Capintec CAPTUS 600 - YES or no Answers; Counting Methods

CAPINTEC, INC. CAPTUS
®
600
YES or NO Answers
Whenever a question is asked, it must be answered Yes or No.
Answer the question by pressing Y and ENTER for YES or N and ENTER for NO.
You can change a YES to a NO answer, and vice versa, if you have not yet pressed the
ENTER key. When you press Y, the word “YES” appears on the screen. If you want to
change this answer to NO, press the backspace BSP key. The word “YES” disappears. Then
press N. The word “NO” appears. Then press the ENTER key to confirm this answer.
COUNTING METHODS
The CAPTUS
®
600 offers two methods of counting time: REAL time and LIVE time. The
Multichannel Analyzer (MCA) in the CAPTUS
®
600 measures each pulse that comes out of
the Sodium Iodide/Photomultiplier tube detector. To measure each pulse requires a finite
amount of time. During the time the MCA is measuring the pulse another pulse cannot be
measured. Any other pulse that occurs during this time is not measured, and therefore, lost.
During this time, the MCA is said to be DEAD.
Live Time is defined as the time during which the MCA can actually measure a pulse.
Real Time is defined as the actual clock interval.
The Percent Dead Time is the Dead Time divided by the clock interval expressed as percent.
The Percent Dead Time increases as counting rate increases. To ensure accurate results,
the Dead Time should not exceed 80%. Moving the source further away from the detector
can decrease the Percent Dead Time. Dead Time is shown in the upper right hand corner of
all measurement screens and is abbreviated as dt.
When selecting a counting method, it is possible to choose a time base called LIVE or REAL.
If Live Time is chosen, the CAPTUS
®
600 counts until the MCA's “LIVE” time reaches the
specified counting period. The actual counting time is always greater than or equal to the
requested live time.
If Real Time is chosen, the CAPTUS
®
600 counts until the actual clock interval reaches the
specified count period. The count rate is calculated from measured Live Time.
November 07 GENERAL OPERATING OVERVIEW 3-9