Change Log


  • Updates to website that change some of the results formatting.


  • Added the NASA Cancer Risk Model, which computes Risk of Exposure Induced Death (REID) and Risk of Exposure Induced Cancer (REIC). These are probabalistic calculations that account for uncertainties in radiobiology and epidemiology. The values returned are presented as the percent increase in risk due to the defined mission. The current permissible exposure limit stated in NASA Standard 3001 is defined such that cumulative exposures received throughout an astronaut's career do not exceed 3% REID, evaluated at the high 95% confidence level. Details of the model can be found in Cucinotta, F.A., Kim, M.Y., Chappell, L.J., Space Radiation Cancer Risk Projections and Uncertainties – 2012, NASA TP 2013-217375, 2013. (
  • Added the capability to use the AP9 trapped radiation model for uploaded trajectories.
  • Added the Badhwar-O'Neil 2020 GCR model. The new model has been updated with data from several new measurement platforms, including ACE/CRIS, AMS-02, and PAMELA. Details of the new model can be found in T. Slaba, K. Whitman, The Badhwar‐O'Neill 2020 GCR Model, Space Weather, vol. 18(6), pp.1-18 , 2020. (
  • Updated website middleware to improve performance and security. The look is a little different, but the behaviour should be the same as before. Let us know if you notice something out of order.
  • Updated to TARIS Fortran Code version 4.2. Codes and algorithms are unchanged from the previous version, but a new FORTRAN compiler was used and the OLTARIS-supplied material cross sections were regenerated. This may result in a very small change in results (less than .1%) compared to TARIS 4.01.


  • Added AP9 trapped radiation model to Circular Earth Orbit environments. The AP9 model is a statistical model based on measurements over several solar cycles and is set up to compute a mean daily flux. More information can be found at the Air Force website (


  • Added SINP (Skobeltsyn Institute of Nuclear Physics) 2016 GCR model. See reference: Kuznetsov, N. V., H. Popova, and M. I. Panasyuk (2017), Empirical model of long-time variations of galactic cosmic ray particle fluxes, J. Geophys. Res. Space Physics, 122, 1463–1472 (
  • Added the ability to select a single ion of the GCR spectra for radiation transport.


  • Fixed a bug that caused incorrect LET response for the trapped/neutron albedo spectra for projects using sphere or slab geometries. This bug also caused the return of the wrong energy grid for the flux tables.


  • Added Badhwar-O'Neil 2014 GCR model and updated data for the Matthia 2013 GCR model so both are valid for dates through January 2017. Removed Badhwar-O'Neil 2004 GCR model.


  • Added 'Sum of October 1989 Tylka Band fits' to historical SPE list. This has been proposed as a design reference for missions beyond Earth orbit. For reference, see: L. Townsend, J. Adams, S. Blattnig, M. Clowdsley, D. Fry, I. Jun, C. McLeod, J. Minow, D. Moore, J. Norbury, R. Norman, D. Reames, N. Schwadron, E. Semones, R. Singleterry, T. Slaba, C. Werneth, M. Xapsos, Solar particle event storm shelter requirements for missions beyond low Earth orbit, Life Sciences in Space Research, vol. 17, pp. 32–39, 2018. (
  • Updated data files used by trapped LEO and neutron albedo codes that may have non-trivial impacts on LEO environment runs with mission dates past 2008. Also extended valid dates through April 2017.
  • Compute the average dose to individual organ locations for effective dose runs.
  • Added the option to select NASA-Q quality factors for the dose equivalent response, which returns quantities for both solid cancer and leukemia. Also, for cases in which the NASA-Q quality factors are selected, the user can select NASA tissue weighting factors, either average US population or average never-smoker population, for the effective dose calculation. For reference, see: Cucinotta, F.A., Kim, M.Y., Chappell, L.J., Space Radiation Cancer Risk Projections and Uncertainties – 2012, NASA TP 2013-217375, 2013. (
  • Added gray equivalent response. This computes the PEL (Permissible Exposure Limit) quantities for Lens, Skin, BFO, CNS (Hippocampus), and CNS (Z>10) (Hippocampus). This response requires one of the four body models (CAM, CAF, MAX, or FAX) similar to the effective dose calculation, thus is only applicable to thickness distributions or sphere geometries. For reference, see: Wilson, J. W., Kim, M. Y., De Angelis, G., Cucinotta, F. A., Yoshizawa, N., Badavi, F. F., Implementation of Gy-Eq for Deterministic Effects Limitation in Shield Design, Journal of Radiation Research, Vol. 43: Suppl., S103-S106; 2002. (
  • The neutron-elastic recoil production channel was added to the light-ion cross section routines. This will effect all results for which the shielding material contains hydrogen, or for whole-body response functions, which transport through tissue. The results will increase by varying amounts depending on the environment and the amount of shielding present.


  • A bug was fixed that affects only the effective dose calculation for ray-by-ray jobs sent with TARIS version 3.4. In the affected jobs, backward neutrons from the bi-directional transport were not included in the neutron flux and corresponding exposure values. This results in an under-estimate of a few percent for free-space environments and on the order of 10% for surface environments. This bug only affected the fluxes and exposure values needed for the effective dose calculation, all of the other responses were computed correctly.


  • Added the Matthia 2013 GCR model (Matthiä, D., Berger, T., Mrigakshi A. , T., Reitz G., A Ready-to-Use Galactic Cosmic Ray Model, Adv. in Space Res. 51 (2013) pp. 329-338).
  • Added the option to use the Mars Climate Database (MCD) as the atmospheric model for Mars surface environments.


  • Add LET response for slab and sphere geometries plus ray-by-ray transport jobs.


  • The Badhwar-O'Neill 2010 GCR model was updated to accept dates through September 2013. This update also made very minor changes to past dates so there is a possibility that a repeated run of an older project could yield slightly different results.


  • The lunar surface environment was updated to allow the user to define a surface normal similar to the Mars surface environment. If a surface normal is defined, the thickness distribution doesn't have to indicate surface-pointing rays, the surface will be indicated by the hemisphere opposite the surface normal.


  • Mars surface environments (for SPE and GCR) have been added. The Mars environments can only be used with vehicle thickness distributions and are always executed using ray-by-ray transport. A surface-local-vertical vector needs to be defined to indicate which hemisphere is up and exposed to the atmosphere. The opposite hemisphere is assumed to be regolith. A Field-of-View (FOV) response has also been added for Mars surface projects to aid in comparisons to particle telescope-type instruments.


  • The transport algorithm for heavy ions (Z > 2) was recently updated. The update includes a revised interpolation scheme for computing the ion fragmentation source term. The updated algorithm is approximately 5x faster than the previous method. Users may notice a very small (less than 2%) difference in integrated quantities such as dose or dose equivalent; differences on individual ion fluxes are generally less than 5%.


  • Generalized spheres can now be created and used for project geometries. These spheres are defined similarly to slabs and can contain any number of layers and materials. These jobs are run using forward-only transport and effective dose calculations use an orientation-averaged or spinning astronaut phantom position.


  • The Badhwar-O'Neill 2010 GCR model was updated to accept dates through Aug. 2012.


  • The lunar surface environment has been updated to add the neutron albedo. Jobs that are submitted as an interpolation-based run will have the neutron albedo applied to surface-pointing rays, while the rest of the rays will receive the free-space environment. The GCR albedo is computed without the vehicle. The SPE albedo is considered negligible since the vehicle would shield the lunar surface in the 1-D transport, thus it is set to zero. In the case of ray-by-ray transport, an appropriate amount of lunar regolith is added to the surface pointing rays, which will automatically account for the neutron albedo in the bi-directional transport along each ray.


  • Added Badhwar-O'Neill 2010 GCR model for both freespace and earth orbit environments. The user can still select the older Badhwar-O'Neill 2004 as well but the site now defaults to the 2010 model.
  • Changed the XML schema for thickness distributions so that type_id="-1" is used to flag rays that point from the target point toward a lunar or planetary surface. Previously, type_id="4" was used for this purpose. If you already had uploaded thickness files with type_id="4" for lunar, the change has been made for you.


  • A low energy transport model for light ions has been added for forward-only transport. This correction reduces overall discretization error and only has a noticeable impact (at most 30%) on exposure quantities at large shielding thicknesses (>50 g/cm2) in SPE environments. The new model numerically processes production cross sections differently than before and requires new material databases to be generated.


  • Added capability to run ray-by-ray transport for vehicle thickness distributions. In this analysis, the transport is run along each ray in the thickness distribution and includes backward neutron transport (like slab calculations). This allows thickness distributions to have up to 100 different materials in any order along each ray. This type of analysis requires thickness distributions that have rays directly opposite of one another, which is met by using one of the OLTARIS supplied ray distributions (except dca_10000_rays). Flux/fluence at a point, dose, dose equivalent, TLD-100, and effective dose equivalent are currently supported.
  • Updated to TARIS Fortran Code version 3.2.


  • The module used to compute trapped proton fluxes at a given time along a trajectory has been modified to allow consistent evaluation between point-by-point and trajectory-averaged analyses. For trajectory-averaged analysis, these modifications produce small changes to overall exposure quantities (few percent).
  • The nucleon-hydrogen differential elastic cross section was modified at high energies to properly evaluate the fraction of forward-scattered and backward-scattered nucleons. This change will have a minor impact (perhaps visible on flux spectra) only in cases with a hydrogenous target exposed to an environment with energies greater than 8 GeV/nucleon. This change only has a noticeable impact when very thick (>> 100 g/cm2) pure-hydrogen targets are exposed to highly energetic (GCR) environments.


  • Added capability to create a LEO environment from a user-uploaded trajectory. User trajectories may either be analyzed as before (by integrating the environment over the trajectory) or on a point-by-point basis. When the job is submitted as an averaged trajectories, the external environment (boundary condition) is computed at each trajectory point and integrated to obtain an average environment. The average environment is then run as a single computation to provide total response quantities (and averaged per-day rates) for the entire trajectory. When the job is submitted as a point-by-point trajectory, the external environment is computed at each trajectory point and run as a separate job. The results are then combined and returned as a function of time along the trajectory. These submissions can take much longer to run since there are as many jobs as there are time steps in the trajectory. The results files can also get quite large if desired responses include spectral data, such as boundary condition flux, flux after transport, or LET. It is best to start with a smaller number of points in the trajectory to get a feel for run time and the resulting data size.
  • The module used to convert flux/fluence spectra to linear energy transfer (LET) spectra was modified to more accurately represent the spectrum near singularities and to provide a physics-based extrapolation at low and high LET values for a given ion. These modifications have a negligible impact on the LET spectrum results except near ion singularities associated with the extrema of the Bragg curves.


  • The electromagnetic (electron, photon, positron) transport module has been updated with improved physics and numerical methods. The new numerical methods provide a more robust algorithm for transporting primary electrons. The improved physics include complete coupling of the electron, photon, and positron production channels. The impact of this change depends on the environment and shielding configuration considered. For high energy environments (Europa), the numerical improvements may only be noticeable at large shielding thicknesses, and the improved physics are important.


  • Added ability to define Solar Particle Events using one of 4 curve fits: Weibull Fit, Exponential in Energy, Exponential in Rigidity, and Band Function.
  • Added ability to defind Galactic Cosmic Ray environment by specifying the solar modulation parameter (Phi value).
  • Added ability to utilize user-defined material in vehicle thickness files. See the updated Thickness Metafile Format Description (which can be downloaded from the bottom of the Thickness Distribution tab), to see how the user-defined materials are defined. Look in the material_table element and the new material_type_define element. The thickness files are still limited to three materials at this time. If effective dose is selected as a response function, only two user-defined materials can be used since tissue is needed for adding the body thicknesses.


  • A bug was fixed in the GCR calculation where the start and end dates where not always being treated correctly. In some parts of the calculation, only the start date was used. The errors caused by this bug were less than a percent in response quantities.


  • The nuclear fragmentation cross section module for heavy ions (Z>2) has been updated with improved models for light ion coalescence and electromagnetic dissociation. These updates can have a noticeable impact on heavy ion secondary fluxes, doses, dose equivalents, etc.; however, the impact on total dose, dose equivalent, or effective dose is generally small (few percent). This update is referenced in the literature as NUCFG3.
  • This update corresponds to the TARIS Fortran Code version 3.0, which also corresponds to the release of HZETRN2010 Beta 3.0.


  • The modules used to compute Dose, Dose Equivalent, and TLD-100 were modified so that individual ion stopping powers were used instead of scaled proton stopping powers. This modification results in a slight reduction in the hellion and alpha results (at most 15%); however, the reduction on total quantities is generally small (few percent).
  • Added trapped light ions and trapped heavy ions to Europa/Jovian design environments. Note, the trapped heavy ions are only available at 5Rj and 9Rj and are averaged fluxes, not peak, as is the case for the trapped electrons at 5Rj and 9Rj.


  • Modified neutron elastic interaction parameters to more accurately describe the angular distribution of neutrons between the forward and backward directions. Also modified discretization parameters in the low energy neutron transport model to improve computational efficiency. Both changes only effect slab geometry results, and require regeneration of material cross sections. The impact of these changes on total neutron flux is noticeable in some cases, but does not significantly alter total dose estimates in a slab.
  • Added electron environments for Europa/Jovian missions and electron transport for vehicle thickness distributions and slab geometries. This initial capability only supports dose in Si for now.


  • Fixed a unit conversion bug in returning the TEPC responses back to the web which produced results an order of magnitude too high. Projects with TEPC response need to be re-run to see the corrected numbers.


  • Fixed a bug in the neutron albedo calculation for the LEO environment. Users can expect a very small change (less than .5%) in total responses which include all three components of the LEO environment since the neutron albedo is very small compared to the GCR component. A new project must be created to see the changes since re-running an existing project will re-use stored post-transport fluxes.


  • Added check to see if material thicknesses in user-supplied thickness distributions exceed 100 g/cm^2 and then extend the interpolation spatial grid if needed. In the past, the spatial grid ended at 100 g/cm^2 and then responses were extrapolated for thicknesses greater. This applies only to projects that reference an uploaded thickness distribution. Slab calculations have always used thicknesses as supplied by the user.


  • Enabled TLD response for slab calculations.


  • Enabled TPEC response for jobs with vehicle thickness distributions.
  • Added capability to visualize dose-like quantities as projections on a sphere. Any response that has values calculated along each ray and then integrated for a total response, will now have a selection next to the total value labeled Sphere Viewer. This link will open a new window and display a color-mapped sphere when can be rotated, zoomed, etc. Selecting the '?' in the window will open another window (turn off popup blocker!) with a summary of interaction instructions.


  • Added silicon as target material for Dose and LET responses.
  • Added OLTARIS supplied materials for use in slab calculations. A list of materials can be viewed under the Materials tab.
  • The static grid of independent variables over which the light particle cross sections are generated was modified to more accurately account for step-sizes less than 0.5 g/cm2. Users can expect minor changes in results for small shielding or slab thicknesses. This change will also require users to regenerate their material cross section databases for those generated before this update.


  • Implemented much faster body/vehicle combination and interpolation for effective dose equivalent calculations.


  • Added capability to create user-defined materials and arbitrary slab geometries. Environments for slab analysis are limited to Free Space (SPE and GCR) or LEO. Responses after the slab are limited to flux/fluence, dose, and dose equivalent. The other responses will be added later.


  • Pushed updated web interface to OLTARIS production site (finally).


  • Added two new body models for Effective Dose Equivalent calculations - Female Adult voXel (FAX) and Male Adult voXel (MAX).
  • Added 'Copy Data' button to plotting window. This will copy any data selected and displayed in the plot window and copy it to your local clipboard. Then you can paste this tab-delimited data into a spreadsheet or any other application of you choice.


  • The target points used to compute mass averaged dosimetric quantities and whole body effective dose in CAM and CAF have been improved and updated.
  • A new computational procedure is being used for the transport algorithms. The updated procedures have been shown to be more accurate and up to 80 times faster than the previous algorithm. NOTE: The differences will only be observed if a new project is created. Re-running an existing project will re-use your previous transport calculation if the environment and vehicle materials haven't changed.


  • Added capability to compute the DSNE specification of the trapped LEO environment.


  • Fixed several bugs in computing and using LEO environments. Previously, in some cases, negative environmental fluxes could result and the wrong energy grid was used in response calculations.


  • Added OLTARIS supplied thickness distributions to pull-down menu so that users don't have to upload one in order to run a job. The models are concentric spheres of Aluminum, Aluminum-Tissue, and Aluminum-Poly.-Tissue.


  • Added capability to generate 1859 Carrington SPE's fitted to Sept. 89 spectrum (hard) and March 91 spectrum (soft).


  • Improved elastic neutron transport algorithm has been implemented. Significant differences will be seen mainly for thick shielding (roughly, depths greater than 30 g/cm^2)
  • Bug fixes were made in transport and light ion cross sections.
  • Light ion cross section table now pre-calculated and interpolated over during transport.
  • NOTE: All these changes affect the transport calculations, so the differences will only be observed if a new project is created. Re-running an existing project will re-use your previous transport calculation if the environment and vehicle materials haven't changed.


  • Made changes to format for downloaded data to make them more readable and to add grids to each file instead of downloading the grids seperately.
  • Changes to download data and flash viewer to display isotope mass and charge instead of just the atomic mass.


  • Major update that allows projects to re-use a previous transport calculation as long as the environment and materials haven't changed. This results in a much faster run since the transport calculations generally take most of the total runtime.


  • Added example thickness distribution to download under 'Thickness Distribution' tab.


  • Fixed bug in GCR environment calculation for events/mission less than one day


  • Not every little change will be recorded here, only those which explain bug fixes, changes in algorithms which may change/improve results, and added/enhanced capabilities. If you notice something that changed that is not mentioned here and you would like an explanation, then contact the site adminstrator by selecting the 'Send a Comment' link at the top of the page.
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