f1 pi- Monte Carlo generation and processing

Generation

The monte carlo is currently being generated with the Notre Dame version of SAGE. The output is in ASCII form. The reaction being generated is pi- p -> X- p -> f1 pi- p -> eta pi+ pi- pi- p. The incident pion is given a momentum and energy distribution similar to the data. The vertex is chosen with a x and y distribution similar to data and a flat z distribution within the hydrogen target. The X mass is generated with a mass of 1.5 GeV and a width of 1 GeV. This gives an accepted X mass distribution similar to the f1 pi- data. The f1 is generated with it's Particle Data Booklet values of mass equal 1.281 GeV and a width of .024 GeV. It is estimated that 1.6 million monte carlo events will need to be generated to give us accepted monte carlo which is 10 times more than the data.

Pre-Processing

Because a cut on the f1 is applied to the data, this cut is being applied everywhere. The f1 in the monte carlo is generated with a Breit-Wigner distribution which doesn't require it be within the f1 cut. Therefore, the first thing done to the monte carlo is to apply the f1 cut to the output of SAGE. This is done with a program in my directories called cutf1. It's output is the generated monte carlo which will be used to create the accepted monte carlo and will also be fed into the Partial Wave Analysis(PWA) code. Before sending the generated monte carlo into gamp (the first PWA program) it must be converted to E852 itape format and the ESR_NPARTICLE group filled. This is done with ndsageToItape. Now we have the generated monte carlo ready for PWA and further processing.

Processing

There are several steps to processing the generated monte carlo. The steps are acceptance cuts, geant processing, patching and trigger simulator processing, analyzing and applying data cuts. These steps are described below.

First the generated monte carlo should have a gamma acceptance cut applied. This will remove much of the generated monre carlo which is useless. This can be done with cutGen. A cut is applied that all gammas hit an area 1.2 times the size of the lgd centered over the lgd. This throws away about 40% of the generated monte carlo.