Infrastructure for Time Projection Chamber Research and Development

For the International Linear Collider (ILC), four concept studies for detectors are ongoing. At least two of these four detector concepts plan to use a Time Projection Chamber (TPC) as the main tracking device. (A short introduction how a TPC works can be found on the webpage of the DESY FLC-TPC working group.)
To meet the demands at the ILC, a worldwide R&D collaboration (LCTPC) is working to develop an advanced TPC. This TPC will meet the following goals:

continuous 3-D tracking, easy pattern recognition throughout large volume, well suited for large magnetic field
~99% tracking efficiency in presence of backgrounds
time stamping to 2 ns together with inner silicon
minimum of X₀ inside Ecal (<3% barrel, <<30% endcaps)
σ_pt ~ 100μm (rφ) and ~ 500μm (rz) @ 4T
2-track resolution <2mm (rφ) and <5-10mm (rz)
dE/dx resolution <5% → e/π separation, for example
easily maintainable if designed properly, in case of beam accidents, for example
design for full precision/efficiency at 20 x estimated backgrounds

These goals will be tested in the R&D phase whenever possible. The EUDET project supports these developments and the R&D phase by suppling essential infrastructure.
This infrastructure includes and large TPC prototype, which will be commonly available. The construction and design of this field cage will prove the feasibility of a very lightweight design which ensures a low material budget, but is nevertheless mechanically stable. Also, the field cage provides a very homogeneous electric field, which is essential to meet the high precision requirements.
‹more information about the field cage›

The second part of the provided infrastructure includes the readout electronics for the large protoype. Here two developments are ongoing. One, is the use of a general purpose readout system and DAQ. This will use a modified ALTRO chip and is based on ADC technology.
‹more information about the ADC readout electronics›
The alternative electronics is based on the TDC technology. Prove of principle tests of this technology have been done before. The next step includes the development and evaluation of this technique using a dedicated small test chamber and later on the large TPC prototype.
‹more information about the TDC readout electronics›

The large prototype is currently being operated at DESY in the test beam area. The provided infrastructure at the testbeam includes a 1T magnet and a lifting table.
‹more information about the testbeam infrastructure at activity JRA1›

The endplate for the large TPC prototype has been designed and produced by the Cornell University, USA.
It is possible to insert readout modules in standardized bounding boxes in the endplate. These boxes can hold modules equipped with different amplification (GEMs, MICROMEGAS) and readout (pads, pixel chips) technologies. So, different working groups can test their readout technologies with the same infrastructure.

A crucial point in understanding the testbeam data is the reconstruction and analysis software. This will be based on a common software framework. This framework has a modular design, which allows the direct comparison of different reconstruction algorithms.
‹more information about the software at activity NA2 and at the MarlinTPC homepage›