MWS head, anticipating this to be the case. It's so even when the slight extra pressure is entirely due to the source gas.

A  1e-5 atm.cc/sec of 17O leak and a 1e-6 atm.cc/sec of neon leak are connected to the source through center tube of the RF transfer antenna.

Ne valve is open for upcoming CSB test.  17O valve is closed. All optics are set to A/Q=5.5.  RF, EL and HV are off for the weekend since no ISAC ops at night.

Keerthi developed a nice 16O7+ beam to FC6 last night. Beam current is about 3nA presently. Here is the first emittance scan from 11:05 today. A little spotty, but it's there. Higher resolution scan at 13:58 follows.

The third plot at 16:12 is 16O6+.

The fourth plot at 17:05 is a 16O5+ scan. However, the emittance rig stopped scanning at position #50, and is frozen at position #0 now. The operators are looking into it, and will reboot IOSIOC. I am ready to restore optics. Later... reboot and restore went well. Continue emittance scans.

The fifth plot at 18:36 is a higher res 16O5+ scan.

The sixth plot at 18:52 is 16O4+ and friends.

The seventh plot at 19:12 is 16O3+. It does not compare well with yesterday's scan of the same beam. Note that recovery from yesterday's IOSIOC reboot required a retuning effort. The source RF was changed in the interim also.

The eigth plot at 19:34 is 16O2+ and friends.

The ninth and final (for tionight) plot at 19:53 is 16O1+ and friends.

A series of 16On+ emittance scans. Benchmark scan of 16O5+ matched well with same scan done this morning. Subsequent scans beginning with 16O1+ were thwarted by an IOSIOC seizure in the emittance rig EPICS panel, and an IOC reboot was required. ICR restored last saved DRAGON tune. So far, so good. Ah, well, not so fast. I have to go fishing for beam on FC6. This may take a while... That's it for today.

A/q = 2 Field = 662.3G FC6 = 150epA (unstable)

No emittance scan possible.

A/q = 2 Field = 667.3 FC6 = ~10enA

A/q = 2.2857 Field = 708.0G FC6 = 70epA (noisy)

No emittance scan possible.

A/q = 2.2857 Field = 710.5G FC6 = 100pA

A/q = 2.6667 Field = 764.7G FC6 = 3.0nA

A/q = 2.666 Field = 767.1G FC6 = 3enA

A/q = 3.2 Field = 837.7G FC6 = 14.5enA

The 16O5+ beam stayed up OK overnight. ICR took some emittance scans this morning. They look interesting. A finer resolution scan is in progress presently. Goals today:

1. Comprehensive mass scan to A/q=100

2. Characterize 16On+ states, including emittance scans where possible.

Mass scan is in progress now. First look is attached below. The full scan is shown in Gabe's Calibrate application. Note the apparent lack of 84Kr, after a night of pumping with the source gas valve closed. A subsequent scan from A/q=0 to 20 is shown next. The same scan zoomed in at yesterday's scale is also shown for comparison of background intensities, particularly 16O5+ with A/q=3.2, which are higher today due to source tweaking this morning. Now I will start a series of emittance scans, starting with 16O5+ as a benchmark. I expect it to be near-identical with this morning's scan.