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We have continued our studies of heavy ion projectile fragmentation using nuclear track detectors. Based on automatic track measurement it was possible to perform experiments with high statistical significance. Beams of different ions from the Berkeley BEVALAC, the Dubna Synchrophasotron, the Brookhaven AGS and the GSI Darmstadt SIS have been used. With CR-39 and BP-1 glass detectors we have studied the process of electromagnetic dissociation, we investigated multifragmentation and continued the search for quark nuclear complexes. This paper gives an overview of these experiments. Details of the experimental technique are discussed.

The single event upset (SEU) imaging has been applied at the GSI heavy ion microprobe to determine the sensitivity of integrated circuits (IC) to heavy ion irradiation. This method offers the possibility to directly image those parts of an IC which are sensitive to ion-induced malfunctions. By a 3-dimensional simulation of charge collection across p-n-micro-junctions, we can predict SEU cross-sections. For a MHS65162 2k x 8bit CMOS SRAM we found two regions per bit with different sensitivity and measured a total cross-section of (71/spl plusmn/18) /spl mu/m/sup 2/ for a bitflip per cell and simulated 60 /spl mu/m/sup 2/ with an argon beam of 1.4 MeV/nucl. (LET of 19.7 MeV/(mg/cm/sup 2/)). >

Using 1 GeV/nucleon ions SEUs have been studied in two types of CMOS-SRAMs with respect to tilt angle and tilt direction. Tracks of upset bits, which have been observed under large tilt angles, were used to determine the charge collection depth in these devices. >

We have investigated the fragmentation of $^{197}\mathrm{Au}$ projectiles at 0.85 to 1 GeV/nucleon in collisions with targets (${\mathrm{CH}}_{2}$${)}_{\mathit{n}}$, C, and Pb. Using plastic nuclear track detectors all projectile fragments with charge 6\ensuremath{\le}${\mathit{Z}}_{\mathit{F}}$\ensuremath{\le}77 produced in a collision were observed in coincidence. The combination of C and (${\mathrm{CH}}_{2}$${)}_{\mathit{n}}$ data allows us to extract the hydrogen component in measured distributions by the use of the statistical subtraction method. Our data show a target dependence of the multifragmentation process which indicates a nonequilibrated source of the fragments and/or the influence of the target nucleus on the relation between size and excitation energy of the spectator. In comparison to the prediction of the statistical model, the transverse momentum dispersions are enhanced with a dominant contribution by Coulomb repulsion between the fragments. Based on the sum of transverse momentum vectors of all fragments we conclude that multifragmentation is observed in collisions with a large momentum and energy transfer to the prefragment. Correlations in the azimuthal emission angles of the fragments are caused by mutual repulsion and momentum conservation. The idea that a liquid-gas phase transition of nuclear matter is the origin of multifragmentation is supported by our observations.

We exposed stacks containing plastic nuclear track detectors and different target materials to heavy ions at the Berkeley BEVALAC. Interactions of the beam particles with Ag and C target nuclei and with the constituents of our detector material CR-39 (C 12 H 18 O 7 ) were studied in detail. For each interaction vertex all projectile fragments with charge Z-6 were measured and their emission angles were determined. Charge yields, transverse momenta, correlations in charge and angle are studied separately for different multiplicities M of observed fragments. We present results of experiments with 980 MeV/nucleon Au projectiles on a Ag/CR-39 target, 1050 MeV/nucleon Au projectiles on a C target and with 920 MeV/nucleon U projectiles on a Ag/CR-39 target.

We analyze the largest set of fragment coincidence data at present available, that of the preceding paper. This set contains all projectile fragments 6\ensuremath{\le}Z\ensuremath{\le}65 produced in 6610 events of Au+Ag and Au+CR-39. We introduce a classification scheme based on the number of heavy fragments in order to define multifragmentation, spallation, and fission events. The multiplicity distribution P(${\mathit{m}}_{\mathit{Z}}$) is Poissonian, and the mean multiplicity as a function of Z can be described either by a power law or by an exponential. The slopes are independent of the projectile energy but depend on the target. While all investigated observables indicate that the multifragmentation in the case of a Ag target is a statistical process, we observe angular correlations in the case of the CR-39 target which indicate that probably the geometry and not the excitation energy is essential. Charge correlations are strong and only partially understood as yet. We find no positive sign for a liquid gas phase transition.

We started a research program using heavy ion beams at the GSI Darmstadt accelerator to investigate radiation effects of heavy ions in microelectronic devices. The understanding of these radiation effects is of particular importance to estimate the radiation rise for microelectronic parts exposed to the cosmic radiation during space missions. In order to expose static RAM devices to heavy ion beams a test system was installed. Additionally we use CCD image sensors to measure the amount of charge deposited inside the sensitive volume of single picture elements. Measurements will be performed with ions of different charge and energy up to 1 GeV/N to investigate the LET dependence of the effects and possible influence of the track structure. The experimental setup is described in this paper and first results are presented.

The authors started a research program using heavy ion beams to investigate radiation effects on microelectronic devices. In order to expose static random access memory (SRAM) devices to heavy ions a test system was installed. This setup was first operated using different ions at the GSI UNILAC with energies below 20 MeV/nucleon. After these first tests further measurements were performed with ions of different charge and energy up to 1 GeV/nucleon at the GSI-SIS. As ions with energies of some hundred MeV/nucleon are a good representation of space conditions such beams are interesting for reliability tests of microelectronic space equipment. The experimental setup and the exposure conditions at GSI are described and first results are presented. >

In reply to the Comment of Morrissey we present the standard deviations [sigma] of distributions of transverse momentum components under the assumption that the ratios [ital A]/[ital Z] of fragments are determined by the parametrization of Suemmerer [ital et] [ital al]. These results do not change in comparison to those derived with a ratio [ital A]/[ital Z] equal to that of the projectile as presented by Dreute [ital et] [ital al].

A stack containing plastic nuclear track detectors and Ag target foils was exposed to a {sup 197}Au beam with an energy of 980 MeV/nucleon. The analysis was restricted to energies between beam energy and 200 MeV/nucleon. 2496 collisions with Ag target nuclei and 4114 with the lighter constituents H, C, and O of the detector material were analyzed in detail. For all interactions, projectile fragments with charge {ital Z}{sub {ital F}}{ge}6 were measured and their emission angles were determined. This paper describes the experiment and presents charge yields and results about transverse momenta for events with different multiplicities. Details of multiplicity distributions, correlations between fragments and signatures related to multifragmentation as a critical process are discussed in a separate paper.

We performed an experiment to investigate the anomalous mean-free-path phenomenon for projectile fragments of /sup 56/Fe. 1846 charge-changing collisions of fragments with charges Z = 20--25 were analyzed with plastic nuclear track detectors. We observed no evidence for anomalous fragments.

We developed a completely automatic scanning and measuring system for nuclear track detectors. The video pictures of particle tracks seen through a microscope are digitized and analyzed in real time by MC 68000 microprocessors. In this paper we present some new developments: The picture analysis software is extended to separate overlapping tracks and to measure elliptical tracks even if these are flawed by surface structures. A software autofocus, a faster hardware version based on the contrast and a modified commercial laser autofocus are now available. A new picture analysis system based on the faster 32-bit microprocessor MC 68020 will operate on two pictures of 1024 × 1024 pixels resident in memory together. This will allow three dimensional track measurements.

Enlarged cross sections for projectile fragments of relativistic nuclei have been observed in Bevalac and cosmic ray experiments with nuclear emulsions. We performed an experiment using plastic track detectors to investigate the anomalon effect. A new automatic measuring technique for heavy ion tracks in plastic detectors enables us to analyze large numbers of fragmentation reactions in reasonable time. Thus we get better statistical significance. Results of the experiment are presented.

This paper describes an experiment measuring the interaction mean free paths for charge changing nuclear collisions of relativistic heavy ion fragments. We use a stack of CR39 plastic nuclear track detectors that was irradiated with 1.8 GeV/nucleon 40 Ar ions at the Berkeley Bevalac. About 1.5 × 10 7 etch cones were measured in this experiment using an automatic measuring system. By tracing the etch cones over successive plastic foils the particle trajectories in the stack were reconstructed. For 14185 trajectories with 6444 nuclear collisions of fragments with charge 9–15 the interaction mean free path in the plastic was determined.

A number of experiments have shown that enhanced cross sections exist for projectile fragments which are emitted in relativistic heavy ion collisions. The present status of these investigations is reviewed. An experiment is described in which this effect is measured with significantly better statistics. First results for fragments of charge 14 emerging from 1.8 MeV/nucleon 40 Ar projectiles are presented.

The experimental technique of computerized track measurements for plastic nuclear track detectors was used in different experiments investigating interactions of relativistic heavy ions. In this paper the method is described, results are presented and discussed. To measure cross sections stacks were exposed at the BEVALAC, at Brookhaven and at CERN to different beam nuclei having energies from 0.6 GeV/nucleon up to 200 GeV/nucleon. The cross sections for one nucleon removal are considerably enhanced at high energies due to electromagnetic dissociation. We investigated the effect of electromagnetic dissociation for different targets and projectiles. For heavy projectiles an exclusive analysis of nuclear fragmentation on an event by event basis was performed. Based on this the effect of multifragmentation can be studied. We exposed a stack of 100 CR39 foils to a 1 GeV/nucleon 197 Au beam at the BEVALAC. Events with up to 10 projectile fragments having a charge Z≥5 and coming out of the same interaction vertex were observed. To search for projectile fragments with fractional charge in relativistic heavy ion collisions, we exposed stacks of 50 CR39 foils behind a lead block of 15 cm depth to the ultrarelativistic heavy ion beams at Brookhaven and CERN. The charge resolution achieved in these experiments is o=0.027e.

In the last few years picture analysis methods have evolved into a powerful technique for measurements of nuclear tracks in plastic detectors. We have developed a microprocessor-based picture analysis system for automatic track measurements. The video pictures of particle tracks seen through a microscope are digitized in real time and the picture analysis is done by software. The microscope is equipped with a stage driven by stepping motors, which are controlled by a separate microprocessor. A PDP 11/23 supervises the operation of all microprocessors and stores the measured data on its mass storage devices. This paper describes the hard- and software of the system and the methods of picture analysis which are used for the track identification and measurement.

We performed an experiment using plastic nuclear track detectors to investigate the phenomenon of enlarged cross sections for projectile fragments of relativistic $^{40}\mathrm{Ar}$ nuclei. This effect had been observed within the first few centimeters after fragment emission in Bevalac and cosmic-ray experiments with nuclear emulsion. On the basis of 6444 charge-changing nuclear collisions we conclude that under our experimental conditions no statistically significant anomalous mean free path effect can be observed.

We exposed a stack of CR39 track detectors containing Ag foils to a 1.7-GeV/nucleon 56Fe beam and investigated the anomalous mean-free-path effect. Neither the whole set of 7517 nor a subset of 2542 interacting fragments produced probably in the Ag target show an effect. By combining the data of this and an earlier experiment we can also exclude an effect for 3219 interacting fragments produced in delta Z = 1 collisions.

We exposed a stack of CR39 track detectors containing Ag foils to a 1.7-GeV/nucleon 56Fe beam and investigated the anomalous mean-free-path effect. Neither the whole set of 7517 nor a subset of 2542 interacting fragments produced probably in the Ag target show an effect. By combining the data of this and an earlier experiment we can also exclude an effect for 3219 interacting fragments produced in delta Z = 1 collisions.

A computer controlled automatic system for scanning and measuring tracks of heavy nuclei in plastic detectors, which works by means of digital picture analysis, is presented. The picture seen by a video camera through a microscope is digitized in real time and stored into computer memory. The picture analysis is done by software running on a 16-bit microprocessor. This automatic system analyzes up to 30000 particle tracks per hour. Results of the automatic measurements of particle tracks in CR 39 are presented.