Minutes from DRAGON group meeting February 28, 2006

Present: DH (recorder), PM, MT, CR, CD, CV, DF, LB, AH, GR, JP

1. Minutes of previous meeting
	* several small corrections
	- in Hardware status "JMPs account" -> "TRIUMF DRAGON account"
	- in CR's report on WRNPPC -> "First prize to Chris Ouellet. 
	  Heather Crawford "honorably mentioned""
	- in CR's report on 26Al(p,g) -> "mistake"

2. Hardware status  (DO)
	* SX1 was found to be wired with reverse polarity.  Measurement 
	was triggered by large spotsize found when the DSSSD was moved
	downstream of Mass slits in the alpha acceptance study.  The SX1
	supply failed in November 2005 and was replaced by a different
	type of supply.  Red/black cable indication at the power supply
	end is wrong, probably left when polarity had to be changed after
	initial installation was backwards. (See minutes of 4 Sept 2001.)
	We are confident the wiring was correct up until November 2006 
	and there should have been little impact on the 40Ca(a,g) running
	in November because of the small 44Ti recoil cone angle.
	  DFO will make up a wall chart giving the simplest possible
	description relating the observable red/blue ends of the probe 
	magnet to the required polarities of quads and sextupoles.
	The red bands on the SXn DC cables will be placed correctly.
	* target vacuum leak: still a pressure rise of 15 Torr overnight
	which is better than before a change of o-ring at the gas target.
	The G.T. o-ring is not a standard thickness for ready-made o-rings
	so will have to try again to make an o-ring by gluing; will
	order new o-ring material.
	* PM had discussions with Franco Mamarella regarding connection of
	Roots blower thermal switches to motor contactors.  This can be
	done by in-house electrician as 'facility upgrade'.

3. Alpha particle acceptance measurements  JP, CR
	* after the Charge slits the Energy-vs-x data look pretty much
	like the GEANT simulation.  The E-vs-y data show a taller spot
	than GEANT.  Possible problem of quad setting?
	* after the Mass slits
	  - with wrong polarity on SX1 E-vs-x not as expected and about
	  30% of alphas were lost between Charge and Mass slit regions.
	  - with right SX1 polarity E-vs-x was as expected but again the
	  y distribution was "too tall" with some particles lost off the
	  bottom of the detector.  Still a fairly good transmission,
	  equivalent in solid angle to >19 mrad cone angle.
	* GEANT (CR) results were
	  - "21.5 mrad" transmission through penultimate downstream
	  pumping tube, as expected from geometry
	  - 98.9% of these particles also passed through MD1 in GEANT
	  - particles which failed to pass the (25 mm) Charge slits
	  were initially extreme left-going at the source
	  - after Mass slits 96.5% transmission, losses again for
	  the left-going angles
	  - with reversed SX1 the x-y spot was bigger and transmission
	  dropped to 82%, now with a few losses at extreme right-going
	  angles as well
	* DH showed BGO-DSSSD hit pattern correlations from run 12129
	  of 12C(a,g) experiment (1.22 MeV/u, mainly cascade, 19 mrad
	  max. cone angle) which might be used for comparison vs
	  GEANT.
	* after short tests tweaking Q1 with DSSSD at Mass slits, plan
	  is to move to the normal end position and measure transmission
	  through the 2nd stage.

4.  Revised beam schedule   (DH)
	* 40Ca(a,g) will run from March 30 through April 9
	* DRAGON on standby to measure beam E for TUDA April 18-30
	* DRAGON development (20Ne) May 3-8
	* Ti beam for C.S.D.'s May 12-15

5. AOB
	* NIC-9 programme is set (LB)
	  (nothing on screening, nothing on 26Al(p,g))
	* CAP abstract deadline tomorrow: CV will submit for 40Ca(a,g)
	* GR's seminar is postponed to March 29th

6. Items for next meeting
	* alpha acceptance