Carbon-Foil for reducing first strike issues Z. Insepov and H. Wang 2/1/2011 LAPD working group

Use of C-foil – ion, high energy particles, van de Graaff accelerator terminals, carbon foils with areal density nominally 2mg/sq.cm are often used. Diamond foils for this purpose were described by Liechtenstein et al. (1995, 1997, 1998), and M. Ivkova et al. (1995) Space physics, imaging of space plasmas, where nominally 0.5mg/sq.cm C foils are typically used. Detect time-of-flight (TOF) ion mass, energetic neutral atom, and energetic particles. McComas et al. (2004) Formvar foil (7%hydrogen, 56% carbon, and 37% oxygen) was used for Coulomb-explosion experiments, detection of recoiling nuclei; heavy ions, when traversing a thin foil within the detector, produce secondary electrons, (ANL, Physics) C-foil bolometer (liq He temp.) TEM experiment – C-foil 5 nm thick, 1 mg/cm2, (electrons can go through)

Transmittance in UV and Visible C-foil 27 nm thick - evaporated For extreme UV Detector 47% T at visible 41% T at 200 nm 1% T at 100 nm Appl Optics 1965 200 nm 100 nm

First strike issues Electrons From Photocathode For biased MCP channels, photoelectrons hitting at slightly different positions may create some timing issues such as jittering, noise,.. For unbiased channels, in addition to the timing issue, photoelectrons may go through the channel directly.

Glass MCP + ALD coated SEM layer + NiCr electrode + C-foil Glass_MCP with 8o bias angle Z. is working on incident angle, energy, simulation with 1KeV electron MCP with C-foil

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ACF-Metals Carbon, arc evaporated, e-beam evaporated, C-foil on mica 2-100 nm thick, 2 mg/cm2 and up C-foil over TEM grid 10-100 nm thick Polycrystalline graphite, 2-100 mm thick, 400-20,000 mg/cm2 Another possible enhancement is to coat C-foil with a thin UNCD diamond layer to enhance the SEM property