Oak Ridge, TN

Changer Labs
"Changing the way you handle samples"

Home  |  Alternate Configurations  |  Software  |  Contact Us  |  Video Clips  |  Download Data Sheet
Applications  |  Links  |  Does Automation Make Sense?


The Assistant - changing the way you handle samples!
Front View of the Assistant

The “Assistant

  • Compatible with all popular MCAs
  • Accommodates all streamlined cryostats
  • Handles samples from <¼ to 3 in diameter
  • High Capacity, up to 200 samples, with 20 mL LSC vials
  • Suitable for well or coaxial Germanium or NaI detectors
  • Table top configuration available for NaI
  • Highly flexible design easy to scale up or down
  • Small foot print for efficient space utilization
  • Power lid option for 4 pi shielding
  • Automated pull back for dead time control in NAA
  • Stainless Steel drip pan for easy clean up
  • Removable sample trays
  • Safe shutdown in the event of power loss
  • Complete systems available including detector, electronics, and PC-based MCA

The Assistant from Changer Labs has been designed to fill the need for an easily customized gamma sample changer that can handle the smaller samples of applications such as NAA or the environmental samples now possible with the new larger Germanium detectors. The Assistant's design is highly flexible so that the sample staging area and shielding can be scaled up or down to tailor the system to the sample size and number needed. The Assistant is equally adept at placing a sample in a well detector or placing the sample on the end cap of a coaxial detector. NaI detectors can be accommodated in either the floor mount configuration or a table top version. The system software adapts to multiple sample trays where the size and spacing of samples is independently defined for each tray.

People doing gamma spectroscopy in bioassay, radiochemistry, waste characterization, sediment analysis or environmental radiation monitoring with either germanium or sodium iodide detectors can often benefit from a gamma sample changer that automates routine counting procedures.

Assistant's structural components are standard industrial extrusions and linear motion bearings. They are available in a wide variety of lengths so that the width, depth, and height of the cabinet and the length of the vertical travel can be customized to optimize sample capacity and shield requirements for any application.

Sample containers from 10 mm test tubes to 3 inch diameter wide mouth jars can be accommodated. The samples are loaded into a removable sample tray that is positioned over a stainless steel drip pan for easy decontamination. Sample container size determines minimum spacing between samples in the tray which determines the maximum number of samples for the system. High sample density in the tray helps to minimize floor space requirements. The sample positions in the tray are defined in software for maximum flexibility

The system shield can range from a simple insertion shield with no lid, to a full 4 pi shield with an automatic top as shown below. There are several standard shields available that are designed to fit the sample size that will be utilized. Most shields use lead bricks stacked into a steel shell and lined with either copper/cadmium (Cu/Cd) or copper/tin (Cu/Sn). Standard wall thickness is 4 inches but 6 inches is available. Extra shielding can be added between the sample storage area and the counting cavity via an optional separate 4 inch wall on the sample storage area side.

Keeping the counting cavity small minimizes the total shield weight. The system design leaves ONLY the detector and the sample inside the cavity during counting. This helps maintain the lowest background possible.



Lead shielding with graded lining

A self-centering, four point hand is used to provide a wide tolerance for variations in the sample container’s dimensions, weight, and positioning. The hand features a positive close and grasp design, so that an unexpected power loss will not cause the sample to drop. The hand senses the absence of a sample when the hand fully closes and a sample is supposed to be present. This condition is treated as a fault condition by the software and results in a safe system shut down.

The system has three operating modes: Master, Slave, and Local. Slave mode is the most typical the whole sample changer is controlled as a peripheral device with high level commands such as load#1, loadnext, reset, unload. Control of the spectral acquisition is through the MCA’s native script/batch/job language. Responsibility for defining the sample queue and taking control of the MCA system rest with a Changer Lab Windows program that runs on the MCA computer system.

In the Master mode the Assistant's software is in control of the sample queue and runs the MCA system through MCA batch commands. Local control allows the user to control all axis movements with easily accessible switches for set up without a computer.

With a significant number of samples loaded into a changer tray there is always the possibility of a hot sample interfering with the background of a low level sample. This may require more shielding between the samples in the tray and the sample in the counting position than is required in the counting shield in general. In this situation the system can be supplied with an additional shield wall between the sample tray and the counting shield.

The system can be configured for either NaI (Tl) or Germanium detector systems. Any standard detector cryostat can be accommodated. Vertical dipstick Germanium detectors have the dewar located underneath the shield inside the system cabinet, while horizontal dipsticks can have the end cap penetrate the shield side wall. An "in-line" type cryostat simplifies the installation and removal of the detector. Well detectors do not represent any special problems as long as the container is longer than the well depth so that there is a place for the hand to grab the sample.

Using two detectors at the same time is possible, as is a split spectrum with low energy and high energy spectra accumulated simultaneously from a single detector

4 prong hand handles a variety of sample sizes and shapes
Closeup of Assistant, showing optional monitor and changer assembly
Overview of single sample holder Assistant

Potential applications for the Changer Lab's Assistant, Gamma Sample Changer: Basically any gamma spectroscopy application with significant numbers of samples can benefit if the samples are relatively small and the detector is either HPGe germanium or NaI with solid or well type detectors

  • Neutron Activation Analysis (NAA)
  • Waste characterization
  • Bio-Assay analysis
  • Food Stuff monitoring
  • Ra-228 in drinking water by HPGe gamma spectroscopy
  • Environmental gamma monitoring
  • Automated well detector spectroscopy (HPGe or NaI)
  • Health Physics applications with large numbers of small samples
  • Air filters and swipes for isotope specific analysis
  • Sediment and Oceanography samples with limited volumes and moderate count times
What's Next?
We'll update this web site based upon our customer, and your, suggestions. Why not bookmark this page and check back later? Questions or Comments for now?

Home  |  Alternate Configurations  |  Software  |  Contact Us  |  Video Clips  |  Download Data Sheet
Applications  |  Links  |  Does Automation Make Sense?

Copyright © 2004-2021 Changer Labs; all rights reserved.
WebWork: Advanced Marketing Services