[Halld-cal] new round of BCAL photo-electron simulations

[Zisis Papandreou]

Hello all:

as discussed in last week's CAL WG meeting, Irina is preparing to launch a new but definitive set of FLUKA simulations in order to extract the number of photo-electron distributions from the proposed BCAL readout segmentation.  These will be used by Fernando to establish our full dynamic range. We had agreed to circulate our proposed plans.  Here they are below and please comment on it.

1. Update the BCAL geometry to its final values, as specified in our global coordinates and the final engineering drawings and based on our construction of four modules.  This includes the average number of build layers (186), and the final matrix build height (22.184 cm) and inner radius (64.24803 cm) from Tim's drawings -- our first three modules are within the specified tolerance (+/-2mm) for the height.  Irina will add the 8mm aluminum plate, but these stand-alone simulations will not include the any inner material (CDC, Start Counter, target.)  Past simulations used values from Prototype 1.

2.  Update the attenuation length and MeV->p.e. conversion factors from the measured fibre data to include the average values over the first eight shipments, including the spread from the means.

3. Run the extreme situation of 3 GeV photons aimed at 14.7 degrees (back, downstream corner of BCAL where we have 67X0 radiation lengths).  See Alex Dzierba's plot below. [Previously we had 2 GeV at 20 degrees.]  See the attached Pythia plot (courtesy of Blake) justifying the 3 GeV. (At 4 GeV there are very few events populating the phase space near 15 degrees, although there are some at 3.5 GeV).  We could also repeat the low end, which was done at 60 MeV and 90 degrees if necessary.

4. Run photons centered on a cell and also equally split in the boundary between two cells (as before).

5. Sum the virtual cells into the appropriate towers as per Elton's plot on page 4 of GlueX-doc-1403, and attached below.

At the conclusion of this exercise, we will produce two reports, one on the BCAL's final dimensions (updating from doc-819) and one for the results (updating from doc-1301).

Please send us our feedback on these values, particularly the energy and angle combination.  

Cheers, Zisis...
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---
Dr. Zisis Papandreou		|  email: zisis at uregina.ca
Department of Physics	|  tel. : (306) 585-5379
University of Regina		|  tel. : (306) 585-4149
Regina, SK  S4S 0A2		|  fax. : (306) 585-5659
World Wide Web:    http://www.phys.uregina.ca/sparro/zisis/