DESC0024010

We propose simulating and constructing a prototype and demonstration brassboard of a Secondary Emission Sensor Module (SESM) for ionizing radiation, as a proof of principle and guide to Phase II and beyond. The simulation and design studies will guide module construction and point to future uses. The module is anticipated to have ~30 stages of sheet dynode with an areal size ~15x15 cm. It will be tested using radio sources and cosmic rays. If successful, this project could lead to: (1) SESMs fabricated in fairly arbitrary shapes (round, square, hex, rectangular), provided that shapes that create E-fields large enough for field emission are not used; (2) SESMs fabricated in a wide variety of sizes from few mm to meters and can be tiled to make arbitrarily large and deep detector systems; (3) SESMs fabricated so that the density is 30%-40% of the density of the metal used for the SE sheet “dynodes”; (4) SEMS with time resolutions approaching ~10ps, similar to that of MCP-PMT or modern etched dynode PMT if the sheet-dynodes are closely packed together, quasi-channelized and effectively proximity focused, with higher interdynode voltages than cesiated PMT and without a large cathode-to-1st dynode distance often necessary for PMT; (5) SEMS, if sheet dynodes are individually powered, may achieve the same high counting rates that individually powered PMT achieve – Gain x BW up to 105 x 300 MHz with low hysterisis; (6) SEMS can be closely packed to make hermetic radiation sensors, such as for energetic particle calorimetry,large scale CT scanning stations or whole body PET scanners; (7) SESMs can incorporate thick absorber plates as part of the top and bottom for calorimetry so that compact stacked calorimeter or radiation sensors can be achieved; (8) SESMs can achieve GigaRad radiation damage resistance, with care in selection of parts such as brazed ceramics and metals; (9) SESMs in hermetic calorimeters, particularly calorimeters located less than 45° from the beam, can require very little services and may not need repairs, if operated with no active electronics. As an example, when individual HV and high impedence last dynode+anode signals are on twisted pair ribbon cables electric power consumption in very low, so little or no cooling is required as might be for semiconductors, photocathodes, or noble liquids, and no gas is required; (10) SESMs can be made to be rugged enough for use in harsh environments, high accelerations, and high temperatures such as might be encountered in hand-held radiation sensors, boreholes, vehicles, reactors, and other situations; (11) SESMs might be fabricated with only a 3-4 sheet dynodes if the dynodes are coated with high secondary emissive but non-cesiated materials such as diamond doped with boron with a gain of 25 per stage(see figs above) or graphene as reflection dynodes, or as free-standing transmission dynodes which would result in the best temporal resolution performance; (12) SESMs may offer superior compensation to jet calorimeters as they have increased signal for heavily ionizing particles and neutrons, compared to crystalline and plastic scintillators with larger Fano factors, and liquid and semiconductor detectors; and (13) SESMs have reduced performance in unshielded magnetic fields over 1 T and at >45° to the axis, similarly to MCP-PMT. The construction requirements for an SE Sensor Module: (1) The entire final assembly can be done in air – no oxygen or water vapor issues; (2) There are no critical controlled thin film vacuum depositions or other required vacuum activation is not necessary (although possibly desired for enhanced performance- for example diamond films); (3) Bake-out can be brief at refractory temperatures; photocathodes degrade at T>300°C; and (4) The SE module is sealed by normal vacuum techniques (welding, brazing, diffusion-bonding or other high temperature joining), with a simple final heated vacuum pump-out and tip-off. The potential and prospects for a large variety of uses in medicine, inspection, scientific instrumentation, homeland security, and frontier experiments in high energy, nuclear and cosmic particle physics are good.