Weekly Meeting Minutes - September 23, 2005

Attending: E. Clinton, M. Ito, D. Lawrence, D. McNulty, V. Mochalov, Y. Prok, M. Wood By phone: D. Dale, L. Gan

Summary of Meeting Discussions:

All. Nominate secretary: Dustin McNulty (next secretary: Yelena)

All. Approval of last week's minutes:

Unanimously Approved. You can find the previous week's minutes here. Highlights: Mike gave VETO results from 3 cluster events (summary--seems that VETO is not finding much under pi0 inv. mass peak, contrary to pre-experiment simulations, however, these simulations had some fundamental differences from the reality of experiment; thus we may want to redo the simulation). Dustin showed distributions of elasticity and inv. mass from carbon pi0 yield analysis which showed that the crystal counters are ~1% high in energy calibration and the glass counters are ~8% low. Ron Pedroni gave Marvin's talk at DNP Hawaii. Roger Wilco means "received and will comply".

All. New Business: Itemized below

1: Dave Lawrence's summary of tagger calib changes:

tagger_calib has been revamped into tagger_calib_lite which now takes better care to calibrate absolute tagm photon time relative to best fixed timing signal (either TAC (most precise), single PS paddle, or HyCal Total Sum (least precise))

Dave has produced new tagger timing calibrations for TAC runs.

Dave created new attribute in Primex CalDB tagger system named "tagm2hycal" which holds the peak timing offset (ns) between HyCal Total Sum (bit 9) and tagm photon time.

2: Dave gives some details of the primex TS trigger bits:

Note that TS bit 9 is HyCal Total Sum trigger and TS bit 10/12 is HyCal total sum in coincidence with tagger MOR.

NOTE: bit 10/12 causes the detector electronics readout which creates the event.

NOTE: even though there can be multiple TS bit 9 and/or 10/12 occurances during an event (because we're using multihit TDCs), there is ONLY one (readout) gate per event--which is initiated (by definition) by the last (most recent) TS bit 10/12 TDC hit.

The TS TDC values for bit 10/12 are defined by the tagger MOR time, whereas the TS TDC values for bit 9 are defined by the HyCal total sum time. Thus, Dave says when searching for tagm photon candidates, cut around the peak difference between TS bit 9 time and tagm time.

Dustin provided time difference distributions for bit 9 and tagm here and bit 10/12 and tagm here. Note that Dave thinks the bit 9 peak difference should have a sigma around 1 ns, not 3.5 ns.

During this discussion, Mark noted that since we had MOR in production trigger circuit, did we also need it in photon flux accounting events? We did not have a conclusive answer, however, it was noted that there is not a big difference in the occurance of bit 9 versus bit 10/12 in our data set--this should perhaps be investigated.

3: Dustin presented follow-up results after implementing energy sparsification linearity correction:

The non-linear sparsification energy correction was introduced and computed last week by Vasily (details can be found here), the resulting function was fit and temporarily implemented in the hycal library package. For this presentation, Dustin replaced Ilya's linearity correction (which was not related to sparsification effects) with the new one which was more defined for clusters between 1.2 and 0 GeV. In retrospect, this was not the ideal procedure; both of the linearity corrections should have been implemented because they address different issues.

The sparsification linearity correction fits can be seen here and the distributions from these corrections and Ilya's from real data can be seen here.

The distributions of elasticity and inv mass resulting from the new correction can be seen here. In conclusion, this new correction gave the data a push in the right direction for glass clusters (however it was only 1 - 2 percent improvement), but worsened the crystal-crystal distributions by +1%. Vasily suggested a more consistent way to implement the new correction would be to first scale its value to 1.00 for 2.0GeV clusters.