Resumen: NEXT-MM is a general-purpose high pressure (10 bar, 25 l active volume) Xenonbased TPC, read out in charge mode with an 0:8 cm 0:8 cm-segmented 700 cm2 plane (1152 ch) of the latest microbulk-Micromegas technology. It has been recently commissioned at University of Zaragoza as part of the R&D; of the NEXT 0nbb experiment, although the experiment’s first stage is currently being built based on a SiPM/PMT-readout concept relying on electroluminescence. Around 2 million events were collected during the last months, stemming from the low energy g- rays emitted by a 241Am source when interacting with the Xenon gas (Eg = 26, 30, 59:5 keV). The localized nature of such events around atmospheric pressure, the long drift times, as well as the possibility to determine their production time from the associated a particle in coincidence, allow the extraction of primordial properties of the TPC filling gas, namely the drift velocity, diffusion and attachment coefficients. In this work we focus on the little explored combination of Xe and trimethylamine (TMA) for which, in particular, such properties are largely unknown. This gas mixture offers potential advantages over pure Xenon when aimed at Rare Event Searches, mainly 2014 JINST 9 C04015 due to its Penning characteristics, wave-length shifting properties and reduced diffusion, and it is being actively investigated by our collaboration. The chamber is currently operated at 2.7 bar, as an intermediate step towards the envisaged 10 bar. We report here its performance as well as a first implementation of the calibration procedures that have allowed the extension of the previously reported energy resolution to the whole readout plane Idioma: Inglés DOI: 10.1088/1748-0221/9/04/C04015 Año: 2014 Publicado en: Journal of Instrumentation 9, C04015 (2014), [23 pp] ISSN: 1748-0221 Factor impacto JCR: 1.399 (2014) Categ. JCR: INSTRUMENTS & INSTRUMENTATION rank: 26 / 56 = 0.464 (2014) - Q2 - T2 Financiación: info:eu-repo/grantAgreement/EC/FP7/ 240054/EU/Novel Developments in Time Projection Chambers (TPCs) for Rare Event Searches in Underground Astroparticle EXperiments/TREX Financiación: info:eu-repo/grantAgreement/ES/MICINN/CPAN-CSD2007-00042 Financiación: info:eu-repo/grantAgreement/ES/MINECO/Consolider-Ingenio-2010/CSD2008-00037 Financiación: info:eu-repo/grantAgreement/ES/MINECO-FEDER/FPA2008-03456 Financiación: info:eu-repo/grantAgreement/ES/MINECO-FEDER/FPA2011-24058 Financiación: info:eu-repo/grantAgreement/ES/MINECO/FIS2012-37947-C04 Financiación: info:eu-repo/grantAgreement/ES/MINECO/FPA2009-13697-C04-04 Tipo y forma: Artículo (PostPrint) Área (Departamento): Área Física Atóm.Molec.y Nucl. (Dpto. Física Teórica)