Performance of a spaghetti calorimeter prototype with tungsten absorber and garnet crystal fibres

TL;DR

This study presents a prototype spaghetti calorimeter with tungsten and garnet crystal fibres tested with electron beams, achieving competitive energy and excellent time resolution suitable for high-energy physics applications.

Contribution

The paper introduces a novel spaghetti calorimeter prototype using garnet crystal fibres and tungsten absorber, demonstrating promising energy and time resolution performance.

Findings

Energy resolution around 10%/√E + 1%

Time resolution down to 18.5 ps at 5 GeV

Comparable to LHCb Shashlik technology

Abstract

A spaghetti calorimeter (SPACAL) prototype with scintillating crystal fibres was assembled and tested with electron beams of energy from 1 to 5 GeV. The prototype comprised radiation-hard Cerium-doped Gd$_3$Al$_2$Ga$_3$O$_{12}$ (GAGG:Ce) and Y$_3$Al$_5$O$_{12}$ (YAG:Ce) embedded in a pure tungsten absorber. The energy resolution was studied as a function of the incidence angle of the beam and found to be of the order of $10\% / \sqrt{E} \oplus1\%$, in line with the LHCb Shashlik technology. The time resolution was measured with metal channel dynodes photomultipliers placed in contact with the fibres or coupled via a light guide, additionally testing an optical tape to glue the components. Time resolution of a few tens of picosecond was achieved for all the energies reaching down to (18.5 $\pm$ 0.2) ps at 5 GeV.