Delay Line Readout Research Articles

A high resolution and fast TDC for sensitive position gas-filled detectors

A time-to-digital converter has been developed for a gas filled detector with a delay line readout. It is based on a time interpolation method with a built-in master oscillator of 200 MHz. A resolution of 80 ps was achieved and the differential non linearity is less than ±1.5%. Also, a rate up to 3 MHz is possible. The circuit has a dynamic range of 16 bits and fed in a single width NIM format. The performance of the TDC and test results are given.

Flare Star Observations with a Single-Photon Counting Imaging Detector

AbstractAt Los Alamos National Laboratory we are developing a new imaging sensor which combines high spatial and high temporal resolution over a large area format, while maintaining single-photon counting sensitivity and sustaining a high count rate. The detector is called a microchannel plate with crossed delay line readout, or MCP/CDL. This detector is ideally suited to the observation of weak transient events, such as stellar flares from red dwarf flare stars in our Galaxy. At present we are initiating an experiment with the MCP/CDL detector which will utilize a 30-cm aperture f/7 telescope to characterize U-band, B-band, and V-band emission from such low-luminosity flare stars, and to search for weak optical transients associated with other astrophysical sources.

Energy resolution using delay line detectors

The use of multiwire proportional chambers (MWPC) with delay line readout for applications involving energy resolution is considered. The main features of this approach and some possible applications are presented. Its extension to neutron detection using MWPC or scintillators with position sensitive photomultipliers is also illustrated.

Development of data acquisition for delay line readout gas proportional chambers

A delay line readout system for the instrumentation of X-ray multiwire gas proportional chambers has been used successfully since 1986. Developments in analogue to digital converter and sample and hold technology have made possible significant re-engineering of the system to provide better resolution, linearity and rate. The resolution has been improved from 512 to 2048 pixels while the differential linearity has been reduced from +/−90% to +/−2%. The system is designed to work with delay lines ≥ 100 ns, giving mean data rates of up to 1.5 MHz of random X-ray events. Images can be collected in 1D or 2D and a pileup rejector is included which reliably rejects multiple or partial events.

Alternative approaches to delay line readout for multiwire proportional chambers

The design and performance of a new time to digital convertor for the readout of delay line multiwire proportional chambers (MWPC) based on a fast (1 GHz) oscillator is described. Further, a test circuit implementing the space-time-space conversion method was built to prove the practical feasibility of this approach.

Dual time to digital converter for delay-line readout of position-sensitive gas-filled detectors

A new dual channel time digitizer has been designed. It is based on the coarse counter and interpolation method. A new technique of interpolation has been employed which gives a FWHM resolution of 50 ps and a differential nonlinearity of ±2%, at a master oscillator frequency of 200 MHz. The module has a dynamic measurement range of 10 bits with a fixed dead time of 30 ns. It is a single width C size VXI format. Presented is a description of the new interpolation method and typical performance results.

Proposals for a new type of microchannel-plate-based vertex detector

We put forward the idea of a new type of position sensitive detector based on microchannel plates (MCP) and a special super high-frequency delay line readout anode. The detector is capable to precisely determine time and two space coordinates of a charged particle track intersecting the MCP's surface.

Two-dimensional X-ray detector based on microstrip and multiwire design

In order to produce detectors providing good spatial resolution and high counting rates for synchrotron radiation scattering applications, the possibilities of gas-filled detectors with microstrip electrodes have been investigated. Three X-ray detectors have been built and tested. A two-dimensional detector combining features of microstrip technology and multiwire proportional counters (MWPC) is presented. The data acquisition system is based on the delay-line readout principle.

A microstrip detector with delay line readout

Principal limitations of position sensitive gasfilled detectors for x-ray synchrotron radiation applications are the counting rate and the positional resolution. Improvements in both areas are expected with microstrip technology. First results of a linear position sensitive microstrip detector with delay line readout are shown, and the possibility to achieve two-dimensional localization is evaluated.

Time-resolved X-ray measurements on muscle using a fast multiwire linear detector

The development of linear detectors, with parallel readout and thus capable of operating at very high speeds, was undertaken in order to make efficient use of the very high X-ray fluxes available from synchrotron cameras for time-resolved scattering studies on muscle. For example, one may expect typical counting rates in the equatorial pattern of 2–10 MHz, well beyond the capability of detectors based on delay-line readout. We describe the use of the multiwire linear detector for measuring the intensity changes in the equatorial and meridional pattern and for measuring the spacing changes in the 143 Å meridional reflection with a time resolution of a few milliseconds at the SRS, Daresbury. These experiments are designed to study the dynamics of acto-myosin cross-bridge behaviour under different mechanical conditions which are imposed by controlled length-changing devices. The spacing changes can be measured to a precision of ±25 μm, despite the relatively coarse sampling of 1 mm in the wire plane, by measuring the centroid of the 143 Å reflection.

High resolution delay line readouts for microchannel plates

We describe the operation and characteristics of two-dimensional planar delay line image readout schemes for microchannel plates. Measurements using a 95×63 mm delay line show that resolution of <35 μm FWHM in X and ≈ 250 μm in Y can be achieved. It is shown that image stability can be of the order of a few μm, and the flat field response is stable and determined by detection efficiency of the microchannel plates.

2D detectors for synchrotron X-ray sources, some comparative tests

Modern diffraction experiments using synchrotron X-ray sources impose requirements on X-ray detectors that can only be met with sophisticated techniques. The limits on the information which can be recorded by the detectors, are under pressure from the requirements of the science. Higher positional resolution, larger dynamic range, and faster image capture rates are all being asked of the latest systems. The suitability of X-ray sensitive emulsions, and the new phosphor imaging plates have been compared to the delay line readout multiwire proportional counter system which is in use of on the Daresbury Laboratory Synchrotron Radiation Source. The three detector types have been studied with respect to their positional resolution, sensitive area, temporal resolution, maximum rate, and dynamic range. Although, in general, the requirements are for detectors working with mono-energetic beams the tests described have been performed at more than one energy. Some results from this study are presented.

Evaluation of an imaging phototube using microchannel plates with delay line readout

An imaging phototube using a bialkali photocathode, 40-mm microchannel plates (MCPs), and a crossed delay line readout has been constructed. The photocathode is found to exhibit good sensitivity, although overall detection efficiency is lowered by the MCP ion-film barrier. The MCP gain characteristics are evaluated over the sensitive area, and the reduction of gain at high count rate is measured. Several overall detector characteristics, including dark count, spatial resolution, and geometric linearity, are described. It is shown that the chevron pair of MCPs provide a highly peaked pulse height distribution at a modal gain sufficiently low to allow local count rates of up to approximately 5500 s/sup -1/mm/sup -2/, yet sufficiently high to produce a spatial resolution, of <or=80 mu m full width at half maximum (FWHM), making them suitable for use in a photon counting detector for X-ray crystallography. A factor of 1.7 variation in the modal gain points to the need for uniformity of MCP burn-in during tube construction.<<ETX>>

Delay line readout of microchannel plates in a prototype position-sensitive photomultiplier tube

A two dimensional delay line anode has been developed for high resolution readout of large format microchannel plates (MCPs). We describe the construction and attenuation properties of the readout, as well as its spatial resolution and image linearity. The delay line readout has been successfully incorporated into a small sealed prototype phototube along with a bialkali photocathode and chevron pair of 40 mm diameter MCPs. The tube's spatial resolution is evaluated and compared with the theoretical value predicted from the summation of the contributions from the individual tube components. Image distortions are found to be small and confined to the periphery of the active area.

Imaging properties of a delay line readout using large microchannel plates

Measurements made on the readout of large microchannel plates (MCPs) with crossed delay line anodes are reported. Two chevron pairs of MCPs were used: a 127-mm-diameter circular pair and a 100-mm*100-mm square pair. The modal gain varied over the surface of the MCPs by as much as a factor of three, both before and after extensive UV scrubbing. Attempts to decrease the variations in gain by further full flood scrubbing and by spot scrubbing the high-gain areas were unsuccessful. The full width at half maximum (FWHM) of the charge distributions was 100% before the scrubbing and improved to 45% afterwards. Characteristic deviations from spatial linearity for the delay line anode are presented. For positions within a diameter of 120 mm, the deviations from linearity were less than +or-150 mu m. For MCP gains greater than 3*10/sup 6/, the FWHM spatial resolution was measured. The resolution at the center at the MCPs was 54 mu m, while at the edge (57 mm from the center) it was 64 mu m.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The application of multiwire x-ray detectors to experiments using synchrotron radiation

Multiwire detectors have certain characteristics that can be used to advantage, particularly in small-angle diffraction or scattering experiments on biological systems. The size of the active region of the detector and the total number of pixels can be conveniently matched to the dimensions of the synchrotron beam and to the optics of the beam line camera. Furthermore, the large dynamic range inherent in single-photon counting systems can be exploited to ensure the collection of high-quality data even when the scattering factor varies over several orders of magnitude. Linear and two-dimensional detectors are in regular use at the Daresbury Synchrotron Radiation Source, all using the delay-line readout method and a standardised data acquisition system which includes facilities for time-resolved measurements. The development of a new system (now at the prototype stage) to operate at the very high count rates available from synchrotron sources is outlined in this paper.

Automatized One-dimensional X-Ray-Detector

One-dimensional gas-filled X-ray detectors with delay line readout have been developed and tested on line with IBM-PC. The pressure of a xenon (90) and CH4 (10) mixture can be set over a range of 1–10 atm. The position resolution for 8 keV photons is about 170 μm. Main properties and possible applications of the detector are presented.

Tests of a time projection chamber module with delay line readout

The results of TPC tests in an accelerator beam are described. This chamber with a 800 x 350 x 60 mm 3 sensitive volume is a module of a large TPC with dimensions 800 x 350 x 1600 mm 3. The coordinate along the signal wires is determined by means of electromagnetic delay lines. The chamber operates with a track efficiency of > 90% and a spatial resolution of 0.2∼0.5 mm for the electron drift and 1–1.5 mm for the delay lines. The TPC module operates with high efficiency in the magnetic field with B = 1.5 T as well. The chamber was investigated using beams with intensities up to 10 6 particles/s. An electric gate, designed for the trigger mode of the chamber operation, was tested in the beam both with and without the magnetic field.

An x-ray gas position sensitive detector: Construction and characterization

A linear x-ray gas position sensitive detector with delay line readout has been constructed. The detector is described, characterized, and used for detecting x-ray diffraction patterns from polycrystals.

Data acquisition systems for linear and area X-ray detectors using delay line readout

Digital systems for fast readout of linear and area position sensitive detectors based on commercially available CAMAC modules are described. The first version of the system has been used extensively for synchrotron radiation work carried out at the EMBL outstation in Hamburg during the last five years. A second system allowing measurements at count rates up to 600 kHz on a continuous source has been recently installed. An overview of the complete acquisition and information processing system is also given.