Edit: The files used are

st_physics_adc_11119033_raw_2500001.daq

st_physics_adc_11116063_raw_1520001.daq

st_physics_adc_11116012_raw_3490001.daq

 We've taken the MinuitVF cuts back to their settings in 2008, and by opening up both the DCA and R parameters to 6cm from the current 3cm and 1.5cm, respectively, we are able to see the beampipe.

So, the above plot was made with ~2000 events, DCA = 6cm, R = 6cm and Minimum number of tracks = 5.

We will be looking further into modifying these three parameters to optimize the Minuit vertexer for the BES data production. More plots to come soon...

Edit: 6 July, 2010 11:45 am

With the current parameter values of R = 1.5cm, DCA = 3cm, min # tracks = 5, the x-y vertex distribution looks like:

Changing the parameter values to R = 1.5cm, DCA = 6cm, min # tracks = 2, the x-y vertex distribution looks like:

Changing the parameter values to R = 3cm, DCA = 6cm, min # tracks = 2, the x-y vertex distribution looks like:

Changing the parameter values to R = 3cm, DCA = 3cm, min # tracks = 2, the x-y vertex distribution looks like:

Changing the parameter values to R = 6cm, DCA = 6cm, min # tracks = 2, the x-y vertex distribution looks like: