Channel Access Multichannel Analyzer


                                   Overview

This program is a display program for multichannel analyzers, which typically
consist of an analog-to-digital converter plus a histogramming memory. This
program could be used to read data from any device, and in fact the present
version obtains its data by simulation.

The program displays data in real-time at update times which can be selected
between 0.1 second and 5 seconds. The user can easily rescale the display to
zoom in on interesting features and obtain on-screen statistical information
about the data.


                             Acquisition Control

These controls allow one to turn data acquisition On and Off and to Erase the
present spectrum. The Acquisition Setup control is not implemented yet. In the
present version turning On data acquisition results in simulated data being
displayed in real time.


                              Markers and Cursor

The program has two markers, which are indicated with short red lines on the
display, and one cursor, which is indicated with a longer red line.

The left marker is positioned with the left mouse button, or by typing in a new
channel number or energy in the text widgets on the top center of the display.

The right marker is positioned with the right mouse button, or by typing in a
new channel number or energy in the text widgets on the top center of the
display.

The cursor is positioned with the center mouse button, or by typing in a new
channel number or energy in the text widgets on the top center of the display.

Statistical information on the region of the spectrum between the left and
right markers is shown at the top of the display. This includes the total
counts, background counts, net counts, total counts/second, background
counts/second, and net counts/second. It also includes the centroid, which is
the first  moment distribution of counts in that region of the spectrum, and the
full width at half maximum (FWHM), which is derived from the second moment. 
The centroid and FWHM are most meaningful if the left and right markers are
positioned on either side of a peak.


                          Regions of Interest (ROIs)

These controls are not yet implemented. They will permit one to highlight
selected regions of the spectrum in another colors and to rapidly position the
left and right markers to these regions.


                               Display Controls

The Zoom Up and Zoom Down controls expand the horizontal scale by a factor of
two each time they are pressed. The zoomed display is centered on the
position of the cursor (the longer red line).

The Display Setup screen allows one to select the vertical scaling (linear,
logarithmic), vertical autoscaling (On/Off), plot line style (dotted, solid or
histogram), plot update rate, and horizontal and vertical plot limits. The
vertical plot limits are disabled if vertical autoscaling is On.