Differential intensity integrated over the mission duration and forecast.

This site provides access to the main HelMod web calcultor - which is an application of the latest available HelMod Code - for unregistered users, e.g.,

HelMod data sets and results can be freely downloaded or copied. However, we strongly suggest user to provide an appropriate acknowledgment and/or citation, e.g., see  Citations or Bibliography  pages.

How to use this HelMod Calculator

This tools evaluates the modulated spectrum at Earth orbit for theorical LIS evaluated with GALPROP. The particle transport is described using the Helmod Model. For information about the computation method please refear to Monte Carlo Integration page.

The input parameters and options for the tool are described below. Once the input form has been completed,  "Submit" button will start the calculation and open the "Results" page (allow for pop-up in your browser settings).


Solar Modulation Model

The website is always updated with the latest HelMod version available, as indicated in the output result.
Previous version remains available for a limited period during updating.

Expected Mission Duration/ Past Missions

User can select either the time interval for the interested simulation or refer to a standard published dataset (e.g., AMS-02).

  • Expected mission  duration: allow to select a single Galactic Cosmic rays species and the expected duration of the mission. By default the module evalute the modulated spectrum for a single Carrington rotation containing the "begin of the mission" value. To evaluate the average modualted spectra over the entire period of the mission, check the box "Average over the entire period" and select the date of the end of the mission.
  • Past missions: allow to compute modulated spectra referring to period and GCR species described in  standard published datasets. User may select, in order, the Experiment (e.g. AMS-02), then the GCR species (e.g. Proton) and finally the publised dataset.

Display Options

  • x-axis value: Select if output result should be computed in Particle Rigidity [GV] or in Kinetic Energy per nucleon [GeV]. If "auto" is selected, the system will choise the best one for the selected dataset.
  • Addittional modulation models: compute the modulated spectrum using  ISO 15390, DLR version or  ISO 15390 models. This features is not available for forecast simulations.



The result page contains the figure of modulated spectrum and and correspondent tabulated data.
Text file and numpy/python archive are also available for Download.


Advanced Controls:

For expert users it is available the possiblity to modify some relevant HelMod parameters.

Available parameters may change for different HelMod version. For latest default parameters please refer to Current and History of default parameters page.

HelMod provide optimized LIS developed with GALPROP and presented on international journals, Expert users may load their own develped LIS. HelMod accept the following formats:

  • GALPROP fits file (*.gz extension). The fits must contain at least the computed LIS for the Galactic Cosmic Rays particle species to be modulated. The Module evaluate the LIS for modulation as the sum of modulated primary spectrum with  secondaries and modulated isotopes.
  • plaintext file. User can provide a txt file for LIS with the follow characteristics:
    • The file should have a mime type 'text/plain' (Checkout this list for allowed extensions).
    • The file must contains two columns only: one for kinetic energy per nucleon [GeV], the second for the LIS flux [ (m\(^2\) s sr GeV)\(^{-1}\)].
    • The file can contains comments. Line starting with '#' character will be ignored.


It should be remarked that data generated by using the Calculator may be used by HelMod developers for statistical purpose.

The SDE integration with HelMod results in a quite expensive effort from the computational point of view since,
to minimize the uncertainties, an huge amount of event should be integrated from Earth to heliosphere boundary.

Monte Carlo integration allows us to evaluate the normalized probability function \(G(R_0|R)\) that a particle observed at Earth with rigidity \(R_0\) entered into the heliosphere with rigidity \(R\).
Thus, the modulated spectrum at specific energy \(R_0\) is proportional to:
 J_{mod}(R_0)= \int_0^\infty J_{LIS}(R)G(R_0|R)dR.
Once that \(G(R_0|R)\) was evaluated, using the numerical approximation, it is possible to apply the modulation directly to LISs provided by GALPROP.

The effect of propagation in heliosphere is then evaluated using a normalized probability function pre-evaluated with HelMod using parameters described in previous section.
We developed a python script that read GALPROP output and provide modulated spectrum for periods of selected experiments.


Download latest released version (from 2017 to 2021)

Download last Python Module (v 4.0):
Download Archive of Calculator for past Mission (v 4.0):
Download Archive of Solar modulator for proton, helium (v 4.0):
Download Archive of Solar modulator for Ions: Oxygen and Carbon (v 4.0)
Download Archive of Solar modulator for Ions: Nitrogen and Silicon (v 4.0)
Download Archive of Solar modulator for Ions: Iron (v 4.0)

HelMod data sets and results can be freely downloaded or copied. However, the user should make the appropriate acknowledgment or citation, e.g., see  Citations or Bibliography  pages.

How to install and configure

install python (>=2.7) packages

  • pyfits
  • scypy >=0.17.0
  • numpy >=1.10
  • wget
  • matplotlib

Download Python file and place in a working directory.

To configure the module you first need to download the HelMod Archive:

> python SolarModulation_Galprop_<version>.py  --Install

This will download and save the Archive in the working directory. To specify a different installing directory use the option -a <PATH> or --ArchivePATH <PATH>

If you are working offline and/or you get different version of the Archive you can skip the download part using --UseLocal to use the local .tgz file in the working directory.


if you want to use the Module everywhere on the local machine you can set the enviroment key that defines the path to installed archive.



How to Use the Module

To use The module you need

  1. The path helmod Archive (see how to install and configure)
  2. A GALPROP fits file or a TXT file

The basic command to get Solar modulated spectrum is:

python SolarModulation_Galprop_<version>.py <GALPROPFits.gz> <ExpNameKey>

where <ExpNameKey>  is the key name that define the paticle species and experiment which you want to modulate.

The list of available species/experiments in the archive can be listed using the command

python SolarModulation_Galprop_<version>.py -l


during the modulation there are few options you can use

-a (--ArchivePATH)  <PATH> to HelMod Archive if you don't set the Envinroment Key

--MakePlot          Create a Plot in png format

--NoExpData         display simulation and LIS only

--Normalize         apply automatic normalization of modulated spectrum to Experimental Data

-o (--output) <FILE_NAME> specify output file name (default is "ModulatedSpectra.dat")

--joinLIS           Sum the LIS in kinetic enery from all Isotope (ex. proton, Deuterium,..) and apply the same modulation

--joinIsotope       apply different modulation for different Isotope, then Sums the results after conversion in Rigidity

-p (--ParametersSet) <PAR_SET_NAME> Define the name of not default parameter Sets available in HelMod Archive (Expert Only)

-t                 specify that a txt file is provided instead of GALPROPFits.

--PrintLIS          Print Complete LIS used for Modulation (note that if --joinIsotope is Activeted output LIS is the sum in Rigidity of all isotopes

--ExtraSource_GeV <FILE_NAME> specify an extrasource to be added to LIS. File must be two column and expressend in GeV/nuc

LIS in text format

User can provide a txt file for LIS with the follow characteristics:

  1. The file must be a text file.
  2. The file must contains two columns only:
    1. one for kinetic energy per nucleon [GeV]
    2. the second for the LIS flux [ (m\(^2\) s sr GeV)\(^{-1}\)].
  3. The file can contains comments. Line starting with '#' character will be ignored.