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This work package comprises two major objectives, the development of a prototype readout for novel high-rate gaseous transition radiation detector (TRD) as well as high-rate resistive plate chambers (RPC) using free-running readout electronics including all data processing elements for an asynchronous readout.

One of the prime challenges of future experiments operating at unprecedented rates is to run without a trigger. They will instead employ a high-resolution timing system in a data-push architecture, i.e. a precision timing signal will be distributed to each individual detector component of an experiment. All classical data processing elements such as pre-amplifiers, shapers, digitizers, filters, readout buffers as well as processors will be located directly on the detector and will be continuously sensitive. As particles traverse a detector the generated signal will be completely processed, time-stamped and forwarded to the data acquisition system in an asynchronous fashion.

The concept has been proven to work on the bench and the main objective of this task lies with the integration of this type of electronics on real detectors and operating them in thigh-rate test beam experiments. In the context of this WP, the readout electronics shall be operated in conjunction with different gaseous transition radiation detectors (TRDs and RPCs) which have very different requirements with regard to proper impedance matching and noise suppression. In addition, the entire design needs to be optimized for power consumption, radiation thickness, and cost.

The performance of transition radiation detectors (TRDs) for a given radiator depends crucially on the efficiency to convert soft X-rays and the precision to which one can measure the specific energy deposit (dE/dx). The main objective of this work package is to build a large-size prototype of a TRD, which employs two thin MWPCs that share a common readout electrode. The demands on this electrode are very high. It needs to be very thin in order not to absorb the transition radiation and, at the same time, it needs to be highly segmented for accurate position measurements in high-rate, high-multiplicity environments. A small-scale prototype (10 cm²) with 1-dimensional charge sharing has been shown to work with excellent performance as a result from work within FP6. The main task now is to develop a thin electrode of large size (up to several 100 cm²). Moreover, the design of the double-sided pads will allow to perform charge sharing in 2 dimension (along the direction fo the wires and along the direction of the long axis of the pad). The precision of the charge sharing will ultimately be limited by the geometrical precision of the pads and the signal-to-noise ratio, which can be achieved. Therefore, it is essential to find a solution for routing the signals from the individual readout pads without inducing significant crosstalk between channels, i.e. very low capacitance readout lines.

A special readout board to match the delicate signal lines using the prototype CBM-XYTER chip will then be implemented on the detector. The entire detector will subsequently be tested in high-rate secondary beams of various momenta at GSI. Two important aspects of the readout shall be studied in detail: the effect of the ion tail on the position resolution and the performance of the de-randomizing buffer on the chip in an environment where the hit density across the detector is non-uniform. By construction the chip is best suited for randomly distributed data (eg. with regard to time and space). The limitations of this readout concept especially for detectors that sit at small angles in high-rate fixed-target experiments shall be explored.

Detectors based on parallel plate geometries like RPCs provide a very efficient way to balance position resolution with detector granularity. Maintaining the superb time resolution the readout structures and the electronics need to be optimised in order to allow for the implementation of large area systems. Large electrode structures are prohibitive due to their large capacitances and large intrinsic cross talk. Innovative solutions with be examined making use of narrow multi-strip designs. Differential readout of the signals is aimed for in order to improve system stability. The necessary modifications to the electrodes and the HV supplies will be incorporated into a prototype counter and the system will be evaluated as part of the work program. 

• Electrode development: The design parameters and anticipated performance of the 2-d prototype will be worked out by all partners of this work package. All of the design work shall be focused on finding solutions that will allow integration of such a detector element into large area designs optimized for maximum efficiency. Based on the experience with the above mentioned small prototype WWU will lead the development of the thin electrode. The work will be carried out in close collaboration with IFIN-HH for integration in the detectors and the electronics designers at IFIN-HH and UHEI for optimum noise performance of the signal lines.
• Readout board development: The design of the readout board has to meet three important criteria: optimum noise performance, power efficiency, and minimum material budget. Based on their experience with analog and digital designs, the actual design work will be performed by IFIN-HH and UHEI and WWU. The task will be led by IFIN-HH.
• Electronics performance test: The electronics is employing low-noise analog electronics and high-speed digital electronics in close proximity. The electronics needs to be first evaluated on the bench under ideal conditions prior to being mounted on the detector. Tests shall be carried out by UHEI and WWU. The task will be led by UHEI.
• On-detector integration: This task involves the integration of the electronics within the anticipated services distribution to a large size set-up as a proof of principle. Given that the main task of the TRD is electron identification, it will be of utmost importance to keep the overall material budget and power dissipation at an absolute minimum. Following a review of the design files by all partners and external experts, this will be prepared by IFIN-HH and WWU. The task will be led by IFIN-HH.
• Test and characterization: The new TRD shall be fully characterized using secondary mixed beams of different momenta and intensities. GSI will be responsible for the operation of the beam line. They will instrument the beam line with monitoring detectors for unique particle identification, tracking, and rate measurements. GSI will also provide part of the equipment for the data acquistion. All participants will participate in the organization of the beam time as well as the operation of the equipment on the bench using ideal input and noise conditions. The responsibility for these measurements lies with the designers at IFIN-HH, WWU and UHEI. GSI will be responsible for the operation of the test beam line.

GSI, IFIN-HH and WWU will organize the analysis of the test beam data and will be responsible for the publication of the major results in a suitable journal.

• In order to improve stability and minimize cross talk, anode strip design with narrow pitch will be explored. All participating institution (GSI, UHEI, IFIN, USDC and FZD) will share the workload by evaluating different concept and contributing the necessary calculations in order to validate the concept. USDC and FZD will contribute in addition with novel electrode material (ceramics).
• To make optimal use of the anticipated differential counter technique a readout board is being developed that matches to the electronic properties of the counter. High resolution ASICs (PADI, DANTE – DDL) will be interfaced in an impedance matched way to the counter signals. An interface to free running DAQ prototype systems will be provided. This work will be carried out in close collaboration in between GSI and UHEI.
• Prototypes will be tested with heavy ion and electron beams at GSI and FZD, respectively. The prototypes will be characterized by noise, time resolution, cross talk, effective granularity and multihit capability.

The successful completion of this work package will provide a new type of autonomous transition radiation detector to the entire nuclear and particle physics community. It will meet the challenges of future high-rate, high-multiplicity fixed target experiments planned e.g. at FAIR.

The development and production of a prototype of the universal readout is essential for the successful operation of detectors in experiments planned at high luminosity future accelerator facilities such as FAIR at Darmstadt and high luminosity LHC. If proven to work, the readout can be used in conjunction not only with gaseous detectors but with virtually any detector with similar primary signal amplitudes.