Microstrip Gas Chamber Research Articles

Development of a multigrid-type microstrip gas chamber

Conventional microstrip gas chambers (MSGCs) have encountered many difficulties, such as limited gas gain and sparking damages. We propose a new multigrid-type MSGC (M-MSGC) to overcome some of these difficulties. Additional grid strips are inserted between the anode and the cathode in this new type of MSGC. Gaps between these strips are chosen to be as small as 10 /spl mu/m where one can expect an efficient removal of the surface charge. With the existence of other strips with lower potentials than the anode, the field strength around the neighboring grid to the anode strip is not as high as the conventional small-gap MSGCs. The contribution of the surface streamer to the damage is greatly suppressed because the electric field parallel to the surface is screened by the intermediate grid electrodes. However, additional electrodes also screen all the electric field of the upper part of the substrate, and we cannot observe induced signals from the backside of the substrate. To overcome that difficulty, we propose another signal readout method using a patterning approach. Floating pads are placed close to the cathode strip on the surface of the M-MSGC, and the induced charges are read out via the pads. If the area of the pads is sufficiently large and the positive charges are moving toward the pads, the backside electrodes can sense the induced charge. Collected charges on the pads are leaked through the surface resistance. The backside signal through 2.3-mm-thick glass readout of the position along the cathode strips is successfully confirmed through experimental results.

Use of a MicroStrip Gas Chamber conductive capillary plate for time-resolved X-ray area detection

The stable operation of MicroStrip Gas Chamber (MSGC) was successfully performed using glass capillary plate as an intermediate gas multiplier. Detection area of 95 mm 2 was available and fine position resolution of 90 μm using digital readout was attained. A charge-up problem of capillary plate under intense radiation source was perfectly removed by surface conductivity inside of capillaries. The quantitative measurements using MSGC is now available in X-ray imaging. This paper also presents novel applications of X-ray diffraction studies and their preliminary results using an MSGC. Rapid measurements for X-ray crystallography of the order of a few tens of seconds were attained successfully.

Test of APV–DMILL circuits with silicon and MSGC micro-strip detectors for CMS

The APVD is a radiation-hard integrated circuit fabricated in DMILL technology and developed for the front-end electronic to read out the tracking detectors of CMS. This paper reports test results obtained with prototypes connected to silicon and Micro-Strip Gas Chambers (MSGC) detectors in a 200 GeV/c pion beam. A signal-to-noise ratio of 12 and 7, affected by residual excess noise from common mode oscillations, a spatial resolution of 7 and 11 μm and a detection efficiency of 98% and 93% were measured for silicon detectors in peak and deconvolution modes, respectively. With the MSGC detector, we obtained a signal-to-noise ratio of 17 and a detection efficiency of 97%. The response of an MSGC with this electronic has also been studied with perpendicular and inclined particle tracks and good agreement with a simulation of detector and electronic was obtained.

Micropattern gas detectors: the CMS MSGC project and gaseous pixel detector applications

We report recent results from the development and testing of two types of micropattern gas detectors—micro-strip gas chambers and GEM-based devices with two types of pixel read-out. Thirty-two micro-strip gas chambers were tested in a high intensity hadron beam as a milestone for CERN's Compact Muon Solenoid (CMS) experiment. The detectors were operated with voltage settings corresponding to 98% hit detection efficiency at CMS for a total high intensity exposure period of 493 h. All of the requirements expected by the milestone—gain stability, number of lost strips, spark rate, etc.—were met, with wide margins. In a separate investigation, we have coupled PCB pixel read-out planes to GEM foils. In one case, 2 mm×2 mm pixels were fanned out to individual discriminators and scalers to provide very fast (2 MHz/pixel) read-out; this system has been used as an imaging device to provide diagnostic information in fusion experiments. The second type of device used smaller pixels (200 μm squares) and a Flash-ADC read-out system to reconstruct individual photoelectron tracks. The angular distribution of the tracks allows the polarisation direction of polarised X-ray sources to be identified, with possible applications for future space experiments studying celestial X-ray emissions.

Development of a hybrid MSGC detector for thermal neutron imaging with a MHz data acquisition and histogramming system

For thermal neutron imaging at the next generation of high-flux pulsed neutron sources a large area and fourfold segmented, hybrid, low-pressure, two-dimensional position sensitive, microstrip gas chamber detector, fabricated in a multilayer technology on glass substrates, is presently being developed, which utilizes a thin composite 157Gd/CsI neutron converter. The present article focusses on the readout scheme and the data acquisition (DAQ) system. For position encoding, interpolating and fast multihit delay line based electronics is applied with up to eightfold sub-segmentation per geometrical detector segment. All signals, i.e. position, time-of-flight and pulse-height signals, are fed into deadtime-less 8-channel multihit TDC chips with 120 ps LSB via constant fraction and time-over-threshold discriminators, respectively. The multihit capability is utilized to raise the count rate limit in combination with a sum check algorithm for disentangling pulses from different events. The first version of the DAQ system uses the PCI form factor and comprises one slow control board and up to four boards for DAQ and real time histogramming with up to 2 MHz per board. Each DAQ board incorporates four TDC chips, up to 256 Mbytes of histogram memory and a 1 GFLOP DSP. The time of flight can be measured with a precision of a few LSB up to ranges >100 ms.

THE CMS MICRO-STRIP GAS CHAMBER — A HIGH RESOLUTION DETECTOR FOR TRACKING AT VERY HIGH RATES

Results from a large scale test performed on the Micro-Strip Gas Chambers developed for the CMS experiment are reported. Irradiation, close to the expected LHC background, was provided by a low energy (350MeV), high rate (6kHz/mm2) pion beam at PSI. Excellent performance of the detectors was obtained using solutions specific to the demanding radiation environment.

Operation of sealed microstrip gas chambers at the ILL

Microstrip Gas Counters (MSGCs) were introduced at the ILL as a response to the problem of fabricating the large area neutron detector of the D20 neutron powder diffractometer. This banana-like detector consists of 48 MSGCs, each comprising 32 counting cells. It was in operation during 18 months before being stopped due to the progressive deterioration of the anode strips. In order to increase its lifetime, significant modifications were introduced in the recently assembled new version. Another instrument, D4C, was recently equipped with a modular detector made of nine MSGCs, each of them in an individual gas vessel. Besides the unidimensional individual readout MSGC of D20 and D4C, the ILL has developed bidimensional MSGCs with a charge division readout. All these detectors employ sealed vessels containing a gas mixture at a pressure which can be as high as 15 bar, necessitating very clean conditions. This paper describes the experience acquired at the ILL in the fabrication and operation of these detectors.

Operation of sealed microstrip gas chambers at the ILL

Microstrip gas chambers (MSGCs) were introduced at the Institut Laue Langevin [(ILL), Grenoble, France] as a response to the problem of fabricating the large-area neutron detector of the D2O neutron powder diffractometer. This banana-like detector consists of 48 MSGCs, each comprising 32 counting cells. It was in operation during 18 months before being stopped due to the progressive deterioration of the anode strips. To increase its lifetime, significant modifications were introduced in the recently assembled new version. Another instrument was equipped with a modular unidimensional detector made of nine MSGCs, each of them in an individual gas vessel. The ILL has also developed bidimensional MSGCs with a charge division readout. All these detectors employ sealed vessels containing a gas mixture at a pressure that can be as high as 15 bars, necessitating very clean conditions. This paper describes the experience acquired at the nL in the fabrication and operation of these detectors.

An optimized process for the production of advanced planar wire grid plates as detectors for high energy physics experiments

This paper introduces a novel production technique for the planar wire grid plates of microstrip gas chambers (MSGCs, gaseous particle detectors), taking advantage from the typical thin film metallization technologies. The aim of the work here presented has been to manufacture MSGC substrates which can meet the challenging requirements proper to particle tracking detectors in highly ionizing environments. These requirements are mainly represented by high reliability and robustness, since the devices are supposed to operate efficiently for at least 10 years in the extremely hostile conditions foreseen at the large hadron collider at CERN (CH). A detailed process description will be given and results will be analyzed both from the production point of view and from the application of the manufactured prototypes as detectors for high energy physics experiments.

Rapid X-ray crystal structure analysis in few second measurements using microstrip gas chamber

X-ray crystal structure analysis using microstrip gas chamber was successfully carried out in a measurement time within a few seconds. The continuous rotation photograph method, in which most of the diffraction peaks can be obtained within one continuous rotation of the sample crystal (without stopping or oscillation), was applied for this measurement. As an example, the structure of a single crystal of ammonium bitartrate ( r=1 mm, spherical) was measured. Diffraction spots from the sample, which were sufficient to obtain crystal structure, were successfully obtained by taking only 2 s measurements with a commercially available laboratory X-ray source.

Performance of a micro-strip gas chamber in solution X-ray scattering

The performance of a Micro-Strip Gas Chamber in solution X-ray scattering was studied at the RIKEN structural biology beamline I of the SPring-8 facility. The practical dynamic range was confirmed to be ∼1,000,000 : 1 by measuring S −4 decay from a polystyrene latex solution. Steep troughs of scattering profile from an apoferritin solution were clearly obtained without smearing. An unfolding process of a pH jump of cytochrome c was measured. A time resolution of 500 μs was achieved.

The inner tracking system of the experiment HERA-B

The inner tracker of HERA-B, built by the Universities of Heidelberg, Siegen, and Zurich, consists of 184 chambers with a total of 140 000 channels. The detectors are composed of microstrip gas chambers (MSGCs) with a preamplifying device in the gas volume, the gas electron multiplier (GEM), During the year 2000, we installed and commissioned a total of 136 GEM-MSGC detectors. Preliminary results from the first year of operation are reported.

Performance of the all-silicon CMS tracker

The Compact Muon Solenoid (CMS) Tracker Collaboration has recently revised the tracking-detector layout. While the previous design relied on Micro Strip Gas Chamber (MSGC) and silicon detectors, the new layout implements solid state sensors as the sole technological choice. The new all-silicon layout is presented and the projected performance is discussed in terms of several benchmark topologies.

The Inner Tracker of HERA-B

The Inner Tracker for the HERA-B experiment consists of 136 micro-strip gas chambers (MSGC) with a pre-amplifying device in the gas volume, the gas electron multiplier (GEM). The 102 000 detector channels are read out with the Helix128 ASIC. The HERA-B Inner Tracker is the first large-scale system using this detector technology in a high-rate hadronic environment comparable to LHC conditions.

Development of a microstrip gas chamber to study the effect of drift gap on its performance

We present a new microstrip gas chamber design and a detailed experimental study of the effect of drift gap on its performance. The chamber has the provision to vary the drift gap in situ which enables one to carry out the performance study without altering the other set operating parameters such as gas pressure, anode voltage, and drift voltage. The effect of drift gap on detector gain and energy resolution is discussed here. The importance of optimization of drift gap is highlighted. The maximum gain obtained with P10 (Ar90%+CH410%) gas is ∼750 and the best resolution achieved is ∼19% for 5.9 keV x rays.

The CMS micro-strip gas chamber project – development of a high-resolution tracking detector for harsh radiation environments

Thirty-two large-area Micro-Strip Gas Chambers were tested in a high-intensity, 350 MeV pion beam at PSI to prove that we had reached a Milestone for the Compact Muon Solenoid (CMS) experiment. The particle rate was approximately 6 kHz/ mm 2 , distributed over the whole active area of the detectors, and this rate was maintained for a total integrated time of 493 h. All of the chambers were operated with signal-to-noise values at or above that corresponding to 98% hit detection efficiency at CMS; the average S/ N was 31. No indications of any gain instabilities or ageing effects were observed. In the official 3-week Milestone period, three strips from a total of 16 384 were damaged, a result which is 20 times lower than the minimal requirement for CMS. The spark rate of the detectors was very low and decreased with time to an average of one spark per chamber per day. The cathode voltages of 24 of the chambers were increased over a one week period to investigate the behaviour of the detectors at higher gains; the maximum S/ N value was 2.4 times that at the normal working point. No significant increase in spark rate or strip loss rate was detected and the chambers operated stably. The detector efficiencies and imaging capabilities were also investigated. The MSGC design features and the assembly and test methodologies that enabled us to achieve these results are reported.

The MSGC-GEM Inner Tracker for HERA-B

The HERA-B Inner Tracker system, which is built by groups from the universities of Heidelberg, Siegen and Zürich, consists of 184 detectors. The detectors are composed of Microstrip Gas Chambers (MSGC) with a pre-amplifying device in the gas volume, the Gas Electron Multiplier (GEM). The complete system of 140k analog and 10k trigger channels will be installed in HERA-B during this year.

Experiment to measure the Lamb shift in muonic hydrogen

The contribution of the root mean square (RMS) proton charge radius to the Lamb shift (2S–2P energy difference) in muonic hydrogen (μp) amounts to 2%. Apart from the uncertainty on this charge radius, theory predicts the Lamb shift with a precision on the ppm level. We are going to measure ΔE (2 S1/2(F=1)–2 P3/2(F=2)) in a laser resonance experiment to a precision of 30 ppm (i.e., 10% of the natural linewidth) and to deduce the RMS proton charge radius with 10−3 relative accuracy, 20 times more precise than presently known. The most important requirement for the feasibility of such an experiment, namely the availability of a sufficient amount of long lived metastable μp atoms in the 2S state, has been investigated in a recent experiment at PSI. Our analysis shows that in the order of one percent of all muons stopped in low pressure hydrogen gas form a long lived μp(2S) with a lifetime of the order of 1 μs. The technical realization of our experiment involves a new high intensity low energy muon beam, an efficient low energy muon entrance detector, a randomly triggered 3 stage laser system providing the 0.5 mJ, 7 ns laser pulses at 6.02 μm wavelength, and a combination of a xenon gas proportional scintillation chamber (GPSC) and a microstrip gas chamber (MSGC) with a CsI coated surface to detect the 2 keV X rays from theμp(2P → 1S) transition.

マイクロストリップガス比例計数管 (MSGC) の現状と展望

The present invention relates to a microstrip gas chamber and microstrip plate capable of reading signals from readout electrodes provided at a rear surface of the substrate in a superior manner while having a simple and compact configuration. The microstrip plate comprises an electrically insulating substrate 1 , cathodes 2 and anodes 3 arranged alternately at the surface of the substrate 1 , read-out electrodes 4 arranged so as to intersect the cathodes 2 and anodes 3 at the rear surface of the substrate 1 , wherein a plurality of unitary regions 20 are provided at the surface of the substrate 1 and each unitary region 20 is electrically floated from the cathode via a resistance region 5.

MICROPATTERNGASEOUSDETECTORS

▪ Abstract Introduced in 1988, microstrip gas chambers perform considerably better than classic multiwire detectors. Excellent localization, high rate capability, and good granularity make them attractive for charged-particle tracking at high-luminosity colliders, among other applications. The technology continues to improve; for example, substrates have been developed that prevent charge accumulations. Some problems persist, namely the slow degradation under sustained irradiation (aging) and the serious damage that can result from accidental discharges. New types of detectors aim at improving on these points; the microdot, micromegas, and gas electron multiplier detectors are promising examples. They are generally more reliable and cheaper.