biodex ATOMLAB 950 - Administration and Calibration Procedures; Daily Calibration and System Checks

Before using the Atomlab 950 PC for counting purposes, it is important that you take a few minutes and
prepare the system for operation. The following functions are set from the Operation screen and control
the system throughout the different program modes.
NOTE: Before you begin with this chapter, be sure to enter your facility name and address in the Site Information
area, as explained in the section on System Setup. This will allow the system to print the facility name on all
printouts
• Daily Calibration
• Chi-Square Test
• High Voltage Adjustment
• Isotope Editing
• Isotope Efficiencies
• Detector Efficiency
• Analysis (also available for each operation)
• MCA Operation
Daily Calibration
(See Figure 3-1and 3-2.)
NOTE: The system must be ON for at least one hour before performing a calibration. This will allow time for the
unit to warm-up and stabilize.
Calibration Information
A daily system calibration must be performed each day the Atomlab 950 is to be used. Separate
calibrations are performed for the probe and well. The system keeps an internal listing of its last
calibration date and displays a message that calibration is needed. The user must then either perform a
calibration or click on the prompt that a calibration will not be performed. The system will not allow
measurement procedures to commence until the calibration prompt has been answered. Standard
calibration may be performed from any operating mode.
Calibration is performed automatically from the MCA Calibration screen. This screen advises when the
last high voltage and calibration were performed for your detectors. It also checks to ensure that the MCA
box and CPU are connected and communicating with each other.
Additionally, the calibration calculates full width half max (FWHM). FWHM is determined by
interpolating between two immediate points above and below the 50% value of the spectrum peak on
both sides of the peak. The difference between the two interpolated channel numbers are then divided by
the channel of the peak itself and multiplied by 100% to arrive at FWHM. The peak is simply the
maximum value in the spectrum.
It is not required to calibrate both detectors each day unless you are going to use them. If you do not
calibrate the detector when you go to use that detector, you will get a message advising you to calibrate.
It is recommended to do your calibrations in the mornings daily so that if you need to use the system, it is
ready to go.
If desired, you may perform additional calibrations on the same day whenever you desire by clicking on
the <Calibration> mode tab.
While the daily calibration is counting, in the upper right you see the ROI counts incrementing and the
CPM incrementing as well. The elapsed time is shown next to the time button. Below the start button is a
box listing estimated time left. This gives the remaining time to complete the calibration. The spectrum
increments as you count as the packets with the data are downloaded to the computer from the MCA.
The <Abort> button is highlighted and is the default button used in this mode at this point. You will
3. ADMINISTRATION
3-1 ADMINISTRATION