Time offset calibration check, starting with elastic runs 4425 through 4427 of Kin4. http://www.jlab.org/~ngo/analysis/time_offset/time_offset/time_offset.html

Found excursions up to +/-0.2ns when looking at the time-differences between hits in planes.

See http://www.jlab.org/~kolarkar/gen_analysis/index.html.

Using the pulsed-beam runs, Ameya is trying to come up with a background-free measurement of the timing resolution. Also is evaluating the relative densities of N2 in the production and reference-cell data so as to determine a dilution factor.

Jon is working on calculating the efficiency of the veto detector, preferably bar-by-bar.
The formalism being used is at http://hallaweb.jlab.org/experiment/E02-013/mtg/2007jan10/JM.pdf, and the preliminary results are at
http://hallaweb.jlab.org/experiment/E02-013/mtg/2007jan10/VetoEfficiency.pdf. This calculated efficiency is much lower than expected and his previous more-robust total-plane efficiency calculation.

He is also working on a "scholarly paper" for U.Maryland as part of his thesis proposal.


Has been working on a runlist for kin4 in Open Office Calc format and Excel format.


Seamus was working on understanding the false (instrumental) asymmetries to produce a value for GEn this week.

• Please look around on the wiki-site for new pages and information about the coincidence time readout, Neutron Detector Analysis, and measuring the Livetime. Pages are in the works about the scaler analysis and asymmetry corrections.

• Examples of an analysis of the kin4 dataset can be found in /work/halla/e02013/disk1/feuerbac/pass1.

The file quasi_elastics.C contains Alias'es useful for identifying neutrons from protons, and is useful for exploring the data via T->Draw.

The files QE.C and QE.h are an analysis based upon the TTree::MakeClass method. This is a bit more involved, but permits for much greater control of the analysis and filling of histograms.

• short document asymm.pdf (34.08 Kb), asymm.tex stating the formalism for removing the false asymmetry contributions.

• The ratio of the DAQ Livetime for the negative and positive helicity states is shown below; the flips indicate the different half-wave plate settings. Checked that the SCALERS and EVENT-BY-EVENT helicity match (not off by factor of -1) by comparing the asymmetries of the T2 events. The overall correction is 0.01%, increasing our observed asymmetry.

Compare to the background-subtracted asymmetry:

• Seamus and I are planning to get corrected asymmetries and, after extended acceptance effects, a value for GEn by the end of the week.

• Closing up on electronic dead-time and tracking efficiency asymmetry checks.

• New ND geometry document from Tim places the ND 1 meter closer to the target than we had during the replay (8.2m vs. 9.3m to the plumb bob).