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The large-scale coordinate-tracking detector TREK for registration of inclined EAS is being developed in MEPhI. The detector is based on multiwire drift chambers from the neutrino experiment at the IHEP U-70 accelerator. Their key advantages are a large effective area (1.85 m2), a good coordinate and angular resolution with a small number of measuring channels. The detector will be operated as part of the experimental complex NEVOD, in particular, jointly with a Cherenkov water detector (CWD) with a volume of 2000 cubic meters and the coordinate detector DECOR. The first part of the detector named Coordinate-Tracking Unit based on the Drift Chambers (CTUDC), representing two coordinate planes of 8 drift chambers in each, has been developed and mounted on opposite sides of the CWD. It has the same principle of joint operation with the NEVOD-DECOR triggering system and the same drift chambers alignment, so the main features of the TREK detector will be examined. Results of the CTUDC development and a joint operation with NEVOD-DECOR complex are presented.

The neutron component of EAS has not been practically studied for many years. Creation of the neutron detector arrays PRISMA-32 and PRISMA-YBJ demonstrated the effectiveness of such investigations. It is important to underline that recording the EAS neutron component is carried out over the whole array area. Development of a new larger scale neutron detector array (URAN) in MEPhI will continue these studies. During the construction of the URAN array, a new design of en-detectors based on the scintillator with natural boron and new electronics was developed. The use of new electronics with a switchable sampling rate allows one to reach EAS fast timing accuracy up to 10 ns. The en-detectors of the URAN are located on the roofs of the buildings. The sensitive area of each detector is 0.36 m2, while the array's starting area is ∼ 103 m2. Total number of the initial array detectors is 72. They are subdivided into 6 independent clusters each of 12 en-detectors, connected with the central data acquisition station.

For explanation of many results obtained in cosmic ray experiments at energies above the knee, the production of heavy particles with large cross section, appearance of large orbital (or rotational) momenta and other unusual phenomena are required. In the paper, these unusual phenomena are analyzed taking into account experimental data from Quark Gluon Plasma investigations and some theoretical models predicting large values of orbital momenta in Quark Gluon Plasma. In general, it is possible to consider cosmic ray data as a bridge between RHIC and future LHC results.

A new approach to cosmic ray description based on the model of particle generation and acceleration in plasma pinches and on supposition that a new state of matter appears in cosmic ray interactions above 1015 eV is considered. Consequences for various aspects of cosmic ray physics and some possibilities to check this hypothesis are discussed.

The appearance of the knee in EAS energy spectrum in the atmosphere in PeV energy interval and observation of various types of unusual events approximately at same energies are considered as evidence for new physics. Some ideas about possible new physical processes at PeV energies are described. Perspectives to check these ideas and their consequences for experiments at higher energies are discussed.

The situation in the investigation of the well-known peculiarities in the cosmic ray energy spectrum (the knee, the ankle and the GZK cut-off) assuming that the primary spectrum does not change its slope is considered. The model of cosmic ray acceleration in plasma pinches supporting such primary spectrum behaviour is described. Some questions of further investigation are analyzed.

Experimental and theoretical situation in investigations of cosmic rays with energies higher than the knee is considered. The evidences of new state of matter production in interactions of PeV cosmic rays are analysed. Theoretical model of cosmic ray acceleration in cosmic plasma pinches with constant slope of energy spectrum γ = 3 is described. Consequences for future experiments and for interpretation of their results around the cutoff are discussed.

A very high-current liner implosion experiment was conducted, using an explosive magnetic-compression generator (EMG) to deliver a peak current of 102 /spl plusmn/ 3 MA, to implode a 4.0-mm-thick aluminum liner. Analysis of experimental data showed that the inner surface of the liner had attained a velocity of between 6.8-8.4 km/s, consistent with detailed numerical calculations. Both calculations and data were consistent with a final liner state that was still substantially solid at target impact time and had a total kinetic energy of over 20 MJ.

The further development of a new approach to explanation of the knee and the ankle appearance, based on heavy short-lived particles production at energies above the knee, is described. A key role of VHE muons is underlined. Additional arguments in favour of their influence on results of non-muon experiments are analysed. Possibilities to check this new approach in existing experiments are considered.

In November 1992, the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF), Arzamas-16, Russia and the Los Alamos National Laboratory, Los Alamos NM, USA embarked on a historic effort to conduct a joint explosive pulse-power experiment. With the concurrence of the Ministry of Atomic Energy (Russia) and the Department of Energy (US), the two laboratories entered into a laboratory-to-laboratory collaboration in the areas of very high-energy pulse power and ultrahigh magnetic fields in order to explore problems of mutual scientific interest. The first experiment to be planned was an explosively powered, fast, high-current pulse-power system demonstration. The experiment used a flux compressor, inductive store, and high-current opening switch to demonstrate the feasibility of supplying many megajoules of electrical energy, on microsecond time scales, to high-energy density physics experiments. The experiment was conducted in Arzamas-16 on September 22, 1993.

Powerful pulse installations are usually used to produce large yields of X-ray radiation. With an increase of the stored energy up to 100 MJ, the costof a single experiment on these installations becomes comparable to the cost of a shot with explosive magnetic generators (EMG), according to expert estimates. The physical scheme of a device with a changeable mass liner forlarge soft X-ray (in the range of 0.3 to 0.5 keV) yields eneration is investigated. The scheme investigated is substantially free from difficulties connected with high precision liners and fast switches for current pulse sharpening.

A new approach to explanation of the knee and the ankle of cosmic ray energy spectrum in the atmosphere is considered. The concept of missing energy, which can be taken away by muons and neutrinos, is introduced. It is shown that in this case a big excess of VHE muons and neutrinos must be produced. Possible experiments on VHE muon investigations are discussed.

The paper discusses devices with a Disk Explosive Magnetic flux compression Generator (DEMG), which are similar to the ALT-1,2 experimental devices and are intended for testing the possibility of producing 1–3 TPa (10–30 Mbar) pressures and the possibility of measuring Hugoniots of different materials at such pressures. It is expected that two-layer, cylindrical liners, Al+Fe and/or Al+W, will be used, driven by 4–5 MG magnetic fields to ∼ 20 km/s velocities. The paper presents and discusses simulated characteristics of these devices, in which currents, energies and powers delivered to the liner load can reach ∼ 70 MA, ∼ 40 MJ and ∼ 20 TW and exceed those in the ALT-1,2 devices by a factor of ∼2, ∼ 4 and ∼ 7, respectively.

A system design for investigation of the feasibility of controlled inertial thermonuclear fusion (ITF), based on target implosion by fast-rising magnetic field was published in 1979. The base of this design became the realization of a powerful explosive-magnetic generator (EMG) of disc type by that time. Only the disc EMG capable to be employed as a current source for energy releasing unit - a ponderomotor unit (PU), in which the magnetic field energy is converted into a kinetic one of axial symmetric shells-liners, imploding and heating a thermonuclear target. A principle scheme of PU with two cylindrical implosion liners is considered in the report. The experimental results with the energetic liner, having initial surface mass m=4.3-10/sup -2/ g/cm/sup 2/and aspect ratio of 10/sup 3/ , accelerated to 25 km/s and with the main liner of 30 mm in diameter (Do) and m=1.06*10/sup -3/g/cm /sup 2/, accelerated to 50 km/s are presented in this report. The problem of the implosion liner compression symmetry is considered. Data on the motion symmetry of heavy nonexploding liners, gaining energy up to 25 MJ during acceleration are available.

Among the known types of electromagnetic energy sources, the explosive magnetic generators (EKG) are the best characterized in terms of their specific energy output and cost. The results of studies on "POTOK" - family helical and multicomponent disk EMGs of various output energy are presented. The physical model of a helical EMG is considered, which describes the effects of circuit compression ratio and dynamic contact point velocity on energy gain and the helix figure of merit. The family of helical EMGs with inner diameters ranging from 50 to 240 mm have been developed and studied. These EMGs can generate 1 to 20 MA current pulses with 3 to 50 /spl mu/s characteristic risetimes into the loads of 25 to 750 nH unductance. With high- inductance helices used in these generators, having insulated turns distributed in a specific way along their axes, 400-fold or more energy amplification can be achieved in experiments. The operation of helical-dink EMG with transmission lines of 200 and 500 mm radii has been studied experimentally. The experimental data are reported. The issues of energy extraction from EMG using explosive and electric-explosive (wire and foil) current opening switches are discussed. For explosive opening switches some techniques of conductor disruption have been tested, based on either throwing the toil at the ribbed dielectric barrier or using the dielectric shaped-charge jets. A device based on disk EMG has been developed and described, 400 mm in diameter and having a foil opening switch, which allows to deliver 10 MJ energy to the load provided with a liner ponderomotor unit with current across the liner 35 MA high and its characteristic risetime 1.1 /spl mu/s.

This paper presents the computational analysis of an experimental three-layer liner system, Al-polyethylene-Cu and Al-water-Cu, designed for the study of dynamic strength of low-density and high-density materials using the perturbation growth caused by the Rayleigh-Taylor instability. Copper and polyethylene dynamic strength models developed by VNIIEF are used. Comparison between computations and experiments showed good agreement with a model for copper obtained previously from analysis of high-pressure explosive driven shock-free experiments. The data also allowed us to refine a model for polyethylene obtained from the analysis of previous experiments.

This paper presents the construction-technology schematic of the device comprising the helical and disk EMGs with a three-layered cylindrical liner (Al-dielectric-Cu) designed for experiments RHSR-0,1,2 at the current of 33-35 MA. Polyethylene or water was used as a dielectric layer. The experiments tested successfully the idea to study the dynamic strength of materials by X-raying the growth of amplitude of axisymmetric sinusoidal perturbations machined initially on the outer surface of the examined inner layer of the liner.

In the three joint VNIIEF/LANL experiments RHSR-0,1,2 with a disk EMG and a three-layer liner system (Al-dielectric-Cu) a method of radial radiography was used to study growth of perturbations amplitude at the boundary between copper layer and polyethylene (in experiments RHSR-0,1) and water (in experiment RHSR-2); the growth occurs during the evolution of the Raleigh-Taylor instability of this boundary.

The high-speed implosion of a condensed liner is an efficient method to achieve the state of substance characterized by high energy density, temperature and pressure. The experimental procedure for radiographing the perturbations growing in the cylindrical aluminum liner having the walls 2 mm thick, which is imploded under the effect of 35 MA pulses produced by high-power explosive magnetic disk generator (DEMG), is described. System shielding the X-ray film situated at a distance of ~ 40 sm from HE explosive of ~ 100 kg in the explosive magnetic generator is described in detail. Specially arranged units having low total thickness equivalent to shield the film ~ 15 mm of aluminum were used to provide the necessary protection from damage but still allowed the needed picture contrast. The developed procedure demonstrates the efficiency of EMG in the experiments on pulsed hydrodynamics and high-speed implosion of liners.

To study dynamic strength of materials according to the initial liner perturbation growth in Rayleigh-Taylor instability development, three-layer liner systems driven by azimuthal magnetic field pressure have been suggested. This paper demonstrates that 0.4 m diameter disk EMG ensuring currents up to /spl sim/70 MA can be used for this purpose. In the three-layer liner systems, the liner shock-free loading to more than 1 Mbar pressures is therewith possible, with the pressures rising for times longer than 1/spl mu/s or longer than 0.3/spl mu/s in different systems. Here the shock loading of the liners under study is possible up to 3-4 Mbar pressures. Examples of 2D computations of the initial perturbation growth in the liners under study at shock-free and shock pressures up to 1 Mbar, strain rates up to 10/sup 8/sec/sup -1/, and strains up to 200 % are given.

Good longitudinal symmetry of magnetically driven metal cylindrical liners may be observed at a relatively short time of current rise, for example, in experiments at PEGASUS-2 facility. Because of interaction of the liner with current-conducting edge walls the symmetry of compression may be much worse in experiments with a longer rise time of current delivered by explosive magnetic generators (EMG). The present paper describes the results of study of near-wall effects negative influence on longitudinal symmetry of compression of liners, close in design to experiments at PEGASUS-2 facility, but at an order higher duration of current supplied by helical EMG. The work was conducted within the frames of liner technology program (LT-1 experiments).

A device is being considered consisting of a helical explosive magnetic generator, a cascade of explosive and electroexplosive opening switches. This device serves to obtain a single pulse or a group of voltage pulses with the amplitude of up to 1 MV and a duration of several hundred nanoseconds in loads having an impedance of 1-15 Ohm. The interval between the pulses is equal to several microseconds. The electroexplosive cascade contains the given (in accordance with a required number of pulses) number of steps of conductor having different cross-sections and lengths. Amplitude, shape of pulses and the interval between them may be within certain limits changed by the way of picking out the conversion cascades' design parameters. The authors have modelled the operation of the exit cascade of the considered device powered by a capacitor facility. Copper wire, having several parts of different cross-sections, was used as the electroexplosive opening switch. Oscillograms with two and three consecutive pulses with an amplitude of about 550 kV and a duration of less than 500 ns were obtained. The interval between the pulses was about 2 /spl mu/s.

High power pulsed energy sources are required to produce a large amount of X-rays. The leading role in creation of ultra-high power stationary machines belongs to the USA national laboratories. VNIIEF has made much progress in creation of ultra-high power explosive magnetic generators (EMG) of a single action, which allow experiments up to 200 MJ of the stored energy and up to 10/sup 13/ W of the power in the load.

During the last 20 years, VNIIEF has been studying the compression of liners accelerated under the effect of pressure by a powerful azimuth magnetic field formed by powerful explosive magnetic generators. The research is carried out in applications to create sources of soft X-rays of megajoule level and to obtain a hot thermonuclear plasma. During the experiments, condensed (speed-10 km/s) and plasma liners (at speeds up to some tens km/s) have been studied. To measure the dynamical characteristics of the liners (speed, longitudinal and angular asymmetry etc.) various probes were developed: electrocontact, light, manganin, piezoelectric, and inductive. In this report examples of the use of these probes in experimental studies of condensed and plasma liner compression are presented.

Summary form only given, as follows. Magnetically imploded cylindrical metal shells (Z-pinch liners) can be used to drive a wide variety of hydrodynamics and materials properties experiments if they can be imploded at high velocity with good azimuthal symmetry and axial uniformity. As in all Z-pinches, the outer surface of the liner is magneto-Rayleigh-Taylor (RT) unstable during acceleration and large-scale distortion of the liners from RT modes growing from initial imperfections could make liners unusable. According to first principles, material strength in the liner should reduce the growth rate of RT modes -and material strength can render some modes analytically stable. To study the evolution of RT modes in liners, a series of experiments have been conducted in which high purity (soft, high conductivity) aluminum liners were accelerated with 6 MA, 7ms risetime driving currents. Initial sub-millimeter perturbations were machined into the outer surface of the liner and perturbation growth monitored with X-ray imaging, optical, magnetic and impact probes, described in a companion paper. Results for 2D MHD simulations were in excellent agreement with observed perturbation growth through the entire course of the implosions. Analytic theory of instability threshold in materials with strength adequately predicted the onset of instability growth and is also in good agreement with 2D calculations. When internal stress substantially exceeded the yield strength of the material, fluid like growth rates were observed as predicted by analytic theory. In general, for high conductivity and soft materials, theory and simulation adequately predicted the behavior of classic magneto-RT modes. This is the first direct verification of the growth of magneto RT in solids with strength known to the authors.

The imploding liner is a cylinder of conducting material through which a current is passed in the longitudinal direction. Interaction of the current with its own magnetic field causes the liner to implode. In August, 1996, a high energy liner experiment (HEL-1) was conducted at the All-Russia Scientific Research Institute (VNIIEF) in Sarov, Russia. A 5 tier 1 meter diameter explosive disk generator provided electrical energy to drive a 48 cm outside diameter, 4 mm thick, aluminum alloy liner having a mass of about 1 kg onto an 11 cm diameter diagnostic package. The purpose of the experiment was to measure performance of the explosive pulse power generator and the heavy imploding liner. Electrical performance diagnostics included inductive (B-dot) probes, Faraday rotation current measurement, Rogowski total current measurement, and voltage probes, flux loss and conductor motion diagnostics included current-joint voltage measurements and motion sensing contact pins. Optical and electrical impact pins, inductive (B-dot) probes, manganin pressure probes, and continuously recording resistance probes in the central measuring unit (CMU) and piezo and manganin pressure probes, optical beam breakers, and inductive probes located in the glide planes were used as liner symmetry and velocity diagnostics. Preliminary analysis of the data indicate that a peak current of more than 100 MA was attained and the liner velocity was between 6.7 km/sec and 7.5 km/sec. Liner kinetic energy was between 22 MJ and 35 MJ.

The paper describes arrangement and the results of the first joint experiment between VNIIEF and LANL with explosive magnetic generators (EMG) of 1 m diameter and a nonevaporating liner. The experiment took place in August 22, 1996. The goal of the experiment was to accelerate magnetically cylindrical relatively thin aluminum liner and to get kinetic energy of 20 MJ or more. As the energy source for the experimental device we chose 5-module DEMG of 1000 mm diameter, tested many times in the experiments for rigid and liner loads. This EMG can store more energy than any other EMG created at VNIIEF. The physical scene of the liner unit was chosen so that the growth of disturbances would have less influence on the liner shape during flight, especially on the liner's inner surface. The shape of glade plane on which the liner slides during flight and the way of contact liner with walls were chosen on the grounds of 2-D calculations, proceeding from the necessity to ensure electrical contact during the liner flight.

In August 1997, the Los Alamos National Laboratory (LANL) and the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) conducted a joint experiment in Sarov, Russia to demonstrate the feasibility of applying explosive pulsed power technology to implode large scale, high velocity cylindrical liners. Kilogram mass metal liners imploding at velocities of 5-25 km/sec are useful scientific tools for producing high energy density environments, ultra-high pressure shocks and for the rapid compression of plasmas. To explore the issues associated with the design, operation and diagnosis of such implosions, VNIIEF and LANL designed and executed a practical demonstration experiment in which a liner of approximately 1 kg mass was accelerated to 5-10 km/sec while undergoing a convergence of about 4:1. The scientific objectives of the experiment were three-fold: first to explore the limits of very large, explosive, pulse power systems delivering about 100 MA as drivers for accelerating solid density imploding liners to kinetic energies of 25 MJ or greater; second to evaluate the behavior of single material (aluminum) liners imploding at 5-10 km/s velocities by comparing experimental data with 1-D and 2 D numerical simulations; and third, to evaluate the condition of the selected liner at radial convergence of 4 and a final radius of 6 cm. A liner of such parameters could be used as a driver for the equation of state measurements at megabar pressures or as a driver for a future experiment in which a magnetized fusion plasma would be compressed to approach ignition conditions.

The paper presents the experimental data analysis of a high-power disk explosive magnetic generator (DEMG) aimed to study the acceleration process and motion stability of bulk condensed liners with the multimegajoule range of the kinetic energy. Five module disk explosive magnetic generator (DEMG), having a diameter of disk elements of 100 cm, powering a quasistationary inductive load with an initial inductance 2.2 nH, was studied. With the initial powering current 9 MA the expected current of the amplitude 170 MA with the maximum current derivative value 15 MA//spl mu/sec was reached in the load. The paper provides the information that with the powering current achieved, the DEMG experimental parameters agree well with the calculated values.

The increase of explosive magnetic generator power may be achieved by selecting construction of foil opening switch (FOS), having extended break surface. In this work, the results of FOS models tests are presented, which were powered from a capacitor bank with the energy of 225 kJ and output voltage of 100 kV. The time (T/4) of opening switch powering was 4 /spl mu/sec. In inductive load L=0.9*10/sup -6/ H connected through a spark gap parallel to the opening switch, the impulse of current derivative with amplitude of /spl sim/0.6 10/sup 9/ A/sec was received. Amplitude of voltage pulse on the FOS model was 550 kV, pulse duration at semiheight was /spl sim/0.5 /spl mu/sec. Electric strength to electroexplosion products of copper foil was 9.2 kV/cm. Empirical dependence of copper specific resistance upon the specific energy is experimentally obtained and it may be used for engineer computations for estimation and prediction of copper conductors electroexplosion processes. FOS models tests results demonstrated principal possibility of current opening switch construction, which is able to operate with EMG at stored energy of more than 90 MJ and intended for obtaining powers more than 2/spl middot/10/sup 13/ W.

Relatively soft X-rays (quantum energy about 0.3 keV) may be produced by acceleration of a plasma liner up to a velocity of /spl sim/300 km/s followed by stagnation in a pinch. This means that if the plasma acceleration distance is several cm, the time of plasma motion must be about 0.1 of a microsecond. This results in a difficulty, associated with the problem of plasma stability and the liner having very small thickness and very small tolerance on initial thickness and density. Besides, quick energy input into the load requires complicated fast opening switches, which need to be experimentally tested. For experiments with explosive magnetic generators (EMG) it is reasonable to develop simpler systems to reach mass velocities about 300 km/sec. The work by A.M Buyko et al. (1995) theoretically considers one of these systems, where a liner mass during its magnetic deceleration significantly decreases and the velocity increases, i.e., a variable mass liner (VML). The same work suggests two experimental designs to test a new concept: full-scale experiment, including X-rays generation and a model experiment, including testing of the initial stage of VML formation (v

A joint US/Russian Advanced Liner Technology experiment ALT-1 was conducted to simulate the anticipated performance of the Atlas capacitor bank. A disk-explosive magnetic generator and foil opening switch were used to produce an electrical current waveform that reached a peak value of 32.5 MA and that imploded an aluminum liner to an inner surface velocity of 12 km/s.

Summary form only given, as follows. The Pegasus-2 liner implosion experiment (RUS 5) has been conducted, in which perturbation growths for two perturbation types were compared. On one half (over height) of a cylindrical liner azimuthally symmetric perturbations were made. On the other half of the liner the perturbations were of the same wavelength and amplitude, but the angle between the wave vector and the cylinder axis was 45 degrees (helical perturbations). The experimental radiographs show that there is essentially no helical perturbation growth, while the azimuthally symmetric perturbations grow by many times. This result agrees with the theoretical prediction.

Summary form only given, as follows. The paper presents the results of the Russian-American experiment (ALT-1) on simulation of the ATLAS capacitor bank energy parameters in the liner load. The capacitor bank ATLAS is being constructed in USA for high energy density physics research (A New Energy Density Physics Research Facility: ATLAS). The experiment was conducted at VNIIEF in November 1999. The experimental device consisted of helical and disk explosive magnetic generators (EMG), of electrically exploded foil opening switch (FOS) and of the liner load connected to FOS with the help of exploded closing switch. The initial parameters of the liner made of technically pure aluminum were: outer radius 40 mm, operating height -/spl sim/40 mm, thickness -2 mm. In the experiment the liner was driven by the pulse of current with the amplitude 31.5 MA with a total risetime of /spl sim/4 ms. 50-gram liner' velocity, measured by the laser interferometer VISAR, was * 10 km/s. The paper gives as well some other characteristics obtained in the experiment for the pulsed power system and for the load. This paper describes the results of the theoretical-computational research, which was the basis for selection of the main parameters of the experimental device. Basic computational and, experimental data comparison was performed.

Summary form only given. One of the most effective ways to get the high energy densities state of a substance (pressure and temperature) is a fast compression of cylindrical Al-liners by an ultra-high magnetic field, used for compression of the materials being studied. VNIIEF has developed a disk explosive magnetic generator (DEMG) with a fast electrical way of energy delivery to the load with an imploding liner, that permits to shape in this load the pulses of current with the amplitude from 30 to 35 MA and with a regulated rise time from 1.5 to 4 microsec. The axial and radial radiography of the compressed liner is the most informative technique, studying the dynamic characteristics of the liner (velocity, symmetry, instabilities amplitude, etc). The difficulty in using the radiography in the DEMG experiments is connected with a big amount (/spl sim/100 kg) of HE in the generator and with, a high magnetic field in a transmission line from DEMG to the load. This magnetic field accelerates the fragments of a reverse conductor above the liner up to high velocities. The protection system is described, that permits to protect the X-ray film cassettes both from the shock waves effect and from the transmission line conductors fragments. The film protection is ensured by means of fast-operation explosive shutters, the elements of passive protection, and also it is ensured by the use of a capsule of a special shape with the X-ray film placed inside of it. This allows providing a free flight of the capsule out of the explosion zone without any damage to the film.

Damage initiation and evolution, failure, and recollection processes under axisymmetric convergence were studied in the Russian-Damage experimental series, a joint effort between the Los Alamos National Laboratory and the All-Russian Institute of Experimental Physics. A helical explosive magnetic generator was used to drive a cylindrical liner shell to produce shock wave loading of a concentric cylindrical target shell. Shock wave amplitude was controlled by the liner-to-target spacing and by the magnetic field amplitude. Variation of the current pulse duration produced either a single impact, to study damage initiation through failure, or a double impact, to study failure with recollection. Both full and partial recollection of the main crack was obtained. By fielding high-precision diagnostics to measure the dynamic drive conditions and material response and by employing post-shot metallographic analysis, this project produced well-characterized experimental data across a range of damage and recollection levels for the chosen material, aluminum. We present selected experimental results to illustrate the methodology and utility of this experimental technique.

A systematic outline of the theory of the pair meter — a method of measuring the muon energy via multiple production of electron-positron pairs in thick layers of matter — is given. Possible variants of the technique of derivation of the muon energy in the pair meter are considered in unified terms on the basis of the maximum likelihood method. Analytical expressions for the energy measurement error have been obtained. An asymptotic limit of the measurement error at high energies has been found. The important role of the background process — the inelastic interaction of muons with nuclei — is elucidated. The problem of optimization of the pair meter for measuring the spectrum of cosmic ray muons is formulated and solved. The results of numerical simulation for the real pair meter are compared with the experimental data of the pair meter of the MUTRON arrangement. The pair meter technique can be used for the spectrometry of muons in the energy region ≳10 12 eV in new experimental arrangements.