The General AntiParticle Spectrometer ( GAPS ) is a balloon-borne cosmic-ray antimatter experiment that uses the exotic atom technique , eliminating the requirement for strong B-fields used by conventional magnetic spectrometers .
It will be sensitive to antideuterons with kinetic energies of 0.05-0.25 GeV / nucleon , which are highly motivated candidates for indirect dark matter detection .
Moreover , GAPS will provide new information on the antiproton spectrum from 0.07 < T < 0.25 GeV .
The GAPS design is based on a lithium drifted silicon tracker and plastic scintillator time of flight ( TOF ) system .
The latter is the focus of this contribution .

Currently , the TOF system includes an outer “ umbrella ” consisting of 132 counters covering an area of 38 m ^ { 2 } and a nearly hermetic inner “ cube ” with 64 counters and area of 15 m ^ { 2 } .
The counters will be mechanically secured to the gondola using an innovative carbon fiber structure .
Each end of the 196 counters will be read out using a silicon photomultiplier ( SiPM ) based analog front end with a high gain timing channel and low gain trigger channel .
The high gain channel is sampled and digitized with a custom readout board that uses the DRS-4 ASIC .
A local trigger monitors multiple programmable threshold levels for all 392 counter ends .
A master trigger analyzes the local trigger hit patterns and initiates a TOF read out for an interesting event .
A central computer then analyzes and estimates key observables .
This contribution summarizes the design , performance , and prototype development of the TOF system and the path going forward in 2019 and 2020 towards construction and integration of the system .