Weekly Meeting Minutes - August 03, 2007

Attending: P. Ambrozewicz, E. Clinton, L. Gan, A. Gasparian, S. Gevorgyan, M. Ito, L. Jiang, X. Li, D. McNulty, E. Pasyuk, A. Teymurazyan By phone: D. Dale

Summary of Meeting Discussions:

All. Nominate secretary: (next secretary: Liping)

All. Approval of last meeting's minutes:

Approved. You can find the previous meeting minutes here. Not many comments on last weeks meeting minutes (only comments about RSS feed in Wiki).

All. New Business: Itemized below

3: Analysis note review status (Eugene):

All new analysis notes are posted and linked through the secure Wiki

Liping gave comments to Eric and Dustin (on secure Wiki) -- they will respond soon.

4: Time walk correction in HyCal (Yelena and Eugene):

Necessary because tdiff has dependence on cluster energy

Using dedicated Compton data and all of HyCal (not just crystal-only fiducial), Yelena and Eugene plotted the relationship between trigphoton.tdiff and hycal total energy sum normalized to incident photon energy (in other words elasticity).

This plot was then fit with a 2nd order polynomial between x = 0.2 and x = 1.2 and used to correct the tdiff.

After applying the correction, the tdiff sigma decreased from 1.8 ns to 1.3 ns and the mean shifted from 1.6 ns to 0.4 ns.

All agreed that this was a good thing to implement in the analysis and that Eugene and (mostly) Yelena would do the work.

Ashot commented that we should look at pi0 runs to see the jump between Lead-Glass and PbWO tdiff.

5: Questions about the clustering algorithm were addressed and answered by Dustin. It was agreed that both Dustin and Vasilly would write a concise paragraph about there contributions to the clustering algorithm.

6: Sergey discusses his improvements and plans for the incoherent cross section calculation:

Calculation will be analytic -- nucleon number times pauli blocking factor times elementary cross section on single nucleon. In addition, the calculation will consider effect of having zero production angle possibility after rescattering (FSI).

It is interesting to note that using the elementary cross section (instead of just simply a constant -- A), the cross section peaks around 3.5 degrees (and does not simply continue to grow linearly at larger and larger angles.