The 10-channel Low-Level Planchet Counter LB 770 offers simultaneous, separate alpha beta measurement of 10 planchets, each up to 60 mm Ø. For each sample there are two separate measuring channels for alpha and beta activities. The planchets are arranged in a matrix consisting of 5 drawers made of copper with 2 samples each. The 10 ultra-flat flow proportional counter tubes are located directly above the planchets. The 10 measuring counters are covered at the top by a large-area flow counter tube acting as common guard counter. Slider and counter tubes are surrounded by a 100 mm thick shielding made of machined lead bricks. The 11-fold alpha/beta discriminator unit (amplifier) is located outside the lead shielding. This unit includes in a common housing the pulse preamplifier discriminators with integral discriminators (alpha and beta channels for direct connection of measuring counter tubes and a discriminator with integral threshold and pulse shaper module for connection of the guard counter tube. It supplies standard pulse to the interface unit.

The major advantages compared with single detector automatic sample changers are:

• higher throughput or large number of samples
• the count results are available 10 times faster with equal statistical accuracy for each individual sample 
• with the same overall counting time as before, the statistical accuracy is three times higher
• instant detection of high-activity outlier samples without having to wait for completion of the counting process 
• extremely low beta background < 1 cpm