Harshaw TLD Model 3500

Background

Thermoluminescence (TL) technology is commonly used in medicine, such as in radiation therapy for dose measurement on the skin and within the body to assess treatment and ensure that safe radiation levels are maintained.  

The Thermo Scientific™ Harshaw TLD™ Model 3500 Manual Reader provides manual readout of TL chips, disks, rods and cubes in a broad variety of sizes. This reader is suitable for all kinds of applications that require thermoluminescence dosimetry (TLD) detectors. Due to planchet heating, this versatile model is able to read powders, an essential feature for food testing and analysis.

Description

The Harshaw TLD Model 3500 Manual Reader includes a sample drawer for a single element TL detector, a linear, programmable heating system, and a cooled photomultiplier tube with associated electronics to measure the TL light output. Planchet heating incorporates a welded thermocouple for best temperature reproducibility. The operational software, Thermo Scientific WinREMS™, which runs on a separate computer, provides the user interface, the reader control and the applications software.

Looking for Quality Assurance? The Harshaw TLD 3500 also addresses standard EN 1788 related to Irradiated Food Testing.

Technical Specifications

• Multiple, programmable, linear heating cycles such as pre-read anneal, acquire and post-read anneal cycles.
• Typical cycle time per detector: typically, 30 seconds.
• Heating temperature capability up to 400°C (standard model) or 600°C  (high-temperature version).
• Thermoelectric PMT cooler for maximum gain stability.
• Seven-decade glow curve acquisition range.
• Options include:
• Glow curve deconvolution software (WinGCF Software)
•  Various types of neutral density filters to extend the high measurement range
• TL element specific planchets for best possible reproducibility
• Easy to operate, service and maintain.
• Size: 31 × 32 × 47 cm.
• Weight: 25 kg

 Instrument Performance

• Dynamic Range: 7 decades.
• HV Stability: ± 0.005% per hour, ± 0.02% per 8 hours.
• Linearity: Better than 1%.
• Test Light: Temperature-Stabilized LED
• Electrical Supply:
• Selectable, 110/120 VAC ± 10%, 60 Hz or 220/240 VAC ± 10%, 50 Hz
• Nitrogen Supply:
• Purified (99.995%), dry
• Pressure: 1.5 to 3 kg/cm2
• Flow Rate: 130 liters/h, subject to external regulation
• Note: The use of nitrogen is optional. Absence of nitrogen will result in understated performance.
• Operating Temperature: 15° to 40°C (59° to 104°F)
• Storage Temperature: -10° to 60°C (14° to 140°F)
• Humidity: Functions within specification after 24-hour exposure to 90% humidity and subsequent 6-hour recovery with use of the nitrogen supply
• Ambient Light Exposure: Functions within specifications when exposed to ambient light up to 1,000 Lux with cover on the reader​

Dosimetry Performance Using LiF:Mg,Ti (TLD-100/600/700):

• Nearly Tissue Equivalent
• Radiation Types
• Photons (E > 5 keV)
• Electrons (E > 70 keV)
• Neutrons (from thermal energies up to 100 MeV, TLD-600 only)
• Measurement Range
• 10 µGy to 1 Gy (linear)
• 1 Gy to 20 Gy (supralinear)
• Detection Threshold: < 10 µGy based on 2.26 standard deviations for 10 sequential readings of an unexposed dosimeter
• Repeatability: Less than 2% variation based on one standard deviation for 10 sequential measurements of 1 mGy Cs137
• Residual TL Signal: < 0.2% of reading
• Fading: < 20% in 3 months without thermal treatment; < 5% in 3 months using pre-read anneal or glow curve deconvolution software (WinGCF Software)
• Batch Uniformity: ± 30% from the factory standard
• Reuse: Typically, > 500​