From dauria@sfu.ca Sun Aug 18 12:08:57 2002 Date: Mon, 16 Sep 2002 20:38:17 -0700 From: John D'Auria To: Alan Chen , Ahmed Hussein , Alison Laird , Dario Gigliotti , John D'Auria , Jennifer Fallis , Hart Sprenger , Don Hunter , hutcheon@alph04.triumf.ca, Cybele Jewett , Joel Rogers , Peter Jackson , Lothar Buchmann , Peter Machule , Michael Lamey , Mohan Lal Chatterjee , Art Olin , Dave Ottewell , Peter Parker , Doug Preddy , Rachel Lewis , Sabine Engel , Shawn Bishop , Uwe Greife , Suzi Lapi , Chris Wrede Subject: Fwd: DRAGON Minutes Aug 13,2002 Minutes of the DRAGON meeting of August 13, 2002 Present: Dave Hutcheon (DAH), Dave Ottewell (DO), Lothar Buchmann (LB), Mohan Chatterjee (MC), Jenn Fallis (JF), Allison Laird (AL), Joel Rogers (JR), Art Olin (AO), Cybele Jewett (CJ), John D'Auria (JDA), Ahmed Hussein (AH), Mike Lamey, (ML), Uwe Greife (UG), Dario Gigliotti (DG, recorder) 1) Previous Meeting: -a correction to the list of those present -> Ahmed Hussein (AH) was present at last meeting (Aug 6,2002) 2) Equipment: -cryo pumps: the cryopump under ED2 was not functoning properly and had to be taken to the vacuum group for repair. (Note added in proof: pump is now fixed and re-installed.) 3) Report on the Ne^21/Na^22 stable beam running of this passed week using just the ionization chamber was given by UG: The main points presented are summarized below: -resonance energies of 506 keV/u and 511 keV/u were looked at -experience with these resonances gives indications that previous MD1 energy calibration fomulas/settings may be off by ~6-7keV -off resonance measurements showed no recoils -problems in the first anode of IC produced the "stretching" to the spectrum present in the 2-D plots showing Energy Anode 1 vs. Total Energy -elastic monitors were working as expected until later in the week when "noise" began to the appear which affected the resolution -JR noted that this noise was beam related as the effect was worsened when beam was present -a graph of the both resonances was presented showing separation of the leaky beam from the recoils in the IC (see attached) -charge state dist'n graphs are being produced for both resonances -the measurement of these two known resonances give two further calibration points which can be used to improve the equation used to calculate MD1 settings for various beam energies -it was noted that there are still difficulties in aquiring/reproducing 1-2keV energy changes from ISAC ops - a rough measure of separator suppression of 5x10^8 was made from a comparison of leakies to elastics -ratio of leakies to recoils decreases at higher charge states -no measurements of gamma/recoil concidences were taken -digital scope measurements by Shawn Bishop showed the possibility of coincidences (see attached) -JR commented that the problems associated with gamma/recoil coincidences can be overcome by requiring the gamma to "wait longer" for the IC which, as a consequence, increases gamma dead time - a second possibility suggested by JR is to require that the IC produces a shaped pulse comparable to other detectors and therefor allowing an earlier trigger 4) Other Business a) Beam time this afternoon -further stable beam time will be available this afternoon -a change made by JR to increase the acceptance gate for gamma/recoil events will be made to allow the possibility of seeing gamma/recoil events between the gamma array and the IC for the first time (note added in proof: gamma-IC coincidences observed in extra beam time using a 10 microsec time delay) b) ECR -JDA reports 60% transmission of the ISAC ECR on the off-line test stand -CO^17 efficiency tests will be taking place soon c) With comments on MD1 related calibration (DAH) -calib measures now could be from 0-4keV low -recent measurements by latest stable beam resonance confirms ~1% discrepancy d) Facility Paper -final revisions taking place -comments are still being accepted e) Na^21 paper -suggestion by JDA to not include the width of the 822keV resonance in this paper -comments upcoming by DAH on this point in ~1 week -measurement of the 822 resonance by various groups is presently -Bateman -> 822keV -Yale -> 822keV -DRAGON-> 823keV -TUDA -> 829keV -more analysis is required before a decision is made - a comment by DAH to refer to the note of July 11, 2002 concerning beta monitor to elastic assignment of energies f) DSSSD Work -AH and Chris Wrede wish to move the MCP to the detector lab to do testing of timing resolution between the MCP and DSSSD with and without cooling -it was noted that the MCP is very fragile and moving it should be avoided if possible -DRAGON beam line is free for two weeks and so the DSSSD could be brought to the MCP instead [ Part 2, Application/PDF 308KB. ] [ Unable to print this part. ] [ Part 3, Application/PDF 457KB. ] [ Unable to print this part. ] [ Part 4: "Attached Text" ]