  We discuss the operational principle and performance of new micro-pattern
gaseous detectors based on the multi-layer Thick Gaseous Electron Multiplier
(M-THGEM) concept coupled to a needle-like anode. The new gas avalanche
structure aims at high-gain operation in nuclear physics and nuclear
astrophysics applications with radioactive isotope beams. It is thereafter
named TIP-HOLE gas amplifier, and consists of a THGEM or a two-layers M-THGEM
mounted in a WELL configuration. The avalanche electrodes are collected by thin
conductive needles (with up to a few ten um radius and a height of 100 um),
located at the center of the hole and acting as point-like anode. The bottom
area of the needle may be surrounded by a cylindrical cathode strip in order to
increase the electron collection efficiency. The electric field lines from the
drift region above the M-THGEM are focused into the holes, and then forced to
converge on the needle tip. An extremely high field is reached at the top of
the needle, creating a point-like avalanche process. Stable, high-gain
operations in a wide range of pressures may be achieved at relatively low
operational voltage, even in pure quencher gas at atmospheric pressure (e.g.
pure isobutene). The TIP-HOLE structure may be produced by the innovative
scalable additive manufacturing technology for large-area, multiple-layer
printed circuit boards, recently developed by the UHV technology company (USA)
and discussed for the first time in this work.
