Captain Renault:  "Why did you come to Casablanca?"

Rick:             "I came for the waters."
                       
Renault:          "The waters? There are no waters in Casablanca. This is a desert."
                       
Rick:             "Then I was misinformed."
                
                      Humphrey Bogart and Claude Rains in Casablanca

The MATRIXBBU, also known as MATBBU, program was written by B.Yunn of TJNAF and CASA some time ago, modified later by L.Merminga, and is now being modified by K.Beard. Its concept is outlined in CEBAF-PR-87-007, "Multiplass Beam Breakup in Recirculating Linacs" by J.Bisognano and R.Gluckstern, and its purpose is to predict the current instability thresholds.

This is the development site; for the release site, refer to the CASA Code Library.

Very simply, it setups a matrix representing the transport around the accelerator and than looks for eigenvalues of that matrix; those eigenvalues on the positive real axis correspond to instabilities as certain beam current thresholds.

The origonal version ran only on a Cray and used the IMSL EVLCG routine. Version 0.0 changed nothing except to port it to other UNIX systems; to that end, several supporting libraries were created and minor changes were made to the source.

When many HOMs with high Q are involved, it becomes very difficult to choose the right frequency; one may use a very small fixed step size and take a long, long time or one can impliment some automatic scheme to find the interesting frequencies. Version 2.2 does exactly that.

	fixed 300 steps	fixed 2359 steps	300 steps nominal automatic hunt
1000 mA full scale
100 mA full scale

Refer to the appropriate directory for current information.

directory