July 15, 2005 E989 discussion of progress and allocation of tasks meeting (EDOPATM) minutes Present: JDA, DAH, CR, HC, AP (rec.) The goal: "a written outline of aims/tasks/time so we can monitor progress" Some constraints: CR is away until Wed. July 27. AP leaves Vancouver on Fri. July 22. HC needs to prepare an oral presentation for July 27, and a report for late August. Summer students leave in late August, LF leaves in December. JDA is away for August. Beam time in November??? Tasks: I. post-July-run calibrations: complete. Ge detector (see ELog): - energy calibration: 5 gamma energies from 500-1900 keV, "from this calibration, expect to see Na-26 peak (1808.6 keV) at approximately channel 1621, much closer to where it was seen during the run" - efficiency calibration: "Detection efficiency (without compensating for attenuation in the steel plate) at the energy of interest now calculated to be (1.86 +/- 0.18)E-05, similar to the highest energy Y-88 gamma (at 1836.1 keV). This is ~35% higher than the previous calibration value." NaI detectors (see ELog): - efficiency calibration: "The detector efficiency for 511 keV coincidences is now calculated to be 0.893 +/- 0.02 %. When taking into account the positron acceptance of the horn, absolute detection efficiency is (5.6 +/- 0.1)E-04 %. This is ~10% lower than the first calibration." new DSSSD calibration: energy calibration with AmPuCm alpha source is complete. II. cutting down leaky-beam rate in BGOs: - leaky beam rate was comparable to that in 21Na expt... - reinstall Pb shielding at the entrance of the gas target? -install a collimator (iris) in the upstream pumping section? It would be best to allow for x-y motion of this iris as well...needs work immediately to be ready for run in the Fall... III. GEANT simulations: -at present a 'mistune' of -2.6% required to maximize (~99 %) recoil transmission from center of gas target to end detector -problem is due to how GEANT treats energy loss in the gas target... -model BGO detection efficiency for cascades, considering we ran for ~ 2 wks using the BGO trigger threshold set to 2.0 MeV, and then ~ 1 wk at 1.75 MeV...(major gammas in 27Si decay are at 3205, 2284, 2164 keV) -CR will immerse himself in the issue when he returns... III. Beam normalization: - for runs with a good elastic peak (strong Sb0 peaks were seen for runs 14948 onwards, once the gain on the TFA was increased) and good FC4-FC1 transmission, find the correlation between FC4 and the elastics (also look at the mass slit current) - for runs 14843 - 14947, use the FCs and the mass slit current - HC and LF have begun compiling this info and will continue, AP will contribute as well IV. Analysis of data: -DSSSD data for second half of run (using new DSSSD) show significant drifts (~100 keV) in the energy of the leaky beam between sets of runs - may need gain tables to account for these drifts...will eventually need a table of necessary inputs before replaying each run...(AP) - NOVA is good for 'quick looks' but cumbersome if complexities such as energy drifts arise...ROOT should be able to deal with this...? -cuts: combination of hard cuts (eg separator time of flight) and probability distributions (eg BGO detector number), CR is working on implementaion of prob. dists. in ROOT analysis - JP is working on a pretty, graphical ROOT interface that allows cuts to be made through pointing-and-clicking...cuts can be saved and applied at will, without resorting all data...CR and AP will translate what they have been doing in ROOT until now... V. Beam requests: CR submitted requests on Friday: 26gAl6+...44 shifts in November 2005, 0.5-1 enA, high power SiC+ lasers for continuation of measurement of 188 keV resonance + < 1 week off-resonance run 29Si6+...4 shifts in Oct-Dec 2005, using OLIS with Silane gas for charge state dists. VI. Energy of 27Si state of interest: - Vogelaar (1989) measured Ep to 1.1 keV, previous measurements were of Ex, to 3 and 5 keV...DRAGON disagrees with Vogelaar? - CR from PW: via 17O + 12C -> 27Si + 2n reaction at ANL using FMA + Gammasphere, the 7652 state was seen...1 night of running this reaction...data is not analyzed yet...maybe get spin of state as well using g-g correlations... - using other facilities to measure the energy of this state (to sub-keV level) if necessary? VII. Other items: -getting accounts on new 'analysis' ELog for HC, AP, anyone else... - issue with charge state distributions if a resonance occurs in the downstream end of the target...? -DSSSD dead layer measurement...?