AccelNET AMS provides a complete facility to control AMS data collection. A supervisory program controls the changing of the cathode in the ion source and starting and stopping of data collection. The status of the accelerator is monitored, and the program will pause data collection in the event of a problem such as a beamline valve closing due to a vacuum fault. Data collection startup is inhibited in cases where the operator may have failed to open a Faraday cup or a beamline valve or other accelerator problems may interfere with data collection.
The supervisory program may be configured to call other programs at various points in its execution. For example, one might implement a program to log accelerator parameters and run this program each time a cathode is measured.
The supervisory program operates from a list of cathodes (a runlist) generated by the user. This list specifies measurement parameters including the number of times to measure the cathode, the warmup time, the data collection time and the data collection mode.
The cathodes may be divided into groups within the list and each group measured consecutively or independently. Data may be collected for a fixed amount of time or a fixed number of rare isotope events.
When collecting for a fixed number of events, a time limit is also used to prevent excessive collection time on cathodes which have low count rate or problems such as low current. This mode collects until one of the limits is reached.
The cathode runlist may be traversed in two ways.
One way is to measure each cathode once and then go to the next cathode in the list. When this method is used the cathode list is traversed as many times as necessary until all cathodes in the list have been measured the number of times specified for each cathode.
The second way to traverse the cathode list is to measure each cathode repeatedly until the cathode has been measured the number of times specified in the runlist. When working in this mode another program in AccelNET can be used to analyze the measurements as they occur and make decisions about whether to go on to the next cathode or measure the same one again.
This is typically used in applications where it is desired to make several short measurements of a cathode and after some minimum number of measurements make a decision based on the scatter of measurements whether to measure again or go to the next cathode.
AccelNET provides a program module which makes this decision based on the results of the most recent N number of runs. It is possible to write program modules using other selection criteria.
IsoNET also provides a "best run" selection feature for off line analysis.