Novel heavy ion focal plane detectors

The aim of this project is to develop a novel heavy ion focal detector for magnetic spectrometers and recoil separators with high time resolution, high energy loss resolution, high energy and position resolution. It will be enabled by a “thin” detector which can provide high energy loss resolution (<1%) with high time resolution (<150 ps FWHM) and a “thick” detector which can provide total energy resolution (<1%) and finally both “thin” and “thick detector” will be 3D integrated through Cactus Materials Inc.’s low temperature (<3500C) wafer bonding technology. This technology will be transformative to instill any combination of enabling functionality or co-ordinates (i.e., energy loss, total energy, timing, position) in combination of 3D integrated bonding to develop next generation detectors in various fields of nuclear energy. Fig. 1 shows a conceptual diagram of a novel heavy ion focal plane detector. The top part is made by a thin silicon sensor, a few tens of microns thick, which has been thinned down before wafer bonding to the bottom thick high resistivity silicon substrate. At the bonding interface, a high dose ion implantation provides the bias to both substrates and can be accessed from either side by a conductive trench. Patterning on both surfaces will proceed after wafer bonding as in a standard double-sided fabrication and, allowing arbitrary shapes, can give X-Y positioning. The use of silicon allows direct detection of charged particles and optimal energy resolution. The thin upper substrate allows for good timing, well below the required 150ps FWHM. Cactus Materials, Inc. and Brookhaven National Lab will be collaborating in this project. Cactus Materials, Inc. will carry out critical work of all wafer bonding steps in a custom bond chamber at Cactus Laboratory. Dr. Islam, PI of this project, has extensive experience in wafer bonding while worked at Intel Corporation and EVG, Inc and developed low temperature wafer bonding techniques. Dr. Gabriele Giacomini, of Brookhaven National lab will co-lead effort of designing detectors and characterizing prototype by end of Phase I of the project.