This is the home page for NJOY, the nuclear data processing code developed at Los Alamos National Laboratory.

Two versions of NJOY are currently managed and distributed from this website:

  • NJOY21 A new version—written in C++—and backwards compatible with NJOY2016. NJOY21 is the future of NJOY and is where all development is currently being done. LA-CC-15-092
  • NJOY2016 The legacy Fortran version that is familiar to long-time NJOY users. NJOY2016 is deprecated. No active development is being done on NJOY2016, only bug fixes. LA-CC-16-075

Open Source Availability

For the first time, NJOY is freely available under the BSD 3-clause license. Both NJOY2016 and NJOY21 are free to use, but the copyright and license must remain with the code.

Getting NJOY

Instructions for obtaining, compiling, and testing NJOY can be found here.

Support or Contact

Technical support for both versions of NJOY can be obtained with an email to: njoy@lanl.gov. NJOY developers are also found lurking in the NJOY-help chat room. Come visit if you have any questions.