GEM detector performance with innovative micro-TPC readout in high magnetic field

¹ INFN - Sezione di Ferrara - via G. Saragat 1, 44122 Ferrara, Italy
² Università di Ferrara, Dipartimento di Fisica e Scienze della Terra - via G. Saragat 1, 44122 Ferrara, Italy
³ INFN - Sezione di Torino - via P. Giuria 1, 10125 Torino, Italy
⁴ )Università di Torino - via P. Giuria 1, 10125 Torino, Italy
⁵ INFN - Laboratori Nazionale di Frascati - via E. Fermi 40, 00044 Frascati (Roma), Italy
⁶ Institute of High Energy Physics, Chinese Academy of Sciences, 19B YuquanLu, Beijing, 100049, China
⁷ INFN - Sezione di Roma, c/o Università la Sapienza, p.le Aldo Moro 2, 00185 Roma, Italy
⁸ Politecnico di Torino, Dipartimento di Elettronica e Telecomunicazioni, C.so Duca degli Abruzzi 24, 10129 Torino, Italy
⁹ INFN - Sezione di Perugia, via A. Pascoli 14, 06123 Perugia, Italy
¹⁰ Università di Perugia, Dipartimento di Fisica e Geologia, via A. Pascoli 14, 06123 Perugia, Italy
¹¹ Joint Institute for Nuclear Research (JINR), Joliot-Curie 6, Dubna, Moscow region, 141980, Russia

Published online: 10 January 2018

Abstract

Gas detector development is one of the pillars of the research in fundamental physics. Since several years, a new concept of detectors, called Micro Pattern Gas Detector (MPGD), allowed to overcome several problems related to other types of commonly used detectors, like drift chamber and micro strips detectors, reducing the rate of discharges and providing better radiation tolerance. Among the most used MPGDs are the Gas Electron Multipliers (GEMs). Invented by Sauli in 1997, nowadays GEMs have become an important reality for particle detectors in high energy physics. Commonly deployed as fast timing detectors and triggers, their fast response, high rate capability and high radiation hardness make them also suitable as tracking detectors. The readout scheme is one of the most important features in tracking technology. Analog readout based on the calculation of the center of gravity technique allows to overcome the limit imposed by digital pads, whose spatial resolution is limited by the pitch dimensions. However, the presence of high external magnetic fields can distort the electronic cloud and affect the performance. The development of the micro-TPC reconstruction method brings GEM detectors into a new prospective, improving significantly the spatial resolutionin presence of high magnetic fields. This innovative technique allows to reconstruct the 3-dimensional particle position, as Time Projection Chamber, but within a drift gap of a few millimeters. In these report, the charge centroid and micro-TPC methods are described in details. We discuss the results of several test beams performed with planar chambers in magnetic field. These results are one of the first developments of micro-TPC technique for GEM detectors, which allows to reach unprecedented performance in a high magnetic field of 1 T.