Straw Tube Research Articles

Precise measurement of internal sense-wire locations in high energy physics detectors

The central tracking region of the Solenoidal Detector Collaboration detector being designed to operate at the Superconducting Super Collider will utilize gas-filled straw tubes for particle tracking; the straws, each containing a thin central wire for charge collection, will be collected into modules of a few hundred straws each. It is crucial for proper interpretation of the data that the positions of the sense wires be known to very high precision. A pattern-deviation scanning system is being investigated for determining if the sense wires in constructed modules are within 35 μm of their intended locations. The system involves moving a module in steps through a broad x-ray beam and comparing a response matrix of transmission measurements to a template which is characteristic of a “perfectly” aligned module. The pattern-deviation scanner approach is described and simulation results are presented.

Resistive Kapton straw tube drift chamber prototype: first results

A straw tube drift chamber prototype for nuclear and high energy physics experiments has been constructed and tested. The straw tube material is carbon

Digital mean timers for the Straw Tube Tracking System at SDC

Application specific integrated circuits (ASICs) are being developed for use with the Straw Tube Tracking System at SDC. These are called digital mean timers, and can be used to accept or reject tracks based on the transverse momentum P/sub t/ of the particle. They can also be used to determine whether a pair of hits left in two tubes or sets of tubes is caused by the same particle, by summing the drift times. These devices use chains of slowed digital buffers whose propagation delay is variable through one or two control voltages. A clock lock circuit on the chip uses an external crystal controlled oscillator to develop the correct control voltage (s) for a given delay per stage. Results from the first two chip designs are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Performance of 2 mm radius straw tube drift cells

The performance of a 128-channel test module made with straw tubes of 2-mm radius was studied in a test beam and with cosmic rays. Different gases were used, and for each one the time-to-distance relation and the hit efficiency were measured. Comparisons are made between results obtained using two different electronics readouts. The best solution, of 135 mu m, was obtained using 50% ethane, 50% argon and reading out the information with the TDCs (time-to-digital converters), at an operating voltage of 1750 V.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A comparison of CF4 + hydrocarbon fast gases for drift chambers and straw tubes

Measurements have been made of the signal charge, drift time distributions and sensitivity to soft photons and charged particles, for several CF4 + hydrocarbon fast gas mixtures. Comparisons are made with Ar + C2H6 (50:50) and with other standard gases. CF4 + CH4 (30:70) is found to have many advantages over CF4 + iC4H10 (80:20), which may make it appropriate for use in high rate particle physics experiments.

Construction and performance of a 2.7 m long straw drift tube prototype chamber for the SSC

Abstract We report the construction and testing of a 2.7 m long straw tube drift chamber consisting of 60 channels. The straw tubes with 2 mm radius are stacked in a pyramid shape up to eight tube layers. There are two wire supports inside each tube for electrostatic stability. 28 tubes out of 60 are instrumented for measurement of resolution, gas gain, and attenuation length. Resolution of close to 110 μm and attenuation length of 500 cm are obtained.

Test-beam performance of a tracking TRD prototype

Abstract A tracking transition radiation detector prototype has been constructed and tested. It consists of 192 straw tubes, 4 mm in diameter, embedded in a polyethylene block acting as radiator. Its performance has been studied as an electron identifier as well as a tracking device for minimum-ionizing particles.

Design and performance of a straw tube drift chamber

The design and performance of the straw drift chambers used in E735 is reported. The chambers are constructed from 2.5 cm radius aluminized mylar straw tubes with wall thickness less than 0.2 mm. Also, presented are the results of tests with 2 mm radius straw tubes. The small tube has a direct detector application at the Superconducting Super Collider.

Laboratory studies of the dynamic behaviour of grass, straw and polystyrene tube during high-speed cutting

Experiments were conducted to study the behaviour of grass and straw stems when cut by sharp and blunt blades at speeds between 5 and 35 m/s; comparative experiments were done with polystyrene tube. Measurements were made of the force and energy during cutting using a piezoelectric force transducer mounted behind the blade on a rotating disc. Stem deflection modes during cutting were recorded photographically by using high-speed film in a camera with an open shutter and firing flash guns sequentially by electronic control, with delay periods ranging from 3 to 425 μs. The lowest speed for efficient cutting (the critical speed) for grass and polystyrene tube was 25–30 m/s. The minimum cutting energy per unit dry matter content for grass with a sharp blade was 55 mJ/mm 2 based on stem wall area. At speeds below the critical speed there was a large stem deflection before cutting was complete, which resulted in long stubble lengths and high cutting energy (up to 400–500 mJ/mm 2 in grass). There was no evidence of a critical speed, however, when cutting straw. The mean peak force for grass per unit dry matter content was 18 N/mm of stem diameter, which was 2.6 times greater than when cutting straw. When cutting above the critical speed for grass (inertia cutting) cutting times were as low as 0.3 ms for the sharp blade, and the stem deflection during cutting was equal to about three stem diameters. For straw, however, the deflection before cutting was complete, represented 8–10 stem diameters, with times of about 1.0 ms. For inefficient cutting at low speeds (c. 5 m/s), cutting times ranged up to 15 ms with stem deflections at the blade of up to 32 diameters for a cutting height of 40mm. The difference between stubble length and nominal cutting height for inertia cutting was about 2 mm for sharp blades but ranged up to 50 mm for inefficient cuts at low speeds. Grass stems showed the widest range of deflection mode immediately after cutting. This varied from stem translation and rotation at low speeds, (c. 5 m/s) to marked bending at intermediate speeds (15–25 m/s) and inertia cutting, with little stem displacement, at higher speeds (>25 m/s). Straw exhibited marked stem translation and rotation with little bending at speeds below 25 m/s but marked bending at higher speeds. Polystyrene tube showed a marked bending over its length at speeds up to 25 m/s, above which cutting was in the inertial mode. The minimum cutting energy for grass stems was three times that required for quasi-static cutting in shear. At low cutting speeds (<12m/s) about 65% of the energy was utilized in overcoming friction. For straw, however, the frictional component was generally relatively low (5–10%) and stem kinetic energy was equal to about 20% of the total energy input. The specific cutting energy was twice as large for the blunt blade as for the sharp blade in grass and straw. The difference between stubble length and nominal cutting height was generally about three times greater when using the blunt blade.

Use of straw tubes in high-radiation environments

We have investigated several aspects of straw tubes relating to their viability for use in SSC detectors. Gas temperature changes and the consequent gain changes resulting from the power dissipated in the tube at high rates are found to be relatively minor effects. Conduction through the gas between the wire and the wall is found to be the major mechanism by which heat is removed. Little aging is observed in straw tubes operating with any of several different gas mixtures. The dependence of aging on gas flow rate is found to be small. Water vapor at low concentrations (1000 ppm) is found to prevent breakdowns. Design and construction of straw tubes are discussed.

Modeling small diameter straw tubes in terms of their high frequency electrical characteristics

As a part of the effort to design a prototype of a low-mass tracking detector, an empirical model of the high-frequency behavior of small-diameter proportional straw tubes was developed. The equivalent circuit is a distributed network RLC-clusters, where the value of the discrete components is directly related to measurable characteristics of the em straws. The model is an approximation of the straw as a low-loss transmission line, and it yields very good agreement with measurements of transmission and reflection coefficients. Measurements and simulations of input impedance in the frequency domain agree well at frequencies below 120 MHz, when termination is close to Z/sub 0/, the characteristic impedance.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Parallel arrays of digital signal processors as central decision elements for upper level triggers in high energy physics experiments

For tracking devices and calorimeters, the conflicting trends toward higher luminosity and improved background rejection have prompted the use of a hierarchical, multilevel trigger logic: the upper levels are usually devoted to 'physical' background rejection and event flagging, as opposed to the lower level logic, mostly dealing with 'dull' background at high rate. For the higher trigger levels, depending on the different machine and detector configurations, it is sometimes possible to design the 'detector data box' as a programmable device, with increased flexibility and efficiency, and to use large arrays of digital signal processors working in parallel, giving excellent data throughputs inexpensively, provided that fast and efficient software algorithms can be implemented. A flexible and powerful scheme of this type is described, for two different experiments: the forward electromagnetic calorimeter of the DELPHI experiments at LEP (CERN), and the straw tube chamber of the E760 experiment at the antiproton accumulator at Fermilab.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>