LB 761 GD α-β Low-Level Counter for 200 mm Planchets

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The measuring system LB 761 GD α-β Low-Level Counter for 200 mm Planchets allows the simultaneous measurement of α- and β- activity of a sample in two separate measuring channels. The background count-rates of the system LB 761 are extraordinarily low, so that good detection limits can be achieved.

Components
Counter: LB 6307 with sample tray
Lead shielding: 10 cm thickness with 78 standard bricks, and 4
bricks machined, 4 pi shield to reduce ambient
radiation.

Weight approx. 800 kg
Alpha-Beta Discriminator: LB 2028-1
Counting gas: Standard P-10 gas (Argon-Methane 90:10)
Operating voltage: Measuring counter1300 V
1700 V
Shielding counter
Window: Hostaphan-foil, alu- steamed on both sides 0.4 mg/cm²
Efficiency for extended soures
(sources 200 mm Ø, surface 11 mm each below upper
edge of the tray, the efficiency can be inreased by placing
the α-source on a higher level)
241Am
90Sr/90Y
14C
18%
46%
26%
Background
(measured with a 200 mm tin-plated planchet)
α-channel
β-channel
approx. 0.02 cps
approx. 0.15 cps
Spillover β- in α-channel
α- in β-channel



< 0.01 α-counts per 1000 β-counts
depending on the type of
nuclide and on self-
absorption of the source.
Typical value for 210Po 2 %
Dimensions of the counting chamber
including shieldi
270 x 600 x 600 mm³ (H x W x L)