MiniBooNE BPM Monitoring System


The Bull's Eye Plot

General Description

This picture shows, from left-to-right and top-to-bottom, the beam position at 873, 875, and just in front of the target. Next is shown the 15 most recent spills projected to the target. Finally, data from multiwires at the 875 and tgt positions are shown.

The circles are the ideal positions for the beam. At the target, and just upstream of the target, the radius of the circle is 0.5 mm. At the other locations, the radius is 1 mm

As previously stated, the target scatter plot shows the 15 most recent spills. The other plots show the 10,000 most recent spills.

This page autorefreshes every 30 seconds. However, like all software, it will, occassionally stall -- so check the timestamp. If the timestamp is not up to date, reload the web page. If that does not work, the program must be restarted from the MiniBooNE control room. To restart the program, follow these instructions. If beam is off for one hour or more, this program will automaticly stop.

You can also watch what AutoTune is doing by calling up this link, choosing menu "W", and finally double-clicking on "Autotune (MiniBooNE)". Once AutoTune is running, click on "Servlet", then "View Histograms..." -- this will produce the AutoTune version of the BullsEye plot. Please be aware that the two programs are completely separate. The BullsEye plot was written for MiniBooNE, using the experiment's resources. AutoTune was written for AD/Operations and is designed for their use.

873 BPM

E:HP873 amd E:VP873 are located upstream of the final-focusing triplet. Because there are a trim magnets located between these devices and the triplet, the beam may not be centered.

875 BPM

E:HP875 amd E:VP875 are located downstream of the final-focusing triplet.

Target BPM

There are four target BPM, which can be read out through two different sets of electronics. Right now, the first and fourth BPM are being read out through the log-amp electronics.

Projection to Target Center

The fifteen most recent pulses are projected to the center of the target. Data from the 875 and log-amp BPM are used. Because there are no intervening optics, a straight line is drawn between the BPM and extrapolated to the target center.

Multiwire data

A multiwire consists of 48 wires in each of the vertical and horizontal planes. The spacing for the 875 multiwire is one millimeter; for the target multiwire it is one-half millimeter. Data is returned as two vectors, one for the horizontal plane and one for the vertical plane. Each vector contains 48 elements, one elements per wire. The signal range is -2.0 to +10.0 volts; because we are taking positive beam, we expect the signal to be positive.

To produce these plots, any signal less than zero is assumed to be noise and set to zero. Next, the outer product of the vertical and horizontal vectors is calculated, and the square root of the result is taken. Data is accumulated for 10,000 spills (just like the BPMs). This should yield a reasonable representation of the physical spot size, assuming minimal cross-plane coupling.