Berthold's measuring solution with vacuum-PMTs
Their widespread adoption is a testament to their proven performance and reliability. The established reputation of vacuum PMTs has led to their integration into various analytical instruments and measurement systems used in industrial processes. One significant advantage of vacuum PMTs in the process industry is their remarkable resilience to temperature variations across a wide range. This immunity is particularly valuable in industrial settings where ambient temperatures can fluctuate significantly. The well-known technology associated with vacuum PMTs is another key factor contributing to their widespread use in the process industry. Over time, components of a vacuum PMT may degrade, affecting performance; however, the well-established nature of these devices allows for effective monitoring and correction of these effects. This reliability is essential in industrial applications where consistency and accuracy are paramount. In addition to their temperature resilience and industry-standard status, the construction of evacuated glass tubes used in vacuum PMTs becomes more and more robust. These tubes are designed to withstand most harsh environmental conditions.
Benefits of Vacuum-Photomultiplier tubes
Vacuum PMTs find extensive application in the process industry due to their immunity to temperature fluctuations, well-known technology with effective ageing compensation, industry standard status, and robust construction. These qualities make vacuum PMTs indispensable tools for precise measurements and reliable data acquisition in various industrial processes.
Graphical schematic of a vacuum PMT with all main components
Detailed descriptions of our photomultiplier technologies
Photomultiplier technologies | ||
|---|---|---|
Installation size (length) | 5 – 20 cm | 0.5 – 1 mm |
| Power consumption | Approx. 12 W | Approx. 30 mW |
Stability | ≤ 0.002 % per °C | ≤ 0.01 % per °C |
Temperature dependency | Slightly dependent | Moderately dependent |
| Quantum efficiency* | 30 – 35 % | 30 – 50 % |
| Aging | Several significant effects e.g. “yellowing”** | No significant effects |
*Quantum efficiency (QE) is a measure of how good a photodetector is at turning light into an electrical signal. Think of it like a "conversion score." In terms of a radiometric detector, it can be thought of as “counting Success”. Quantum efficiency tells you how many photons manage to knock loose an electron. For example, if 100 photons hit the device and 80 electrons are released, the QE is 80%.
**Yellowing of a vacuum photomultilier tube
The “yellowing” of a photomultiplier refers to the discoloration or degradation of the photocathode or other internal components of a photomultiplier tube (PMT), which can impair its performance. This phenomenon is usually caused by prolonged exposure to environmental factors or operational conditions that induce chemical or structural changes within the PMT. The main causes are:
- UV/Radiation Damage: Alters the glass or photocathode, reducing light transmission.
- Photocathode Degradation: Chemical or thermal stress changes its spectral sensitivity.
- Ion Bombardment: Internal ions damage the photocathode, causing defects.
- Contamination/Aging: Outgassed materials redeposit, worsening discoloration.
While yellowing has a significant effect on radiometric measurement systems over time, we use our patented cosmic radiation compensation to avoid these effects. By measuring cosmic radiation from out of space, Berthold ensures that the high voltage of the detectors is automatically adjusted over time, so that the aging effects are fully compensated.
Successful applications of vacuum PMTs
The vacuum PMT technology plays a crucial role in various applications within the process industry, with vacuum PMTs being particularly prominent due to their unique characteristics. Moreover, vacuum PMTs have become the industry standard in many applications within the process industry such as the oil and gas, the petrochemical industry or the mining industry.
Berthold detectors with vacuum PMTs
The vaccum-PMT-measurement is available as a level gauge in the following SENSseries detector versions:
- CrystalSENS (point detector)
- UniSENS (rod detector)
- SuperSENS (point detector with highest sensitivity)
In PRC measurements, a point detector is preferably used, because it is easier and better to shield. Moreover the point detector is located at a significantly larger distance to the radioactive product, as it is mounted at the 100% level position.