  An iron- plastic-scintillator shashlik calorimeter with a 4.3 $X_0$
longitudinal segmentation was tested in November 2016 at the CERN East Area
facility with charged particles up to 5 GeV. The performance of this detector
in terms of electron energy resolution, linearity, response to muons and hadron
showers are presented in this paper and compared with simulation. Such a
fine-grained longitudinal segmentation is achieved using a very compact light
readout system developed by the SCENTT and ENUBET Collaborations, which is
based on fiber-SiPM coupling boards embedded in the bulk of the detector. We
demonstrate that this system fulfills the requirements for neutrino physics
applications and discuss performance and additional improvements.
