CRAB                  Version 3.0b now Available
 

Scott Pratt
National Superconducting Cyclotron Laboratory
Michigan State University, East Lansing, MI 48824
pratt@nscl.msu.edu (517) 333-6438

CRAB stands for ``Correlation After Burner''. It is a set of codes used to generate correlation codes from semi-classical transport codes. It reads files of phase space points, which describe the final momentum and point of last interaction of generated particles. From this information, along with knowledge of the impact parameters used for the transport-code runs, CRAB will generate correlation functions which account for impact-parameter averaging, experimental acceptances, experimental resolution and kinematic cuts.

CRAB can implement full quantum corrections for Coulomb interactions between the two particles as well as strong interactions for an arbitrary number of partial waves. There is also an option to include interactions of a Breit-Wigner form. CRAB does not account for strong interactions that mix partial waves or for interactions with third bodies, e.g. interacting with the residue of a compound nucleus.

Version 3.0 is completely rewritten in C++, but shares a great deal of philosophy with the previous FORTRAN version. Differences with previous versions are summarized below:

1. Different momentum binnings can be incorporated in the same run. For example, if one wishes to perform cuts in p_t and rapidity at the same time you perform calculations for Q_inv, it is straight-forward to implement. One can perform an arbitrary number of binnings in the same run.

2. The mesh used for calculating strong-interaction corrections to partial waves can be as fine as one wishes and is not tied to the resolution of the meshes used for binning.

3. Three-dimensional binnings can be incorporated.

4. It is easier to change the interaction between particles as parameters that define the interaction reside in one short file.

5. Phase space pt.s can be read from a file which contains information about all emitted particles, even those that are not considered in the correlation analyses. One can set which kinds of particles are used for the analyses. For instance, one may wish to include phase space pt.s for p⁺, p^- and p⁰ for greater statistics, even though only negative pions are truly being considered. The default input format is OSCAR 1997A.

6. Estimates of statistical errors accompany the calculation.

Although previous versions were easy to use, they were not easy to modify. The new version was designed with the intention of making it easy for the user to modify rather than just making it easy to run.

Files:
version2.tar.gz (FORTRAN)
version3.tar.gz, Version 3 updates (C++, last modified Dec. 21 2000)