Marcia's BPRS mapping page


This page was written by Marcia Maria de Moura in January 2005 and ported into Drupal in October 2007

We are interested in determine in which sequence the measurements of the pre-shower "cells" come into the DAQ system.

The path from the detector to the DAQ system is not so trivial. There are many connections and they are all tagged but, sometimes, in order to allow a better assembly of the system, the final sequence in which the data from the cells is sent to DAQ is not an ordinary one.

In order to ilustrate better what is the mapping for the pre-shower, we show the correlation of some connections and also the correlation with the towers.

In figure 1 we show part of the barrel EMC corresponding to three modules. The modules are presented from η=0 to η=1. The coloured boxes are the towers. The four rows correspond to a photomultiplier box (PMB). One PMB corresponds to one entire module plus two halves of neighbor modules on each side of the central one. In the left side of the figure there is the legend for the series of conectors ST1,ST2,ST3 and ST4 for the towers. In the figure it is shown how this connectors are related to the towers.

Figure 1 - Correlation of PMT connectors and towers' positions. For a larger view, click on figure.

In figure 2 we show an example of numbering for towers for the PMB 11W (W stands for west). This numbering is the one used for analysis and we call it software id. By analogy, we aplly the same numbering for the pre-shower cells. For the complete numbering of towers and pre-shower cells, see EMC distribution.

Figure 2 - Example of tower numbering for PMB 11W

In the case of the pre-shower cells, the light is not send to the same photomultiplier tubes as the ones for towers, but to sets of Multi-Anode Photomultipliers (MPMT). There are five sets of MPMT's in each PMB and the conecctors for that are identified by MP1, MP2, MP3 MP4 and MP5. In figure 3 we show the correlation of MPX connections to the pre-shower cells, also for PMB 11W. The distribution looks similar but actually the rows are different from figure 2. In the right side of the figure is indicated which is the correspondence in rows with the figure 2. From Vladimir Petrov we obtained how the MPX connectors are related to some eletronics ids (FEE number, SCA number and SCA channel) which are correlated to the muxwire number. The muxwire number is the one that determines the sequence of data to DAQ. In figure 3 it is shown the muxwire, just below the software id.

From all the eletronics parameters above, the algorythm to associate the software id with the data from DAQ was determined, and is in the StEmcDecoder. In previous attempts. some information about the electronics ids was not updated, which caused to a wrong mapping in the first place. One parameter of the algorythm, an offset (PsdOffset_tmp[40])was wrongly determined. The electronics ids information has been updated and the algorythm has been corrected. In table 1 and 2 we show the values of some parameters for PMB 11W. They are analogous to other PMB's and the only thing that changes is the software id, but the distribution in position is the same. Among the many parameters in table 1 and 2, the updated offset values that are used in the StEmcDecoder are displayed.

Of course there are aditional parameters in the algorythm but there is no meaning in explaining all of it here. For more details, go to StEmcDecoder STAR Computing software guide.

The following image has the power supply number, module, and channel for PMT box 11 on both east and west.