Nanoparticulate Coatings Enhance Ion Detection

Ionwerks, Inc., Houston TX

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Abstract

(Project Summary Changes 7/3/2023 for Equipment Supplement in bold) Ionwerks' phase II has been the catalyst by which Hamamatsu USA (Sommerville NJ) has become interested in our project and in our interaction with Rutgers University (New Brunswick NJ). In a joint meeting at Rutgers (Dec 2022) Hamamatsu made us aware of two of their new commercially released remarkable innovations: 1) A silicon based Avalanche Particle Detector (APD) which has unit sensitivity and subnanosecond pulse response to >1KeV electrons. 2) Hamamatsu's new Borosilicate MCPs coated with MgO SE emissive thin films which outperforms conventional Pb glass MCP in every way: orders of magnitude longer lifetime, higher gain --which improves with ion dose--, and a constant picosecond time response maintained at the higher gain and long lifetimes. Hamamatsu offers both for sale internationally. Addition of our Nanoparticulate thin films during our existing phase II could likely improve either of these products. However, we do not have electronics which can measure changes in picosecond pulsed timing performance and gain increase (or degradation) on the sub-nanosecond time scale. Thus the opportunity to acquire an advanced oscilloscope which would measure these parameters could not come at a more perfect time. Our previously described goals of the parent phase II application remain unaltered as follows. Ionwerks new thin film deposition technique for increasing the gain and sensitivity of existing microchannel ion detectors was proven in a previously completed NIH phase I. An increased Secondary Electron (SE) yield from these films was found to improve with ion doses of helium up to > 100 Coulombs/cm2 while the electron yield from the uncoated detector first surface decreased after 1 Coulombs/cm2. A NIH Phase II is using these films to vary elemental composition and morphology of the first surface to increase the first hit SE yield and to prolong the deposited layer lifetime. Detector testing will proceed with in-house ion and electron sources. Methods for putting these thin film coatings onto the sidewalls of the MCP (in addition to covering the front detector surface) should increase the detector gain and substantially prolong the MCP detector lifetime. We will emphasize the use of the Zeiss Orion helium ion microscope at Rutgers to perform accelerated lifetime testing of the MCP pulse height, gain and first surface secondary electron yield from individual pores. Elemental composition change in the first hit area of the microchannel pore will also be determined by Nanoscale Rutherford backscattering within the Orion and will be correlated with the lifetime and yield measurement. The combination of the Zeiss Orion helium ion microscope configured with the Ionwerks NanoRBS spectrometer should prove to be a crucial tool in detector physics. In addition the overall performance of the NanoRBS will improve when this spectrometer is retrofitted with newly enhanced MCPs combined with new APDs from this phase II effort.