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We report improved measurements of elemental abundances and spectra for galactic cosmic-ray (GCR) nuclei obtained by the Cosmic Ray Isotope Spectrometer on board NASA's Advanced Composition Explorer (ACE) spacecraft during the minimum and maximum phases of solar cycle 23. We discuss results for particles with nuclear charge 5 ≤ Z ≤ 28 and typical energies between 50 and 500 MeV nucleon^(–1). We demonstrate that a detailed "leaky box" Galactic propagation model combined with a spherically symmetric solar modulation model gives a good (but not perfect) fit to the observed spectra by using a solar modulation parameter of φ = 325 MV at solar minimum and φ = 900 MV at solar maximum. Although our results are generally consistent with previous measurements from space-based and balloon-based missions, there are significant differences. The large geometrical acceptance and excellent charge resolution of the instrument result in the most detailed and statistically significant record of GCR composition to date in this energy range. The measurements reported here serve as a high-precision baseline for continued studies of GCR composition, solar modulation over the solar cycle, space radiation hazards, and other applications.

Background Schizophrenia is characterized by executive functioning deficits, presumably mediated by prefrontal cortex dysfunction. For example, schizophrenia participants show performance deficits on ocular motor delayed response (ODR) tasks, which require both inhibition and spatial working memory for correct performance. Methods The present functional magnetic resonance imaging (fMRI) study compared neural activity of 14 schizophrenia and 14 normal participants while they performed ODR tasks. Results Schizophrenia participants generated: 1) more trials with anticipatory saccades (saccades made during the delay period), 2) memory saccades with longer latencies, and 3) memory saccades of decreased accuracy. Increased blood oxygenation level-dependent (BOLD) signal changes were observed in both groups in ocular motor circuitry (e.g., supplementary eye fields [SEF], lateral frontal eye fields [FEF], inferior parietal lobule [IPL], cuneus, and precuneus). The normal, but not the schizophrenia, group demonstrated BOLD signal changes in dorsolateral prefrontal regions (right Brodmann area [BA] 9 and bilateral BA 10), medial FEF, insula, thalamus, and basal ganglia. Correlations between percentage of anticipatory saccade trials and BOLD signal changes were more similar between groups for subcortical regions and less similar for cortical regions. Conclusions These results suggest that executive functioning deficits in schizophrenia may be associated with dysfunction of the basal ganglia-thalamocortical circuitry, evidenced by decreased prefrontal cortex, basal ganglia, and thalamus activity in the schizophrenia group during ODR task performance.

Previous research has demonstrated the ability of diffuse red light to suppress activity in the magnocellular (M) visual pathway. An earlier psychophysical study found that a subset of nonpsychotic relatives of persons with schizophrenia showed the opposite effect when compared to healthy adults (Bedwell et al., 2003), suggesting a novel biobehavioral marker for the disorder. The present study attempted to replicate and explore the mechanism for this effect using fMRI. Results provide physiological evidence that the M pathway response to red light is in the opposite direction than expected in a subset of nonpsychotic relatives of persons with schizophrenia.

We report on abundance measurements of ^(10)Be, ^(26)Al, ^(36)Cl, and ^(54)Mn in the Galactic cosmic rays (GCRs) using the Cosmic-Ray Isotope Spectrometer (CRIS) instrument aboard the Advanced Composition Explorer spacecraft at energies from ~70 to ~400 MeV nucleon^(-1). We also report an upper limit on the abundance of GCR ^(14)C. The high statistical significance of these measurements allows the energy dependence of their relative abundances to be studied. A steady-state, leaky-box propagation model, incorporating observations of the local interstellar medium (ISM) composition and density and recent partial fragmentation cross section measurements, is used to interpret these abundances. Using this model, the individual galactic confinement times derived using data for each species are consistent with a unique confinement time value of τ_(esc) = 15.0 ± 1.6 Myr. The CRIS abundance measurements are consistent with propagation through an average ISM hydrogen number density n_H = 0.34 ± 0.04 H atoms cm^(-3). The surviving fractions, f, for each radioactive species have been calculated. From predictions of the diffusion models of Ptuskin & Soutoul, the values of f indicate an interstellar cosmic-ray diffusion coefficient of D = (3.5 ± 2.0) × 10^(28) cm^2 s^(-1).

We present measurements of neon isotopic abundances from the ACE-CRIS experiment. These abundances have been obtained in seven energy intervals over the energy range of ∼80≤E≤280 MeV/nucleon. We find that the ^(22)Ne/^(20)Ne abundance ratio at the cosmic-ray source is a factor of 5.0±0.2 greater than for the solar wind. These measured abundances agree well with previous experiments. The significance of these results is discussed.

Radionuclides in the galactic cosmic rays serve as chronometers for measuring the characteristic time of physical processes affecting cosmic ray energy spectra and composition. The radionuclide ^(59)Ni, present in the ejecta of supernovae, will decay to ^(59)Co via electron-capture with a halflife of T_(1/2) = 7.6 × 10^4 yr. However, if the cosmic ray acceleration time scale is shorter than the decay halflife, ^(59)Ni will become fully-stripped of electrons and will be present in the cosmic rays. Abundances of cosmic ray ^(59)Ni and ^(59)Co measured with the Cosmic Ray Isotope Spectrometer (CRIS) are consistent with the decay of all source ^(59)Ni, implying an acceleration time delay > 10^5 yr. Abundances of the β-decay radioactive secondaries, produced by fragmentation of the cosmic rays during transport in the interstellar medium (ISM), depend on the time scales for spallation and escape from the Galaxy. Consequently, measurement of these abundances can be used to derive the galactic confinement time, τ_(esc), for cosmic rays. Using the abundances of the β-decay species ^(10)Be, ^(26)Al, ^(36)Cl, and ^(54)Mn measured by CRIS, we find a confinement time τ_(esc) ∼ 15 Myr.

The isotopic composition of cosmic-ray Fe, Co, and Ni at energies ∼150–500 MeV/nucleon has been measured with the Cosmic-Ray Isotope Spectrometer (CRIS) instrument on ACE. Source abundances have been derived from a leaky-box propagation model using secondary species in the range 41 ≤ A ≤ 55 to constrain the calculated secondary contributions to the Fe, Co, and Ni isotopes. The derived relative source abundances bear a strong resemblance to solar-system values. The most significant difference, an excess of ∼ (70 ± 30)%, is found for the source abundance ratio ^(58)Fe/^(56)Fe. Some implications of the derived source composition for the origin of cosmic rays are discussed.

Studies of the galactic cosmic-ray source composition reveal a pattern in the elemental abundances that may be controlled by the first ionization potential (FIP) or a closely correlated parameter, the condensation temperature (volatility). Determining the true parameter is key identifying the galactic cosmic-ray source (GCRS) material. Using data from the CRIS instrument onboard the ACE spacecraft, we examine five elements that are more volatile than other elements of similar FIP. Three of these (Na, Cu, Ge) show small deficits in their source abundances that may suggest a volatility-dependent fractionation. The source abundances of Ga and Zn (an intermediate FIP element) are consistent with either model. Possible systematic uncertainties from the cosmic-ray pathlength estimate as well as effects due to the instrumental acceptance are discussed. We also compare the GCRS composition to that observed in solar energetic particles.

Measurements of the abundances of cosmic-ray ^(59)Ni and ^(59)Co are reported from the Cosmic-Ray Isotope Spectrometer (CRIS) on the Advanced Composition Explorer. These nuclides form a parent-daughter pair in a radioactive decay which can occur only by electron capture. This decay cannot occur once the nuclei are accelerated to high energies and stripped of their electrons. The CRIS data indicate that the decay of ^(59)Ni to ^(59)Co has occurred, leading to the conclusion that a time longer than the 7.6 × 10^4 yr half-life of ^(59)Ni elapsed before the particles were accelerated. Such long delays indicate the acceleration of old, stellar or interstellar material rather than fresh supernova ejecta. For cosmic-ray source material to have the composition of supernova ejecta would require that these ejecta not undergo significant mixing with normal interstellar gas before ~10^5 yr has elapsed.

Ionic manganese in divalent form (Mn2+) is a particularly useful contrast agent known for its sensitivity as well as its function as a calcium (Ca2+) analog in magnetic resonance imaging. Consequently, the use of Mn2+ in imaging studies has increased dramatically as molecular medicine incorporates clinical imaging techniques. Both the physical and chemical characteristics of Mn2+ are reviewed in Chapter XXXXX.

Although diffusion tensor imaging (DTI) shows great potential for the diagnosis of a variety of pathologies, no consensus for an appropriate assessment standard of DTI exists. This study examined the feasibility of using water-filled arrays of glass capillaries to construct a DTI phantom suitable for making repeated and reproducible measurements required in a quality assessment program. Three phantoms were constructed using arrays of capillaries with three inner diameters (23, 48, and 82 microm). Data were acquired using DTI protocols; the fractional anisotropy (FA), mean apparent diffusion coefficient (ADC) and principal eigenvectors of the diffusion tensors were calculated. This study demonstrated four results: (1) echo-planar images show that susceptibility within the capillary arrays does not lead to substantial differences in precessional frequency in regions containing the arrays and neither do the regions show noticeable image distortion; (2) principal eigenvectors of the diffusion tensors agree to within

The abundance of Li, Be, and B isotopes in galactic cosmic rays (GCR) between E=50-200 MeV/nucleon has been observed by the Cosmic Ray Isotope Spectrometer (CRIS) on NASA's ACE mission since 1997 with high statistical accuracy. Precise observations of Li, Be, B can be used to constrain GCR propagation models. \iffalse Precise observations of Li, Be, and B in addition to well-measured production cross-sections are used to further constrain GCR propagation models. \fi We find that a diffusive reacceleration model with parameters that best match CRIS results (e.g. B/C, Li/C, etc) are also consistent with other GCR observations. A $\sim$15--20% overproduction of Li and Be in the model predictions is attributed to uncertainties in the production cross-section data. The latter becomes a significant limitation to the study of rare GCR species that are generated predominantly via spallation., Comment: 9 pages of TeX format with three figures. Accepted for publication to Advances in Space Research (Elsevier)

The radiation dose from galactic cosmic rays during a manned mission to Mars is expected to be comparable to the allowable limit for space shuttle astronauts. Most of this dose would be due to galactic cosmic rays with energies < 1 GeV nucleon^(−1), with important contributions from heavy nuclei in spite of their low abundance relative to H and He. Using instruments on NASA's Advanced Composition Explorer (ACE) spacecraft, we have made the most statistically precise measurements to date of the solar minimum energy spectra of cosmic ray nuclei with charge Z = 4–28 in the energy range ∼ 40–500 MeV nucleon^(−1). We compare these measurements obtained during the 1997–1998 solar minimum period with measurements from previous solar minima and with models of the near-Earth radiation environment currently used to perform shielding and dose calculations. We find that the cosmic ray heavy-element spectra measured by ACE are as much as 20% higher than previously published solar minimum measurements. We also find significant differences between the ACE measurements and the predictions of available models of the near-Earth radiation environment, suggesting that these models need revision. We describe a cosmic ray interstellar propagation and solar modulation model that provides an improved fit to the ACE measurements compared to radiation environment models currently in use.

Understanding the evolution of the universe from Big Bang to its present state requires an understanding of the evolution of the abundances of the elements and isotopes in galaxies, stars, the interstellar medium, the Sun and the heliosphere, planets and meteorites. Processes that change the state of the universe include Big Bang nucleosynthesis, star formation and stellar nucleosynthesis, galactic chemical evolution, propagation of cosmic rays, spallation, ionization and particle transport of interstellar material, formation of the solar system, solar wind emission and its fractionation (FIP/FIT effect), mixing processes in stellar interiors, condensation of material and subsequent geochemical fractionation. Here, we attempt to compile some major issues in cosmochemistry that can be addressed with a better knowledge of the respective element or isotope abundances. Present and future missions such as Genesis, Stardust, Interstellar Pathfinder, and Interstellar Probe, improvements of remote sensing instrumentation and experiments on extraterrestrial material such as meteorites, presolar grains, and lunar or returned planetary or cometary samples will result in an improved database of elemental and isotopic abundances. This includes the primordial abundances of D, ^3He, ^4He, and ^7Li, abundances of the heavier elements in stars and galaxies, the composition of the interstellar medium, solar wind and comets as well as the (highly) volatile elements in the solar system such as helium, nitrogen, oxygen or xenon.

Measurements of the neon isotopic abundances from the ACE-CRIS experiment are presented. These abundances have been obtained in seven energy intervals over the energy range of ~80≤E≤280 MeV/nucleon. The ^(22)Ne/^(20)Ne source ratio is derived using the measured ^(21)Ne/^(20)Ne abundance as a "tracer" of secondary production of the neon isotopes. We find that the ^(22)Ne/^(20)Ne abundance ratio at the cosmic-ray source is a factor of 5.0±0.2 greater than in the solar wind. The GCR ^(22)Ne/^(20)Ne ratio is also shown to be considerably larger than that found in anomalous cosmic rays, solar energetic particles, most meteoritic samples of matter, and interplanetary dust particles. Recent two-component Wolf-Rayet models provide predictions for the ^(22)Ne/^(20)Ne ratio and other isotope ratios. Comparison of the CRIS neon, iron, and nickel isotopic source abundance ratios with predictions indicate possible enhanced abundances of some neutron-rich nuclides that are expected to accompany the ^(22)Ne excess.

Abundances of the isotopes of the refractory elements Ca, Fe, Co, and Ni in the galactic cosmic-ray source are compared with corresponding abundances in solar-system matter. For the 12 nuclides considered, relative abundances agree to within a factor of 2, and typically within 20–30%. In addition, comparisons of cosmic-ray abundances with model calculations of supernova yields are used to argue that cosmic rays contain contributions from stars with a broad range of masses. Based on these and other results we suggest that cosmic rays probably represent a sample of contemporary interstellar matter, at least for refractory species.

Galactic cosmic-ray (GCR) elemental abundances display a fractionation compared to solar-system values that appears ordered by atomic properties such as the first ionization potential (FIP) or condensation temperature (volatility). Determining which parameter controls the observed fractionation is crucial to distinguish between GCR origin models. The Cosmic-Ray Isotope Spectrometer (CRIS) instrument on board NASA’s Advanced Composition Explorer (ACE) spacecraft can measure the abundances of several elements that break the general correlation between FIP and volatility (e.g., Na, P, K, Cu, Zn, Ga, and Ge). Phosphorus is a particularly interesting case as it is a refractory (high condensation temperature) element with a FIP value nearly identical to that of its semi-volatile neighbor, sulfur. Using a leaky-box galactic propagation model we find that the P/S and Na/Mg ratios in the GCR source favor volatility as the controlling parameter.

Inelastic collisions between the galactic cosmic rays (GCRs) and the interstellar medium (ISM) are responsible for producing essentially all of the light elements Li, Be, and B (LiBeB) observed in the cosmic rays. Previous calculations (e.g., [1]) have shown that GCR fragmentation can explain the bulk of the existing LiBeB abundance in the present day Galaxy. However, elemental abundances of LiBeB in old halo stars indicate inconsistencies with this explanation. We have used a simple leaky-box model to predict the cosmic-ray elemental and isotopic abundances of LiBeB in the present epoch. We conducted a survey of recent scientific literature on fragmentation cross sections and have calculated the amount of uncertainty they introduce into our model. The predicted particle intensities of this model were compared with high energy (E_(ISM) = 200–500 MeV/nucleon) cosmic-ray data from the Cosmic Ray Isotope Spectrometer (CRIS), which indicates fairly good agreement with absolute fluxes for Z ≥ 5 and relative isotopic abundances for all LiBeB species.

The isotopes of lithium, beryllium, and boron (LiBeB) are known in nature to be produced primarily by CNO spallation and α-α fusion from interactions between cosmic rays and interstellar nuclei. While the dominant source of LiBeB isotopes in the present epoch is cosmic-ray interactions, other sources are known to exist, including the production of ^(7)Li from big bang nucleosynthesis. Precise observations of galactic cosmic-ray LiBeB in addition to accurate modeling of cosmic-ray transport can help to constrain the relative importance among the different production mechanisms. The Cosmic Ray Isotope Spectrometer (CRIS) on the Advanced Composition Explorer (ACE) has measured nuclei with 2 ≲ Z ≲ 30 in the energy range ~30–500 MeV/nucleon since 1997 with good statistical accuracy. We present measurements of the isotopic abundances of LiBeB and discuss these observations in the context of previous cosmic-ray measurements and spectroscopic observations.

Cosmic-ray isotope observations from NASA’s Advanced Composition Explorer (ACE) mission have been used to investigate the composition of cosmic-ray source material. Source abundances relative to 56Fe are reported for eleven isotopes of Ca, Fe, Co, and Ni, including the very rare isotopes 48Ca and 64Ni. Although the source abundances range over a factor ~ 104, most of the ratios to 56Fe are consistent with solar-system values to within ~ 20%. However, there are some notable differences, the most significant being an excess of ~ (70 ± 30)% relative to the solar system for the cosmic-ray source ratio 58Fe/56Fe. The possible association of such an excess with a contribution to the cosmic-ray source from Wolf—Rayet star ejecta is discussed.

Measurements of neon isotopic abundances from the ACE-CRIS experiment are presented. Abundances have been obtained in six energy intervals over the energy range of ~100≤E≤280 MeV/nucleon. These measurements are compared with the ACE-SIS data for lower energies extending down to ~8 MeV/nucleon. We find that the CRIS ^(22)Ne/^(20)Ne abundance ratio at the source is a factor of 5.0±0.3 greater than for the solar wind. The CRIS measured abundances agree well with previous experiments. The CRIS and SIS measurements are in good agreement for the higher SIS energies. However for the lower energy SIS data, where the anomalous cosmic rays (ACR) are being sampled, the ratio decreases and agrees with solar wind abundances. The implications of these results are discussed.

Observations from the Cosmic Ray Isotope Spectrometer (CRIS) on ACE have been used to derive constraints on the locations, physical conditions, and time scales for cosmic-ray acceleration and transport. The isotopic composition of Fe, Co, and Ni is very similar to that of solar system material, indicating that cosmic rays contain contributions from supernovae of both Type II and Type Ia. The electron-capture primary ^(59)Ni produced in supernovae has decayed, demonstrating that a time ≳10^5 yr elapses before acceleration of the bulk of the cosmic rays and showing that most of the accelerated material is derived from old stellar or interstellar material rather than from fresh supernova ejecta.

Galactic cosmic rays (GCRs) pass through the interstellar medium (ISM) and undergo nuclear interactions that produce secondary fragments. The abundances of radioactive secondary species can be used to derive a galactic confinement time for cosmic rays using the amount of ISM material traversed by the cosmic rays inferred from stable GCR secondary abundances. Abundance measurements of long-lived species such as ^(10)Be, ^(26)Al, ^(36)Cl, and ^(54)Mn allow a comparison of propagation histories for different parent nuclei. Abundances for these species, measured in the energy range ~ 50 - 500 MeV/nuc using the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) spacecraft, indicate a confinement time τ(esc) 16.2±0.8 Myr. We have modeled the production and propagation of the radioactive secondaries and discuss the implications for GCR transport.

The galactic cosmic ray elemental source abundances display a fractionation that is possibly based on first ionization potential (FIP) or volatility. A few elements break the general correlation of FIP and volatility and the abundances of these may help to distinguish between models for the origin of the cosmic ray source material. Data from the Cosmic Ray Isotope Spectrometer instrument on NASA’s Advanced Composition Explorer spacecraft were used to derive source abundances for several of these elements (Na, Cu, Zn, Ga, Ge). Three (Na, Cu, Ge) show depletions which could be consistent with a volatility-based source fractionation model.

Galactic cosmic ray (GCR) secondary/primary ratios such as B/C and (Sc+Ti+V)/Fe are commonly used to determine the mean amount of interstellar material through which cosmic rays travel before escaping from the Galaxy (Λ_(esc)). These ratios are observed to be energy-dependent, with a relative maximum at ~1 GeV/nucleon, implying a corresponding peak in Λ_(esc). The decrease in Λ_(esc) at energies above 1 GeV/nucleon is commonly taken to indicate that higher energy cosmic rays escape more easily from the Galaxy. The decrease in Λ_(esc) at energies

We report the first observation of an energy dependence in the titanium, vanadium, and chromium isotopic abundances in cosmic rays. The observations were made in the 100–500 MeV/nucleon energy interval using data from the Cosmic Ray Isotope Spectrometer on the ACE spacecraft. The ^(51)Cr and ^(49)V isotopes in cosmic rays are produced by fragmentation of heavier cosmic ray nuclides and decay only by electron capture. The observations indicate that electron-capture decay occurred primarily at the lower energies measured, and that there is a resulting energy dependence in the abundances of these isotopes and their decay products.

Between the launch of the Advanced Composition Explorer (ACE) in 1997 and the end of 1999, the intensities of galactic cosmic rays at 1 AU have dropped almost a factor of 2, and the anomalous cosmic rays have decreased by an even larger amount. The large collecting power of the Cosmic Ray Isotope Spectrometer (CRIS) and the Solar Isotope Spectrometer (SIS) instruments on ACE allow us to investigate the changing modulation on short time scales and at different rigidities. Using anomalous cosmic ray (ACR) and galactic cosmic ray (OCR) intensities of He, C, O, Ne, Si, S, and Fe, and energies from ~ 6 MeV/nucleon to ~ 460 MeV/nucleon, we examine the differences between the short term and long term effects. We observe the expected correlation of these intensities with neutron monitor data, but see little correlation of OCR and ACR intensities with the locally measured magnetic field.

Physiological research with monkeys and psychophysical research with humans has demonstrated the ability of diffuse red light to suppress activity in the magnocellular (M) visual pathway. In contrast, a previous psychophysical study found that a subset of nonpsychotic relatives of persons with schizophrenia showed the opposite effect, suggesting a novel biobehavioral marker for the disorder. Other research suggests that persons with schizophrenia have a dysfunctional M pathway under neutral (non-red) light conditions. However, it does not appear that these findings have been explored with physiological methods in nonpsychotic relatives, which would provide support for genetic contributions. The current study used physiological methodology to explore whether, as a group: 1) healthy adults show suppression of the M pathway in response to diffuse red light; 2) nonpsychotic relatives of persons with schizophrenia have a dysfunctional M pathway under neutral light conditions; and 3) nonpsychotic relatives of persons with schizophrenia have a differential M pathway response to red light. Functional magnetic resonance imaging (fMRI) was used to investigate a group of 13 nonpsychotic relatives of persons with schizophrenia and 11 controls. Moving concentric rings were presented on both red and green backgrounds to stimulate the M pathway. The fMRI signal strength in bilateral cortical region V5 (MT) was measured as a marker of M pathway functioning. Statistically significant results were limited to measures of fMRI signal in right hemisphere V5 relative to signal from bilateral V5, and suggested that: 1) the control group had reduced M pathway activity in response to diffuse red light; 2) the relative group had a hypoactive M pathway; and 3) a subset of the relatives had the opposite M pathway response to diffuse red light. The differential M pathway response to red light in the relatives remained a statistical trend after controlling for M pathway signal from the neutral (green) background condition. Results provide preliminary evidence that genetic risk for schizophrenia is related to a hypoactive M pathway and an independent differential response (increase in activity) of the M pathway to red light. These features may be more evident in the right hemisphere when examining cortical region V5.

Purpose: The goal of this project is to demonstrate that usage of different gradient directions during the acquisition and reconstruction phases of a DTI scan can produce images exhibiting complex diffusioncharacteristics. In this manner, a simple anisotropic phantom (e.g., “hot dog” geometry) could be employed to infer the quality of data for more clinically‐realistic tissue structures (e.g., oblate, or “pancake” structures, and two prolate structures that intersect). Method and Materials: A water‐filled phantom containing glass capillary arrays was constructed. Three DTI series of images from a 3.0T GE HDx scanner were acquired by specifying sets of acquisition directions to produce synthetic oblate diffusion distributions and two diffusion distributions where prolate distributions intersect, using standard gradient directions for reconstruction. Acquisition directions were calculated so that diffusion was most restricted in the y‐direction. The three desired diffusion distributions were first simulated using MATLAB, and acquisition directions appropriate for each were computed. Eigenvalues,eigenvectors, and fractional anisotropy of the oblate tensor were calculated within an ROI. RMS differences between generated and measured ADCs were determined. Results: The simulated oblate data produced a tensor with reasonable symmetry in the x‐z plane, restricted in the y direction. Eigenvalue magnitudes were consistent with those measured for the capillary array, albeit with the values associated with different eigenvectors. ADC distributions for intersecting prolate distributions qualitatively resemble the simulated distributions, and quantitatively match the simulated distributions more closely than a spherical distribution. Conclusion: This work suggests that one could use simple phantoms to monitor scanner performance for measuring diffusion distributions with more similarity to tissue. Gradient duty cycle is similar to an ordinary diffusion protocol; the effect of noise, originating from sources other than the gradients, on complicated diffusion distributions could be characterized empirically.

Une connaissance precise de tous les noyaux produits par spallation est necessaire pour predire la radioactivite et les modifications chimiques induites dans une cible de spallation. Des donnees experimentales obtenues par la technique de la cinematique inverse sont presentees. De nouveaux resultats preliminaires plus complets sont aussi presentes. Ces mesures de production d'isotopes dans le fer permettent d'estimer directement les alterations et dommages generes dans une fenetre metallique d'un ADS.