Main Drift Chamber Research Articles

Design of the waveform distinction algorithm for the main drift chamber at the Super Tau-Charm facility

Drift chambers are essential in high-energy collider experiments for tracking the trajectory of charged particles. With the increase in peak luminosity, the detector's counting rate also rises, leading to challenges such as high beam backgrounds and an increased probability of signal pile-up in a single drift chamber channel. The Super Tau-Charm Facility (STCF) is a new electron-positron collider proposed by the Chinese particle physics community and the Main Drift Chamber (MDC) is the primary component of the STCF tracking system. The average hit rate of the innermost layer is 440 kHz with the cell size of 1 cm. This high count rate increases the pile-up probability of waveforms, making it difficult to achieve waveform discrimination even with optimized readout electronics performance. Modifying the cell size from approximately 1 cm to 5 mm is expected to decrease the innermost layer hit rate to approximately 210 kHz per channel. This paper presents a novel algorithm for waveform distinction using digital waveform data and integration curves. The algorithm is implemented on an evaluation board based on the Xilinx FPGA to achieve real-time waveform distinction. The algorithm's performance is validated through testing with the evaluation board. The test results indicate that the probability of distinction closely matches the theoretical value, the efficiency of the algorithm is about 96%, and the error probability is less than 4%. This result can serve as a reference for optimizing the MDC structure.

Track-based alignment for the BESIII CGEM detector in the cosmic-ray test

The Beijing Electron Spectrometer III (BESIII) is a multipurpose detector operating on the Beijing Electron Positron Collider II (BEPCII). After more than ten years operation, the efficiency of the inner layers of the Main Drift Chamber (MDC) decreased significantly. To solve this issue, the BESIII collaboration is planning to replace the inner part of the MDC with three layers of Cylindrical triple Gas Electron Multipliers (CGEM).The transverse plane spatial resolution of CGEM is required to be 120μm or better. To meet this goal, a careful calibration of the detector is necessary to fully exploit the potential of the CGEM detector. In all the calibrations, the detector alignment plays an important role to improve the detector precision. The track-based alignment for the CGEM detector with the Millepede algorithm is implemented to reduce the uncertainties of the hit position measurement. Using the cosmic-ray data taken in 2020 with the two layers setup, the displacement and rotation of the outer layer with respect to the inner layer is determined by a simultaneous fit applied to more than 160000 tracks. A good alignment precision has been achieved that guarantees the design request could be satisfied in the future. A further alignment is going to be performed using the combined information of tracks from cosmic-ray and collisions after the CGEM is installed into the BESIII detector.

FPGA-based fast track reconstruction for the conceptual design of STCF MDC trigger

The Super Tau-Charm Facility (STCF) is a future high luminosity electron-positron collider proposed in China, with a peak luminosity greater than 0.5× 1035 cm2s-1 at center-of-mass energy of 4.0 GeV. The main drift chamber (MDC) is designed as the central tracker, which provides the charged particle information for the level-1 trigger. This paper presents an FPGA-based fast trigger algorithm with the function of finding the charged particle tracks and reconstructing their transverse momentum and azimuthal angle. It adopts a two-stage lookup-table-based pattern matching architecture. The prototype trigger logic was implemented in a Xilinx XCKU060 FPGA. Test results with simulated data suggest that the trigger efficiency of J/Ψ events is better than 96%, and the resolution in the reconstructed track's azimuthal angle at the interaction point is better than 12 mrad. The overall dead time is 24 ns and the total latency is 339 ns. All these performances meet the requirements of the MDC trigger in the current conceptual design stage of STCF project.

Design of a MAPS readout electronics prototype for BESIII inner tracker

The spatial resolution and the reconstruction efficiency of the main drift chamber of the Beijing Spectrometer III has degraded after more than nine years of operation. An improved new inner drift chamber has been constructed to replace the old chamber in case of the radiation damage. A monolithic active pixel sensor (MAPS) based detector prototype is selected as one of the prototype schemes for the inner chamber upgrade. Design a set of MAPS readout electronics system for the inner drift chamber upgrade. This system can verify the function and performance of the selected MAPS chip and discover the matters needing attention when designing large-scale detectors. The electronics system design is composed of three parts. The first part is flexible printed circuit boards (PCBs) assembled with the MAPS chips. The second part is digital readout boards, which are connected to the flexible PCBs via FPGA mezzanine card cables. The digital readout board realizes the configuration of the MAPS chip register, receives and processes the data output by the MAPS chip, and transfers the processed data to the DAQ device. The third part includes a readout control board and two fan-out boards that used to separately fan out the trigger signal and the start signal to all the digital readout boards. A MAPS readout electronics system consisting of five MAPS based detector prototypes is designed. The system can work stably under the electron beam experimental conditions with a frequency up to 2 kHz and energy ranging from 1 to 5 GeV. The system detection efficiency of the electron beam is $$\sim 95\%$$, and the spatial resolution is $$\sim 5.3\, \upmu \hbox {m}$$ at electron energies of 1 GeV. The design of the electronics system meets the requirements for verifying the performance of the MAPS chips and the technical feasibility of the detector structure.

Improvement of main drift chamber Monte-Carlo tuning model at BESIII

Based on real data, a new parameterized model of the main drift chamber response is proposed. In this model, we tune the ratio of good hits and the residual distribution separately. By data quality checking, the difference between simulation and data in track reconstruction efficiency reduces from 1% to 0.5% averagely for the pion in J/ψ → π+π−π0, and the momentum resolution agreement improves significantly for the proton in J/ψ → pp̄.

Temperature fields across the BES III beam pipe

During the operations of the new generation Beijing Electron and Positron Collider (BEPC II) and the Beijing Spectrometer (BES III), the inner surface of the beam pipe is subjected to high radiation heat loads. Continuous high temperatures or large temperature fluctuations can cause the main drift chamber (MDC) to detect particles abnormally. Hence, a beam pipe with a cooling system was designed, and temperature fields across the beam pipe and the MDC inner cylinder were studied experimentally and by finite-element simulations. When the inlet temperatures of the cooling oil and cooling water for the central and extended beam pipes were set to 291.4K and 291.6K, respectively, results showed that the inner surface temperature of the MDC inner cylinder can be controlled within the range of 292.8–293.9K for various powers of radiation heat. This range satisfies the operating requirements of 293±2K.

A photon conversion finder at BESIII

A photon conversion finder (PCF) based on track information from the main drift chamber (MDC) of the Beijing Spectrometer (BESIII) at the Beijing Electron Positron Collider (BEPCII) is developed. The validation of the PCF is done by reconstructing π0 and measuring the branching fraction of J/ψ → γη′. Using the developed PCF tool, we mapped the materials from the interaction point through the BEPCII beam pipe up to the inner wall of the MDC.

Study of low momentum track reconstruction for the BESIII main drift chamber

In order to overcome the difficulty brought by the circling charged tracks with transverse momentum less than 120 MeV in the BESIII Main Drift Chamber (MDC), a specialized method called TCurlFinder was developed. This tracking method focuses on the charged track reconstruction under 120 MeV and possesses a special mechanism to reject background noise hits. The performance of the package has been carefully checked and tuned by both Monte Carlo data and real data. The study shows that this tracking method could obviously enhance the reconstruction efficiency in the low transverse momentum region, providing physics analysis with more and reliable data.

Magnetic Field Mapping in the BESIII Solenoid

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The Beijing Spectrometer III (BESIII) superconducting solenoid magnet, which is running in the Beijing Electron Positron Collider II (BEPC-II), is an important part of BESIII and provides a 1 Tesla field in the main drift chamber. A 3-D mapping device with three 3-D probes was fabricated to measure the field components of <formula formulatype="inline"><tex Notation="TeX">$B_{z}$</tex> </formula>, <formula formulatype="inline"><tex Notation="TeX">$B_{r}$</tex> </formula> and <formula formulatype="inline"><tex Notation="TeX">$B_{\mit\Phi}$</tex> </formula>. The mapping of the magnetic field of the BESIII superconducting solenoid magnet is presented, with the accelerator interaction region magnets located inside the BESIII solenoid excited to different current values. A set of polynomials, and a few trigonometric-Bessel terms are used to fit the data. The measurements and the functional model agree to 5 Gauss within the main drift chamber tracking volume at nominal field values. </para>

Track reconstruction in the BESIII muon counter

The reconstruction algorithm for BESIII Muon Counter, MucRecAlg, is developed with the object-oriented language C++ in BESIII offline software environment. MucRecAlg consists of the following functions: to find track seeds either from extrapolation of tracks in the main drift chamber or from the fired strips in muon counter, to select fired strips associated to the candidate tracks, to fit the candidate tracks with a linear or quadratic function and to calculate other parameters of the tracks for muon identification. Monte Carlo samples are generated to check the performance of the reconstruction package, such as reconstruction efficiency, muon remaining rate and pion rejection rate, etc. The preliminary results show that the pion rejection rate is around 3%–4% while the muon remaining rate is better than 90% in 0.4–1.6 GeV/c momentum region, which meets the requirement as shown in the design report.

Chapter 2 The BES-III Detector and Offline Software

The following sections are included: Overview of the BES-III Detector BES-III Offline Software Main Drift Chamber Time-Of-Flight System Electromagnetic Calorimeter Muon Identifier Trigger

Software alignment of the BESIII main drift chamber using the Kalman Filter method

Software alignment is quite important for a tracking detector to reach its ultimate position accuracy and momentum resolution. We developed a new alignment algorithm for the BESIII Main Drift Chamber using the Kalman Filter method. Two different types of data which are helix tracks and straight tracks are used to test this algorithm, and the results show that the design and implementation is successful.

Track reconstruction using the TSF method for the BESIII main drift chamber**Supported by CAS Knowledge Innovation Project (U-602, U-34), National Natural Science Foundation of China (10491300, 10491303, 10605030) and 100 Talents Program of CAS (U-25, U-54)

We describe the algorithm to reconstruct the charged tracks for BESIII main drift chamber at BEPCII, including the track finding and fitting. With a new method of the Track Segment Finder (TSF), the results of present study indicate that the algorithm can reconstruct the charged tracks over a wide range of momentum with high efficiency, while improving the robustness against the background noise in the drift chamber. The overall performances, including spatial resolution, momentum resolution and secondary vertices reconstruction efficiency, etc. satisfy the requirements of BESIII experiment.

Fea for entire procedure of thread stretching in main drift chamber of Beijing spectrometerⅢ

The calculational model of main drift chamber in spectrometer of Beijing electron-positron collider(BEPCⅡ) and the entire thread stretching procedure is built based on FEM for the research of mechanics rule and the control of accuracy the and structure.Theelement activationtechnic is used to avoid element rebuliding because of structure change and en- sure the efficiency and accuracy of calculation.The calculation is linearized with the sequential couple method after the vis- coelasticity of the wires investigated by stress relaxation ex- periment.The method is proved effective by both theory and experiment.The result of the change of the wires'initial stress is gained and the stretching method with pretightening force for the control of the change of the wire stress is used to ensure the accuracy of the drift element.The result used in the BEPCU modification works will exert an important role for the building of main drift chamber.

Numerical analyses of design and assembly for main components of BESIII

The design and manufacture of the main drift chamber(MDC)and the electro-magnetic calorimeter are most important issues in Beijing electron-positron collider upgraded projects.The whole mass of electro-magnetic calorimeter(EMC)in BESIII is 40t,thus high stiffness,strength and dynamical properties are required for the design of entire structural of electro-magnetic calorimeter. Based on numerical technique,the strength and the dynamical properties of EMC are analyzed, which provide theoretical reference f...

Argus: A universal detector at DORIS II

The detector ARGUS has been designed as a universal tool to investigate final states from e +e − annihilation processes in the energy range of the ϒ resonances. ARGUS started operation in October 1982 and has since successfully taken data at the ϒ(1S), ϒ(2S) and ϒ(4S) energies, and in the nearby continuum. The detector combines excellent charged particle identification and good photon energy resolution over more than 90% of the full solid angle. A particle originating from the interaction vertex and leaving the beam tube traverses the following components: the vertex drift chamber, the main drift chamber which determines its momentum and specific ionization, the time-of-flight system through which its velocity is determined, and the electromagnetic calorimeter. Muons pass through the magnet coils and the flux return yoke and finally hit the muon chamber system which surrounds the detector. The momentum resolution of ARGUS is σ (p T ) P T = (0.01 2 + (0.009p T [ GeV/c]) 2) 1 2 , the photon energy resolution in the barrel shower counters is σ (E) E = ( 0.072 2+0.065 2 E[ GeV] ) 1 2 . Combining the information from all p devices, more than 80% of all charged hadrons can be recognized unambiguously. The electron-hadron and muon-hadron rejection rates are 1:200 and 1:50 respectively.

A fast track finding trigger processor for the BES detector

The Beijing Spectrometer (BES) is being designed and constructed for use at the Beijing 2 × 2.8 GeV center-of-mass energy electron-positron collider (BEPC). The BES detector will have approximately 20 K channels of electronics, and the beam collision rate will be 1.25 MHz, corresponding to a luminosity of 10 30−10 31 cm −2 s −1. A fast programmable track finding processor to be used in the second level trigger is described. This processor, mainly consisting of 3 out of 4 logic and track finding logic, is simple and flexible. Only 96 pieces of 4K × 1 bit random access memory (RAM) chips are used for the track finding logic on 4 layers of the main drift chamber.

Measurement of the tau -lepton lifetime.

We report a new and precise measurement of the lifetime of the τ lepton. The data were taken with the High Resolution Spectrometer at the SLAC e+e− colliding-beam facility PEP operating at 29 GeV center-of-mass energy. The flight distances of 1311 τ decays to three charged particles were measured with a four-layer tubular-cell vertex chamber in conjunction with the main drift chamber. The resulting lifetime of the τ lepton is ττ=(2.99±0.15±0.10)×10−13 sec.Received 27 April 1987DOI:https://doi.org/10.1103/PhysRevLett.59.2519©1987 American Physical Society

The SLAC Mark II Upgrade Drift Chamber Front End Electronics

The SLAC Mark II detector is being improved by the addition of a new main drift chamber and associated electronics to prepare it for operation as the first detector at SLC. Presented here are the initial signal processing electronics, the preamplifiers, amplifiers and discriminators for the 5832 sense wires, which are located on the detector itself. The performance of the detector is established almost entirely by the drift chamber and this electronics.