BxDecay0 - C++ port of the legacy Decay0 FORTRAN library

authors: François Mauger, Volodymyr Tretyak
date: 2023-08-29
copyright: Copyright (C) 2017-2023 the BxCppDev group

The BxDecay0 C++ library provides a set of classes and functions for the random generation of simulated nuclear decays. It consists in a C++ port of the original Decay0 Fortran program (also known as GENBB in some other context) written and maintained by Volodymyr Tretyak (KINR). Decay0 was created to address the Monte Carlo generation of nuclear decays in the context of double beta decay and dark matter experimental research.

BxDecay0 aims to be used by any C++ simulation program that needs to generate the kinematics of primary particles emitted from specific nuclear decays (example: input for a Geant4 based Monte Carlo simulation program). It can be easily interfaced with the HepMC event/particle model or any other client application.

From version 1.0.7, BxDecay0 provides an optional extension library which implements an interface for Geant4 (through a PrimaryGeneratorAction class and its associated messenger). See the relevant section below.

History

The first version of the Decay0 program was written in the early 90's by Volodymyr Tretyak and collaborators, using the Fortran 77 programming language and the CERNLIB library. It has been maintained and improved up to now (2020).

From 1992 to 2010, the Decay0/GENBB code was embedded in the GEANT3 based simulation software of the NEMO2 and then NEMO3 double beta decay experiments.

From 2005 to 2011, the NEMO3 collaboration has initiated a R&D program to design a new generation double beta decay experiment: SuperNEMO. The choice was made to use C++ as the main programming language. In this context, François Mauger has created a C++ version of GENBB. The first version was a C++ wrapper of the original Fortran code, using binding mechanism based on plain static C structures.

Later, a pure C++ version was released without any dependency on Fortran and CERNLIB. This code was integrated in 2011 as the genbb_help module of the Bayeux C++ library (version < 4).

This release of the BxDecay0 C++ library is extracted from the Bayeux genbb_help module with some changes from the 2017-03-01 release of the Decay0 program by Volodymyr Tretyak. It has then been updated to the 2018-12-05 and 2020-04-20 releases.

BxDecay0 is a standalone library with very few dependencies (mostly the GSL library for numerical integration and a few special math functions). External random engines can be used through a simple wrapping functor interface, particularly the ones provided by the C++ standard random library can be used by default. However the user is free to provide its own uniform deviates random generator (based on GSL, ROOT or whatever).

Versions:

Prerelease 1.0.0 : mixed port from Decay0 2017-03-01 and embedded decay0 C++ code in Bayeux 3 based on Decay0 2013.
First release 1.0.0 : updated from Decay0 2018-12-05
First production release 1.0.1 : updated build system
Release 1.0.2 :
- updated from Decay0 2020-04-20,
- add optional support for 2nubb gA processes for a few isotopes of interest (as a pure C++ implementation with required large external datasets from the https://gitlab.in2p3.fr/francois.mauger/bxdecay0data project which is automatically loaded).
Release 1.0.3 :
- fix kinematics issue in DBD gA process
Release 1.0.4 :
- fix usage of the optional BXDECAY0_RESOURCE_DIR env in bxdecay0-config script
- support the optional BXDECAY0_PREFIX_DIR env in bxdecay0-config script and resource.cc.in (very basic manual support for package relocation)
Release 1.0.5 :
- make BxDecay0 relocatable
- fix missing/odd references for some background decays
- add Rn222 decay generator
Release 1.0.6:
- add support for clang-format and clang-tidy
- add a few background isotopes, namely Po210, Po218, Th230, U234 and U238, as simplified alpha emitters
Release 1.0.7:
- move some resource files
- DBD gA processes are not optional anymore but associated phase space data files are only installed through the BXDECAY0_INSTALL_DBD_GA_DATA option (default: OFF)
- add support for the BXDECAY0_DBD_GA_DATA_DIR environment variable to locate the DBD gA phase space data files
- add the bxdecay0-run program to generate BxDecay0 decay events and store the output in some ASCII files
- add the bxdecay0::event_reader class (compatible with the output files generated by the bxdecay0-run program)
- add the BxDecay0 Geant4 extension library
Release 1.0.8:
- The Y90 decay generator now reproduces as well as possible the positron energy spectrum from the internal pair production using an approximated shape using a truncated polynomial of degree two (see Dryák P. Jaroslav Š., Measurement of the branching ratio related to the internal pair production of Y-90., Applied Radiation and Isotopes 156 (2020): 108942). Thanks to Daniel Bonifacio (IRD/CNEN, Rio de Janeiro, Brazil) for stimulating this improvement.
Release 1.0.9:
- The BxDecay0 Geant4 extension library can be specified as a requested component from the find_package command. Example:
```
find_package(BxDecay0 1.0.9 REQUIRED COMPONENTS Geant4 CONFIG)
```
Release 1.0.10:
- The bxdecay0::decay0_generator now supports a mechanism which automates post-generation event operations (PGO).
- Only one post-generation event op is provided for now: the Momentum Direction Lock (MDL) algorithm which allows to apply a bias on the emission direction of some particle(s) in each generated event. Specific documentation is provided in documentation/PostGenEventOps/MDL/. The MDL PGO proposes also the possibility to use a simple rectangular cut on the emission cone aperture.
- The Geant4 extension (primary generation action and messenger classes) is also modified to enable the use of the MDL mechanism.
- The Geant4 extension provides an interface to use an arbitrary vertex generator engine to be coupled with the BxDecay0 primary generator action.
- The generated companion file now uses extension .d0c to reflect the fact it contains informations about the configuration of the generator. It also lists the post-generation event operations used by the generator with their configuration parameters. This file must be considered as a helper log file, and not a configuration file. Users are responsible of the configuration of their usage of BxDecay0 through their own simulation framework and associated configuration system.
Release 1.0.11:
- Fix missing CMake policy (issue #20)
- Fix buggy support of the quadruple beta decay mode for Zr96, Xe136 and Nd150 (issue #21)
- Fix buggy test in Geant4 extension (issue #22)
Release 1.0.12:
- Add an advanced example about vertex generation from the G4 extension (issue #24)
- Fix spurious printouts in Geant4 extension (issue #25)
Release 1.1.0:
- Fix G4String issue in Geant4 extension (issue #26)
- Fix bugs concerning the manipulation of particles' generation times in a generated event from examples (issue #27)
Release 1.1.1:
- Minor fix for GCC 13

Design

Plumbing

The core of the BxDecay0 code does not follow a fully object-oriented approach. In order to ensure the easy synchronization of its low level code with the original Decay0 code, BxDecay0 mimics the layout of the Fortran code (including massive usage of GOTO statements!). BxDecay0 provides a large collection of plain generator functions for about 100 radioactive nuclei split in two categories: double beta decay and background/calibration decay. When a Decay0 fix or improvement is published in the original Fortran code by its author (V.Tretyak), it is thus rather easy to adequately change/adapt the C++ code in the relevant section of BxDecay0.

Porcelain

Hopefully, BxDecay0 gets rid of the original common block based data model in Decay0 which has strong limitations (static data structures) in terms of usability in a modern OOP and possibly multi-threaded context. The BxDecay0 API introduces its own OOP data model through the bxdecay0::event and bxdecay0::particle classes (see the ex01 example). It is thus easy to use such classes through any C++ client program and/or to interface with some high level event generator library (i.e. HepMC3). See the ex02 example.

More, BxDecay0 provides the bxdecay0::decay0_generator class which wraps low-level functions with a simple OOP interface.

Finally, it is also possible to use the low level C++ functions ported from the original Fortran code. However it is not recommended and should be reserved to experts and developpers of the library.

Installing BxDecay0

Preparation of your system

BxDecay0 is developped on a Ubuntu Linux (18.04/20.04 LTS) and should work on any Unix/BSD flavor with a recent C++ compiler with c++11 support (i.e. GNU g++ >= 4.9 or clang) including macOS.

Requirements for Ubuntu 20.04 LTS

The following lines give some hints to prepare your system before the installation of BxDecay0. Some instructions may vary depending on your own system.

Install GNU C++ compiler:
```
$ sudo apt-get install g++
```
Install CMake:
```
$ sudo apt-get install cmake
```

Install the GNU scientific library (development package):

$ sudo apt-get install libgsl-dev
$ gsl-config --version
2.5

Install git-lfs (optional but required for supporting DBD gA data):
```
$ sudo apt-get install git-lfs
$ git lfs install
```
Install clang-tidy, clang-format (optional, useful for development/contributors)

$ sudo apt-get install clang-format clang-tidy

Requirements for macOS (Catalina)

If you use the Homebrew package manager, then all dependencies can be obtained through that:

Install either Xcode from the App Store, or the command line tools from the Terminal:

$ xcode-select -install

Install Homebrew following the instructions here: https://brew.sh
Install the following required packages:

$ brew install cmake gsl

Install git-lfs (required for DBD gA data):
```
$ brew install git-lfs
$ git lfs install
```
Install clang-tidy, clang-format (optional, useful for development/contributors)

$ brew install clang-format llvm

Download BxDecay0 source code from the GitHub repository

Clone the Git development repository on your filesystem:

$ cd /tmp
$ git clone https://github.com/BxCppDev/bxdecay0.git bxdecay0.git
$ ls -l bxdecay0.git/

Or download the archive associated to a released version :

$ cd /tmp
$ curl -L https://github.com/BxCppDev/bxdecay0/archive/1.1.1.tar.gz -o bxdecay0-1.1.1.tar.gz
$ tar xvzf bxdecay0-1.1.1.tar.gz
$ ls -l bxdecay0-1.1.1/

Configuration

Here we use a temporary build directory and choose to install BxDecay0 in our home directory:

$ mkdir /tmp/_build.d
$ cd /tmp/_build.d
$ cmake -DCMAKE_INSTALL_PREFIX=${HOME}/sw/bxdecay0 /tmp/bxdecay0.git

or:

$ cmake -DCMAKE_INSTALL_PREFIX=${HOME}/sw/bxdecay0 /tmp/bxdecay0-1.1.1

Configuration options:

BXDECAY0_INSTALL_DBD_GA_DATA : Install phase-space factor data files for various supported BxDecay0 DBD gA processes (default: OFF). The DBD gA generator requires large datasets of tabulated phase-space factors so if you don't need it in your client code, it is better to disable this features for it implies the downloading of huge external resource files (~1.7 GB).

If set to ON, the DBD gA processes' data files will be installed in the resources/data directory and handled like other BxDecay0's resource files. Alternatively, the DBD gA processes' data files can be located through the BXDECAY0_DBD_GA_DATA_DIR environment variable which must point to a directory which contains the expected data/dbd_gA/vX.Y directory, following the format conventionaly used by the DBD gA datasets.

Example for auto-installing DBD gA generators data files:
```
$ cmake ... -DBXDECAY0_INSTALL_DBD_GA_DATA=ON ...
```
BXDECAY0_WITH_GEANT4_EXTENSION : Build and install the BxDecay0 Geant4 extension library (needs Geant4 version >= 10.6).

Example for building and installing the Geant4 extension:
```
$ cmake ... -DBXDECAY0_WITH_GEANT4_EXTENSION=ON -DGeant_DIR=/path/to/geant4/installation/dir ...
```
The current release has been tested on Ubuntu 20.04 LTS with a GSL 2.5 system installation, Geant4 10.7 and a standalone CLHEP 2.4.4.0 setup.

Build, test and install

From the build directory:

$ make -j4

If you are developing bxdecay0, you can optionally use the supplied support files for clang-format and clang-tidy to apply format and static an analysis checks.

Integration and use of clang-format with a range of text editors and IDEs is documented here: https://clang.llvm.org/docs/ClangFormat.html

Use of clang-tidy may be enabled through CMake by configuring with the CMAKE_CXX_CLANG_TIDY option:

$ cmake ... -DCMAKE_CXX_CLANG_TIDY=/path/to/clang-tidy ...

When building bxdecay0 with this setting, clang-tidy will print warnings when code should be fixed to conform with security, readability, performance, and modern C++ requirements. The suggestions can be applied manually, or automatically by configuring as:

$ cmake ... -DCMAKE_CXX_CLANG_TIDY="/path/to/clang-tidy;-fix" ...

If you are submitting changes, it is recommended that you split your commits into a sequence that implement your change, followed by one that applies any suggested fixes by clang-tidy. This allows easier review and testing.

Post-build test

Run the tests with:

$ make test

To run a specific test:

$ ctest -I 15,15

You can also run the bxdecay0-run program from the build directory before installation. First you must declare the BXDECAY0_RESOURCE_DIR environment variable to locate the resource files which are not installed yet in the proper path. Here we generate four Cs137 decay primary events using the MDL bias mechanism to force the beta ray to be emitted along the X-axis.

$ export BXDECAY0_RESOURCE_DIR=$(pwd)/../resources
$ ./bxdecay0-run --logging "debug" -s 314159 \
     -n 4 -c background -N "Cs137+Ba137m" \
 --pgop-mdl-particle "e-" \
 --pgop-mdl-rank 0  \
 --pgop-mdl-cone-phi 0.0 \
 --pgop-mdl-cone-theta 90.0 \
 --pgop-mdl-cone-aperture 0.0 \
 "/tmp/genCs137"
$ cat /tmp/genCs137.d0c 
$ cat /tmp/genCs137.d0t

The output file /tmp/genCs137.d0c contains the summary of event generation informations. The output file /tmp/genCs137.d0t contains the list of generated events in a very simple ASCII format.

Install

From the build directory:

$ make install

Manual setup

Add the following line in your shell startup script (i.e. ~/.bashrc):

$ export PATH=${HOME}/sw/bxdecay0/bin:${PATH}

The bxdecay0-config script will be usable from your projects:

$ which bxdecay0-config

One may want to use the pkg-config utility:

$ export PKG_CONFIG_PATH=${HOME}/sw/bxdecay0/lib/pkgconfig:${PKG_CONFIG_PATH}
$ pkg-config --exists bxdecay0 && echo ok
ok

Utility

The bxdecay0-config utility script allows you to fetch informations about your installation of the BxDecay0 library.
```
$ bxdecay0-config --help
$ bxdecay0-config --prefix
$ bxdecay0-config --version
$ bxdecay0-config --cmakedir
```

Usage

Build support

BxDecay0 comes with CMake and pkg-config support. The BxDecay0 installation directory contains dedicated scripts usable by client applications.

CMake configuration scripts are provided:
- BxDecay0Config.cmake,
- BxDecay0ConfigVersion.cmake.
The find_package(BxDecay0 REQUIRED 1.1.1 CONFIG) CMake command can be given the following variable to locate BxDecay0 on your system from a client project which uses the CMake build system:
```
$ cmake -DBxDecay0_DIR="$(bxdecay0-config --cmakedir)" ...
```

A pkg-config script is provided:

bxdecay0.pc.

Usage:

$ pkg-config --cflags bxdecay0 
-I/path/to/bxdecay0/install/dir/lib/pkgconfig/../../include
$ pkg-config --libs bxdecay0 
-L/path/to/bxdecay0/install/dir/lib/pkgconfig/../../lib \
  -lBxDecay0 -lgsl -lgslcblas -lm

Basic program

The following program is extracted from the BxDecay0's ex00 example. It randomly generates 10 simulated events corresponding to the neutrinoless double beta decay (DBD) process of ¹⁰⁰ Mo to the ground state of ¹⁰⁰ Ru. The resulting events are printed in the terminal in a very simple format. It is of course possible to adapt this program and use the OOP interface of the bxdecay0::event class in order to extract physical quantities of interest (particles' type and momentum...).

#include <iostream>
#include <bxdecay0/std_random.h>       // Wrapper for the standard random PRNG
#include <bxdecay0/event.h>            // Decay event data model
#include <bxdecay0/decay0_generator.h> // Decay0 generator with OOP interface

int main()
{
  // Declare a PRNG:
  unsigned int seed = 314159;                 // Random seed
  std::default_random_engine generator(seed); // Standard PRNG
  bxdecay0::std_random prng(generator);       // PRNG wrapper

  // Declare a Decay0 generator:
  bxdecay0::decay0_generator decay0;

  // Configure the Decay0 generator:
  decay0.set_decay_category(bxdecay0::decay0_generator::DECAY_CATEGORY_DBD);
                                                  // Double-beta decay process
  decay0.set_decay_isotope("Mo100");              // Emitter nucleus
  decay0.set_decay_dbd_level(0);                  // Ground state of the daughter
                                                  // nucleus
  decay0.set_decay_dbd_mode(bxdecay0::DBDMODE_1); // Neutrinoless DBD (mass mechanism)
  // or :
  // decay0.set_decay_dbd_mode_by_label("0nubb_mn");

  // Initialize the Decay0 generator.
  // We need to pass some PRNG to pre-compute some quantities
  // from energy distributions:
  decay0.initialize(prng);

  // Shoot some decay events:
  std::size_t nevents = 10;
  for (std::size_t ievent = 0; ievent < nevents; ievent++) {
    bxdecay0::event gendecay;     // Declare an empty decay event
    decay0.shoot(prng, gendecay); // Randomize the decay event
    gendecay.store(std::cout);    // Basic ASCII output
  }

  decay0.reset(); // Terminate the generator
  return 0;
}

List of examples

ex00 : Minimal program for the generation of Mo100 neutrinoless double beta decay events (mass mechanism) with plain ASCII output,
ex01 : Generation of Mo100 two neutrino double beta decay events with plain ASCII output,
ex02 : Generation of Mo100 two neutrino double beta decay events with HepMC3 formatted ASCII output (requires a proper installation of the HepMC3 library),
ex03 : Generation of Co60 decay events with plain ASCII output,
ex04 : Use of the plumbing bxdecay0::genbbsub function (expert/developper only),
ex05 : Use of the bxdecay0::dbd_gA class (optional).

Units

BxDecay0 uses the Decay0's legacy system for physical units.

Here the c quantity is the speed of light in vacuum (with c ~ 300 000 km/s in S.I.).

Let m be the rest mass of a particle, BxDecay0 expresses this mass as M = m c^2 where M is the associated rest mass-energy. The implicit unit for M is megaelectronvolts (MeV). This is equivalent to say that M=m using c=1.
let p be some component of the momentum of a particle, BxDecay0 expresses this quantity as P = p x c where P has the dimension of an energy explicitly expressed in megaelectronvolts (MeV). This is equivalent to say that P=p using c=1.
Let t be the decay time of a particle (with respect to some arbitrary time reference), then BxDecay0 expresses t in second (s).

Given these rules, it is up to the client application to operate physical quantities of interest using its own unit system.

Example:

Code snippet using the CLHEP system of units, for example for interfacing with Geant4

#include <CLHEP/Units/SystemOfUnits.h>
#include <bxdecay0/event.h>
#include <bxdecay0/particle.h>
 ...
{
  bxdecay0::event gendecay;
  // Fill the event object with particles...
  ...

  // Extract informations from the BxDecay0 event model and define some physical quantities
  // for use within CLHEP or Geant4 with the proper explicit units:

  double g4_decay_time = gendecay.get_particles().front().get_time() * CLHEP::second;
  std::cout << "Decay time : " <<  g4_decay_time / CLHEP::nanosecond << " ns" << std::endl;

  double g4_momentum = gendecay.get_particles().front().get_momentum() * CLHEP::MeV;
  std::cout << "Momentum : " << g4_momentum / CLHEP::keV << " keV" << std::endl;
  ...
}

The Post-Generation Event Operation mechanism (PGOp)

The bxdecay0::decay0_generator class accepts an ordered list of Post-Generation event operations (PGOp) to be automatically applied on each generated event.

Any PGOp is embodied by an instance of a class inherited from the bxdecay0::i_event_op abstract class.

Only one type of PGOp algorithm is provided for now, namely the Momentum Direction Lock operation (MDL), which enables to select a target particle in an event and force its momentum to point in a given emission cone. See the documentation/PostGenEventOps/MDL/ directory for more informations. The test_cs137_mdl function in the bxdecay0/testing/test_decay0_generator.cxx program illustrates the use of this feature. This mechanism also proposes a few more features to bias a generated event with respect to the emission direction of the primary particles.

The `bxdecay0-run` program

bxdecay0-run is a standalone program which generates decay events from a BxDecay0 driver and stores them in ASCII files using a very simple format. The files can be thus easily parsed by some external program or read by the provided bxdecay0::event_reader class.

Usage:

$ bxdecay0-run --help

Example: Generation of 1000 Co60 decay events from the BxDecay0 driver.

$ bxdecay0-run \
    --seed 314159 --nb-events 1000 \
    --decay-category "background" --nuclide "Co60" \
    "/tmp/genCo60"

The program saves the generated events in the /tmp/genCo60.d0t ASCII file. The extension .d0t is automatically appended to the /tmp/genCo60 file basename. The ASCII format of the /tmp/genCo60.d0t output file is based on a sequence of event records using the following multiline structure:

EventID EventTime NuclideName
NumberOfParticles
ParticleId0 ParticleDecayTime0 MomentumX0 MomentumY0 MomentumZ0
ParticleId1 ParticleDecayTime1 MomentumX1 MomentumY1 MomentumZ1
...
ParticleIdN ParticleDecayTimeN MomentumXN MomentumYN MomentumZN
<blank line>

Times are expressed in seconds and momentum in MeV (see the Units section).

Excerpt of the /tmp/genCo60.d0t decay events output file.

0 0 Co60
3
3  0 0.0890847724997921 0.107233155968529 0.210656674296868
1  3.77695634726014e-13 0.0393104551877891 -0.0730829396361298 -1.1700609266389
1  1.55399097807134e-12 -0.0847475363407502 -0.978273612294033 0.901491871606925

1 0 Co60
3
3  0 0.0687351093356929 0.378071569687282 -0.0429368022433981
1  4.74314079126286e-13 0.0742298643154087 -1.16402137524005 -0.124391178256253
1  8.81837403089513e-13 -0.139316386007182 -0.515867914935887 -1.22121261004364

...

A /tmp/genCo60.d0c companion file is also created. It stores configuration informations associated to the BxDecay0 run, using a very simple ASCII format with key=value pairs. The extension .d0c is automatically appended to the /tmp/genCo60 basename.

Typical contents of the /tmp/genCo60.d0c configuration informations output file:

library-name=BxDecay0
library-version=1.1.1
decay-category=background
nuclide=Co60
seed=314159
time-from-epoch-s=1606423151
nb-events=10
@status=0

The directory which should contain these files must exist and be writable before you run the program.

The BxDecay0 Geant4 extension library

The BxDecay0 library can be built with an optional companion library named BxDecay0_Geant4. Of course Geant4 (>=10.6) must be installed and setup on your system to make it work (former version may work but have not been tested). This extension library proposes a primary generator action which wraps the BxDecay0 event generator.

Some additional features are proposed:

a dedicated messenger for the Geant4 interface,
an interface which allows to install your own algorithm for vertex generation,
support for the MDL PGOp (with messenger), allowing to bias the emission directions of generated particles (within some arbitrary emission cone).

The option to activate this extension is: BXDECAY0_WITH_GEANT4_EXTENSION.

Example:

$ cmake ... -DBXDECAY0_WITH_GEANT4_EXTENSION=ON -DGeant4_DIR=/path/to/geant4/installation ...

Under Linux, this generates the libBxDecay0_Geant4.so shared library which is linked to the core libBxDecay0.so shared library. This also installs the include/bxdecay0_g4/ header directory in the BxDecay0 installation path.

A specific example is also available to illustrate the use of this interface in a Geant4 based program (bxdecay0_g4_ex01).

License

BxDecay0 is free and open source software. Following the GSL library it depends on, it is released under the GNU GENERAL PUBLIC LICENSE, version 3. See the LICENSE.txt file.

You must take care of this licensing terms. Distributing your own software linked to BxDecay0 implies you also use the GNU GENERAL PUBLIC LICENSE.

If it turns you cannot link safely your distributable software with the BxDecay0 library because of some licensing incompatibility, you may use the standalone bxdecay0-run program to generate standalone datafiles which contain simulated events and then operate you own specific internal ASCII reader software tool to benefit of BxDecay0's functionalities.

Authors and contributors

Volodymyr Tretyak (KINR, Kiev Institute for Nuclear Research, Ukraine) is the original author and maintener of the legacy Fortran Decay0 package.
François Mauger (LPC Caen, Laboratoire de Physique Corpusculaire de Caen, Université de Caen Normandie, Caen, France) is the author and maintener of the original C++ port of Decay0 within Bayeux and the BxDecay0 library.
Emma Mauger (formerly Université de Caen Normandie, Caen, France) has done a large part of the extraction of the standalone BxDecay0 from the original Bayeux genbb library module.
Ben Morgan (Warwick University, Warwick, United Kingdom): CMake build system and package reorganization, support for clang-format and clang-tidy.
Malak Hoballah and Laurent Simard (IJCLab, Orsay, France) (support for DBD generator with gA process).
Rastislav Dvornicky (Comenius University, Bratislava, Slovakia) has calculated specific phase space factors for some DBD gA process.
Pierre Lasorak (University of Sussex, Oxford, United Kingdom) has added simplified versions of Po210, Po218, Th230, U234 and U238 alpha emitters.
Luigi Pertoldi (T. U. München) provides the BxDecay0's Arch Linux packaging.

Who uses and supports BxDecay0...

The SuperNEMO experiment through its Bayeux and Falaise software simulation stack (2017+).
The LArSoft Collaboration, which proposes, among others, tools for the simulation of Liquid Argon Time Projection Chambers for several neutrino experiments, has incorporated the BxDecay0 library (2020+).
The DUPhy research group (Deep Underground Physics).
remage project (2021+).

The above logos and web sites are referenced with the kind permission of their respective authors and/or scientific communities.

References

Volodymyr Tretyak, DECAY0 event generator for initial kinematics of particles in alpha, beta and double beta decays, talk given at Laboratori Nazionali del Gran Sasso, 17 March 2015 :
O.A.Ponkratenko, V.I.Tretyak, Yu.G.Zdesenko, Event Generator DECAY4 for Simulating Double-Beta Processes and Decays of Radioactive Nuclei, Phys. At. Nucl. 63 (2000) 1282 (nucl-ex/0104018)

Appendix 1: Supported radioactive isotopes and associated details

List of supported double beta decay isotopes

From the dbd_isotopes.lis resource file:

Ca40
Ca46
Ca48
Ni58
Zn64
Zn70
Ge76
Se74
Se82
Sr84
Zr94
Zr96
Mo92
Mo100
Ru96
Ru104
Cd106
Cd108
Cd114
Cd116
Sn112
Sn122
Sn124
Te120
Te128
Te130
Xe136
Ce136
Ce138
Ce142
Nd148
Nd150
Dy156
Dy158
W180
W186
Os184
Os192
Pt190
Pt198
Bi214 (for Bi214+At214)
Pb214 (for Pb214+Po214)
Po218 (for Po218+Rn218+Po214)
Rn222 (for Rn222+Ra222+Rn218+Po214)
Sm144
Sm154
Er162
Er164
Er170
Yb168
Yb176

List of daughter nucleus excited states in double beta decay

Ca40 -> Ar40 :
1. 0+ (gs) {0 MeV}
Ca46 -> Ti46 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.889 MeV}
Ca48 -> Ti48 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.984 MeV}
3. 2+ (2) {2.421 MeV}
Ni58 -> Fe58 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.811 MeV}
3. 2+ (2) {1.675 MeV}
Zn64 -> Ni64 :
1. 0+ (gs) {0 MeV}
Zn70 -> Ge70 :
1. 0+ (gs) {0 MeV}
Ge76 -> Se76 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.559 MeV}
3. 0+ (1) {1.122 MeV}
4. 2+ (2) {1.216 MeV}
Se74 -> Ge74 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.596 MeV}
3. 2+ (2) {1.204 MeV}
Se82 -> Kr82 : (updated from Decay0 : 2020-04-20)
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.777 MeV}
3. 2+ (2) {1.475 MeV}
4. 0+ (1) {1.488 MeV}
5. 2+ (3) {1.957 MeV}
6. 0+ (2) {2.172 MeV}
7. 0+ (3) {2.450 MeV}
8. 2+ (4) {2.480 MeV}
9. 2+ (5) {2.656 MeV}
10. 2+ (6) {2.945 MeV}
Sr84 -> Kr84 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.882 MeV}
Zr94 -> Mo94 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.871 MeV}
Zr96 -> Mo96 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.778 MeV}
3. 0+ (1) {1.148 MeV}
4. 2+ (2) {1.498 MeV}
5. 2+ (3) {1.626 MeV}
6. 2+ (4) {2.096 MeV}
7. 2+ (5) {2.426 MeV}
8. 0+ (2) {2.623 MeV}
9. 2+ (6) {2.700 MeV}
10. 2+?(7) {2.713 MeV}
Mo92 -> Zr92 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.934 MeV}
3. 0+ (1) {1.383 MeV}
Mo100 -> Ru100 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.540 MeV}
3. 0+ (1) {1.130 MeV}
4. 2+ (2) {1.362 MeV}
5. 0+ (2) {1.741 MeV}
Ru96 -> Mo96 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.778 MeV}
3. 0+ (1) {1.148 MeV}
4. 2+ (2) {1.498 MeV}
5. 2+ (3) {1.626 MeV}
6. 2+ (4) {2.096 MeV}
7. 2+ (5) {2.426 MeV}
8. 0+ (2) {2.623 MeV}
9. 2+ (6) {2.700 MeV}
10. 2+?(7) {2.713 MeV}
Ru104 -> Pd104 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.556 MeV}
Cd106 -> Pd106 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.512 MeV}
3. 2+ (2) {1.128 MeV}
4. 0+ (1) {1.134 MeV}
5. 2+ (3) {1.562 MeV}
6. 0+ (2) {1.706 MeV}
Cd108 -> Pd108 :
1. 0+ (gs) {0 MeV}
Cd114 -> Sn114 :
1. 0+ (gs) {0 MeV}
Cd116 -> Sn116 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {1.294 MeV}
3. 0+ (1) {1.757 MeV}
4. 0+ (2) {2.027 MeV}
5. 2+ (2) {2.112 MeV}
6. 2+ (3) {2.225 MeV}
Sn112 -> Cd112 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.618 MeV}
3. 0+ (1) {1.224 MeV}
4. 2+ (2) {1.312 MeV}
5. 0+ (2) {1.433 MeV}
6. 2+ (3) {1.469 MeV}
7. 0+ (3) {1.871 MeV}
Sn122 -> Te122 :
1. 0+ (gs) {0 MeV}
Sn124 -> Te124 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.603 MeV}
3. 2+ (2) {1.326 MeV}
4. 0+ (1) {1.657 MeV}
5. 0+ (2) {1.883 MeV}
6. 2+ (3) {2.039 MeV}
7. 2+ (4) {2.092 MeV}
8. 0+ (3) {2.153 MeV}
9. 2+ (5) {2.182 MeV}
Te120 -> Sn120 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {1.171 MeV}
Te128 -> Xe128 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.443 MeV}
Te130 -> Xe130 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.536 MeV}
3. 2+ (2) {1.122 MeV}
4. 0+ (1) {1.794 MeV}
Xe136 -> Ba136 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.819 MeV}
3. 2+ (2) {1.551 MeV}
4. 0+ (1) {1.579 MeV}
5. 2+ (3) (2.080 MeV}
6. 2+ (4) {2.129 MeV}
7. 0+ (2) {2.141 MeV}
8. 2+ (5) {2.223 MeV}
9. 0+ (3) {2.315 MeV}
10. 2+ (6) {2.400 MeV}
Ce136 -> Ba136 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.819 MeV}
3. 2+ (2) {1.551 MeV}
4. 0+ (1) {1.579 MeV}
5. 2+ (3) (2.080 MeV}
6. 2+ (4) {2.129 MeV}
7. 0+ (2) {2.141 MeV}
8. 2+ (5) {2.223 MeV}
9. 0+ (3) {2.315 MeV}
10. 2+ (6) {2.400 MeV}
Ce138 -> Ba138 :
1. 0+ (gs) {0 MeV}
Ce142 -> Nd142 :
1. 0+ (gs) {0 MeV}
Nd148 -> Sm148 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.550 MeV}
3. 0+ (1) {1.424 MeV}
4. 2+ (2) {1.454 MeV}
5. 2+ (3) {1.664 MeV}
6. 0+ (2) {1.921 MeV}
Nd150 -> Sm150 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.334 MeV}
3. 0+ (1) {0.740 MeV}
4. 2+ (2) {1.046 MeV}
5. 2+ (3) {1.194 MeV}
6. 0+ (2) {1.256 MeV}
Sm144 -> Nd144 (new : Decay0 2018-12-05) :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.697 MeV}
3. 2+ (2) {1.561 MeV}
Sm154 -> Gd144 (new : Decay0 2018-12-05) :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.123 MeV}
3. 0+ (1) {0.681 MeV}
4. 2+ (2) {0.815 MeV}
5. 2+ (3) {0.996 MeV}
6. 0+ (2) {1.182 MeV}
Dy156 -> Gd156 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.089 MeV}
3. 0+ (1) {1.050 MeV}
4. 2+ (2) {1.129 MeV}
5. 2+ (3) {1.154 MeV}
6. 0+ (2) {1.168 MeV}
7. 2+ (4) {1.258 MeV}
8. 0+ (3) {1.715 MeV}
9. 2+ (5) {1.771 MeV}
10. 2+ (6) {1.828 MeV}
11. 0+ (4) {1.851 MeV}
12. 2+ (7) {1.915 MeV}
13. 1- {1.946 MeV}
14. 0- {1.952 MeV}
15. 0+ (5) {1.989 MeV}
16. 2+ (8) {2.004 MeV}
Dy158 -> Gd158 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.080 MeV}
3. 4+ (1) {0.261 MeV}
Er162 -> Dy162 (new : Decay0 2018-12-05) :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.081 MeV}
3. 2+ (2) {0.888 MeV}
4. 0+ (1) {1.400 MeV}
5. 2+ (3) {1.453 MeV}
6. 0+ (2) {1.666 MeV}
7. 2+ (4) {1.728 MeV}
8. 2+ (5) {1.783 MeV}
Er164 -> Dy164 (new : Decay0 2018-12-05) :
1. 0+ (gs) {0 MeV};
Er170 -> Yb170 (new : Decay0 2018-12-05) :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.084 MeV}
Yb168 -> Er168 (new : Decay0 2018-12-05) :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.080 MeV}
3. 2+ (2) {0.821 MeV}
4. 0+ (1) {1.217 MeV}
5. 2+ (3) {1.276 MeV}
Yb176 -> Hf176 (new : Decay0 2018-12-05) :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.088 MeV}
W180 -> Hf180 :
1. 0+ (gs) {0 MeV}
W186 -> Os186 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.137 MeV}
Os184 -> W184 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.111 MeV}
3. 2+ (2) {0.903 MeV}
4. 0+ (1) {1.002 MeV}
5. 2+ (3) {1.121 MeV}
6. 0+ (2) {1.322 MeV}
7. 2+ (4) {1.386 MeV}
8. 2+ (5) {1.431 MeV}
Os192 -> Pt192 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.317 MeV}
Pt190 -> Os190 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.187 MeV}
3. 2+ (2) {0.558 MeV}
4. 0+ (1) {0.912 MeV}
5. 2+ (3) {1.115 MeV}
6. 0+ (2) {1.382 MeV}
Pt198 -> Hg198 :
1. 0+ (gs) {0 MeV}
2. 2+ (1) {0.412 MeV}
Bi214 -> At214 :
1. 1- (gs) {0 MeV}
Pb214 -> Po214 :
1. 0+ (gs) {0 MeV}
Po218 -> Rn218 :
1. 0+ (gs) {0 MeV}
Rn222 -> Ra222 :
1. 0+ (gs) {0 MeV}

List of supported double beta decay modes

From the bxdecay0::bb_utils.h C++ header and the dbd_modes.lis resource file:

BxDecay0 mode	Identification label	Decay0 mode	Description
`DBDMODE_1`	`0nubb_mn`	1	0nubb(mn) 0+ -> 0+ {2n} with neutrino mass
`DBDMODE_2`	`0nubb_rhc_lambda_0`	2	0nubb(rhc-lambda) 0+ -> 0+ {2n} with RHC lambda
`DBDMODE_3`	`0nubb_rhc_lambda_02`	3	0nubb(rhc-lambda) 0+ -> 0+, 2+ {N*} with RHC lambda
`DBDMODE_4`	`2nubb`	4	2nubb 0+ -> 0+ {2n}
`DBDMODE_5`	`0nubbM1`	5	0nubbM1 0+ -> 0+ {2n} (Majoron, SI=1)
`DBDMODE_6`	`0nubbM3`	7	0nubbM3 0+ -> 0+ {2n} (Majoron, SI=3)
`DBDMODE_7`	`0nubb_rhc_lambda_2`	9	0nubb(rhc-lambda) 0+ -> 2+ {2n} with RHC lambda
`DBDMODE_8`	`2nubb_2`	10	2nubb 0+ -> 2+ {2n}, {N*}
`DBDMODE_9`	`0nuKb+`	11	0nuKb+ 0+ -> 0+, 2+
`DBDMODE_10`	`2nuKb+`	12	2nuKb+ 0+ -> 0+, 2+
`DBDMODE_11`	`0nu2K`	13	0nu2K 0+ -> 0+, 2+
`DBDMODE_12`	`2nu2K`	14	2nu2K 0+ -> 0+, 2+
`DBDMODE_13`	`0nubbM7`	8	0nubbM7 0+ -> 0+ {2n} (Majoron, SI=7)
`DBDMODE_14`	`0nubbM2`	6	0nubbM2 0+ -> 0+ (2n} (Majoron, SI=2)
`DBDMODE_15`	`2nubb_bosonic_0`	15	2nubb 0+ -> 0+ with bosonic neutrinos
`DBDMODE_16`	`2nubb_bosonic_2`	16	2nubb 0+ -> 2+ with bosonic neutrinos
`DBDMODE_17`	`0nubb_rhc_eta_s`	17	0nubb(rhc-eta) 0+ -> 0+ with RHC eta simplified expression
`DBDMODE_18`	`0nubb_rhc_eta_nmes`	18	0nubb(rhc-eta) 0+ -> 0+ with RHC eta and specific NMEs
`DBDMODE_19`	`2nub_lv`	19	2nubb(LV) 0+ -> 0+ with Lorentz violation
`DBDMODE_20`	`0nu4b`	20	0nu4b 0+ -> 0+ Quadruple beta decay
`DBDMODE_21`	`2nubb_gA_g0`	NA	2nubbg0 0+ -> 0+ {2n} (g0)
`DBDMODE_22`	`2nubb_gA_g2`	NA	2nubbg2 0+ -> 0+ {2n} (g2)
`DBDMODE_23`	`2nubb_gA_g22`	NA	2nubbg22 0+ -> 0+ {2n} (g22)
`DBDMODE_24`	`2nubb_gA_g4`	NA	2nubbg4 0+ -> 0+ {2n} (g4)

Comments on specific modes:

The original Decay0 code has changed the so-called modebb index of some Majoron modes from versions above 2017 with respect to former versions. We thus use an index map to ensure backward compatibility and force the BxDecay0's interface stable with respect to the original C++ port in the Bayeux/genbb module.
5, 6, 13, 14 are Majoron modes with respective spectral index SI:
- SI=1 - old Gelmini-Roncadelli Majoron
- SI=3 - double M, vector M, charged M
- SI=7
- SI=2 - bulk M of Mohapatra
20: quadruple beta decay, possible only for Zr96, Xe136, Nd150 (only to the daughter nucleus' ground state)
21, 22, 23, 24: two neutrino double beta decay, gA modes g0, g2, g22, g4 possible only for Se82, Mo100, Cd116, Nd150 (only to the daughter nucleus' ground state).

List of standard radioactive isotopes (background/calibration)

From the background_isotopes.lis resource file:

Ac228
Am241
Ar39
Ar42
As79 (for As79+Se79m)
Bi207 (for Bi207+Pb207m)
Bi208
Bi210
Bi212 (for Bi212+Po212)
Bi214 (for Bi214+Po214)
C14
Ca48 (for Ca48+Sc48)
Cd113
Co60
Cs136
Cs137 (for Cs137+Ba137m)
Eu147
Eu152
Eu154
Gd146
Hf182
I126
I133
I134
I135
K40
K42
Kr81
Kr85
Mn54
Na22
P32
Pa231 (added from Bayeux : 2013-09-06)
Pa234m
Pb210
Pb211
Pb212
Pb214
Po210 (simplified through pure alpha emission : from tag 1.0.6)
Po218 (simplified through pure alpha emission : from tag 1.0.6)
Ra226 (added from Bayeux : 2013-07-11)
Ra228
Rb87
Rh106
Rn222 (added : 2020-07-17)
Sb125
Sb126
Sb133
Sr90
Ta180m-B-
Ta180m-EC
Ta182
Te133
Te133m
Te134
Th230 (simplified through pure alpha emission : from tag 1.0.6)
Th234
Tl207
Tl208
U234 (simplified through pure alpha emission : from tag 1.0.6)
U238 (simplified through pure alpha emission : from tag 1.0.6)
Xe129m
Xe131m
Xe133
Xe135
Y88
Y90 (new realistic model for positron energy spectrum : from tag 1.0.8)
Zn65
Zr96 (for Zr96+Nb96)

Additional comment

Unlike the original Decay0 code, BxDecay0 does not support the generation of so-called artifical events (Compton, Moller scattering, e+e- pair). It should not be difficult to implement such generators by yourself independently of BxDecay0.

Name		Name	Last commit message	Last commit date
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.github/workflows		.github/workflows
bxdecay0		bxdecay0
cmake		cmake
documentation		documentation
examples		examples
extensions		extensions
programs		programs
resources		resources
tools		tools
.clang-format		.clang-format
.clang-tidy		.clang-tidy
.gitattributes		.gitattributes
.gitignore		.gitignore
CMakeLists.txt		CMakeLists.txt
LICENSE.txt		LICENSE.txt
README.rst		README.rst
bxdecay0-config.in		bxdecay0-config.in

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BxDecay0 - C++ port of the legacy Decay0 FORTRAN library

History

Design

Plumbing

Porcelain

Installing BxDecay0

Preparation of your system

Requirements for Ubuntu 20.04 LTS

Requirements for macOS (Catalina)

Download BxDecay0 source code from the GitHub repository

Configuration

Configuration options:

Build, test and install

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Install

Manual setup

Utility

Usage

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Units

The Post-Generation Event Operation mechanism (PGOp)

The bxdecay0-run program

The BxDecay0 Geant4 extension library

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Who uses and supports BxDecay0...

References

Appendix 1: Supported radioactive isotopes and associated details

List of supported double beta decay isotopes

List of daughter nucleus excited states in double beta decay

List of supported double beta decay modes

List of standard radioactive isotopes (background/calibration)

Additional comment

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