Chemical method to increase extreme ultraviolet microchannel-plate quantum efficiency

Area of Science:

• Photon detection
• Microchannel plate technology
• Extreme ultraviolet optics

Background:

• Microchannel-plate (MCP) detectors are crucial for photon counting in scientific instruments.
• Enhancing quantum detection efficiency (QDE) in the extreme ultraviolet (EUV) is vital for astronomical observations.
• Current MCPs have limitations in EUV sensitivity and long-term stability.

Purpose of the Study:

• To investigate a chemical treatment method for enhancing MCP detector efficiency.
• To assess the stability and longevity of the efficiency improvement.
• To quantify the QDE increase in the EUV bandpass.

Main Methods:

• Subjecting MCP input channel plates to a specific chemical solution treatment.
• Overcoating chemically treated MCPs with opaque photocathodes of potassium bromide (KBr) and cesium iodide (CsI).
• Measuring quantum detection efficiency across various EUV wavelengths (256 Å to 1024 Å and 834 Å to 1100 Å).

Main Results:

• A twofold increase in quantum detection efficiency was achieved for MCP detector channels in the 256 Å to 1024 Å bandpass.
• The efficiency enhancement remained stable after exposure to laboratory atmosphere.
• Chemically treated MCPs with KBr and CsI photocathodes demonstrated a twofold QDE increase from 834 Å to 1100 Å compared to untreated MCPs.
• The stability of the efficiency increase was confirmed over a charge lifetime equivalent to multiyear observations.

Conclusions:

• Chemical treatment is an effective method for significantly boosting MCP detector QDE in the EUV.
• The achieved efficiency gains are robust against environmental exposure and exhibit long-term stability.
• This advancement holds promise for improving the sensitivity of future EUV astronomical instruments.