Summary of the Wire Chamber Working Group meeting on June 09 2000

(compiled by Burkhard)

1. Discussion on design issues

a) Panels
Celeste reported about the contacts to DITRON. A first sample of a foam based panel with copper cladded FR4 glued on both sides has been produced. As this sample has been rather samll, checks on the flatness of a full size panel have to be done still.
We agreed that the option of foam based panels should be pursued. However, for the prototypes to be build this summer one should not rely (entirely) on them.
Mauro reported about the contacts to Excel. A prototype panel based on NOMEX honeycomb with 3mm cells will be delivered to Ferrara soon. The tight production schedule imposes problems with glueing of copper cladded FR4 boards to the honeycomb. Details have to be sorted out. It was decided to take honeycomb panels as baseline for the prototypes to be build this summer.

b) Wire Fixation and Gap Bars
The PNPI, Ferrara and CERN groups reported about ideas on how to realize the border region of the chamber. The design of PNPI foresees two fully independent bars, similar to CMS, while the INFN and CERN  designs foresee two bars on top of each other. Although we didn't converge in the meeting on the details of the layout of the bars, we agreed that the space between the sensitive area and the border of the chamber (excluding the electronics) should not exceed 40mm (in y).  The constaint comes from the fact that space between the chambers is very limited (cables have to brought out) and that the available space between the beampipe-shielding and the sensitive area of chambers in R1 is less than 50mm.
We agreed to follow two options for the production of the wire fixation bars: the PCB-workshop at CERN and DITRON. Details should be reported in the next meeting.

c) Connection to the FE-electonics
The discussion on this issue was very prelimary. The ideas of the various groups are rather different, partially coming form the fact that the requirements vary significantly between R1 and R4. Although we didn't agree on the allocated space yet, it is obvious that it should be minimized. It has been shown that it could be done within 60-70mm of space between the sensitive area and the border of the chamber. As we want to use to a large extend the same FE-electronics, it is important that we come to a more unified design.


2. Discussion about prototypes (copies of transparencies available)

a) PNPI
Besides a small prototype for testing some design ideas, PNPI intends to build a prototype for R4 of M3 (anode wire readout). The length will be limited to 150cm due to the wiring possibilities currently available in PNPI. The basic concept has been presented by Alexei.

b) INFN
The Ferrara and Frascati groups intend to build a prototype for R2 of M5, 151.2cm long (cathode pad readout, anode wire readout only for test purposes). The basic concept have been presented by Mauro. The cathode structure is under study in Frascati and details should be discussed in the next meeting.

c) CERN and LAPE
The CERN and Rio groups intend to build a prototype for the inner part of M2, mainly focussing on R2 (R1 option) (both anode wire and cathode pad readout, high granularity). Details have been discussed by Thomas. The cathode structure, as well as the interface to the FE-elctronics is under study.

Burkhard presented an estimation for the cluster size for this area, considering the contributions from tracks between 2 wires, the OR between 2 layers, and real crosstalk due to capacitive coupling of the complex anode-wire cathode-pad system (details for the later part are under study by Werner). Ideally, a total cluster around 1.2 for R2 and around 1.3 for R1 could be reached due to this contributions. Considering the fact that the contribution from multiple scattering to the pt-resolution is similar to the one from the granularity, a clustersize of the indicated size should be ok.


3. Discussion on Tooling

The discussion has been very short, as the study of the required tools for chamber construction has only started. It is evident that all three prototypes will not be build with the tools to be used in the mass production. However, mass production has to be kept in mind in designing and construsting the prototypes!

The next meeting will be on June 22 at CERN.