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专利 C 系列低能量 X 射线窗口

与聚合物窗口不同,专利
C 系列窗口不透水

Amptek 专利“C 系列”X 射线窗口通过采用氮化硅(Si3N4)和铝涂层,将硅漂移探测器(SDD)的低能量响应扩展到了硼(B);它们只被用在我们的 FastSDD® 上。

Amptek 在推出第一款热电制冷探测器的同时也推出了一种液氮的替代物。现在,通过专利“C 系列”,我们为常规 XRF 分析提供了一种替代铍(Be)窗口的产品,与软 X 射线分析的聚合物窗口相比,它具有更高的性能。

应用

C1 窗口:实验室、台式和手持式仪器。  此窗口不透光,因此可以在普通的室内光线下使用。

C2 窗口:真空应用和扫描电子显微镜(SEM)中的 EDS(EDX)。  C2 窗口在最低能量下效率更高,但是会透光,因此必须在黑暗环境中使用。

Amptek 低能量专利“C 系列”X 射线窗口

该图显示了 NICER X 射线定时仪器上的 Amptek FAST SDD®,其中 C2 窗口在安装遮光罩之前安装在焦平面上。鸣谢:NASA/Keith Gendreau

  • 低 Z 元素的透射 +


    ElementC1C28 µm Be
    (0.3 mil)
    12 µm Be
    (0.5 mil)
    Li0%29%0%0%
    Be0%13%0%0%
    B0.06%19.7%0%0%
    C4.3%43.9%0%0%
    N20.2%59.2%0%0%
    O29.4%62%0%0%
    F46.1%69%4%1%
    Ne58.1%72.9%20%9%
    Na65.4%75.1%40%27%
    Mg70.6%77.3%59%47%
    Al75.4%80.3%73%64%
    Si64.7%81.8%82%75%
  • 规格参数 +


      C1 C2
    厚度(Si3N4) 150 nm 40 nm
    铝涂层(接地) 250 nm 30 nm
    窗口直径 6.3 mm 5 mm
    窗口面积 30 mm² 20 mm²
    网格类型 六角形硅,15 µm 厚
    开口面积网格 80% 80%
    氦气泄漏率 <1 x 10-10 mbar l/s 切勿将 C2 窗口放到 He 气体中!
    工作温度 -55°C 至 +150°C(0 巴压差)
    -40°C 至 +85°C(1 巴前方压差)
    C1 和 C2 窗口压力测试: 1.6 巴前方压差,时长 10 秒
    10 个 1 秒周期,1.6 巴前方差压

    Amptek 专利 C 系列窗口常见问题解答(FAQ)

  • 专利 C 系列窗口有哪些优点? +


    The Patented C-Series windows offer less attenuation (higher intrinsic efficiency) than the standard Be windows for X-ray energies below 1.5 keV (for elements below Al). The C windows are about a factor of 2 more efficient for Na Ka X-rays (at 1.04 keV) than the thinnest Be window (8 µm). With Be windows it is virtually impossible to measure elements below Na in the periodic table, and even Na and Mg are marginal. The Patented C-Series windows make it practical to measure light elements.

    One should measure in vacuum to take full advantage of the Patented C-series windows. Attenuation in air can be more important than attenuation in the windows for low energies. For Na Ka X-rays at 1.04 keV the attenuation length in air is only 2.2 mm: an air path of 2.2 mm will attenuate these X-rays as much as a Be window. This not only reduces the sensitivity at Na, but path length variations become very important: an additional 0.2 mm of air changes the Na Ka intensity by 10%, making accurate analysis difficult.

  • 专利 C 系列窗口是否有任何缺点? +


    Above 1.5 keV the Patented C-series windows offer slightly more attenuation (lower efficiency) than the Be windows. This difference is small for most elements. For example the C windows offer 10-15% lower efficiency than Be around 3 keV. For X-rays above 6 keV the efficiency for the two windows is nearly identical.

    The Patented C-Series windows are made from silicon nitride and coated with aluminum. The characteristic X-rays of Al, Si, and N are all observed in the spectrum. All Amptek detectors contain aluminum (e.g. the multilayer collimator is coated with aluminum) so this interference is always present. The Si interference may be a disadvantage in some applications.

    The C2 windows are not light-tight. They are intended only for use in a dark system. Operating a C2 detector in light will not damage the detector, but the photocurrent through the detector will make it impossible to detect X-rays. The C1 windows can be operated in normal ambient light.

  • 专利 C 系列窗口是否足以承受真空? +


    Yes, the Patented C-Series windows will hold vacuum. The detector hybrid has a vacuum inside, so the Patented C-series windows usually hold 1 atmosphere of pressure. Used in a vacuum chamber, the pressure across the window is actually reduced.

    One must be careful when using these detectors in vacuum systems. It is common for debris from samples or from handling to exist inside the chamber of an XRF system. When one begins to pump or breaks vacuum, the pieces of debris can fly around inside the chamber and penetrate C1 and C2 windows. Cleanliness is vital, but one must not touch the Patented C-series windows when cleaning the system.

    While best practice has typically been to allow at least two minutes to vent from vacuum to atmosphere, and that you vent to dry nitrogen (preferable) or air which has passed through desiccants and filters, we have found that reducing turbulent airflow in the chamber during venting, and locating the vent such that it doesn’t allow particulate to impact the window is most useful.

  • 专利 C 系列窗口是否可以在氦(He)气环境中使用? +


    联系我们,以便我们详细地讨论您的应用。

    标准 C1 窗口对 He 不气密。C1 窗口有一个特殊的 He 气密选件。

    C2 窗口对 He 不气密。将 C2 窗口放入 He 中将破坏探测器中的真空并使保修失效。

  • 专利 C 系列窗口是否可以同时用于高能量和低能量? +


    Yes, the Patented C-Series windows are fine for high energies. Above roughly 6 keV, they offer essentially the same sensitivity as Be windows.

  • 专利 C 系列窗口推荐用于哪些应用? +


    The C1 windows are very well suited to the ED-XRF of samples containing Na, Mg, and heavier elements, particularly when a dark environment is not possible (e.g. handheld and portable instruments).

    The ideal application for the C2 windows is SEM-EDS, also known as EDX i.e. the excitation of characteristic X-rays by electrons in an SEM. Because these electrons have a short range in the sample, they excite the X-rays very close to the surface, yielding many X-rays from all the elements down to carbon. The high efficiency of these windows at the low energies makes these detectors very useful.

    The C2 windows can certainly be used for ED-XRF from light elements, i.e. measuring characteristic X-rays produced by X-ray excitation. But the X-ray yield for light elements is low and their attenuation length in most samples is low. A powerful low energy X-ray source is required for ED-XRF of light elements.

  • 公布的衰减曲线有多精确? +


    These curves represent nominal material parameters and normal incidence. Manufacturing variations will occur, so some variation is expected. In many applications the beam of incident X-rays may not be at normal incidence. Even more commonly a range of angles are incident on the window. This will cause the path length to be longer, hence greater attenuation will occur. It is good practice to calibrate each system with known standards.


  • 钠(Na)谱图:C1 与 0.5 密耳 Be 窗口

    使用配备 C2 窗口的 Amptek SDD 在真空中采集的碳(C)谱图

    Amptek C 系列 X 射线窗口与聚合物窗口之间的比较

    Amptek C2 窗口与聚合物窗口之间的比较(0 至 2 keV)

    配备 C1、C2 和 13 µm(0.5 密耳)Be 窗口的 Amptek SDD 的频谱

    使用配备 C2 窗口和 13 µm(0.5 密耳)Be 窗口的 Amptek SDD 在真空中采集的 FLX-SP1 频谱。

    使用配备 C2 窗口和 13 µm(0.5 密耳)Be 窗口的 Amptek SDD 在真空中采集的 FLX-C2 频谱