Si-PIN X-123 Detection System

X-123 – a complete solution for gamma-ray detection in one compact, hand-held package

Without using liquid nitrogen!

Fig. 1.

Includes:

• Gamma detector and preamplifier
• Digital Pulse Processor and MCA
• Power supply and software compatible with PC

Advantages

• Compactness of the system
• Ease of use
• Small size (7 x 10 x 2.5 cm)
• Low power consumption (2.5W)
• Light weight (180g)
• USB and RS232 connections
• Compatible with other detector types

Application

• RFA
• RoHS/WEE compliance for instrumentation
• Control of technological processes
• Art and Archaeology

Detector

• Si-PIN Gamma Particle Detector
• 2-stage thermoelectric cooler
• Area: 6 to 25 mm2
• Thickness: 300 and 500 microns
• Multi-channel collimator

General characteristics

• Resolution: 145 to 260 eV FWHM at 5.9 eV
• Optimal energy range: 1 keV to 40 keV
• Maximum counting speed: up to 2 x 10 5 events per second

*The specific implementation depends on the configuration that is most applicable to the given task.

Fig. 3. Spectrum of 55 Fe obtained using a 6 mm2 / 500 µm detector.

The X-123 is the result of 14 years of development of gamma detectors at Amptek. The company's philosophy has always been to produce compact, low power, high performance detectors that are easy to operate. The X-123 is an example of this philosophy and is a combination of the XR100CR detector and charge sensitive preamplifier, DP5 digital pulse processor, multi-channel analyzer (MCA), software and PC5 power supply in one housing. All that is needed is +5 V input voltage and a USB or RS232 connection to a computer.

Description

Amptek specializes in gamma spectrometers that are small, low power, and easy to use. The X-123 combines Amptek's standards with high performance components in a single package: the XR100CR detector and preamplifier, the DP5 digital pulse processor and MCA, and the PC5 power supply. The result is a complete integrated system that fits in the palm of your hand. In many available systems, the preamplifier alone is larger, heavier, and consumes more power than the entire X-123 detection system . It requires only two connections to run: +5 V and a standard RS-232 or USB connector.

The detector has a Si-PIN photodiode: gamma particles interact in silicon and create on average one electron-hole pair, each of which accounts for an energy loss of 3.62 eV, which is the input signal.

The detector is mounted on a thermoelectric cooler on a base with an input field-effect transistor and is connected to a charge-sensitive preamplifier. The thermoelectric cooler reduces noise from the electronics in the detector and preamplifier, but the cooling remains open and understandable to the user: it works like a normal air conditioning system. The charge-sensitive preamplifier uses classic feedback, resetting the pulse to its initial position via high voltage to the detector.

The DP5 Pulse Processor is a digital processor that replaces both the pulse amplifier and the multichannel analyzer (MCA) found in most similar systems. The use of digital technology improves the following key parameters:

1) better performance, better resolution and higher counting speed;

2) excellent flexibility in configuring options;

3) Improved stability. DP5 digitizes the output signal from the preamplifier, applies real-time digital processing to the signal, detects the peak amplitude and (digitally) and collects these values into memory histograms, generating an energy spectrum. The spectrum is then transmitted to the upper level - the user's PC.

DP5 has 6 main function blocks to implement the following functions:

1) analog input filter;

2) ADC;

3) electronic signal generator;

4) pulse selection logic;

5) histogram;

6) connecting wires (which include the microcontroller) and software.

There is one power supply, the PC5. The input voltage is approximately +5 V, with a current of 200 mA. The PC5 uses switches to generate all the low voltage needed by the digital processor and preamplifier. It also includes a high voltage to generate bias voltage up to 400 V, and powers a thermoelectric cooler that provides a closed-loop feedback loop with a maximum temperature range of 85 C. Both of these components are customized for each detector at production.

The entire system is housed in a 7 x 10 x 2.5 cm3 aluminum case. This is the standard configuration, requiring only two connections: +5 V and a USB or RS232 connection to a PC. The DP5 supports several additional inputs and outputs if the X123 is integrated with other equipment. This includes a multi-channel analyzer circuit and selective signal memory, time control, and a single-channel analyzer.

Fig. 4. X-123 architecture and connection diagram.

X-123 Specifications

Options

• Other thickness of beryllium window (0.3mm - 7.5 µm).
• A set of collimators for large flows.
• Vacuum execution
• As a component in the production of electronic systems

Fig. 5. Versions of the X-123 detector.

Fig. 6. X-123 with PA-230 preamplifier in the case. This option is similar to the X-123 detector itself, except that the detector/preamplifier is removed from the electronics case and connected to it via a flexible wire.

Fig. 7. Resolution versus Formation Time/Peak Time for Si-PIN and SDD detectors.

Fig. 8. Resolution versus count rate for different peak times.

Fig. 9. Dependence of the input count rate on the output one.

Using a collimator

All Si-PIN detectors are equipped with built-in collimators to improve spectral sensitivity. Gamma particles interact near the boundary of the active volume of the detector and can produce small pulses due to partial charge collection. These pulses result in a spectrum, which, in some cases, blurs the useful signal. The built-in collimator limits the flow of gamma particles in the active volume, where a “clean” signal occurs. Depending on the type of detector, collimators can:

• improve signal to noise ratio
• reduce the border effect
• eliminate false peaks

Vacuum execution

The X-123CR can operate in both air and vacuum at pressures up to 10-8 Torr. There are two options for operating the X-123CR in vacuum: 1) The entire X-123CR detector and preamplifier can be placed inside the chamber. In order to avoid overheating and dissipating the 1 W of power required to operate the X-123CR, good thermal conductivity to the chamber walls must be ensured using four mounting holes. 2) The X-123CR can be located outside the vacuum chamber, a standard ConFlat port is used for X-ray detection in the chamber.

Efficiency curves

Fig. 10 (linear) Shows the true total energy detection efficiency for the XR-100CR detector. This efficiency corresponds to the possibility that gamma particles will penetrate the detector and lose all their energy inside the detector as a result of the photoelectric effect.

Fig. 11 (logarithm). Shows the probability of interaction when a photon passes from the probability of photoelectric interaction as a result of which the total energy will decrease. It is shown that the photoelectric effect predominates at low energies, but at energies above 40 keV the Compton effect predominates, when photons lose almost all their energy in the detector.

X-123 Application: RoHS/WEEE Compliance

RoHS/WEEE [Restriction of Hazardous Substances/Waste Electrical and Electronic Equipment] directives require the electronics industry to certify their products to the maximum degree of composition of their constituent components. The X123 can be used to monitor RoHS/WEEE compliance as part of a quality program such as XRF. It allows users to measure the concentration of individual elements quickly, accurately and non-destructively. Companies can monitor supplier compliance and demonstrate their own compliance. The X123 provides OEMs and end users with a powerful gamma spectrometer in a convenient, small, easy-to-use instrument that can be quickly deployed to minimize time to market. There are no additional engineering requirements for the spectrometer and all components can be manufactured in-house. All that is needed is a +5V supply and a USB or RS232 connection to a PC.

The X-123 does not sacrifice performance for size. The 5.9 keV peak resolution of 55 Fe ranges from 145 eV FWHM to 260 eV FWHM depending on detector type and acquisition time. This makes the X-123 a turnkey system, an excellent choice for rapid product analysis, and provides OEMs with fast time to market.

Fig. 12. RoHS/WEEE spectrum examples.

X-123 Examples of Si-PIN Detector Measurement Results

Fig. 13. X-ray fluorescence analysis of a multielement sample of 109 Cd.

Rice. 14. XRF analysis from Pb to 109 Cd.

Fig. 15. XRF analysis of several elements based on PC from 109 Cd.

Fig. 16. X-ray fluorescence analysis of various elements from 109 Cd.

Construction. Dimensions

Fig. 17.

Joining

Fig. 18. X-123 with mounting plate and corner mount.

Fig. 19. Mounting plate for X-123.

Fig. 20. Corner fastener for X-123.

Complete system for XRF analysis

Fig. 21. Complete system for XRF analysis.

The general XRF system includes:

• X-123 gamma spectrometer;
• Mini-X USB X-ray Tube Controller;
• XRF-FP Software for quantitative analysis;
• MP1 XRF mounting plate.