Minutes of DRAGON meeting, 14 October 2003.

Present:  Aaron Bebington (AB), Alison Laird (AL), Art Olin (AO), Chris Ruiz (CR),
Cybele Jewett (CJ), Dave Hutcheon (DH), Dave Ottewell (DFOT), John D'Auria (JDA), 
Lothar Buchmann (LB), Mike Lamey (ML), Nicole Chorney (NC), Peter Machule (PM), 
Zihong Li (ZL), Mike Trinczek (MT) - rookie recorder.


1.  Corrections to Previous Minutes:

Last section, MT report:  "GEANT and GIOS now agree..." should read "GEANT Standard
tune and Joel's GIOS-Derived Broad 1st Half tune now agree to ~1% point when 
measured just after the Mass Slits." 


DH is missing a grey Nuclear Reactions book, Marion & Young.  Please return!


2.  Facility Update:

DH - Have Carbon beam (as CO?) out of OLIS.  rf people will condition today.
Will install previously damaged DSSSD (with loose wires!) at Mass Slit box.
Tuning hopefully starts at 4pm...

JDA - Formal schedule starting tomorrow night [Ed - posted on web].  DRAGON 
tutorial by DH will happen at 1pm today;  newbies should attend, others perhaps
need remedial lessons.

LB - Is Data Acq ready?  

JDA - Asks questions about the run plan posted on the web.  Much debating, but 
agree to proceed...

DFOT - We can't run at 5 Torr anymore because the newly installed downstream
pumping tubes are a lot bigger.  (Old tubes seem smaller than we thought, though
no consensus was reached on this.)  Trapezoidal gas target ports now have a 
different size.  New: 4mm in, 10mm out.  Old: 6mm in, 8mm out.  New tubes are
designed for 25 mrad, whereas old were for 15 mrad or thereabouts...

[Attachment1]

AO - Check that old tube sizes in GEANT were correct; NIM article has them
listed.  Need new tube sizes to input into the simulation.

DFOT - Power is up in TP1, because of larger tubes.  Probably running at 4 Torr
will be okay.  "What we give up in gas pressure, we gain in solid angle."

DH - Vacuum diagnostics isn't as shown in EPICS around the Mass Slit box because
of DSSSD mounting.  Will point out in tutorial session.  Need to unplug large
gatevalve to ED2.

JDA - Continues to go over run plan.  What is a bearable rate?  500 Hz is probably
too high.  "We need wisdom, experience..."

AO - What will be used as the Standard tune?  Will the slits be open all the way
as in the Broad tune?  Decide to open the slits all the way and measure with the
Standard tune before switching to the Broad tune.


3.  MT GEANT report:

Comparing GEANT Standard tune with Joel's GIOS-derived Broad 1st Half tune.

[Attachment2]

Four simulation runs are shown.  The top two (1001 and 1014) are for the Standard 
tune, the bottom two (1002 and 1015) are for the Broad tune.  In all cases, the 
Charge and Mass Slits are fully open.  The second run in each group (1014 and 1015)
also have the downstream pumping tubes removed (as opposed to including the old 
tubes).

Results show that the Standard tune and the Broad tune give essentially the same
transmission through the first half of the detector.


4.  AB Ion Chamber Simulation:

[Ed - AB generously provides typed summary of his report (as a .txt or .doc file),
along with figures.]

[Attachment3]
[Attachment4]
[Attachment5]

Discussion ensues...

AB - Next step is to mistune the beam in the simulation and see what happens.

By simulating the ion chamber with GEANT, might be able to explain the recoil
peak in the C-13 data.

CR - Acceptance or leaky beam?

This is difficult, but worthwhile...

AO - Do we have the wrong dE/dx for these ions?  Is GEANT overestimating energy
loss in the low pressure gas?

CR - This would be consistent with the ions stopping in Anode 2 (too early).

May have to kluge GEANT to make it fit...


5.  CJ Mini-report on Analysis of ORNL data:

Shows three spectra of C-12 + C-12 -> 2n, 2p, np, ... + Mg-22, Na-22, ...

[Attachment6]

First spectrum is Recoil, gamma, gamma
Second spectrum is gating on 1246 keV
Third spectrum is gating on 2060 keV

Do we want to request more beam or not?


6.  AOB

JDA - Goetz Ruprecht has agreed to join the group as a post-doc.  How soon he
arrives depends on the paperwork...