Notes from Local Meeting on April 15, 2004

In attendance: David Armstrong, Hachemi Benaoum, Tim Holmstrom, Bob Michaels, Lisa Kaufman, Kent Paschke, Ryan Snyder, Bryan Moffit

Hypernuclear plans to run with cryotarget this weekend. This presents an opportunity for us to commission the lumi and test target boiling.
Our goals for this weekend are:

Riad will submit a test plan for the 15 cm LH2 target. We agree that to avoid a large impact on hypernuclear, we will keep out plan short (1 hour or less). Dave Armstrong points out that, in addition to several current setpoints, this test should include two raster settings. This should be possible in a one hour test.

Analysis Log
The HAPLOG linked from the HAPPEX webpage is the HAPPEX Analysis Log. We should use this to keep track of our work during hypernuclear and pentaquark experiments, to avoid cluttering up the HALOG.
Lumi pedestals (Hachemi)

Beam lumi pedestals are all 3-5 channels, seen in a 1 hour run.
Some double peaking, at a few ppm level, is visible in some runs, but not in others. All helicity control signals have been eliminated from this DAQ crate, so the double peaking must be correlated with something else.
Occasional periods occur in which the noise in some of the lumi detectors becomes relatively large. This is the intermittent pickup which has been seen in previous pedestal studies.
Currently, the ground lead of the differential PMT signal for each lumi detector is isolated using a 100 pF capacitor. It is pointed out that if any other approach is to be tried, for example, using a large resistor in place of the capacitor, action must be taken soon as beam will be in the Hall on Friday.
Bryan points out that the lumi HV settings are now recorded in the start- and end-of-run logs in the HALOG.

Kees announced at Hall A meeting that the Compton would not see beam during hypernuclear.
There are 4 primary goals for the Compton commissioning

Optimize beam spot, aspect, and position in Compton
Scan master slit settings versus background.
Phase trombone - the phase trombone should not modify beam spot or aspect in the polarimeter, but this should be directly verified by checking signal vs. background.
The effect of the dithering magnets must be checked for the optics configuration through the Compton.

Test Plans
Several test plans should be completed during Hypernuclear.
- Dithering will be attempted for the first time.
- The effect of the phase trombone on helicity-correlated position differences will be tested using the PZT, after accelerator completes initial testing.
Laser Table

One new cell, Sam, has been characterized. Birefringence gradients have been observed to be as small as those seen in Arwen.
Steering scans converge quickly. Few 10's of ppms expected from steering in tunnel.
Estimates of birefringence gradients at "geometric" (zero-steering), scaled by expected analyzing power on cathode, lead to estimates as low as 50 nm of position differences due to birefringence gradients.

We are about to start modeling aspects of the expected tunnel setup on the laser table.
Ryan summarized work on imaging

Imaging solution appears possible
Started investigation of beam telescope ("expander") and beam spot size.
We will probably check effect of spot size on birefringence-gradient induced position-differences.

Riad and Time haven't started yet, but there is still a strong desire to see this done.
Bryan points out that an sql client is needed on the adaq cluster, Tim will need to consult Ole for this.
Dave Armstrong advocates a mirror for the database, to increase reliability.

Charge asymmetry feedback will be done with either the IA cell (unlikely) or the PITA voltage (likely). panFFB will need to be changed to be able to use either device.
In order to achieve the necessary fine control with the PITA voltage, it will be necessary to use the EPICS setpoint as an offset from a constant which is near the quarterwave voltage. Again, this probably requires a small change in panFFB.
PZT feedback may also be used. The PZT motion induces a charge asymmetry (always has, and the mechanism is completely not understood), so it will likely be necessary to use a 3x3 matrix feedback for PZT changes. This requires further modification of panFFB.
Bryan will take the lead of preparing panFFB for feedback.

Injector DAQ. 6 bpms presently readout, 9 will be desired eventually (+ one bcm, one quad photodiode and a battery or two). One ADC will be used for the BCM, and otherwise all bpms will be read out using the V2F.scalers.
ADC supply

Bryan is now a "confident ADC-fixer". He has fixed 4 ADCs so far, each with a failure due to bad solder joints. He is confident that he can track down and fix bad solder joints as they appear, and it seems likely that more will appear over the next few months.
Two voltage ADCs have been removed from the injector, and will be used to readout the Cavity BPMs.

Left HRS DAQ has been installed and configured. The full 4-crate DAQ has been run without problems.
The sync monitor has been installed on the Right-HRS DAQ crate, and all control signals except for MPS have been removed from that crate. The sync monitor has not yet been installed on the Left-HRS crate.

Bryan's new online monitor, named PANGUIN (PAN GUI moNitor) should be ready for release this weekend!
There is a small problem with a memory leak from a flaw in ROOT's handling of scatter plots (bug report submitted, problem is being worked on). This is manageable, but will require periodic restarts of PANGUIN

Larry has told Dave that HAPPEX-He will be up for jeopardy if it is not completed by the Fall'04 PAC. We had previously understood that an experiment which had received a portion of its data was immune from jeopardy, but this appears to not be the case.
Presumably this applies to the HAPPEX-H run, as well.
It may be that appearing on the schedule in the first half of '05 will exempt these experiments from jeopardy, but this isn't clearly understood right now.