Minutes of DRAGON meeting, 15 November 2006.

Present:  Chris Ruiz (CR), Christof Vockenhuber (CV), Chuck Davis (CD), Dave Hutcheon (DH), 
Dave Ottewell (DFOT), Goetz Ruprecht (GR), John D'Auria (JDA), Jonty Pearson (JEP), 
Lothar Buchmann (LB), Peter Machule (PM), Mike Trinczek (MT) - recorder.


1. Previous minutes:

Under Hardware a., the quote for NaI tube mounts was from Saint Gobain.


2. Business arising:

DH - Saint Gobain offers everything but the HV supplies for $650, which is more desirable
than the $1500 quote from Ortec for everything and HV.

CV will find Victor Verzilov to explore TOF method to measure beam energy.

DH will meet with Stu Austin of the Design Office to have a designer assigned to the 
22Na chamber for the experiment to be done in Seattle.

CR will show SFU students DRAGON and TUDA on Saturday.


3. Hardware:

PM performed leak tests of the MCP-detector chamber.  While doing so, it was found
that the shaft which supports the MCP targets/foils was bent, presumably by a 
malfunction of FCF and accompanying interlocks.  Said shaft has been removed
to be "fixed":
[PM eMail]
"The bend shaft  is now ...less bend .  ;-}
Machine shop and I kicked it for 1/2 hr.
It now seems true to  +/- 1 mm  .

The whole unit  is back together.
We should test it in air before putting it back into the Final Slit box.
Check wobble etc.

also try to figure out why / what happened ??
Implement real / Hard Interlocks on the Faraday Cup ( as I said 5 years ago
!! ) vs. the soft one now .
??


 ..peter.."

Still need to verify that FCF was the culprit.  A cursory exam shows the Cup
to be devoid of large marks...

The leak test did indeed reveal two leaks which were addressed:
[PM eMail]
"Vacuum in box  9.7 x 10-7 Torr with With Final slit box valved off from ED2
and downstream Vac boxes.
Found two small leaks .
One of the rubber stoppers in a blank-off-plate  on top was leaking.
The roughing valve on the bottom of the box was under too much mechanical
stress / pull as the bellows roughing line was a bit short ( 2mm )
The pull on the valve was enough to cause the O-ring to leak.Tightening the
KF-40 Flange made the leak worse.

solution
Replaced blank-off-plate with another one, as the solar cell test was over.
Replaced O-ring on the roughing valve and then raised the main steel
roughing line the runs below our beamline by 2 mm .

Vacuum in box is now 4 x 10-7 Torr.


..peter.."

The DSSSD chamber has not yet been checked for leaks.  It will worsen the vacuum
by virtue of all the material inside the chamber and may contain several virtual
leaks.

With the improved vacuum in the MCP-detector chamber, CV re-tested the MCP with
better results:
[CV eMail]
"I had a quick look at the MCP now with the improved vacuum, ~3 x 10-7 
Torr. The strange multi-triggering pulses are all gone. If you set the 
threshold on the timing discriminator right then every timing pulse is 
in coincidence with a signal at the anode. I watched the signals for 
about 15 min and couldn't find a strange signal. So it looks like the 
MCP behaves as it should be.
Note, the signals we see without beam are likely from single electrons 
coming from anywhere. The real beam signals should be due to several 
electrons and thus the signals should be much higher. The (dark) count 
rate is a few per second right now.

Christof"

DH has shipped a dead DSSSD to Micron in an attempt to have broken wires
re-bonded.  Its declared value was too high to be accepted, so it will be
reshipped with amended paperwork.

In the ongoing battle to determine why the gas target moves when it is
pumped down, PM found:
[PM eMail]
 "I took a look at the 4 turnbuckles that try to contain the bellows at the
 bottom of the gas target.
 Two were semi loose. This was under Vacuum . The design does not work  ???
 The two hocks on either side of the turnbuckle are too large for the bolts 
that go thru them .
 So we need  shoulder bolts or spacers to make up the gap.
 The washers (on those bolts )  used to hold/ clamp the hocks are too small.
 Each turnbuckle need a " sister buckle on the other side of the assembly as 
the torques are too much for one.
 Even if we now keep the bellows from moving ...that may not do much!
 Bottom of the bellows goes to a large T . This T is hard bolted to a roots
 blower on one side and a bellows that goes to another  roots blower on the 
other side.
 Both Blower sit on dense plastic foam insulators ...that sit on a sub
 platform this is itself insulated for the concrete floor .
 i.e. the whole assembly floats in space and wiggles and vibrates . It is 
supposed to do this.
 By trying to contain the bellows we are actually   !@#$%!$%  with the 
original design .
 LOL
 The upper target and turbos were supposed to be isolated as much as 
possible
 from the roughing / roots blower side.
 This is why we have a totally separated upper frame and lower floor.
See drawing  IHE0002D  " inner and outer Frames are NOT bolted together 
during operation "


 Dave H. and   I came up with what we believe is a much better design to 
hold  the gas target in space.
 ( maybe ;-}

 See drawing  IHE0005D
 Insert two additional  U Channel pieces  beside the two existing ones on 
the
 yellow gas target support frame.
 Back to back and almost touching the 6 inch vacuum pipe that goes between
 the gas target and the bottom bellows .
 The U channels will almost touch the flange of the vacuum pipe . i.e.. just 
below the gas target.
 Leave a 1mm gap or so .
 Use the existing bolts on the west side ( make them longer ) and drill 3 
holes per channel on the east side .
 This can be done "insitue "    (sp ?  )         ( grunt ! )
 Then shim the 1 mm gaps as required .
 This is all best explained while  standing on the platform and maybe a 
visual aid or two.  ;-}


 Remove the bottom turnbuckles as we want as little torque / force from 
there  as possible!


 Peter Machule"
It was decided that this solution will be pursued when PM returns.

MT suggests the group should attempt to better document when repairs/upgrades
are made, especially when "drawings don't match reality".  With the impending
changing of the guard, this becomes even more important.  General agreement.
No decision yet on how to implement (eLog? Docushare? ...)

DH - Rolf Keitel will be working on providing DRAGON an assignable meter (for, 
say, FC4) once the Maya controls are completed.


4. 20Ne beamtime:

DH suggests the opportunity for more beam before Monday morning.  JEP and others
would like to continue the mistuning and steering studies.  CV would also like
to further test the MCP and foils.  Ideally, we would like to have the gas target
(and pumping tubes...) properly aligned, but there isn't time for a proper fix.
DH and PM will see what can be done on this short timescale.  DH will confer with
Bob&Marco to see when time would be available.


5. Other business:

JDA has gathered specs for the desired, ideal alpha source:  10MBq, 2mm spot size, 
1% energy spread, 4m to 1a half-life.  He will send specs to JAC at PNL and find
out about cost and compromises.

DH will ship the Yale source back to Peter Parker.

MT reports that ISAC Operations is also having trouble with EPICS not updating
or spontaneously jumping in values.  We should be extra vigilant with DRAGON.

MT reports no beam measurements have yet to be done with the new FEBIAD source
due to commissioning problems with power supplies, valves, gas cylinders, ...
Hopefully, later this week proton beam will be put on target.

CV asks if we can decide to purchase the second MCP.  Yes.  We will buy a 75mm
diameter MCP from Burle with 10mcm channels (for improved timing response and
position information).  The electronics will be ordered from Ortec.  DH to prepare
the paperwork.

JEP, GR and CR have been making steady progress with the VF48 digital electronics.