The Tynode: A new vacuum electron multiplier

Abstract

By placing, in vacuum, a stack of transmission dynodes (tynodes) on top of a CMOS pixel chip, a single free electron detector could be made with outstanding performance in terms of spatial and time resolution. The essential object is the tynode: an ultra thin membrane, which emits, at the impact of an energetic electron on one side, a multiple of electrons at the other side. The electron yields of tynodes have been calculated by means of GEANT-4 Monte Carlo simulations, applying special lowenergy extensions. The results are in line with another simulation based on a continuous charge-diffusion model. By means of Micro Electro Mechanical System (MEMS) technology, tynodes and test samples have been realised. The secondary electron yield of several samples has been measured in three different setups. Finally, several possibilities to improve the yield are presented.

Secondary Electron Emission Materials for Transmission Dynodes in Novel Photomultipliers: A Review

“…Within the LAPPD collaboration [31], the ALD synthesized MgO is reported to have a significantly higher RSEY than Al 2 O 3 [27,28]. This is also confirmed by the recent experiments within the MEMBrane project [26]. Therefore, a systematic measurement of TSEY of ALD MgO will be the first priority of the MEMBrane project.…”

“…The TSEY of a thin homogeneous Al 2 O 3 membrane reaches a maximum of 2.5 for a thickness of 10 nm, for primary electron energy of 1200 eV [26]. The TSEY, under these conditions, is 20% lower than the RSEY.…”

“…The search for suitable materials used in dynodes for PMs started in the early 30s. Many insulating materials (summarized in Table 1 ) [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ] were found to have high SEY and were successfully employed in commercial PMs based on a reflection configuration ( Section 4.1 ). Since the 90s, diamond based materials ( Section 4.2 ) have been another extensively studied system for SEE applications.…”

“…A selection of materials without NEA activation process with RSEY (>3) [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ] have been summarized in Table 1 . The majority of the RSEY data were documented by Kenneth et al in 1948 [ 25 ] and Joy et al in 2008 [ 1 ].…”

Effect of thermal annealing and chemical treatments on secondary electron emission properties of atomic layer deposited MgO

“…10 Here, we investigate the SEE properties of ALD MgO for application in the Timed Photon Counter (TiPC), a novel photodetector which utilizes a vertical stack of ultrathin membranes (tynodes) for electron multiplication in vacuum. 11 Due to the significant reduction in size and weight of the device, as well as spatial and time resolution, TiPC will have a noteworthy role among existing photodetectors. 12 Secondary electron yield (SEY) of MgO films prepared by various techniques is reported to be in the range from 2 to 22, 13,14 whereas ALD MgO exhibits the maximum SEY of 6.9.…”