(present: AA, MF, IG, TI, NK, ML, TS)

Michel - Meeting-time for fall term
Michel pointed out that during the fall term, the time of the testbeam meeting will have to change because he will be teaching most of the time. He proposes Tuesday morning. That is really the only time slot that is free for him (MAYBE Friday morning might work too, but that's still unclear).
Tamara's and Tayfun's lab schedules won't be known until the last minute before term, and Richard's schedule will have to be considered. Those who have time constraints should consult with Richard on the best time and then let Michel know.
Michel also mentioned that he will be away until the end of the month. Richard should chair the meeting while he is away, and replacements for Richard would be, in the unlikely(?) event that her departure will be delayed, Naoko, or Margret.

Status Reports

Naoko showed plots of the response vs global time - in contrast to the plots she had at the last meeting, she now used the spread in response as the error, rather than the error on the mean. She mentioned that A. Maslennikov's talk during the June LArg week mentions a correction for this, but it was performed on a cluster rather than cell by cell.
Naoko also looked at the pulse shape. For this she used the code that Michel had written to check Pavol's weights - it plots 5 time samples per event vs time. Naoko plotted the ratio of (digital filtering peak)/(cubic peak) vs phase and finds variations of about 10% in this ratio over phase. She plotted this distribution for several cells, and finds that it varies from cells to cell. She hopes that it might be possible to perform a correction on a cell by cell basis. If that is not possible, then a correction at the cluster level might be the only option.
Michel explained that it would probably not be a good idea to use the cubic peak to parametrize the correction. A better approach would probably be to do a correction independent of the cubic fit. Then he pointed out the question as to where to set the reference point in time where the correction has the factor 1. He mentions that it need to be determined whether this is some kind of universal problem or whether it is cell to cell and at this point in time he has no clear idea as to how to perform the correction. Faced with these problems he wonders how uniformity studies can be done, and whether the MPI group has attempted them so far (Naoko doesn't think so). He explained why with these problems uniformity studies can't be done and that a cell by cell correction is needed and would be much better than a cluster correction, and he explains that Naoko thinks that for a given cell there is one function that can be applied to get a correction.
Alan wondered whether the shapes change with energy, and Michel said that there is no evidence that they do. Then Alan's conclusion was that if you go to high energy, where cubic fit does a good job, then a fix for cells should be possible.
Tayfun wondered whether the noise would be affected by such a correction. Michel said that it would most likely be a second order effect and not make much of a difference.

Margret pointed out that there is an update to her z-coordinate note. Michel has put it on his web-page under the geometry information.
She then showed some plots on occupancy and energy/volume for the EMEC of e runs at 60 GeV and 148 GeV based on a clustering algorithm as well as on a radial algorithm.
Michel pointed out that she would have gotten better results had she used his the NoiseAlg systemAlg rather than ped_rms for the threshold selection. The tails of the occupancy distributions are affected and will give better results if the NoiseAlg algorithm is used. Furthermore, the OccupancyAlg systemAlg should rather be used as it is written for this purpose. And finally, the energy/volume plots should rather be energy/(volume*sampl.fraction) to give a real idea of the energy density deposited. The sampling fraction for em showers changes from about 1.4 to 2.2 over the EMEC area covered in our testbeam and really needs to be taken into account.

Tamara showed plots of the occupancy of pion runs and demonstrated that a cut based on the noise algorithm is far superior to a cut based on ped_rms.
You can see this by comparing the channels occupancy distribution optained using the pedestal rms as noise characterization (ps) with the channels occupancy distribution optained using the digital filtering noise obtained with NoiseAlg as noise characterization (ps). The later peaks at around 5%, as expected since the occupancy of each channel was calculated by counting the fraction of events where the absolute value of the signal is above 2 noise sigmas. Michel noted that using ped_rms produces wrong absolute values of the occupancy of cells with no signal in them, as well as broadening the occupancy distribution for these channels (which should populate a Dirac delta at 5% occupancy!). While high occupancy channel would give similar results, most other channels would have inacurate occupancy. There are still a few channels that have inacurate noise estimate (because of the non-gaussian nature of their noise profile) and hence have inacurate occupancy estimate. Naoko and Michel have studied this. He also pointed out that Naoko found that the pedestal is Gaussian, but she thinks that the digital filtering weights distort things and actually turn a Gaussian into a non-Gaussian. This affects about half a dozen cells.
Tamara continued her presentation with plots of an `x-weight' vs resolution. The x-weight will be used to combine the HEC and EMEC to obtain a total energy, and it will be chosen such that the resolution is minimized. She minimized the resolution for various energies at impact point I and plotted the weights as a function of energy. Then she showed a plots of the ratio of (reconstructed energy)/(beam energy) vs beam energy. She is improving her analysis by fitting the energy with a Gaussian over the peak region only (rather than a larger region).

Tayfun showed some slides of the theory of the lateral EMEC shower profile. He has written an algorithm that takes as an input a point in 3D in local coordinate system and produces as an output the depth in Xo at that point as well as the size of a Moliere radius at that point. He showed us an example at a radius of 156.5cm: He finds that the total depth of the calorimeter is 24.6 Xo, and the size of the Moliere radius is 2.02cm. By assuming that the entire EMEc is made out of Lead, he finds that in the centre of S1 (the first EMEC compartment) the shower is laterally 90% contained within 0.15 Rm, which corresponds to an actual size of 0.3 cm. In the centre of S2 the shower size is 0.8 Rm, corresponding to 1.62 cm and in the center of S3 it is 1.7 Rm, corresponding to 3.43 cm. Tayfun is planning to expand the code using a line through the calorimeter as the starting point, rather than a 3D point. Michel pointed out that what needs to be looked at is how the Moliere radius is affected by the varying material density around a given point. He notes that calculations with a line as an input parameter will be valuable if one want to predict the shower behaviour in ATLAS.

Ian - TBRootAna
Ian mentioned that there isn't an awful lot new..., however Michel pointed out that there have been touch-ups to the Geometry package. Also Ian has succeeded in prapering a stand-alone geometry release which allows people to use our geometry code without using TBRootAna.
Michel also noted that Ian is now preparing his term report and that it will be a maintainer's manual for TBRootAna. Michel will probably be the one who will take on maintaining the package, even though he will be very busy once fall arrives.

Michel - Final note
Michel told us that there is a testbeam workshop at CERN during the week before the September LArg week. Presentations will include
- Status report of Athena beam test code (Naoko to write)
- HEC-EMEC analysis results. This will include Naoko's work on electron analysis including details of the timing problem and related corrections. (Naoko to write). If anybody else has results that are ready to be presented, they should let Naoko and Rob know. He suggested that Tamara could prepare some occupancy based plots to show the quality of the digital filtering noise characterization. (He will discuss with Tamara what to include.) Margret, Tayfun and Richard could prepare slides on what they have been doing.
- TBRootAna and geometry considerations (Michel to write, with help from Ian)