產品介紹∣用於閃爍體探測器和 PMT 的 OEM 數位脈衝處理器

特點
Features

Amptek DP5G 套件是一款先進、高性能、低功耗的數位脈衝處理器，設計用於閃爍光譜測量系統。它連接到 PMT 的陽極，包括一個電荷靈敏前置放大器和一個數位脈衝處理器，該數位脈衝處理器取代了傳統核光譜測量系統中的整形放大器和 MCA。該套件包括用於為這些電路供電的所有電源，並採用易於使用的標準介面（USB、乙太網路…等）。與傳統系統相比，DP5G 具有多種優勢，包括更高的性能、更高的靈活性、小尺寸和低成本等。

DP5G 套件由三塊堆疊在一起的電路板組成：DP5G 數字脈衝處理器板、PCG 介面板和 AUX 板。整個系統還必須包括一個探測器模組（閃爍體探測器/PMT）和一個高壓電源（未隨附）。

DP5G 象徵著最新一代的數位脈衝處理技術。它是 DP5 的升級版，針對閃爍讀數進行了最佳化。 DP5 技術有更快的峰值時間、改進的堆積刪除和脈衝形狀鑒別、更好的死區時間校正、“清單模式”等附加功能以及增強的介面。

如需了解包括探測器和高壓電源在內的完全整合、與堅固耐用的系統，請參閱 Gamma-RAD5。

如需了解包括所有電子元件和高壓電源的傳統電子管底座，請參閱 TB-5。

特點

整合了前置放大器、整形放大器和 MCA ，專為閃爍系統最佳化設計。
可處理 PMT 陽極訊號，提供完整光譜。
包括用於前置放大器和處理器的所有電源。
標準USB和乙太網路介面。
整個系統可以通過 USB 或乙太網路供電。
適用於 OEM 或特定實驗室使用者。
高度可配置性
低功耗：600 mW（典型值）
清單模式

方塊圖

DP5G 套件方塊圖

DP5G 電荷放大器

DP5G 中的類比前置濾波器不同於 Amptek 其他數位處理器中的類比前置濾波器：DP5G 的第一級是電荷放大器，而不是電壓放大器。這種差異對 DP5G 的性能以及如何與它連接具有重要影響。下圖顯示了 DP5G 電荷放大器以及它通常如何連接到 PMT。

DP5G 電荷靈敏前置放大器配置

快速閃爍體探測器

電荷放大器允許 DP5G 與時間常數非常快的閃爍體探測器一起使用。客戶經常會問：「由於 ADC 以 80 MHz （12 ns）運行，那麼如何才能測量衰減時間為 10 ns 的閃爍體探測器？ “流入 J2 的電流脈衝 Iin（t）可能很快，但 U11 的輸出是 Iin（t）的時間積分（用 3.2 μs 的時間常數求微分）。更快的閃爍體探測器會為U11的輸出提供更快的上升沿。下圖顯示了三個不同時間常數的模擬結果。 DP5G 可以準確地數位化非常快速的閃爍體探測器，因為它數位化的是電荷放大器的輸出，而不是輸入電流。

圖左：具有 10 ns（紅色）、20 ns（藍色）和 230 ns（黑色）時間常數的閃爍體探測器的類比輸入電流。圖右：相同三種情況下U11的模擬輸出。

電流輸入

DP5G 的輸入必須是電流，而不是電壓。 U11 對來自 PMT 的電流脈衝進行積分。一些使用者在 PMT 和 DP5G 之間插入一個跨阻放大器，為 DP5G 提供電壓輸入。這在標準 DP5G 配置中不可行。用戶可以重新配置電路以處理電壓輸入，但標準 DP5G 需要輸入電流脈衝。

PMT 極性

大多數應用在 PMT 陽極上使用正高壓，並將陰極接地。但是，如果將陰極保持在負高壓且陽極位於虛擬接地，DP5G 可以正常工作。在這兩種情況下，電子脈衝從陰極加速，並穿過耦合電容器注入 DP5G。

DP5G 可以同時使用正負高壓極性

機械部件

客製化配置

DP5G 套件旨在為使用者提供易於使用的完整閃爍體脈衝處理系統。在定製或嵌入式應用中，如果系統中其他地方有電源和連接器，則可能不需要 PCG 板。有關這些應用的更多信息，或者如果您希望只使用 DP5G 板而不使用接口板或 AUX 板，請聯繫我們。

如需了解更多信息，請立即聯繫我們！

The Amptek DP5G Kit is a state-of-the-art, high performance, low power digital pulse processor designed for use in scintillation spectroscopy systems. Connected to the anode of a PMT, it includes a charge sensitive preamplifier and a digital pulse processor, which replaces both the shaping amplifier and the MCA in a traditional nuclear spectroscopy system. The kit includes all the power supplies necessary to power those circuits and uses standard connectors for easy of use (USB, Ethernet, etc.). The DP5G offers several advantages over traditional systems, including higher performance, enhanced flexibility, small size, and low cost.

The DP5G Kit consists of three boards stacked together: The DP5G digital pulse processor board, the PCG interface board, and the AUX board. A complete system must also include a detector module (scintillator/PMT) and a HV supply (not included).

The DP5G represents the latest generation in digital pulse processing. It is a variant of the DP5, optimized for scintillation readout. The DP5 technology includes faster peaking times, improved pile-up rejection and pulse shape discrimination, better dead time correction, additional features such as a “List Mode,” and enhanced interfaces.

For a completely integrated and ruggedized system including the detector an HV supply please see the Gamma-RAD5.

For a traditional tube base which includes all the electronics and HV supply please see the TB-5.

Features

Integrated preamplifier, shaping amplifier, and MCA optimized for scintillation systems
Processes PMT anode signal, giving complete spectrum
Includes all power supplies for preamplifier and processor
Standard USB and Ethernet connectors
Whole system can be powered by USB or power over Ethernet
For OEMs or custom laboratory users
Highly configurable
Low Power: 600 mW typical
List Mode

Block Diagram

Block diagram of the DP5G Kit.

DP5G Charge Amplifier
The analog prefilter in the DP5G differs from that of Amptek’s other digital processors: the first stage of the DP5G is a charge amplifier rather than a voltage amplifier. This difference has important implications for the performance of the DP5G and how one interfaces with it. The plot below shows the DP5G charge amplifier and how it is typically connected to a PMT.

DP5G charge sensitive preamplifier configuration.

Fast scintillators

The charge amplifier permits the DP5G to be used with scintillators having a very fast time constant. Customers often ask “Since the ADC operates at 80 MHz (12 ns), how can you measure a scintillator with a 10 ns decay time”? The current pulse Iin(t) into J2 may be fast, but the output of U11 is the time integral of Iin(t) (differentiated by a 3.2 µs time constant). A faster scintillator simply gives a faster rising edge to the output of U11. The figure below shows simulated results for three different time constants. The DP5G can accurately digitize very fast scintillators, because it is digitizing the output of the charge amplifier, not the input current.

Left: Simulated input currents for scintillators with 10 ns (red), 20 ns (blue), and 230 ns (black) time constants. Right: Simulated outputs for U11 for the same three cases.

Current input

The input to the DP5G must be a current, not a voltage. U11 integrates the current pulse from the PMT. Some users have inserted a transimpedance amplifier between the PMT and the DP5G, providing a voltage input to the DP5G. This will not work properly with the standard DP5G configuration. The user can reconfigure the circuit to handle voltage inputs but the standard DP5G requires an input current pulse.

PMT polarity

Most applications use a positive HV on the PMT anode, with the cathode grounded. But the DP5G works fine if the cathode is held at a negative HV and the anode is at virtual ground. In both cases, a pulse of electrons is accelerated from the cathode and injected across the coupling capacitor into the DP5G.

Both positive and negative HV polarity can be used with the DP5G.

Mechanicals

DP5G Kit mechanical.

Custom Configurations

The DP5G kit is designed to provide the user with a complete pulse processing system for scintillators that it easy to use. In custom or embedded applications the PCG boards may not be necessary if power supplies and connectors are available elsewhere in the system. Contact Amptek for more information on these applications or if you wish to use only the DP5G board and not the interface or AUX boards.