arXiv subjects

W. R. Webber

Publications and source records attributed to W. R. Webber.

At least 19 recordsLinked to original sources

arXiv2018

Fitting the Galactic Electron Spectrum Measured by Voyager at Low Energies and also by CALET/AMS-2 at High Energies Using a Monte Carlo Diffusion Model for Electron Propagation - One Spectrum Fits All

In this paper we compare galactic electron spectra measured up to TeV energies by AMS2 and CALET and that measured by Voyager at the lowest energies down to 1 MeV with that calculated using a Monte Carlo diffusion model for electron propagation in the galaxy. The observations and calculations at both ends of the electron spectrum, differing by a factor ~10^6 in energy, can be matched to within a few percent with a minimal set of assumptions. This includes an electron spectrum which has an index increasing from ~2.1 at the lowest energies to 2.4 at ~1 TeV, along with a diffusion coefficient that remains essentially constant below ~1.5 GV above which it becomes P^0.45. The Monte Carlo calculations indicate that the lowest and highest energy electrons originate within a local region near the galactic plane of size, less than L where L is the thickness of the trapping region. The remarkable agreement to within a few percent between the calculations and measurements from 20 GeV up to ~1 TeV also indicates that there are no individual sources greater than 10-20 percent of the Monte Carlo calculated background that are contributing to the observed electron intensity in this energy range.

physics.space-ph↗

arXiv2018

Measurements in Interstellar Space of Galactic Cosmic Ray Isotopes of Li, Be, B and N, Ne Nuclei Between 40-160 MeV/nuc by the CRS Instrument on Voyager 1

In this paper we report a study of the isotopic composition of Li, Be, B and N, Ne nuclei from a 5 year time period beyond the heliopause using the CRS instruments on Voyager. By comparing the isotopic ratios, 15N/14N and 22Ne/20Ne outside the heliosphere as measured at Voyager, and which are found to be significantly lower than those measured at the same energy inside the heliosphere, we have provided strong evidence that cosmic rays of this energy have lost as much as 200 MeV/nuc or more in the solar modulation process. This is in accordance with the so called force field description of this overall modulation by Gleeson and Axford. The measurements at Voyager confirm that the unusual 14N and 22Ne cosmic ray source abundances relative to solar abundances made earlier inside the heliosphere extend to the lower energies not accessible from near Earth measurements. The low energy Li, Be and B nuclei, which are believed to be purely secondary nuclei, are found to have a (previously unobservable) peak in the differential intensity spectrum at ~100 MeV/nuc. This is in agreement with propagation predictions. The intensities of these nuclei are ~10-20% higher than those predicted in a propagation model with a matter path length lambda = 9 g/cm2 at these low energies. The isotopic composition of Li, Be and B nuclei is also consistent with that expected from propagation through interstellar matter.

physics.space-ph↗

arXiv2018

Cosmic Ray Electrons and Protons ~1 MeV - A 40 Year Study of Their Intensities from the Earth to the Heliopause and Beyond Into Local Interstellar Space by the CRS Experiment on Voyager 1

Studies on Voyager 1 using the CRS instrument have shown the presence of sub-MeV electrons in the interstellar medium beyond the heliopause. We believe that these electrons are the very low energy tail of the distribution of galactic GeV cosmic ray electrons produced in the galaxy. If so this observation places constraints on the origin and possible source distribution of these electrons in the galaxy. The intensities of these electrons as well as MeV protons and other higher energy electrons and nuclei have been followed outward from the Earth to beyond the heliopause during the 40 years of the Voyager mission. Among the other new features found in this study of the radial dependence of the electron intensity in the heliosphere are: 1. The heliosheath is a source of sub-MeV electrons as well as the already known anomalous cosmic rays of MeV and above, none of which appear to escape from the heliosphere because of an almost impenetrable heliopause at these lower energies; 2. Solar modulation effects are observed for these MeV electrons throughout the heliosphere. These modulation effects are particularly strong for electrons in the heliosheath and comprise over 90 percent of the observed intensity change of these electrons of 10-60 MeV between the Earth and the heliopause. Even for nuclei of 1 GV in rigidity, over 30 percent of the total intensity difference between the Earth and the LIM occurs in the heliosheath; 3. The 2 MeV protons studied here for the first time beyond the heliopause are also part of the low energy tail of the spectrum of galactic cosmic ray protons, similar to the tail noted above for sub MeV galactic cosmic ray electrons.

physics.space-ph↗

arXiv2018

A Comparison of the Galactic Cosmic Ray Electron and Proton Intensities From 1 MeV/nuc to 1 TeV/nuc Using Voyager and Higher Energy Magnetic Spectrometer Measurements Are There Differences in the Source Spectra of These Particles?

Using Leaky Box Model propagation calculations for H nuclei and a Monte Carlo diffusion propagation model for electrons, starting from specific source spectra, we have matched the observed LIS spectra of these cosmic rays measured by Voyager at lower energies and AMS-2 at higher energies, a range from ~10 MeV to ~1 TeV. The source spectra required are very similar rigidity spectra. Below ~6-10 GV the source spectra for both particles are ~P-2.25 and above 10 GV the spectra are ~P-2.36-2.40. This break in the source spectral index is not seen for He and C nuclei in a match of Voyager and AMS-2 intensities both of which have source rigidity spectra with an index ~-2.24 throughout the entire range of measured energies from ~10 MeV//nuc to ~1 TeV/nuc. The absolute source intensities of electrons and H nuclei are derived and the source ratio of accelerated electrons to H nuclei is between 2-5%. The total number of accelerated electrons is much greater than that for protons, however, because the accelerated electron spectrum extends down to ~1-2 MV rigidity whereas the H nuclei spectrum cannot be observed below ~50-100 MV because of ionization energy loss. Most of these low energy electrons escape from the galaxy forming an intergalactic background.

physics.space-ph↗

arXiv2018

A Comparison of Galactic Cosmic Ray Proton and Helium Nuclei Spectra From ~10 MeV/nuc to 1 TeV/nuc Using New Voyager and Higher Energy Magnetic Spectrometer Measurements - Are There Differences In the Source Spectra of The Two Nuclei

This paper determines the relative source spectra of cosmic ray H and He nuclei using a Leaky Box model for galactic propagation and the observed spectra of these nuclei from ~10 MeV/nuc to ~1 TeV/nuc. The observations consist of Voyager 1 measurements up to several hundred MeV/nuc in local interstellar space and measurements above ~10 GeV/nuc where solar modulation effects are small by experiments on BESS, PAMELA and AMS-2. Using BESS and PAMELA measurements which agree with each other, the observed spectra for H and He nuclei and the H/He ratio are well fit by source rigidity spectra for both nuclei which are ~P-2.24 over the entire range of rigidities corresponding to energies between 10 MeV/nuc and several hundred GeV/nuc. In this case, the H/He rigidity source ratio is 5.0 + 1. The recent and presumably more accurate measurements of these spectra above 10 GeV/nuc made by AMS-2 do not entirely agree with the earlier measurements, however. In particular the H spectrum is found to be steeper than that of He by about 0.10 in the spectral exponent. Using the same model for galactic propagation the AMS-2 data leads to source spectra of H and He which are ~P-2.24 up to a break rigidity ~6-8 GV. At higher rigidities the He source spectrum continues to be ~P-2.24 but the required source spectrum for H steepens to an index ~P-2.36 above ~8 GV and, as a result, the H/He source ratio decreases with increasing rigidity using the AMS-2 data.

physics.space-ph↗

arXiv2018

The Spectra of 2H and 3He Secondary Cosmic Ray Isotopes from ~20-85 MeV/nuc as Measured Using the B-end HET Telescope on Voyager beyond the Heliopause and a Fit to These Interstellar Spectra Using a Leaky Box Propagation Model

We have measured the intensity and spectra of the cosmic ray secondary isotopes 2H and 3He and the primary isotopes H and 4He between 20-85 MeV/nuc during a 5 year time period after Voyager 1 (V1) crossed the heliopause. The data reported here is from the B-end high energy telescope. The ratios of the intensities of the secondary to primary spectra of these nuclei at low energies are sensitive indicators for determining the amount of matter traversed at these energies by their galactic cosmic ray progenitor nuclei, after acceleration, in this case mostly 4He nuclei. The measurements of secondary 3He abundances indicate that cosmic ray 4He of energies between 30-100 MeV/nuc have traversed between 7-9 g/cm2 of interstellar matter (90% H, 10% He) in a Leaky Box propagation model. This path length is also consistent with the production of secondary 2H nuclei between 20-50 MeV/nuc, which is also produced mainly by 4He in a LBM. The Boron abundance, studied in separate papers, is also consistent with this path length at energies >30 MeV/nuc. These secondary intensities imply that the interstellar cosmic ray path length may be described in a LBM in a manner consistent with a mean path length,gamma= 20.6 beta P-0.45 at rigidities above ~0.5 GV (30 MeV/nuc for A/Z=2 nuclei). Both 2H and Boron have an excess intensity vs. the predictions for path lengths of 9 g/cm2 below 30 MeV/nuc.

physics.space-ph↗

arXiv2017

Voyager 1 Measurements Beyond the Heliopause of Galactic Cosmic Ray Helium, Boron, Carbon, Oxygen, Magnesium, Silicon and Iron Nuclei with Energies 0.5 to >1.5 GeV/nuc

We have obtained the energy spectra of cosmic ray He, B, C, O, Mg, S and Fe nuclei in the range 0.5-1.5 GeV/nuc and above using the penetrating particle mode of the High Energy Telescope, part of the Cosmic Ray Science (CRS) experiment on Voyagers 1 and 2. The data analysis procedures are the same as those used to obtain similar spectra from the identical V2 HET telescope while it was in the heliosphere between about 23 and 54 AU. The time period of analysis includes 4 years of data beyond the heliopause (HP). These new interstellar spectra are compared with various earlier experiments at the same energies at the Earth to determine the solar modulation parameter, phi. These new spectra are also compared with recent measurements of the spectra of the same nuclei measured by the same telescope at low energies. It is found that the ratio of intensities at 100 MeV/nuc to those at 1.0 GeV/nuc are significantly Z dependent. Some of this Z dependence can be explained by the Z2 dependence of energy loss by ionization in the 7-10 g/cm2 of interstellar H and He traversed by cosmic rays of these energies in the galaxy; some by the Z dependent loss due to nuclear interactions in this same material; some by possible differences in the source spectra of these nuclei and some by the non-uniformity of the source distribution and propagation conditions. The observed features of the spectra, also including a Z dependence of the peak intensities of the various nuclei, pose interesting problems related to the propagation and source distribution of these cosmic rays.

physics.space-ph↗

arXiv2017

The Different Shapes of the LIS Energy Spectra of Cosmic Ray He and C Nuclei Below ~1 GeV/nuc and The Cosmic Ray He/C Nuclei Ratio vs. Energy -V1 Measurements and LBM Propagation Predictions

This paper examines the cosmic ray He and C nuclei spectra below ~1 GeV/nuc, as well as the very rapid increase in the He/C ratio below ~100 MeV/nuc, measured by Voyager 1 beyond the heliopause. Using a simple Leaky Box Model (LBM) for galactic propagation we have not been able to simultaneously reproduce the individual He and C nuclei spectra and the large increase in He/C ratio that is observed at low energies. However, using a truncated LBM with different truncation parameters for each nucleus that are related to their rate of energy loss by ionization which is ~Z2/A, these different features can be matched. This suggests that we are observing the effects of the source distribution of cosmic rays in the galaxy on the low energy spectra of cosmic ray nuclei and that there may be a paucity of nearby sources. In this propagation model we start very specific source spectra for He and C which are ~dj/dP = P-2.24, the same for each nucleus and also for all rigidities. These source spectra become spectra with spectral indices ~-2.69 at high rigidities for both charges as a result of a rigidity dependence of the diffusion coefficient governing the propagation which is taken to be ~P-0.45. This exponent is determined directly from the B/C ratio measured by AMS-2. These propagated P-2.69 spectra, when extended to high energies, predict He and C intensities and a He/C ratio that are within +3-5% of the intensities and ratio recently measured by AMS-2 in the energy range from 10 to 1000 GeV/nuc.

physics.space-ph↗

arXiv2017

The Cosmic Ray Boron/Carbon Ratio Measured at Voyager and at AMS-2 from 10 MeV/nuc up to ~1 TeV/nuc and a Comparison With Propagation Calculations

We have used new measurements of the B/C ratio in galactic cosmic rays at both low and high energies by the Voyager and AMS-2 spacecraft, respectively, along with propagation calculations using a truncated LBM to examine the implications of these new measurements over an extended energy range from a few MeV/nuc to 1 TeV/nuc. We find that the predictions from both the truncated LBM and the Diffusive Reacceleration model for GALPROP both agree with the Voyager and AMS-2 measurements of the B/C ratio to within +/- 10 percent throughout the entire energy range from 50 MeV/nuc to 1 TeV/nuc. The two propagation approaches also agree with each other to within +/-10 percent or less throughout this energy range. In effect a diffusion model, without significant additional acceleration, provides a match within +/-10 percent to the combined data from Voyager 1 and AMS-2 on the B/C ratio from 50 MeV/nuc to 1 TeV/nuc. The B/C ratio below 50 MeV/nuc measured at V1 exceeds the predictions of both propagation models by as much as 3 sigma in the data measurement errors.

physics.space-ph↗

arXiv2017

A Galactic Cosmic Ray Electron Intensity Increase of a factor of up to 100 At Energies between 3 and 50 MeV in the Heliosheath between the Termination Shock and the Heliopause Due to Solar Modulation As Measured by Voyager 1

We have derived background corrected intensities of 3-50 MeV galactic electrons observed by Voyager 1 as it passes through the heliosheath from 95 to 122 AU. The overall intensity change of the background corrected data from the inner to the outer boundary of the heliosheath is a maximum of a factor ~100 at 15 MeV. At lower energies this fractional change becomes less and the corrected electron spectra in the heliosheath becomes progressively steeper, reaching values ~ -2.5 for the spectral index just outside of the termination shock. At higher energies the spectra of electrons has an exponent changing from the negative LIS spectral index of -1.3 to values approaching zero in the heliosheath as a result of the solar modulation of the galactic electron component. The large modulation effects observed below ~100 MV are possible evidence for enhanced diffusion as part of the modulation process for electrons in the heliosheath.

physics.space-ph↗

arXiv2017

The Intensities of Cosmic Ray H and He Nuclei at ~250 MeV/nuc Measured by Voyagers 1 and 2 - Using these Intensities to Determine the Solar Modulation Parameter in the Inner Heliosphere and the Heliosheath Over a 40 Year Time Period

We have determined the solar modulation potential, phi, vs. time that is observed at Voyager 1 and 2 from measurements of the H and He nuclei intensities at a common energy of 250 MeVnuc. The H nuclei have a rigidity 0.7 GV, the He nuclei 1.4 GV. These measurements cover a 40 year time period, which includes almost 4 cycles of solar 11 year sunspot variations, throughout the inner heliosphere out to the HTS at distances of 95 AU and 85 AU, respectively at V1 and V2, and then beyond in the heliosheath. Inside the HTS the modulation potential vs. time curves at V1 and V2 show a very similar temporal structure to those observed at the Earth. During a later period of maximum solar modulation from 2000.0 to 2005.0 when V1 and V2 are in the outer heliosphere between 60-94 AU, the main temporal features of the modulation potential curves at all 3 locations match up with appropriate time delays at V1 and V2 if it is assumed that spatially coherent structures are moving outward past V1 and V2, with outward speeds of up to 700 Kms negative 1. After 2004.0 V1 and V2 are at latitudes of positive 35 and negative 30 respectively, placing lower limits on the latitude extent of these structures. Beyond the HTS in the heliosheath the modulation potential slowly decreases at both spacecraft with only a weak evidence of the unusual modulation minimum observed at the Earth in 2009, for example. A sudden decrease of the modulation potential 50 MV for both H and He nuclei occurs at V1 just before the heliopause crossing at about 122 AU. This decrease has not yet been observed at V2, which is now at 113 AU and still observing a modulation potential 60 MV.

physics.space-ph↗

arXiv2017

The Galactic Cosmic Ray Electron Spectrum from 3 to 70 MeV Measured by Voyager 1 Beyond the Heliopause, What This Tells Us About the Propagation of Electrons and Nuclei In and Out of the Galaxy at Low Energies

The cosmic ray electrons measured by Voyager 1 between 3-70 MeV beyond the heliopause have intensities several hundred times those measured at the Earth by PAMELA at nearly the same energies. This paper compares this new V1 data with data from the earth-orbiting PAMELA experiment up to energies greater than 10 GeV where solar modulation effects are negligible. In this energy regime we assume the main parameters governing electron propagation are diffusion and energy loss and we use a Monte Carlo program to describe this propagation in the galaxy. To reproduce the new Voyager electron spectrum, which is E-1.3, together with that measured by PAMELA which is E-3.20 above 10 GeV, we require a diffusion coefficient which is P 0.45 at energies above 0.5 GeV changing to a P-1.00 dependence at lower rigidities. The entire electron spectrum observed at both V1 and PAMELA from 3 MeV to 30 GeV can then be described by a simple source spectrum, dj/dP P-2.25, with a spectral exponent that is independent of rigidity. The change in exponent of the measured electron spectrum from -1.3 at low energies to 3.2 at the highest energies can be explained by galactic propagation effects related to the changing dependence of the diffusion coefficient below 0.5 GeV, and the increasing importance above 0.5 GV of energy loss from synchrotron and inverse Compton radiation, which are both E2, and which are responsible for most of the changing spectral exponent above 1.0 GV. As a result of the P-1.00 dependence of the diffusion coefficient below 0.5 GV that is required to fit the V1 electron spectrum, there is a rapid flow of these low energy electrons out of the galaxy. These electrons in local IG space are unobservable to us at any wave length and therefore form a dark energy component which is 100 times the electrons rest energy.

physics.space-ph↗

arXiv2016

Observations of the Abundances of Secondary Galactic Cosmic Rays from Z equals 5 to 28 Between 10 and 200 MeV/nuc Beyond the Heliopause by Voyager, Some Unexpected Anomalies and Their Interpretation Using a LBM for Galactic Propagation

Voyager observations for over 3 years beyond the heliopause have started to define features of the low energy, less than 100 MeV per nuc, cosmic ray secondary nuclei that have a zero or negligibly small source component. As an example, the abundance of B between about 7 and 15 MeV per nuc is unexpectedly large, greater than the prediction of a LBM by 2 or 3 in the measurement and cross section error. On the other hand, for several other heavier secondary nuclei with a low source abundance such as F and Z equal 17 to 19 and 21 to 23 nuclei, in the corresponding energy channels between about 10-20 MeV/nuc, zero nuclei have been observed. The same LBM calculations would predict about 6 to 7 events for the sum of these three groups of nuclei. The B observed intensities could be more closely matched by considering a nested LBM with 0.3-1.0 g/cm2 of matter near the cosmic ray sources, essentially a source component of B. This nested LBM calculation, if extended to the production of the above groups of secondaries, would however predict a total 8 to 12 events thus leading to an even larger discrepancy with the zero events that are observed. The measurements of heavier secondaries at low energies therefore make it very problematical that a nested LBM with more than a few 0.1 g/cm2 or more of matter near the sources could be the source of the large B abundance seen by Voyager. The large abundance of B at the lowest energies is best understood, so far, as the result of production mostly from a matter traversal of 10 g/cm2 in the galaxy, possibly in combination with uncertainties in the data and cross sections at these low energies.

physics.space-ph↗

arXiv2016

A Study of the B/C Ratio Between 10 MeV/nuc and 1 TeV/nuc in Cosmic Rays Using New Voyager and AMS-2 Data and a Comparison with the Predictions of Leaky Box Propagation Models

This paper seeks to find an explanation of the galactic cosmic ray B/C ratio newly measured in cosmic rays between ~10 MeV/nuc and 1 TeV/nuc. Voyager measurements of this ratio at low energies and AMS-2 measurements at high energies are used in this study. These measurements both considerably exceed at both low and high energies the ratio predicted using a simple Leaky Box Model for propagation of cosmic rays in the galaxy. Between 1-70 GeV/nuc, however, this same model provides an excellent fit (within +2-3%) to the new AMS-2 measurements using an escape length ~P-0.45. This would imply a diffusion coefficient ~P0.45, very close to the Kraichian cascade value of 0.50 for the exponent. Extending this same diffusion dependence to high energies, still in a LBM, along with a truncation of short path lengths in the galaxy will predict a B/C ratio of 4.5% at ~800 GeV/nuc which is very close to the AMS-2 measurement at that energy. This would indicate that the amount of material traversed near the source in a Nested LBM, for example, is less than about 0.5 g/cm2 at these energies since this process, with additional matter near the sources, would increase the B/C ratio. At low energies, however, the B/C ratio of 14% +3% at ~10 MeV/nuc measured by Voyager is more difficult to explain. The same parameters used in a LBM that fit the high energy B/C measurements predicts a B/C ratio of only ~4% at 10 MeV/nuc where the path length is about 1.5 g/cm2. If the cosmic rays have traversed ~10 g/cm2 of material in the galaxy at low energies the prediction for B/C is still only 8%, which is between 2.0-3.0 sigma below the measurement and its errors.

physics.space-ph↗

arXiv2016

Determination of the Total Solar Modulation Factors in the Heliosphere For Cosmic Ray Protons and Electrons by Comparing Interstellar Spectra Deduced from Voyager Measurements and PAMELA Spectra of These Particles at the Earth

We have determined the interstellar spectra of cosmic ray protons and electrons from a few MeV to ~10 GeV. These interstellar spectra are based on Voyager data and a normalization of specific galactic propagation model calculations of both protons and electrons to PAMELA data at the Earth at 10 GeV, where the solar modulation is small. These resulting interstellar spectra are then compared with spectra of protons and electrons measured at lower energies at the Earth by PAMELA in 2009. The total amount of modulation at lower rigidities (energies) is found to be nearly the same at the same rigidity for both protons and electrons and ranges in magnitude from a factor ~400 at 0.1 GV for electrons, to a factor ~15 at 0.44 GV (100 MeV for protons), to a factor ~3.3 at 1 GV for both components. The magnitude of this total modulation of both components are the same to within + 10% from ~0.3 to ~3 GV in rigidity. The observed total modulation for protons can be matched quite closely using a simple spherically symmetric modulation picture involving a force field model for the modulation and a constant energy loss at all energies. The electrons require a set of parameters to calculate more detailed features of the modulation using the diffusion coefficient and its variation with rigidity and radius at rigidities less than few GV.

physics.space-ph↗

arXiv2016

Fitting the Low Energy Spectra of Cosmic Ray Primary Nuclei from C to Fe as Measured on Voyager 1

The intensities of the low energy part of the spectra of primary cosmic ray nuclei including C, O, Ne, Mg, Si and Fe measured by Voyager 1 beyond the heliopause are deficient relative to the spectra measured at energies above ~100 MeV/nuc as calculated using a standard Leaky Box Model with the path length a function of rigidity. Modifications to the normal exponential distribution of path lengths at a single rigidity as is used in a simple LBM will provide a good fit to this new Voyager 1 data at low energies. These modifications, sometimes called a truncation, lead to a deficiency of short path lengths relative to an exponential distribution. This deficiency in the intensities can be described by a truncation parameter = 0.12. This modification can be produced in several ways including a non-uniform local distribution of cosmic ray sources. A uniform source distribution in the galactic plane that is deficient in sources within 0.2-0.4 Kpc of the Sun is indicated by the data. Further studies of these low energy spectra in more detail will improve these estimates and help define other features of the local galactic distribution of these cosmic rays.

physics.space-ph↗

arXiv2015

The Abundance of Low Energy Cosmic Ray Boron and Nitrogen Nuclei Measured at Voyager 1 Beyond the Heliopause, Where Do They All Come From? An Interpretation Using a Leaky Box Galactic Propagation Model

Uncertainties in the Voyager data itself as well as the cross sections for production of these secondaries at these low energies are an important limitation on the estimates of the amount of matter traversed. We also attempt a fit to the B observations at low energies by considering a source component of B generated in 1.0 g/cm2 of matter near the sources but after acceleration. This would be equivalent to a Nested LBM. In this model the V1 data below 40 MeV/nuc is now well fit. For Nitrogen, which is dominated by a source component at these low energies, a fit to the data between 10-130 MeV/nuc can be obtained with a N/O source ratio = 6.3 + 1.0% and a path length compatible with the H and He propagation as noted above. This Voyager observation confirms earlier measurements of a low N abundance in the cosmic ray source relative to what is found for solar abundances, for example, where the N/O ratio is found to be ~12%.

physics.space-ph↗

arXiv2015

The Separation of Secondary Positrons Produced in the Galaxy from the High Energy Positrons that are Observed Recent Space Experiments on PAMELA and AMS2

The large intensity of greater than 10 GeV positrons which apparently come from sources outside the Earth-Sun system observed recently by many spacecraft (PAMELA, FERMI, AMS2) is still a mystery with broad implications. In our attempts to solve this mystery we have first tried to define reasonable limits to the positrons produced in our own galaxy by nuclear interactions of cosmic rays. This is best done by using the secondary B/C ratio produced by these same cosmic rays in order to define the amount of matter traversed by galactic cosmic ray nuclei. Using new values of the B/C ratio together with earlier calculations of positron production by Moskalenko and Strong, 1998, we find that at 10 GeV this galactic production is from 70% to almost 100% of the positrons observed by the above experiments. At 100 GeV these fractions are still from 20 to 33% of the positrons observed. The resulting excess positron spectrum above this normal galactic background is found to have an exponent -2.75, possibly flattening at lower energies. If these positrons are coming to us from a uniform source distribution in and beyond the disk of the galaxy with a source spectrum that is E-2.0, a spectral steepening caused by synchrotron and inverse Compton losses, which are largest near the galactic plane, will produce a spectrum E-2.75 at the Earth. This is similar to the excess spectrum we find. The excess positron spectrum E-2.75 that we obtain is also very similar to the positron spectrum produced by galactic protons in the Earths atmosphere and in the spacecraft itself which also has a spectrum E-2.75. This results in a background for all the above experiments. The assumption is that this type of background is removed by the stringent criteria that are imposed on each event. This calculation needs to be reconsidered before the implications of these important positron results can be fully evaluated.

physics.space-ph↗