Edward Diehl

Fault detection and diagnosis of gear systems using vibration measurements play an important role in ensuring their functional reliability and safety. Computational intelligence, leveraging upon classification through various surrogate models, has recently demonstrated certain level of success. Major challenge however remains. The establishment of surrogate models generally requires large size of training data with specific labels corresponding to explicitly known gear fault conditions, which may not be available in practical applications. Both the size of available data and the respective labels may be quite limited due to the high cost, which hinders the diagnosis of unseen/unexpected faults with desired reliability. In this research we synthesize a deep convolutional generative adversarial network (DCGAN) to tackle this challenge. This new approach follows the semi-supervised learning concept, the performance of which is significantly enhanced by introducing additionally the inexpensive unlabeled data. The balanced adversarial effect between the discriminator and generator in DCGAN is realized by appropriately designing their architectures, which as a result can enable the high accuracy of diagnosis with scarce labeled data. More importantly, by taking full advantage of the rich fault signatures in the unlabeled data that point to the diverse unseen faults, the intrinsic correlation of underlying physics between the unseen and known faults can be implicitly elucidated via unique semi-supervised learning strategy featured in DCGAN. Therefore, the extended capability in diagnosing the unseen faults that are beyond the known faults in training dataset can be realized, which bears practical significance. Systematic case studies using experimental data acquired from a lab-scale gear system are carried out to validate the new diagnosis framework.

Silicon samples containing various p- and n-type dopants have been implanted with spin-polarized $^{12}\mathrm{B}$ between 300 and 950 K. Using \ensuremath{\beta}-radiation-detected nuclear magnetic resonance, the fraction of $^{13}\mathrm{B}$ in normal substitutional sites has been determined. This fraction increases from about 20% at 300 K to \ensuremath{\simeq}100% at temperatures that systematically depend on the bulk doping. We argue that the diffusive motion of interstitial boron leads to boron in substitutional sites.

We discuss the preparation of different samples of the CR39 polymer and a number of tests performed with high energy heavy ions. The quality and reproducibility of the manufactured CR39 is discussed as well as the implications for a large area detector (MACRO) used for a search for cosmic magnetic monopoles.

A large ring-imaging Čerenkov telescope (RICH-II) was flown on a high altitude balloon from Fort Sumner, New Mexico, USA in October 1997. This instrument is designed to determine the energy spectra of light cosmic-ray nuclei over the energy range 30–150 GeV/n through a precise measurement of the angle of Čerenkov emission from each particle. We give details about the design and performance of the instrument and present results on the absolute intensity of cosmic-ray protons and helium nuclei. The observed ratio of proton to helium intensities does not change significantly over this energy range. We also find that the abundances of protons and helium nuclei at 100 GeV/n at the cosmic-ray source relative to elemental galactic abundances are much smaller than those of other elements with comparable first ionization potential.

The ATLAS Muon Spectrometer incorporates 354 000 drift tubes assembled into 1200 Monitored Drift Tube (MDT) precision chambers, with a total gas volume of 723m3. This MDT gas, Ar 93% and CO2 7% at 3 bar, is cycled through the spectrometer at a rate of one total detector volume per day. Achieving the 80μm drift tube design resolution requires stringent gas quality control as a fundamental component of the MDT calibration program. We report on the design, deployment and performance of a dedicated MDT mini-chamber conceived for continuous monitoring and drift time calibration of the ATLAS MDT operating gas. This chamber enables measurement of the drift spectra from which gas properties relevant to MDT calibrations and stable operating conditions are determined. Located in the ATLAS gas facility at CERN, the mini-chamber produces hourly drift spectra which are automatically analyzed. Results are published online and disseminated to the ATLAS muon system conditions and calibration databases in real time.

We report on studies of fast triggering and high-precision tracking using Resistive Plate Chambers (RPCs). Two beam tests were carried out with the 180 GeV muon beam at CERN using RPCs with gas gaps of 1.00 or 1.15 mm and equipped with readout strips with 1.27 mm pitch. This is the first beam test of RPCs with fine-pitch readout strips that explores simultaneously precision tracking and triggering capabilities. RPC signals were acquired with precision timing and charge integrating readout electronics at both ends of the strips. The time resolution was measured to be better than 600 ps and the average spatial resolution was found to be 220 um using charge information and 287 um using timing information. The dual-ended readout allows the determination of the average and the difference of the signal arrival times. The average time was found to be independent of the incident particle position along the strip and is useful for triggering purposes. The time difference yielded a determination of the hit position with a precision of 7.5 mm along the strip. These results demonstrate the feasibility using RPCs for fast and high-resolution triggering and tracking.

This paper presents results on the search for dark matter with the ATLAS experiment at the Large Hadron Collider. The studies discussed involve searches for events with a single (mono) jet or photon plus missing transverse energy interpreted with effective field theory as well as searches for light gravitinos and lepton-jets. No evidence for dark matter production has been found and the results have been translated into exclusion limits on physics beyond the Standard Model for several different scenarios. In particular, ATLAS bounds on weakly interacting massive particles are seen to be both complementary and quite competitive to those from direct detection experiments.

The muon spectrometer of the ATLAS detector for the Large Hadron Collider is designed to provide a muon transverse momentum resolution of 2%–10% for momenta between 6 GeV and 1 TeV over a pseudo-rapidity range of |η|⩽2.7. This required the development of precision drift chambers with a track position resolution of 40μm, the Monitored Drift Tube (MDT) chambers. We report about the construction of the three main types of MDT chambers for ATLAS, test results and the first production experience.

The ATLAS Muon Spectrometer is designed to measure the momentum of muons with a resolution of dp/p = 3% and 10% at 100 GeV and 1 TeV momentum respectively.For this task, the spectrometer employs 355,000 Monitored Drift Tubes (MDTs) arrayed in 1200 Chambers. Calibration (RT) functions convert drift time measurements into tube-centered impact parameters for track segment reconstruction. RT functions depend on MDT environmental parameters and so must be appropriately calibrated for local chamber conditions. We report on the creation and application of a gas monitor system based calibration program for muon track reconstruction in the LHC startup phase.

The precision chambers of the ATLAS Muon Spectrometer are built with Monitored Drift Tubes (MDT). The requirement of high accuracy and low systematic error, to achieve a transverse momentum resolution of 10% at 1 TeV, can only be accomplished if the calibrations are known with an accuracy of 20 μm. The relation between the drift path and the measured time (the socalled r-t relation) depends on many parameters (temperature T, hit rate, gas composition, thresholds,...) subject to time variations. The r-t relation has to be measured from the data without the use of an external detector, using the autocalibration technique. This method relies on an iterative procedure applied to the same data sample, starting from a preliminary set of constants. The required precision can be achieved using a large (few thousand) number of non-parallel tracks crossing a region, called calibration region, i.e. the region of the MDT chamber sharing the same r-t relation.

A new small-diameter Monitored Drift Tube (sMDT) chamber has been developed for the muon spectrometer of the ATLAS experiment to handle the higher collision rates expected at the CERN High Luminosity Large Hadron Collider (HL-LHC). This paper presents measurements of the tracking resolution and hit efficiency of two prototype sMDT chambers constructed at the University of Michigan. Using cosmic-ray muons the sMDT tracking resolution of 103.7$\pm8.1$ \textmu m was measured for one chamber and 101.8$\pm$7.8 \textmu m for the other, compared with a design resolution of 106 \textmu m. A further tracking resolution improvement to 83.4$\pm$7.8 \textmu m was obtained by using new high-gain readout electronics which will be added for HL-LHC. An average tracking efficiency of (98.5$\pm$0.2)\% was found for both chambers. The methodology used to determine the detector tracking resolution and efficiency, including reconstruction of sMDT data and a Geant4 simulation of the test chamber, is presented in detail.

Abstract This paper describes the small-diameter monitored drift-tube detector construction at the University of Michigan as a contribution to the ATLAS Muon Spectrometer upgrade for the high-luminosity Large Hadron Collider at CERN. Measurements of the first 30 chambers built at Michigan show that the drift tube wire position accuracy meets the specification of 20 μm. The positions of the platforms for alignment and magnetic field sensors are all installed well within the required precision. The cosmic ray test measurements show single wire tracking resolution of 100 ± 7 μm with an average detection efficiency above 99%. The infrastructure, tooling, techniques, and procedures for chamber production are described in detail. The results from the chamber quality control tests of the first 30 constructed chambers are reported.

Abstract The goal of this project is to develop a dependable and effective LiDAR scanner for autonomous quadcopters to map the landscape. The LiDAR sensor enables scanning of the ground, locating obstructions, and determining secure landing areas. For secure navigation in uncharted territory, the system creates a 3D point cloud map. By scanning at the precise target angle, the control system makes sure that accurate data gathering is accomplished. The control system’s servo is controlled by the IMU, allowing the LiDAR sensor to adapt in response to quadcopter motion. With an effective range of 100 meters, the terrain scanner is essential for selecting a secure landing spot for cargo delivery. The operating code of the gadget enables interoperability with more potent LiDAR units for prolonged use. The LiDAR terrain scanner has both physical and financial capabilities. The strategy attempts to deliver technologies at the intermediate level with easily controllable design complexity. The system is tested in an outdoor environment with variable density scans. Sparse and dense maps are compared for lane segmentation purposes.

Abstract β-radiation detected nuclear magnetic resonance (β NMR) has been applied to observe substitutional positions of 12 B (τ β = 29 ms ) implanted into Si crystals containing various n- and p-type dopants. The height of the β-NMR signal at the Larmor frequency is a direct measure of the fraction ƒ s , of the 12B ions located in normal substitutional sites. ƒ s increases monotonically from about zero at 50 K up to saturation values of nearly 100% at 1000 K. In heavily p-doped material two annealing stages were found with a plateau between about 400 and 600 K. Going to intrinsic and further to n-type material the plateau becomes smaller and eventually disappears completely. In p-type Si quadrupole split β-NMR spectra were observed at room temperature. They correspond to 12B located in nonsubstitutional sites with an electric field gradient parallel to a 〈111〉 direction.

The ATLAS Muon spectrometer contains more than 350,000, Monitored Drift Tubes (MDTs). The tubes are three cm diameter, one to six meter length, and filled with a three bar mixture of Ar/CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> . As the MDT operation is very sensitive to changes in gas composition and environmental conditions, monitoring changes in these parameters is crucial to attain the required MDT spatial resolution of 80 microns. The Michigan-Tel Aviv gas monitoring system is a mini MDT chamber located in the ATLAS gas facility at CERN. The system monitors simultaneously the input feed and exhaust gas to the complete MDT system. By monitoring these two lines it is sensitive to changes of about 1 part per mil to the internal MDT gas composition, and consequently to the drift time to drift radius calibration. As such the system has an important role in the MDT calibration chain. The mini-chamber acquires cosmic ray muon data and monitors continuously the drift times, gas flow rates, temperature and pressure, as well as deriving the radius-time (RT) relations of the drift-tubes. Results of the monitoring are published hourly. This system has been in operation since August 2007. We present a one-year analysis of the results and their correspondence to ambient conditions in the ATLAS cavern as well as interventions in the ATLAS gas facility, demonstrating the sensitivity of the system.

This paper reports on the design and construction of infrastructure and test stations for small-diameter monitored drift tube (sMDT) assembly and testing at the University of Michigan (UM) to prepare for the ATLAS Muon Spectrometer upgrade for the high-luminosity program of the Large Hadron Collider. Procedures of the tube assembly and quality assurance and control (QA/QC) tests are described in detail. More than 99% of the tubes meet the tube QA/QC specifications based on 2100 tubes built at UM. The UM test stations are also used for QA/QC testing on the tubes constructed at Michigan State University. These tubes are being used to construct the sMDT chambers which will replace the current MDT chambers of the barrel inner station of the Muon Spectrometer.

The ATLAS muon spectrometer consists of several major components: Monitored Drift Tubes (MDTs) for precision measurements in the bending plane of the muons, supplemented by Cathode Strip Chambers (CSC) in the high eta region; Resistive Plate Chambers (RPCs) and Thin Gap Chambers (TGCs) for trigger and second coordinate measurement in the barrel and endcap regions, respectively; an optical alignment system to track the relative positions of all chambers; and, finally, the world's largest air-core magnetic toroid system. We will describe the status and commissioning of the muon system with cosmic rays and plans for commissioning with early beams.

Abstract The temperature dependence of impurity induced EFG 's around implanted 12 B ions in Cu was measured for two lattice locations using the β-NMR method. The induced EFG at the nearest neighbouring host atoms decreases with increasing temperature for the case of 12 B stopped on interstitial sites, whereas the opposite temperature behaviour was found if 12 B is situated in substi­tutional sites.

Abstract β‐radiation detected nuclear magnetic resonance was applied to determine the location of 12 B probe nuclei in a Ni 3 Al single crystal. Combining our results with those of channeling experiments it turned out that more than 90% of the 12 B ions occupy the octahedral interstitial site with six Ni ions as nearest neighbours.

In the ATLAS experiment, the calibration of the precision chambers of the muon spectrometer is very demanding, since the rate of muon tracks required to get a complete calibration in homogeneous conditions and to feed prompt reconstruction with fresh calibration constants is very high. The best place to get muon tracks suitable for muon detector calibration is the second level trigger, where the pre-selection of data related to a limited space region by the first level trigger allows the selection of all (and only) the hits from a single track and to add some useful information to speed up the calibration process. Furthermore, online data extractions allows calibration data collection without performing special runs that would require special tuning of parameters of the ATLAS TDAQ system. A complex system, involving a specific data collection path in the ATLAS TDAQ, the quasi-online distribution of data through the grid to three calibration farms sitting in Tier-2 computing centers and the storage and replication of calibration parameters into local and central databases, is described, and its current performance are discussed.

The ATLAS muon spectrometer consists of a system of precision tracking and trigger chambers embedded in a 2T magnetic field generated by three large aircore superconducting toroids. The precision Monitored Drift Tube (MDT) chambers measure the track sagitta up to a pseudorapidity of 2.7 with a 50 μm uncertainty yielding a design muon transverse momentum resolution of 10% at 1 TeV. Muon tracking is augmented in the very forward region by Cathode Strip Chambers (CSC). The calibration program, essential to achieve the spectrometer design performance and physics reach, is conducted at three worldwide computing centers. These centers each receive a dedicated High Level Trigger data stream that enables high statistics based determination of t0 and drifttime to driftspace relations. During the first year of data taking a system of periodic calibration updates has been established. The calibration algorithms, methods and tools and performance results using LHC collision data are discussed.

The fraction of B ions occupying substitutional sites after implantation into Si, ƒs, is measured at extremely low doses with the β-NMR technique. The temperature dependence of ƒs(T) is compared with earlier channeling results from literature. The annealing behaviour is strikingly different in the two cases and can be understood in terms of dose-dependent defect reactions.

Muon track reconstruction in the ATLAS Muon Precision (MDT) Chambers relies on many thousands of calibration parameters: T-zeros offsets and on time-to-space (RT) functions that convert drift time to drift radius. A data intensive computing program has been created to obtain compute these constants daily for each of thousands of muon-spectrometer subregions. For early LHC running a simplified calibration employing a single universal RT function (URT) provided by a dedicated gas-monitor MDT chamber can be invoked. Constructed with standard MDT’s, the monitor chamber records cosmic ray drift-time spectra derived from gas flowing in the input and output arteries of the main ATLAS MDT gas supply. These spectra are used to compute the URT bi-hourly, referenced to a standard operating pressure and temperature.

The ATLAS muon spectrometer consists of several major components: Monitored Drift Tubes (MDTs) for precision measurements in the bending plane of the muons, supplemented by Cathode Strip Chambers (CSC) in the high eta region; Resistive Plate Chambers (RPCs) and Thin Gap Chambers (TGCs) for trigger and second coordinate measurement in the barrel and endcap regions, respectively; an optical alignment system to track the relative positions of all chambers; and, finally, the world's largest air-core magnetic toroid system. We will describe the status and commissioning of the muon system with cosmic rays and plans for commissioning with early beams.

Spin-polarized radioactive 12B and 12N probe nuclei are produced in nuclear reactions and implanted into nominally undoped ZnSe at stationary concentrations ≲ 108 cm−3. The implanted impurities are characterized by β-radiation detected nuclear magnetic resonance (β-NMR) measurements within ∼20 ms after the implantation event. About 85% of the implanted B occupy substitutional Zn-sites after moderate annealing and are immobile there up to at least 950 K. Our first data on N implantation show a substantial fraction reaching cubic lattice sites, essentially without any annealing. We tentatively assign this fraction to unperturbed NSe−.

The ATLAS Muon Spectrometer incorporates some 354,000 drift tubes assembled into 1200 monitored drift tube (MDT) precision chambers, with a total gas volume of 723,000 dm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . A gas mixture of 93% Ar and 7% CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> at 3 bar flows in a parallel feed at a rate of one chamber volume per day. Achieving the 80 mum single drift tube design resolution requires stringent gas quality control. We report on the design and initial performance of a dedicated MDT mini-chamber conceived for continuous monitoring of the ATLAS Muon Spectrometer MDT system operating gas. This chamber enables measurement of the drift spectra from which gas properties relevent to MDT calibrations are determined.

Engineering Dynamics Course Companion, Part 2: Rigid Bodies: Kinematics and Kinetics is a supplemental textbook intended to assist students, especially visual learners, in their approach to Sophomore-

Engineering Dynamics Course Companion, Part 1: Particles: Kinematics and Kinetics is a supplemental textbook intended to assist students, especially visual learners, in their approach to Sophomore-lev

The characteristic dependence of x-ray transition radiation on the Lorentz factor of the parent particle can be utilized in cosmic-ray observations on balloons or in space in order to discriminate between relativistic electrons and hadrons, or to determine the energy spectra of heavy cosmic-ray nuclei at very high energies. To obtain statistically meaningful results, exposure factors of the instruments of the order of 100 - 1000 m2sr days are essential. While the intrinsic weight of transition radiation detectors is low, this requires novel approaches and precludes the use of heavy pressurized containers for the instrument. We have developed a system using large arrays of xenon filled proportional tubes as detectors which can operate in a zero pressure environment. We shall discuss this design and present results from prototype evaluations. Finally, we shall describe the capabilities of a practical detector system that will measure the elemental composition and individual energy spectra of heavy cosmic ray nuclei up to energies around 1015 eV.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The High Luminosity Large Hadron Collider (HL-LHC) operations requires the experiments at the LHC to upgrade the detectors with new technologies to cope with much increased event rates. A new small-diameter Monitored Drift Tube (sMDT) chamber has been developed to upgrade the muon spectrometer of the ATLAS experiment. A prototype sMDT chamber has been constructed at the University of Michigan to demonstrate the required performance. Using cosmic ray muons the sMDT tracking resolution of 103.7$\pm8.1$ \textmu m was measured, to be compared with a designed resolution of 106 \textmu m. The average tracking efficiency of (98.5$\pm$0.2)\% was also measured. The methodology used to determine the detector tracking resolution and efficiency, which includes a reconstruction of sMDT data and a simulation of the test chamber with Geant4 is presented in detail. Further tracking resolution improvement has been evaluated when using the new high-gain readout electronics.

A new small-diameter Monitored Drift Tube (sMDT) chamber has been developed for the muon spectrometer of the ATLAS experiment to handle the higher collision rates expected at the CERN High Luminosity Large Hadron Collider (HL-LHC). This paper presents measurements of the tracking resolution and hit efficiency of two prototype sMDT chambers constructed at the University of Michigan. Using cosmic-ray muons the sMDT tracking resolution of 103.7$\pm8.1$ \textmu m was measured for one chamber and 101.8$\pm$7.8 \textmu m for the other, compared with a design resolution of 106 \textmu m. A further tracking resolution improvement to 83.4$\pm$7.8 \textmu m was obtained by using new high-gain readout electronics which will be added for HL-LHC. An average tracking efficiency of (98.5$\pm$0.2)\% was found for both chambers. The methodology used to determine the detector tracking resolution and efficiency, including reconstruction of sMDT data and a Geant4 simulation of the test chamber, is presented in detail.

B.L.U.F. (Bottom Line Up Front)

B.L.U.F. (Bottom Line Up Front) An impact on a rigid object away from its center of mass will create or exchange angular momentum. The “Ballistic Pendulum” problem is a common application of eccentric impact of rigid bodies. We still need to create a normal and tangential coordinate system, but it should be located at the point of impact. The velocities used in the CoR must be at the point of impact.

B.L.U.F. (Bottom Line Up Front)

B.L.U.F. (Bottom Line Up Front)

B.L.U.F. (Bottom Line Up Front)

B.L.U.F. (Bottom Line Up Front) Acceleration Analysis where the reference frame is also in motion creates an extra term that must be included. We’ve already introduced the “Coriolis” acceleration in Particle Polar Coordinates acceleration: \(2\dot r\dot \theta .\) The complete acceleration equation for planar rigid body motion is:\({{\rm{\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\rightharpoonup$}}\over a} }}_B} = {{\rm{\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\rightharpoonup$}}\over a} }}_c} + {\ddot \theta _{BC}}{\rm{\hat k}} \times {{\rm{\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\rightharpoonup$}}\over r} }}_{B/C}} - \dot \theta _{BC}^2{{\rm{\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\rightharpoonup$}}\over r} }}_{B/c}} + 2{\dot \theta _{BC}}{\rm{\hat k}} \times {{\rm{\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\rightharpoonup$}}\over v} }}_{B/C}} + {{\rm{\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\rightharpoonup$}}\over a} }}_{B/C,rel}}.\)

B.L.U.F. (Bottom Line Up Front) Polar Coordinates (a.k.a. “Radial and Transverse”): rotating about an origin to follow a particle, based on distance from the origin and angle from horizontal. Velocity is expressed in Polar Coordinates as: \({\rm{\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\rightharpoonup$}}\over v} }}\,{\rm{ = }}\,\left( {\dot r} \right){{\rm{\hat e}}_r}\, + \,\left( {r\dot \theta } \right){{\rm{\hat e}}_\theta }.\) Acceleration is expressed in Polar Coordinates as: \({\rm{\mathord{\buildrel{\lower3pt\hbox{$\scriptscriptstyle\rightharpoonup$}}\over a} }}\,{\rm{ = }}\,\left( {\ddot r\, - r{{\dot \theta }^2}} \right){{\rm{\hat e}}_r}\, + \,\left( {r\ddot \theta \, + \,2\dot r\dot \theta } \right){{\rm{\hat e}}_\theta }.\)

B.L.U.F. (Bottom Line Up Front) Just as with all rigid body kinetics we include the rotational contribution when applying Work-Energy. Kinetic Energy of rigid bodies also includes \(KE = {1 \over 2}T{\omega ^2}.\) Work in rigid bodies also includes the moment integrated against the change in angle \({U_{1 \to 2}} = \smallint _{{\theta _1}}^{{\theta _2}}M\,d\theta .\).

B.L.U.F. (Bottom Line Up Front) The Velocity Diagram of Rigid Body Motion (RBM) depicts a combination of translation and rotation. The Velocity Diagram is also a graphical representation of relative motion between two points on a rigid body. Either point on an object represented in a Velocity Diagram can be used as the reference. $$\matrix{ {{{{\rm{\vec v}}}_A} = {{{\rm{\vec v}}}_B} + {{{\rm{\vec v}}}_{A/B}}} \cr {{{{\rm{\vec v}}}_B} = {{{\rm{\vec v}}}_A} + {{{\rm{\vec v}}}_{B/A}}} \cr } $$ There are several approaches to solving a velocity analysis using the Velocity Diagram.

Over a wide range of energies, the cosmic ray composition can be described with a uniform source spectrum for all components, and by a propagation pathlength that continually decreases with energy. However, there are indications that this description may no longer be valid above ∼ 1013eV/particle, where observational data become scarce. We discuss how progress can be made in new direct measurements above the atmosphere over the region 1013–1015eV/particle. Most important is the availability of well calibrated detectors with known charge and energy resolution and very large sensitive area. For the heavier nuclei (Z ≥ 3), these specifications can be met with a new generation of light weight transition radiation detectors. In balloon flights of a few days duration these will reach maximum energies of ∼ 0.5 × 1015eV for oxygen and ∼ 2 × 1015eV for iron nuclei with good statistical accuracy.

We have developed a detector of 1.5 × 1.4 m2 area which measures individual photons with a spatial resolution of ∼1 cm. This device is in the focal plane of a 3 m long gas-filled Ring Imaging CHerenkov (RICH) instrument designed to make precision measurements of the velocity of high energy cosmic rays at the top of the atmosphere. In future applications this type of detector may be combined with a magnet spectrometer to make mass measurements of cosmic rays at high energy. The detector is a wire chamber filled with an ethane/TMAE mixture having fused silica windows. The signals are collected by 18 432 cathode pads of 1 cm2 area connected to a VLSI electronic readout system. The quantum efficiency of the detector in the wavelength region of 180–200 nm is ∼12%. We shall discuss the design and operation of this detector.

A large Ring-Imaging CHerenkov (RICH) has been used in high altitude ballon flights in 1996 and 1997. These experiments are specifically aimed at measuring the energy spectra of light nuclei near 100GeV/n. The RICH method, which measures particle Lorentz factor, has a fundamentally different character from other techniques used in this energy region. The establishment of energy scale and the quality of background rejection is discussed.

The measurement of particle velocities in cosmic ray experiments has largely been made by counters which determine the total amount of Cherenkov light emitted by a radiator material. Here we discuss a far more accurate technique which measures the angle of emission of individual Cherenkov photons by imaging the emission cone onto a ring. This approach has the advantage of supplying a velocity estimate from each detected photon and a large reduction in the effects of background light. As an example, we shall discuss our ring imaging Cherenkov detector (RICH) for high altitude balloon cosmic ray experiments. This instrument combines a 3 m gas Cherenkov radiator with 1.5 m multiplied by 1.5 m of position sensitive photon detectors based on TMAE gas mixtures. The photon detector assembly detects individual photons with a quantum efficiency of 10 - 20% in the UV region of the spectrum. The use of VLSI electronics provides individual readout of 18,000 1 cm by 1 cm pixels. The future application of this technique in cosmic ray instruments also is discussed.