Two-dimensional position sensitive transition radiation detector
Highlights
► Two-dimensional position sensitive TRD. ► Highly efficient dedicated front-end electronics. ► Very good pion rejection of for six TRD layers.
Introduction
The CBM (Compressed Baryonic Matter) experiment [1] at the future Facility for Antiproton and Ion Research (FAIR) [2] is designed to measure hadrons, multi-strange hyperons, lepton pairs and charmed particles produced in nuclear collisions at up to 10 MHz; it is a large acceptance and high-rate detection system. The CBM experiment includes a transition radiation detector (TRD) for identification of high-momentum electrons with a pion efficiency better than 1% for 90% electron efficiency. At the same time it will perform intermediate tracking with a position resolution of in order to match tracks reconstructed in the silicon tracking system (STS) to the time-of-flight (TOF) system. Being a fixed target experiment, the most forward angles of CBM have to cope with a counting rate up to 100 kHz/cm2. Therefore a fast detector is required.
The original TRD architecture for electron discrimination in a high counting rate environment is based on two multiwire proportional chambers with a common double-sided pad structure read-out electrode [3], [4]. The detector maintains the timing properties of a single multiwire proportional chambers (MWPC) [5] while the gas thickness for transition radiation (TR) absorption is doubled. An extrapolated pion efficiency better than 1% for a six layer configuration [3] and position resolution of the order of [4] were obtained. Negligible gain drop and less than position resolution degradation were observed up to an average particle rate of 200 kHz/cm2. In order to cope with the requirement of a reasonable geometrical efficiency, a larger size prototype using the same architecture, but increasing the size of the rectangular pads of the central double sided read-out electrode was built. With the aim to access the position information in both coordinates of the readout electrode pad-plane (across and along the pads) with a single TRD layer, the rectangular pads of the read-out electrode were split diagonally, each triangular pad being readout separately. The paper is focused on the discrimination and position resolution of two such TRD prototypes which were tested in a mixed secondary beam at the CERN PS.
Section snippets
Detector design
As mentioned in the Introduction, the structure of prototypes is based on two MWPC read out by a common double-sided central pad structure electrode [6]. A schematic view is shown in Fig. 1. In the upper part we present a cross-section through the detector parallel to the direction of the wires and in the lower part a cross-section perpendicular to the direction of the wires. The central readout electrode separates the detector into two identical sections. The two multiwire anode planes, below
Experimental setup
Both detectors were tested in the detector laboratory of the Hadron Physics Department of IFIN-HH with a 5.9 keV X-ray 55Fe source using 80%Ar+20%CO2 gas mixture flushed trough the counters at atmospheric pressure. The energy resolution was measured using both anode and pad signals. The anode signals were amplified by a charge sensitive preamplifier followed by a shaping amplifier.
For pad signal processing a new dedicated front-end electronics (FEE) called fast analog signal processor (FASP) [8]
Detector simulation
The maximum drift time is an important parameter for the optimization of the counter geometry for a minimum drift time required by the operation in a high counting rate environment and for the choice of the front-end electronics parameters (i.e. shaping time).
The drift time of an ionization cluster produced by a charged particle crossing the detector depends on its position relative to the anode wire and the electric field configuration. We used the Garfield/Magboltz [11] software package for
Experimental setup
The detectors were tested with a mixed electron/pion beam of 1–5 GeV/c momenta at T10 beam line of the CERN PS accelerator in a joint measurement campaign of the CBM Collaboration [10].
In the common beam test, prototypes of three CBM subsystems were tested as shown in Fig. 6: upstream, the first in the beam line, was a STS prototype, followed by a ring imaging Cherenkov detector (RICH) prototype and nine TRD prototypes from four research sites (Bucharest, Dubna, Frankfurt and Münster). The
Conclusions
We have investigated the electron–pion discrimination and two-dimensional position resolution of the developed TRD prototypes operated with the dedicated new front-end electronics—FASP. The design based on two MWPC readout by a common pad plane electrode with a negligible absorption of TR improves the rejection power of a single TRD layer while conserving the timing properties of a single MWPC with the same anode–cathode distance [5]. The readout electrode with triangular shaped pads allows for
Acknowledgments
We acknowledge V. Aprodu, L. Prodan and A. Radu for their skillful contributions to the construction of the detectors. This work was supported by EU-FP7/HP2-WP18 Grant no. 227431, EU-FP7/HP3-WP19 Grant no. 283286, NASR/CAPACITATI 42EU Project and NASR/NUCLEU Project.
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Cited by (3)
TRD detector development for the CBM experiment
2013, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated EquipmentCitation Excerpt :Each Double-Sided TRD prototype is based on two MWPCs readout by a common double-sided pad structure electrode [3]. The performance of the two DSTRD versions was already reported in Ref. [5]. In order to optimize the operation of the SSTRD prototype with a new version of the FASP amplifier, the response of the front-end electronics has been simulated using CADENCE software [11].
Review of Particle Physics
2022, Progress of Theoretical and Experimental PhysicsA QTC-based signal readout for position-sensitive multi-output detectors
2016, Nuclear Science and Techniques