Planar Calibration Standards

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This series includes the Extended Alpha or Beta Standards (EAB) and the Large Decade Standards (LDS). These standards are used for the calibration of alpha, beta and wide area counters. EAB standards are typically disks and LDS standards are either large square or large rectangular standards. All sources are NIST traceable based on output or contained activity. NIST certification on contained activity is not available on some alpha and beta sources. The surface emission rate in 2π is given on the certificate and is NIST traceable for most nuclides. Note that the emission rate for a given energy spectrum is a function of detector geometry, gas composition, pressure and material of construction, so that virtually every detector may have a different response. All electroplated sources are prepared +/- 30% of nominal activity.

EAB—Unmounted Foil
These are rugged sources designed primarily for the calibration of portable survey instruments in the plant or field.
These sources are annealed, so that the active surface of the source may be gently wiped our touched without removing activity from the surface.

Planchet—EAB-PL
These standards simulate cupped planchet samples and can be used as calibration or performance check standards.

Ring and Disk—EAB-LB
EAB-LB disk standards are designed to check the performance and to determine the efficiency of low level counting systems such as proportional counters. The stainless steel disk containing the active element is surrounded by an aluminum ring which holds the window assembly in place.

Planchet—EAB-PL-FP
Filter paper standards are designed to simulate surface smears and thus establish efficiencies for smear samples of similar construction. Since alpha and beta particlesare easily attenuated by the filter paper, the actual surface emission may not appear to relate to the contained activity. Therefore, efficiencies derived with such standards
have a large uncertainty caused by the inherent absorption. Filter paper standards are most useful in establishing action levels for smear samples. The calibration certificate provides both the contained activity and the surface emission rate of the standard.

Beta standards are covered with 0.9 mg/cm2 aluminized Mylar. Alpha standards are covered with 100 - 200 μg/cm2 of acrylic. In addition to the mounts described above, the active filter paper can be mounted in any of the EAB-LB or EAB-PL configurations.

Ring and Disk—EAB-LB-FP
The stainless steel disk containing the active element is surrounded by an aluminum ring which holds the window assembly in place.

Large Area Standards—LDS Sources

The Large Area Standards (LDS Series) are intended for the calibration of large area survey probes currently
used for area and personnel monitoring.

A comprehensive range of alpha and beta energies is listed in the tables on pages 76–77. Requirements for other
nuclides, activity levels and larger geometries can be accommodated upon request.

Active elements are prepared by electroplating or by evaporative deposition.

Sources may be supplied with aluminum or Mylar windows or as uncovered sources depending on the nature of the active deposit and the emitted energy.

Electroplated standards are supplied on an aluminum or stainless steel backing plate. Deposited standards employing Mylar covers are supplied with a plastic backing plate. All standards are supplied in plastic storage boxes.

Two Standard Sizes are Available

Model 1620: 3.94” x 3.94” (100 mm x 100 mm) active area

Model 1621: 3.94” x 5.91” (100 mm x 150 mm) active area

Calibration: the contained activity is certified in nanocuries or microcuries and becquerels or kilobecquerels and is NIST traceable ± 5%.

The surface emission rate in 2π is given on the certificate and is NIST traceable for most nuclides.

Standard Sets for Specialized Applications

Decade Standard Sets (LDS-300) are designed to routinely check the tracking of G.M. and proportional counters from scale to scale. They may be supplied as an alpha, low energy beta, or high energy beta/gamma set. Each set is supplied as 3 standards with activities at 1,000 dpm, 10,000 dpm and 100,000 dpm (16.7 Bq, 166.7 Bq and 1.67 kBq). Each source is NIST traceable ± 5% on contained activity.

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