S. A. Movchan

Cathode strip chamber for CMS ME1/1 endcap muon station

Seventy-six serial ME1/1 cathode strip chambers have been produced in Dubna. These chambers are the coordinate detectors of the first muon station of the CMS detector at CERN. This paper describes the design of the chamber, its main mechanical parameters, and the results of the cosmic ray test.

Using the cathode surface of straw tube for measuring the track coordinates along the wire

The coordinate detectors based on straw tubes provide a high accuracy of the radial coordinate measurement using the drift time and a small amount of matter in the way of the measured particles. However, the measurement of the coordinate along the wire constitutes a problem. This paper proposes a method for measuring the hit coordinate along the wire with an accuracy better than 1 mm in a straw tube detector using the signals from the cathodes of the detector.

Robust estimates of track parameters and spatial resolution for CMS muon chambers

A robust technique with a sub-optimal weight function (M-estimate) was applied to investigate track fitting in cathode strip chambers (CSCs) and determine the CSC spatial resolution. The comparative analysis with the conventional least squares method was made on simulated data and experimental data from the Dubna CSC prototype. The results obtained definitely prove a necessity of using robust track fitting for a reliable estimation of muon chamber spatial resolution.

Equivalent noise charge for different impedance-matching schemes of the drift straw-tube and the amplifier

Impedance matching of the drift straw-tube and the amplifier influences the signal-to-noise ratio, which, in turn, determines the coordinate resolution of the detector, the minimal threshold, and the minimal gas amplification necessary for efficient signal registration by the detector. Five impedance-matching schemes for the straw-tube detector with a length of 2.5 m are studied. It is shown that ENC = 4000−5000 electrons for C det = 20−30 pF, which is good from the practical point of view, is achieved using the simple resistor connected in series to amplifier at the open far-end of the straw-tube.

2-D straw detectors with high rate capability

Precise measurement of straw axial coordinate (along the anode wire) with accuracy compatible with straw radial coordinate determination by drift time measurement and increase of straw detector rate capability by using straw cathode readout instead of anode readout are presented.

The use of a segmented cathode of a drift tube for designing a track detector with a high rate capability

Detector rate capability is one of the main parameters for designing a new detector for high energy physics due to the permanent rise of the beam luminosity of modern accelerators. One of the widely used detectors for particle track reconstruction is a straw-detector based on drift tubes. The rate capability of such detectors is limited by the parameters of readout electronics. The traditional method of increasing detector rate capability consists in increasing their granularity (the number of “elementary” detectors = readout channels) by reducing the straw diameter and/or by dividing the straw anode wire into two parts (for decreasing the rate per readout channel). A new method of designing straw detectors with a high rate capability is presented and tested. The method is based on dividing the straw cathode into parts and the independent readout of each part.

Detector with a profile-based cathode and the two-coordinate pad-strip readout system

A detector with a profile-based cathode and a two-coordinate cathode readout system has been experimentally investigated. Cathode pads located in each profile along the anode wire are diagonally interconnected, thus forming strips that cross the detector at some angle with respect to the anode wire. Owing to the availability of the two cathode coordinates and the coordinate associated with the anode wire, it is possible to solve the problem of identifying high-multiplicity events in a single detector.

Robust Optimal Estimates of the Parameters of Muon Track Segments in Cathode Strip Chambers for CMS Experiments

Cathode strip chambers are designed for the muon system of the compact muon solenoid under construction at CERN. These chambers must ensure a high accuracy (∼100 μm) of measurements of muon coordinates under heavy background conditions, when ∼20% of measured muon coordinates are contaminated by a secondary electromagnetic accompaniment and it is often impossible to separate overlapping hits. As a result of this contamination, the distribution of measurement errors differs substantially from a normal (Gaussian) distribution. In these cases, the traditional least squares method is inapplicable. For this reason, a robust (stable against noise) iteration procedure is proposed for fitting track segments in cathode strip chambers. The optimal weight function is derived in an explicit form with allowance for actual contamination introduced by the electromagnetic accompaniment. A comparative analysis is carried out for simulated and experimental data from the chamber prototype. The results conclusively indicate that the robust approach must be applied to fit tracks in cathode strip chambers when data are heavily contaminated.

New type of drift tubes for gas-discharge detectors operating in vacuum: Production technology and quality control

A device for fabricating thin-wall (straw) drift tubes using polyethylene terephthalate film 36 μm thick by ultrasonic welding is described together with the technique for controlling their quality. The joint width amounts to 0.4–1.0 mm. The joint breaking strength is 31.9 kg/mm2. The argon leakage from a tube of volume 188.6 cm3 under a pressure gradient of 1.0 atm does not exceed 0.3 × 10–3 cm3/min, which is mainly related to the absence of metallization in the joint vicinity. The high strength, the low tensile creep due to the absence of glued layers, the small value of gas leakage makes the new tubes capable of reliable and long-term operation in vacuum, which is confirmed by the operation of 7168 straw tubes for two years in the NA62 experiment.

TPC status for MPD experiment of NICA project

In a frame of the JINR scientific program on study of hot and dense baryonic matter a new accelerator complex Ion Collider fAcility (NICA) based on the Nuclotron-M is under realization. It will operate at luminosity up to 1027 cm−2s−1 for Au79+ ions. Two interaction points are foreseen at NICA for two detectors which will operate simultaneously. One of these detectors, the Multi-Purpose Detector (MPD), is optimized for investigations of heavy-ion collisions. The Time-Projection Chamber (TPC) is the main tracking detector of the MPD central barrel. It is a well-known detector for 3-dimensional tracking and particle identification for high multiplicity events. The conceptual layout of MPD and detailed description of the design and main working parameters of TPC, the readout system based on MWPC and readout electronics as well as the TPC subsystems and tooling for assembling and integration TPC into MPD are presented.